Battery To Battery Charger – Sterling Power BB1260 Review

Last Updated: June 24, 2021

Battery To Battery Charger – Sterling Power BB1260 Review


The Sterling Power BB1260 battery to battery charger (aka “DC-to-DC” or “B2B”) plays a major role in keeping our camper van electrical system balanced and healthy. How’s that? The battery to battery charger uses the van alternator power to charge our house (auxiliary) battery while we drive. It’s an install-and-forget device: it turns itself ON/OFF automatically when driving the van, doing its things without user intervention. Neat! It means that we don’t have to worry about running out of power, AND the house battery lifespan is maximized. Sounds too good? Keep reading this review as we get into more details…


Battery to battery charger Sterling Power BB1260


How does the Sterling Power battery to battery charger work?

The Sterling Power battery to battery charger is installed “between” the van battery and the house battery (more installation details further in this article). There is no switch or button to initiate the charge! You see, when you start your vehicle, the alternator kicks-in and raises the voltage of the van battery in order to charge it. The B2B charger senses the higher voltage and turns itself ON automatically. Now when you turn your vehicle OFF, the alternator stops and the voltage of the van battery drops; the B2B charger senses the dropped voltage and turns itself OFF. All of that happens without user intervention (well, except the part where you drive your vehicle!).


What are the benefits of a battery to battery charger?

Each type of battery (Gel, AGM, Lithium, etc.) requires a specific charging profile (bulk, absorption, float). Charging with the wrong profile might result in:

  • Incomplete charge (cannot reach 100%);
  • Reduced lifespan (waste of $);
  • Sulfuration (reduced total capacity) of Lead Acid batteries (AGM).

If a lead acid battery doesn’t get a proper multi-stage charge (bulk, absorption, float), it loses its total capacity and that’s non-reversible (knowledge is power: we recommend reading the Charging Profile section of our Electrical System page to really understand what that means). Bad charge = wasted money (the battery has to be replaced more often), so we think the B2B charger pretty much pays for itself in the long run.


Battery to battery charger vs Isolator: what’s the difference?

  • A B2B charger provides the adequate charge profile to the house battery (see paragraph above for benefits); in other words, it charges and keeps the battery in good health in the long term.
  • An isolator is simply an automatic “switch” that connects and disconnects the house battery to the starter battery. An isolator does NOT provide an adequate charge profile (bulk, absorption, float), and, therefore, might not be able to charge the house battery to 100%, might reduce its lifespan or reduce its total capacity. The only real advantage of an isolator is that it’s cheaper upfront (but not in the long term as you might have to change your house battery more frequently).


Are solar power AND alternator power (battery to battery charger) both needed?

Solar Panels Installation

Here’s what we think about that:

  • If you live full time in your van, we say a B2B charger is a must. Energy is a basic need, it’s not cool worrying about running out of it…
  • If you take your van for adventures in summer only, you can probably live without it as solar can provide the bulk + absorption charge on its own.
  • For fall and spring adventures, we highly recommend it as the solar days get shorter and weaker. Alternator power is a good way to quickly go through the bulk charge, then solar power can complete the absorption stage.
  • For winter there’s no question about it, our opinion is that you want it. The sun angle is too low, the solar day is too short and overcast weather is more common (for USA and Canada at least).


What we Like…

  • Surprisingly easy to install (scroll down for installation write-up).
  • Install-and-Forget!
  • Fast Charge.
  • Provides a nice multi-stage charge that keeps the battery (Gel, AGM, Lithium, etc.) healthy in the long run.


What we Don’t Like …

  • The internal cooling fan is quite noisy; think of a tiny hair dryer. If possible, install the Sterling charger further back away from driver/passenger seats to minimize the noise.


Models & Where to Buy

There are a few variants of the Sterling Power Battery to Battery charger, so make sure to select the appropriate one according to:

  1. Input voltage (most likely 12V…)
  2. Output voltage (most likely 12V…)
  3. Input current (30A, 60A or 120A).

It basically comes down to either BB1230 (Input: 12V, 30A. Output: 12V, 22A), BB1260 (Input: 12V, 60A. Output: 12V, 45A) or BBW12120 (Input: 12V, 120A. Output: 12V, 90A). We highly recommend the BB1260 for a faster charge (so a short drive goes a long way 🙂 ), unless of course 60A is over the maximum current recommended for your battery.

Sterling Power bb1230 battery to battery charger
Sterling Power BB1230 battery to battery charger. Buy from Amazon.
Sterling Power bb1260 battery to battery charger
Sterling Power BB1260 battery to battery charger. Buy from Amazon.
Sterling Power BBW12120 battery to battery charger
Sterling Power BBW12120* battery to battery charger. Buy from Amazon.

*But before selecting the BBw12120, please consider the following:

  1. Batteries generally have recommended and maximum charge current. Going overboard is a waste of space (this charger is bigger) and money.
    • Check your battery manual or data sheet to find out.
  2. Make sure your alternator can handle that much current so that you’re not draining your van battery.
    • For example there are two alternator options on the Ford Transit: basic (150A) and Heavy-Duty (230A). It is believed (not official info) the Transit needs roughly 70A for itself (lights, radio, etc.), so we’re left with 80A extra current with the basic alternator and 160A extra current with the Heavy-Duty alternator. If you have the basic 150A alternator (80A extra current) and you’re charging your house battery at 120A, it probably means you are “borrowing” that extra power from the van battery…
  3. Overworking an alternator might reduce its lifespan.
  4. The BBW12120 has, according to Sterling Power, reduced cooling capacities due to the fact that it’s waterproof. Therefore it’s not ideal to install that in a van. Instead, they recommend installing two BB1260 in parallel to get a higher output.



Sterling Power recommends to use the following breaker/fuse size:


Installing the Sterling BB1260 battery to battery charger

First of all, as always, make sure to read the manual (choose the latest version). The manufacturer knows their product better than anyone else.



Make sure to install the B2B charger in a well vented space, and do not obstruct the hot air exhaust:



Wiring and Electrical

It’s honestly quite simple. Here are the required connections:

  1. Positive Input (From vehicle battery)
  2. Positive Output (To house battery)
  3. Negative (Common to vehicle and house battery)
  4. Optional Temperature Sensor (Recommended for lead acid batteries (AGM), but not for Lithium. Connects to house battery negative post. This is to correct the voltage according to temperature change)



Follow this wiring diagram ( to make sure your B2B charger works as it’s intended to. The wiring diagram had a built-in calculator for fuses/breakers, wire gauge, and wire length/terminal count. Pretty neat!

Download this wiring diagram:


Ford Transit Connection:


This official Ford SVE Bulletin shows how to connect to POSITIVE for the SINGLE or DOUBLE battery variant: SVE Bulletin Q-226 (.pdf):

Ford Transit Accessing Battery Power
Ford SVE Bulletin Q-226 (pdf file)


Connect to one of the recommended ground points provided in the BEMM (we personally used the ground point between the driver & passenger seat):Ground-Point-Ford-Transit-Passenger-Driver-seat



Ford Transit with twin batteries configuration, year 2020 & up:

Since 2020, the Transit with dual batteries configuration comes with two (2) CCP (Customer Connection Point) located on the driver seat pedestal (on the door side). The CCP2 is rated for up to 175A, so it’s an ideal connection point (positive) for a B2B since there is no need to remove the seat:

Ford Transit 2020 Twin Batteries CCP#2 location (175A).
Here is an example on how to connect a B2B to the CCP2. Thanks to Chuck on our Facebook group for the photo. Note how the breaker (positive) is isolated from the pedestal (negative) with a piece of wood (non-conductor). Personally, we’d build a small enclosure out of non-conductor material (wood, plastic) for the breaker to completely eliminate the risk of accidental short circuit between the positive (terminals on the breaker) and the negative (seat pedestal).


Mercedes Sprinter Connection:

Please check the Mercedes Sprinter “Body And Equipment Guideline” on how to use the battery power (alternator):

Sprinter Power Tapping Option 2 (page 1)


Default Options

Here are the factory options for the Sterling BB1260 Charger:

  • MODE: 1
    • (Mode 2 is identical to mode 1, except it needs a live signal on the ignition feed input in order to charge)
  • ACTIVATION VOLTAGE: vehicle battery above 13.2v (for 5 seconds)
  • TURN-OFF VOLTAGE: vehicle battery below 13.2V
  • TURN-OFF TIMER: 240 seconds
    • (A timer is required to complement the regenerative braking aspect of modern Euro 5 / 6 + engines – where the alternator’s voltage can drop below 13V for a short period of time)
    • Because our Ford Transit 2016 does not have regenerative braking, we changed the turn-off timer to 30 seconds (procedure in manual). This prevents draining the van battery, especially when running errands (multiple short drives).


First Time Use

The unit will enter “config” mode at first startup; this is your opportunity to change the charging profile according to your battery type.

  • The configuration can be changed later, check the manual.
  • To find out which charging profile to select, check your battery manual.


First Time Use Configuration Sequence:

  1. To initiate the first startup, turn on the vehicle and wait a few seconds. To indicate the battery to battery charger has turned ON, LEDs will light up, a beep will sound, and the fan will run for 5 seconds. If none of that happens, try to “force-start” the unit: simply press and hold SETUP/ENTER for 5-9 seconds.
  2. At this point, an LED is flashing to indicate the battery type (default = lead acid).
  3. To change the battery type, press and hold SETUP/ENTER buttons for 10-12 seconds (up to 20 seconds); all LEDs are now flashing.
  4. Scroll down (SELECT button) or up (ENTER button) to select your battery type; Press and hold SETUP/ENTER buttons for 2-3 seconds to confirm the selection.
  5. At this point, the B2B charger will restart.
  6. If you have a battery monitor, such as the Victron (, you can observe that the B2B is charging the house battery…
  7. That’s it! Go for a ride!


To change the configuration later or for advanced options, check the manual.



Once the installation and initial setup completed, just drive and let the Sterling Power battery to battery charger do its thing!



We installed the Sterling Power BB1260 battery to battery charger in October 2018; so far so good! We will keep you updated if anything happens! Subscribe to our Mailing List to be notified.





New for 2019, Renogy is now offering a DC to DC charger (B2B). We haven’t tested it ourselves, but Renogy is known for their good, reasonably priced products, so it’s most likely a safe buy. That being said, READ THIS BEFORE BUYING:

  • The Renogy B2B starts the charge when the ignition is set to “ON”, even if the engine is not running. Consequently, you could drain your starter battery (when listening to music, for example). For this reason, we would personally stay away from it.
  • The Renogy B2B requires a connection to the ignition signal of the vehicle, making the installation a bit more complicated than with the Sterling Power.
Renogy 40A DC to DC Battery Charger 20A
Renogy DC to DC Battery Charger 20A. Buy on Amazon.
Renogy 40A DC to DC Battery Charger 40A
Renogy DC to DC Battery Charger 40A. Buy on Amazon.
Renogy DC to DC 60A Alternator Charger
Renogy DC to DC Battery Charger 60A. Buy on Amazon.


Renogy also released the DCC50S which combines a DC to DC charger & Solar (MPPT) charger. As opposed to the Renogy B2B charger above, this model starts the charge based on the starter battery voltage (so it won’t drain your battery when your engine is not running, that’s better). Looks like a sweet product, but be aware of the limitations:

  • Maximum alternator charging current: 25A
  • Maximum solar charging current: 25A
  • Maximum solar voltage: 25V (so if using multiple panels, series connection is not possible)
Renogy DCC50S Alternator and MPPT Charger
Renogy DCC50S Alternator & Solar Charger. Buy on Amazon.


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About us



Hello! We’re Isabelle and Antoine 🙂 In 2017, we sold our house (and everything in it), quit our engineering careers, and moved into our self-built campervan. We’ve been on the road since then, and every day is an opportunity for a new adventure; we’re chasing our dreams, and hopefully it inspires others to do the same!

102 thoughts on “Battery To Battery Charger – Sterling Power BB1260 Review”

  1. Hey Antoine! Got my B2B all installed and of course i took the short cut and attached the ground to a hole in the chassis… The B2B is struggling and i believe that’s part of the reason why =\
    I am no inspecting the ground point between the seats that you recommend and I am surprised to the that the ground point is painted… Am I looking at the wrong point (it seems to be in the same place as on your picture, closer to the passenger seat) or will this ground point work well even though it’s painted?
    Thanks so much!

    • Yeah, it’s super important to use a recommended grounding point (close to the van’s battery), especially when a lot of current goes through that connection. I think the floor was also painted and there were already wires connected to that ground, if that can help you pinpoint it.

  2. Hello

    On a 2020 sprinter, I want to install this bb1260, but I need to know if I need to use the same battery as the vans stock batterys? I have 2- 200ah renogy 12v that I am using for my battery bank and want to tap in to the system and have it charge from the alternator.

  3. Interesting, however i cant follow the articles expectations regarding alternator output in relation to systems demands, and a 150amp alt doesnt output 150amps, in fact closer to 50% of that would be considered max continuous output according to various experts.

  4. My Sterling went dead !!

    My little experience with Sterling’s BB1260.

    We’ve done 70,000 in 18 months with our Promaster 2500. So that’s a lot of starting and stopping, a lot of short distance and longer. Two weeks ago an alarm sounded. The Sterling was going into overheat mode !!! Little panic on board, I didn’t want it to catch fire, there was a little smell of overheating plastic !! ‘The breaker recommended by Antoine had its use. I managed to stop everything !!

    After diagnosis, the two (2) ventilators no longer work. They do not start at any time. Neither when the charger is started, nor when the thermostat calls for ventilation. Caput! After some discussion with STERLING and my reseller here in Quebec – “Volts Énergie”. The charger will be replaced tomorrow (swap) under warranty. ! Good service and a good 24 month warranty.

    Now I am wondering if I will keep the charger running continuously. Like Antoine, I think I’ll close it during the summer and in hot weather. For the moment, since it is shot my batteries hold the charge only with the solar (315w) for 3 lithium BattleBorn. There is no shortage of electricity…..

      • I know, I know I have so much confidence in this charger. Well built and solid. An electronic glitch. On the other hand, like you I will keep it closed when the use is not necessary, it will prolong its life. Besides, I would take your opinion on it!

        I have three options I don’t know which is the best.

        A) my 100A “breaker” (positive cable) is located under the floor of the promaster. Eurk! Opening, closing the hatch to turn ON or OFF is not friendly and moving the “breaker” out of the hatch does not excite me at all because of the “positive cable” near the driver seat in the environment.

        B) Or The STERLING is turned off / on by pressing the two buttons between 5 and 10 seconds, but the LEDs remain on continuously eurk.

        C) Or I am using my Victron BMV712 connected to STERLING via the BMS port (2). Especially in winter while waiting for the batteries to heat up. There is therefore 0V sent to the batteries, the sterling is like in STANDBY mode but it is in full working and not switched off. I wrote an article on it.

        The “KILL” switch might be the best option, I’ll keep thinking about it. !

        • reply to myself ! Okay finally, after a few tests. the best option is to use the charger on / off function. the LEDs eventually go out after a while, so no glowing at night. When the vehicle is started up, the LEDs light up to indicate that the device is off !! it’s perfect for us.

  5. Hi guys, my Sterling B2B1260 has been sitting uninstalled in my van for months. With a week of rain in the forecast, I need to tackle this. One thing I do not understand is the ‘common’ ground. Your diagram shows running the negative from the Sterling to the Negative bus bar and that’s least from what I can tell. But your instructions also mention finding a grounding point on the van chassis. I’m not sure what I should do I run two negative lines? One to the house battery and the other to the chassis?

    Thank you

    • The common ground is achieved as follow:
      1) B2B connected to the negative bus bar;
      2) Battery bank connected to the negative bus bar;
      3) Negative bus bar connected to the van grounding point.

      I think you got 1) and 2); 3) is where it says “see tutorial” (with ground symbol) on the diagram.

      Make sense?

      • Just curious here, because Sterling’s wiring diagram for common ground is different from yours. Sterling simply shows:

        1) B2B negative to Starter Battery
        2) Starter battery common ground negative to House battery bank negative

        and it says in bold “Important Negatives should all be common. DON’T USE CHASSIS. We recommend joining the BB’s neg. to the starter battery negative for improved efficiency”


  6. I notice in your wiring diagram that you only have the positive cable running from the starter battery to the b2b charger. Is this a difference between the Sterling and the Renogy (i.e. perhaps the neg terminals on the Sterling are connected)? The Renogy manual states the need for a negative cable to the input side of the device. The Renogy manuals seem to be wrong so often and there technical support folks never get back to me, so I’m wanting to double check the need for adding this run of cable.

  7. Hi guys! Do you run your battery to battery charger all of the time? I installed mine and have the fuse breaker open most of the time and close it when the battery needs to be topped off. Just curious what your thinking is on this.

    If you had a 150a alternator would you still occasionally run the charger and eventually upgrade to the 250a alternator or just upgrade to the 250a and bite the bullet?

    Thanks I’m advance!

    • We leave our B2B at ON all autumn/winter/spring, but we turn it OFF in summer (because solar alone is enough, unless when weather is bad for a few days consecutively). In short, there is no need to turn it OFF in between charges, expect for very long period.

      I think the 150A can handle the 60A B2B; I would leave it as is I think…

  8. Probably an obvious answer (making this a dumb question), but can I put a switch on the positive lead before the Sterling 1230, allowing me to turn it off when there is plenty of sun or shore power? Or will breaking the circuit with a switch reset the Sterling to default settings?

    • The overcurrent devices we recommend in our wiring diagram ( are BREAKER/SWITCH, so they can be used as switch (no need for extra switch like you propose). In summer, we turn off our B2B (like you said) because it’s not needed most of the time (except when bad weather lasts for a few days). It does NOT erase the B2B settings.

  9. Would you feel comfortable installing a 60A B2B on a stock (i.e. no aftermarket loads on the alternator other than said B2B) Transit with the basic 150A alternator? It sounds like it has the capacity, but perhaps with limited margin. Perhaps running that close to the limits can have a deleterious effect on the alternator reliability?

  10. If I recall correctly, you have a lithium ion battery bank. Why is it that you recommend connecting the temperature sensor for voltage compensation? From my experience in setting up my victron components, temperature compensation is not required nor recommended for lithium banks. I had connected mine originally not knowing any better (I have a battleborn lithium bank), but am planning to disconnect it unless there is something that I’m missing?

    Thanks for all the great posts!

    • Oups, you are correct!
      I just updated the article: “Optional Temperature Sensor (Recommended for lead acid batteries (AGM), but not for Lithium. To house battery negative post. This is to correct the voltage according to temperature change)”

      Sorry for the confusion,

  11. Two days ago I spent forever going in circles with Renology tech customer service. I was told by two different techs that you could not connect one of their dc-dc chargers to your battery while the solar controller was also connected and charging without damaging your battery. They said you can not have two chargers connected. I was told to use an isolator or use the 50s charger, which I had already found reviews complaining of exactly what you pointed out above about the 25a limitation. Can you clarify?

  12. For the Renogy unit, has anyone tried to connect the D+ wire to a toggle switch that turns the unit on/off so as to control the Renogy charging manually? The idea of a combine MPPT and DC charging is a simple and easy approach with limitations of course as stated. Be great if we can confirm it’s actual successful application. Thanks.

  13. Hey Guys!

    Thanks for all your pictures and explanations!! Why did you pick the Sterling over one of various Victron Energy Orion-Tr Smart B2B chargers? Have read a few reviews of people having probs with Sterling and much of your system already has Victron components. Thank you again for your time a response. Hope to see you out there in the POW!


    • Victron Orion-Tr Smart can charge up to 30A ( and we felt it wasn’t enough for us. Victron makes good products, so if 30A is enough of you, go for it 🙂
      Note: Wiring two Orion-Tr Smart in parallel would give you 60A. We simply didn’t have the space for it as the B2B was added couple years after the van conversion was finished.

    • Fuse block terminals are not meant have multiple terminal connectors and support high current. For safety reasons, it’s better to use bus bars that can support the current of the whole system.

  14. Thank you for describing when and why a B2B is a good addition to a solar system. What about the other way around? If you have a B2B, when and why do you need solar panels? Also, thanks for sharing all this info. You guys are awesome!

      • Thank you for the quick reply! I was trying to find my way back to this comment and I ran into the absorption discussion, so by the time I got here I had answered my own question. Have fun in Mexico, and enjoy the warm weather! Btw, put my downpayment down today on my first van. Wish me luck!

  15. I’ve had a Sterling B2B 1260 installed in my van for a year and I’m looking for folks with experience with the same unit. My unit is installed as recommended, 270A alternator, plenty of ventilation and I have always observed the unit will reach the 185*F max temperature of the heat sinks and de-rate from the 45A output to (1/2 power) 30A output until cooling to 170*F, then increasing back to full output. This cycle will repeat, depending on ambient temp, up to a 50/50 duty cycle. I have observed this behavior with ambient temps as low as 45*F. The fans are running at 100% speed and continuous. My question is, are other users of the exact unit observing this same behavior? I’m just trying to access if I have a defective unit or is this normal. I have reached out to Sterling Power with no response.

  16. Hello , Thanks for the great info. I have a Ford Transit 2020 with two batteries and I am looking to use the CCP. Can you tell us what the other end of the ground cable is attached to? I can see the one end is attached to the chassis ground behind and to the right of the hand break. What is the other end of that cable attached to. Also, it is not seem to be represented on your wiring diagram.
    Thanks for the help

      • Thank you for the reply. OK, I took a second look. That 12 foot 2/0 AWG cable is running the length of the van and attaching behind and to the right of the hand break? Could it be grounded closer to the negative bus bar in the rear of the van? Any Specific reason to ground 12 feet away?

        • As stated in the Tutorial page 4, modern vehicles have finicky electronics and it is recommended to follow OEM recommendations. For the Transit, the BEMM recommends specific grounding points; and on top of that, for high-current devices, it is recommended to ground as close to the battery as possible. That’s why we run our ground cable all the way to the front (between passenger/driver seat)! 🙂

          • The passenger cab grounding point is closest to the CCP as a tiny imaginary crow flies, but isn’t the 10+ feet back to the front from a electrical cabinet in the back the distance that matters? Or are there other factors involved that I don’t understand?

  17. Antoine,
    I have a 2015 Ford Transit and recently purchased your Standard wiring diagram and tutorial. I am confused on how to connect my Sterling BB1260. Per your diagram, I have run a 4 AWG wire from the Sterling negative to my negative bus bar. In your review/installation article of the BB1260, you also grounded the negative at the ground point between the driver and passenger seat….here is my question. Where does the other end of the ground wire that is grounded between the two seats originate? Is it at the house battery or the negative bus bar? Also, is 4 AWG wire adequate for this run of about 13 feet?

    Thank you.

    • The other end is connected to the negative bus bar. On the diagram, this is the wire that goes from the negative bus bar to the ground symbol.
      4AWG should be alright for 13 feet.


  18. Hey there,

    SO thankful for everything you have compiled on this site. Amazing resource. So many rabbit-holes!

    One question I have regarding installing the Sterling B2B Charger. Seems likely many people place the first breaker coming of the starter battery terminal on the front seat pedestal. Is there a reason it should be installed close to the starter battery rather than running the positive wire to, say an electrical closet, and installing both the pre- and post- B2B breakers in a convenient location? Rather than having a breaker sitting on the pedestal? Hope this doesn’t betray my complete lack of any real technical knowledge on DC wiring!

    Thanks again!

  19. I purchased the Sterling b2b 1260 but had a question about the negative connection. It looks like you connected the neg to the ground screw between the driver and passenger seat. Your wiring diagram shows connecting ground wire to neg bus bar. The instructions that came with b2b specifically says not to connect neg to chassis and to connect to starter battery. I’m a little confused. Any help would be appreciated. Thanks!

    • The ground chassis would be any metallic surface on the van’s structure; that can work but that’s not recommended. The ground point we used (between the seats) is a ground point recommended by the manufacturer (See BEMM).

      • To follow up on Ryan’s question, in the manual they connect the negative terminal of the house batteries to the negative terminal of the starter battery and then run a negative cable from the negative terminal of the starting battery to the “NEG-” terminal of the battery charger. The manual also states, “The reason to not use CHASSIS ground is that the conductivity is poor. This shall result in worsened performance. Output voltage shall climb at a slower rate. Charging rate shall be slower. Please use direct cable for best performance.”

        However, your diagram skips all that and just has the “NEG-” terminal of the battery charger connected to the ground point via the bus bar. Your way seems easier and I was planning on doing the same, but am somewhat reluctant to not follow the manual. Have you noticed any of the “worsened performance” or slower charging the manual mentions? Thanks!

        • In the case of the Ford Transit, the BEMM specifically says NOT TO connect to the negative post of the battery, and instead recommend a few other connection points (referred as “ground” point). We chose the ground point nearest to the battery.

          I believe Sterling recommend not to choose a random ground point on the chassis (e.g. like drilling a hole anywhere and use this); we agree with that recommendation.

  20. Thanks for the great information!

    Quick question: On your electrical diagram, you guys have 100amp breakers sandwiching the input and output of this. Do you need those since the b2b charger already limits amps?

    • These are the “fuses” recommended by Sterling. Remember, fuses/breakers are installed to protect the wires in case something goes wrong.

  21. Your link to purchase Sterling BB1260 on Amazon has been re-directed to Bb1230.
    Question: I want you to get the credit of my purchase of the BB1260 product. Can you confirm link?

  22. Thanks for the information.
    I will have dual alternators on the Ford Transit that I recently ordered.
    To charge the house batteries I would like to charge them with the second alternator and not do a Battery to Battery charge. What would I need to do this?

    • Not a fan of the Battle Born BIM. To reduce the workload on the alternator, it’s programmed to cycle as follows:
      – ON for 15 minutes (at full workload which is rough on the alternator).
      – OFF for 20 minutes.
      – and so on.

      So it’s ON 42% of the time. Let’s say it charges at a rated of 100A (if you have a HD alternator) you get 42A on average, which is less than the Sterling B2B. And you don’t get a nice charge profile with it. The wiring is also more complicated (you have to hook it to the ignition). So personally I would stick with the Sterling!

  23. Hey Guys, I have the Sterling BB1260, Victron 100/30 and 2×100 BattleBorn. First stage of my build, I connected my solar and all was good, solar charged my batteries great and used for a few trips. Secondly, I disconnected the solar hookup when I connect up the BB1260 and it has worked good for a few trips. Right now Im running only BB1260 for charging and have not connected solar and BB1260 at same time. My question is, are there any conflicting issues when connecting both units at same time?

  24. Hello Antoine,
    Thank you for the great content!

    I am installing a BB1230 and following the recommend cable size for the current required for the 30A model. As recommended I am running the ground back to the house battery terminal creating a total length of 27ft of wire (Positive, Negative and Ground at 9ft each).

    Was this your thought process for sizing your wire’s gauge?


  25. Hello:
    When you installed your Sterling B2B battery charger you say you reduced the after engine shut off B2B timer to 30 seconds to avoid discharge of the engine battery.
    I wish to do the same.
    Question: Why did you choose 30 seconds rather than 15 sec or some other low number? Was there a specific reason to pick 30 seconds?
    Thanks so much. Stay well & happy.

  26. Hi, excuse my ignorance about things electrical, but is it possible with this to use the house batteries to “jump” the vehicle starter battery if necessary?

  27. A piece of feedback about the Renogy B2B units, since you mention them and this website has significant readership:

    The Renogy units are NOT activated by voltage sensing. In other words, they do not automatically turn on or off based on the voltage from the alternator. They have an input that turns them on and off instead. So, you need to connect 1 additional wire to something like the ignition switch, to tell it when to turn on. And, because they are not voltage detecting, they will charge your house battery off the starter battery if this input is high, even if the engine isn’t running. So you need to be extra careful, and you could drain your starter battery if you did something like leave the ignition switch on to listen to the radio. You also could have a charging load on your starter battery when trying to start the vehicle, which is not ideal.

    In my opinion, these downsides make the Renogy unit a significantly less appealing option than Sterling, Ctek, or Victron.

    • Good info, Kyle.
      I’ve updated the page to reflect that. “The Renogy B2B starts the charge when the ignition is set to “ON”, even if the engine is not running. Consequently, you could drain your starter battery (when listening to music, for example). For this reason, we would personally stay away from it.”

      Thanks for your input!

  28. Hi Antoine,

    FYI, I have 2 x 100Ah Battleborn and the higher output BBW12120 (120 Amp) charger.

    You mention concerns about overcharging your battery bank, and you are right that folks think about that.

    But if you buy the remote with this device, you can define the “Current Limit” from 100% down to 30%, which gives you a scalable solution, even if you are starting with 1 x 100Ah battery.

    For the record, I leave mine at 100%, and have never seen more than 92 Amps going into the sytem, which is in line with the recommended charging rate (0.5c = 100Amps on a 200Amp bank). For the recored, 92 amps occurred when I was at about 50% DOD. I never really get below that. I might get more amps from the 12120, if my DOD was below 50%, or if — as you suggest – I chained two BB1260s.

    Note: I have the HD alternator (230Amps) and similar daily amp usage as you.

    Just thought I’d share.


    • Pour le Transit (et la plupart des van similaires), la (les) batteries sont sous le siège conducteur. De plus, il serait mieux de l’installer à l’intérieur ca c’est pour ça qu’il est conçu (pas 100% waterproof).

      Au plaisir.

  29. Thank you for all your information on one site.
    I like the Sterling setup other than the noise of the fan (have not made purchase yet).
    So I am researching for alternative and have found Victron’s Orion TR Smart DC-DC 12/12/30.
    Realize this is only 30 amp but my system is simple.
    Any thoughts on the Orion vs Sterling.?

    • I haven’t tried/tested the Victron myself, but I’d trust Victron. As you mentioned, they only downside I see with the Victron (looking at the specs) is it’s only 30 amps. But if you can live with it, it’s all good!

    • Mark, you can parallel the Orions to get 30 or 60 or 90 etc. charge amps. They say an unlimited amount. Of course that makes the cost a major consideration but it can be done.

  30. I’ve liked using the Sterling B2B charger with Lithium Batteries in a truck camper and travel trailer. As a result, I have delayed indefinitely the install of roof mounted solar. I can go 3 to 5 days on my battery without a charge and that’s about as long as I’m going to be in a spot before driving again. Normally, I’m driving more frequently and because the B2B tops the battery off quickly, it’s be a great solution.

    • If you have the dual batteries, there’s an auxiliary terminal available; it’s easier than wiring 2 CCP connections in parallel (each CCP is 60A, i’d be worried of using only one). But both solutions work, so feel free to use the one you like better!

  31. Hello faroutride/Antoine,

    Thank you for your wonderful writeup and we’re glad our unit has impressed you and worked to your needs perfectly.

    I should note, however, that we typically aren’t comfortable recommending people to fit a BBW12120 inside vans as it is a waterproof product. Waterproof products are obviously very sealed and thus the cooling can be more difficult. Inside of a van where there is, I believe it is fair to say, normally not perfect ventilation or cooling the fact that it is waterproof ends up being a detriment as it may be prone to overheating or losing efficiency. Only fit waterproof products in areas where you do need the unit to be waterproof. It’s not a cool extra feature, it’s a product to fulfil a purpose.

    If you do need to reach closer to 120A rather than just 60, running two BBs, either a BB1230 and a BB1260 or two BB1260s, in parallel will give you the higher A output.

    Thank you again,

  32. Thanks for taking the time in sharing your product review

    I understand an alternator on its own will only charge to 80%, is this the same for the VSR?

    I understand the B2B will charge to 100%. Is that correct? Thats the selling point right there. Making use of a potential 20% loss. I mean in terms as a generic summary, using a run of the mill leisure battery and start battery you only ever get to use between a range of 50%-80%. So with multiple batteries, thats a loss of 20% per battery within your power bank.

    I do however, acknowledge with newer technology allows us to use 100%, but comes at a premium.

    So if my R&D serves me well, then this would be the best solution above the rest.

    I have a calcium 5000 Yuasa 100ah battery as starter, and two Banner 100ah leisure batteries.

    I plan to live in it full time, and am a gamer an a bit of a film buff. Of course this is when I am not driving, travelling and taking my family away and enjoying the beautiful world around us.

    I wish you well in your endeavours.



    • A B2B charger is programmable to deliver the appropriate charge profile (bulk, absorption, float: current VS voltage) according to your specific battery chemistry (Lead Acid, AGM, Lithium, etc). While a relay doesn’t have the ability to do charge profiles.

      At the end of the day, the result seems identical: your battery is charged. But with the B2B charger you’re taking care of your battery and it’ll last much longer. More info here:

      Hope that makes sense!

  33. I purchased your wiring diagram and have found it to be very helpful. Two quick questions regarding the sterling B2B charger- your diagram called for common wire running to the negative terminal on the starting battery- the fitting on that battery does not accommodate additional cables so can I run that cable to a factory installed ground point on the vehicle instead? Also, the sterling manual called for 100 amp fuses on either side of the charger, but the diagram that you guys provided calls for 70 amp (I bought the 60 amp sterling charger you specified). Please let me know. Thank you!

    • 1- Yep, we used the ground point between the driver/passenger seat.
      2- The manual was recently updated to a 100A fuse (it used to be 70A); so yeah go for 100A (but we personally don’t have a 100A and it works fine).


  34. When you connected to the starter battery did you go through the CCP and if so did you only need one since they are rated with a 60A fuse themselves, also I see your using 4AWG wire which seems a bit large for the small CCP terminals. Or did you go straight to the battery positive post. I only have a single starter battery and the 150A alt so as per the bulletin you posted if i go to the pos post I would need another terminal but there is no part number only for additional CCPs. Unfortunately my local Ford dealer technicians won’t answer my questions.
    One last thing, I have 3 100ah BattleBorn batts with 600w of panels all in my 2018 Transit. Would you suggest the 60a or 30a B2B?

  35. Hi,

    Thanks for all the info and wiring diagram. I am reading that the recommended charging rate for AGM batteries is 20% of the capacity (0.2C). I have a 200 AH AGM battery and would like to get the 1260 with 60A of charging but that is 0.3C. Did you have any issues charging your 220 AH AGM with the 60A Sterling? Should I get the 1230 or 1260? THANKS.

  36. Hi, DO you know anywhere it is documented on how to attach to the vehicle battery? Also what size lugs are needed?

    You mention 70amp breakers, whereas the sterling manual mentions 100amp fuse? Any reason for using 30 amp less?


    • Considering that the Single Heavy Duty alternator (230A) can run the BBW12120, I’m sure the dual alternators (250A) will be able to handle it as well! 🙂

  37. Hello! This might sound like a silly question, but I noticed from your wiring diagram that the negative bus bar is connected both to the sterling AND the alternator. why is that?

    • – An isolator put your house battery in parallel with your van battery. As a result, the house battery receive a “random” charge profile and might not get up to 100% in some case. Also, the alternator might overwork.
      – A B2B charges the house battery with a proper profile (bulk/absorption/float, just like a smart charger would) and also act as current reducer so the alternator doesn’t overwork.

      A battery charged with a B2B will last longer (especially flooded/gel/agm).


  38. Question: I have been to a major battery supplier and asked about Lithiom Batteries. FYI… they sell millions of dollars of batteries yearly. I was told they were not safe. They supply batteries to major custom boat builders and said they cause alot of fires. Please advise.

    • In 2015 when we designed our van, we went with AGM (not lithium) because of safety concerns. Fast forward now to 2019, Lithium batteries now come with built-in BMS (Battery Management System): the BMS will disconnect the battery if any parameter is out of range (charge/discharge current, temperature, short circuit, etc). Technology has come a long way and many MANY people use Lithium them in their van/RV now. My advise would be to go for a major brand (Battle Born, Trojan, Relion, Renogy) and not worry about it. I think in 2019 Lithium is the way to go (until your battery is install outside your van and you’re dealing with freezing temperatures).


  39. Hi there,

    About to install the B2B charger (60amp) and I had a question about charging. When I normally charge from a plug-in 120v charger I shut down all the loads on the battery so it can charge correctly in three stages. When I do this I have the input go to an extension with two outputs, one for the charger and the other to plug my fridge in while charging so no load is on the battery during charging.

    I am wondering if turning off loads while charging is needed with the Sterling charger? And if so, how do you approach?
    Id like to be able to charge while driving and keep the fridge on but do not want to damage the batteries while charging them. Please let me know if you have solved for this or have any suggestions, thanks!


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