Sterling Power BB1260 DC-to-DC (b2b) Alternator Charger | Review

Sterling Power BB1260 DC-to-DC (b2b) Alternator Charger | Review

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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 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).
Breaker Enclosure Ford Transit Driver Seat Alternator to B2B
We designed and 3D printed an enclosure to mount the breaker to the driver’s pedestal. More info: Enclosure for Circuit Breaker

Negative (ground):

Ideally you want to use a ground point recommended in the BEMM (BEMM included in our Builder’s Package), and it’s a good practice to use one as close as possible to the battery (which is located under the driver seat). In our van, we are using the ground point located between the passenger/driver seat:


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)
Sprinter Power Tapping Option 2 (page 2)

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. Every day is an opportunity for a new adventure... We’re chasing our dreams, and hopefully it inspires others to do the same!

Heads Up: Exclusive Deals!

Thanks to all of you, we managed to negociate group discount on these. Strength in numbers!

117 thoughts on “Sterling Power BB1260 DC-to-DC (b2b) Alternator Charger | Review”

  1. 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?

  2. 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,

  3. 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?

  4. 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.

  5. 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.

  6. 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!

  7. 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.

  8. 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?

  9. 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.


  10. 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!

  11. 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.

  12. 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.

  13. 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?

  14. 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!

  15. 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?

  16. 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?


  17. 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.


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