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!

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

  1. I’ve read that some people are running a dual alternator setup – the original and then adding a secondary alternator for the charging the additional batteries. Seems a lot easier to just purchase an upgraded alternator that can handle both but wasn’t very clear on what the benefits of having two vs one stronger alternator would be. And people are very opinionated online haha. Any thoughts?

    I was looking at this company as far as a stronger alternator:

  2. Is there a limitation on how long the pos in from vehicle battery cable can be? I want to run from vehicle battery all the way to nearly the rear of the van and it’s more than 12 feet. Thanks

  3. Hi, just found your site and am loving it, we are in the UK but will ship our self-built van to N America for 5 months this summer – so excited!
    That aside just wanted to add a comment on the Stirling B2B , we have no affiliation but built one into our previous van that is still going strong over 10 years later. We had a problem with our B2B charger is Scotland last year and did all the diagnostics to isolate the problem. We talked to Stirling in the UK and they confirmed the B2B was faulty. The said send it back and they would look at it.
    So we mailed it overnight delivery to them 4:00pm from Dundee. They phoned us at 10am the next morning and said they had isolated and fixed the problem (a failed / faulty solder joint) and the unit would be on bench test all day and they would ship it back that afternoon. It duly arrived at our stopover in Edinburgh at 1:00pm the next day and was fitted that afternoon. Worked perfectly and is still going strong.
    So we think they make a great product and their service (under 48 hrs turnaround) was absolutely brilliant, can’t thank them enough as we still had another month on the road.
    The other point was that they checked the warranty and it was out, but they fixed it for free (not even charging us for shipping) and offered a big discount on a replacement if our unit had been beyond repair. Its just that attitude that would make me buy again. Things will always break / go wrong and the key thing is the attitude to fixing the problem that is so important, and the ‘oh well just throw it away and buy a new one’ is not always the best.

  4. First off, thank you Antoine and Isabelle, I’ve followed so much of your electrical systems. The detail that you provided through this site is just so awesome and gave me the confidence to dive into electrical for the first time. I’ve been successfully running my system for a little over a year now and feel quite comfortable troubleshooting any challenges that arise, but it’s honestly been quite smooth sailing for the last year.

    That was until my Renogy Battery to Battery Charger 60amp decided to fry the internal circuitry instead of blowing an internal fuse or tripping an external breaker. This appliance worked for me for about a year but once I started using the air conditioning in my van regularly during this summer heatwave, it became too much for the device. And as you have previously noted, the “ignition” line is an absolute pain to run. I had to plug this line into a 6 pin connector only accessible by removing the car battery. And had to do this multiple times from not having the right Molex connector but needing to reconnect it so I could drive my vehicle. Absolute pain. I have a few other Renogy appliances (MMPT, Solar panel) but have refrained from them when it truly matters, such as with the inverter and house batteries.

    tldr: Buy nice or buy twice, go for Sterling from the start

  5. In a combined solar + alternator charging setup, is it necessary to have some kind of disconnect to prevent the controller from charging when the b2b charger is running?

    I’m concerned that feeding everything into the positive busbar will overcharge the battery, is this a realistic concern?

  6. Hola Antoine

    Very helpful, thank you. I’m a little confused though. You say “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”. However, the “input” for the B2B appears to be 60A. Can the 175A CCP connection be used with a 60A B2B?

    Thanks in advance!

    • “The CCP2 is rated for up to 175A” means that up to 175A is AVAILABLE. The B2B charger is the one pulling the current and will only take what it needs.
      For example, you could have two B2B chargers: 2*60A = 120A < 175A, but three B2B chargers would be too much 3*60A = 180A > 175A.
      Hope this helps!

  7. 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.

  8. Hope you’re enjoying your visit. A very basic question. I’ve installed two Battleborn 12V LiFePO4 batteries and the Sterling BB1260. I can’t decipher the Sterling manual for initial setup. Should I select 13.8V on the left column for the appropriate profile? Thanks

  9. I’m a bit confused as I see multiple indications in the manual ( that there should be a common negative between starter and leisure batteries but in the post above this doesn’t exist.

    1. The wiring diagram
    2. The note stating “IMPORTANT: negatives should all be common. We recommend joining the BB. neg to the starter battery negative for improved efficiency.”
    3. In installation precautions “Device connects to common negative. Common negative must be earthed.”

    P.s. Thanks for all the detailed posts.

      • Thanks for all the information. Will having the BusBar grounded to the chassis in the back of the van and the B2B connected to the BusBar achieve a common ground? Or do I need to run a wire from the negative starter battery to the BusBar?

  10. 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.

  11. 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.

  12. 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.

  13. 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”


  14. 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.

  15. 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…

  16. 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.


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