The Sterling Power BB1260 Battery to Battery (B2B) Charger play a major role in keeping our camper van electrical system balanced and healthy. How’s that? The B2B 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 that the house battery lifespan is maximized. Sounds too good? Keep reading this review as we get into more details…

 

 

How does it 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 raise the voltage of the van battery in order to charge it. The B2B 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 senses the dropped voltage and turns itself OFF. All of that happens without user intervention (well, except the part where you drive your vehicle!).

 

Why is it beneficial to the house battery lifespan?

Each type of battery (Gel, AGM, Lithium, etc.) has a specific charge voltage; with an isolator or an ACR (instead of a B2B), the house battery receive a “random” voltage (same as the van battery). You probably heard of battery’s memory effect, right? It’s real! If a battery doesn’t get a proper multi-stage charge (bulk, absorption, float), it looses 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.

 

Are solar power AND alternator power (B2B) both needed?

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. Sun angle is too low, 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 (up to 60A during the bulk 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. Charge current (30A or 60A).

It basically comes down to either BB1230 (12V input, 12V output, 30A) or BB1260 (12V input, 12V output, 60A) model. 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.

 

OK there’s actually another model, the Sterling Power BBW12120 which has 120A output (12V):

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 your 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 to install two BB1260 in parallel to get a higher output.

 

Installing the Sterling BB1260 B2B Charger

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

 

Location

Make sure to install the B2B charger into 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. Temperature sensor (To house battery negative post. Optional, but recommended. This is to correct the voltage according to temperature change)

 

For safety sake, remember to add fuses (or breakers) on the positive wires and to select the right wire diameter according to length / fuses. Not sure why or how? In this case, make sure to read our electrical system guide! We first start with the theory (so you understand what’s going on), then YOU do the work using our Interactive Diagram and our Tutorial:

DIY Van Electrical Guide: Build Your Knowledge

Here is a sneak peak of what you will find inside the article:

 

Ford Transit Connection:

 

 

Mercedes Sprinter Connection:

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

 

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 is the prevent 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 B2B 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, a 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 (faroutride.com/victron-review), 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.

 

Operation

Once the installation and initial setup completed, just drive and let the Sterling Power B2B charger do its thing!

 

Reliability

We installed the Sterling Power BB1260 B2B Charger in October 2018; so far so good! We will keep you updated if anything happens! Subscribe to our Mailing List to be notified.

 

Resources

• BB1260 Manufacturer Website (product info, manual, regenerative braking compatibility, etc.)

 

Runner-Up

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:

 

Renogy also released the DCC50S which combines a DC to DC charger & Solar (MPPT) charger. 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)

 

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