Sterling Power A2B (Alternator to Batter charger) vs. Sterling Power B2B (Battery to Battery charger)

[MetalChef]

Update on Sterling Power A2B (Alternator to Batter charger) vs. Sterling Power B2B (Battery to Battery charger). Which works better to use while charging LiFePO4 batteries from your high output alternator? Recently I was searching everywhere for an alternative to the Renogy DC to DC 60a charger (which Renogy says "they do not recommend combining more than 1 Renogy DC to DC charger together) as well as an alternative to the Victron 30a Orion 12v/12v DC to DC charger as stacking Victron DC to DC chargers $263.50 p/ 30a just gets too expensive when you add them up. So my internet research found that Sterling Power sells an A2B and they also sell a B2B (DC to DC) charger. But no where on the internet could I find out what the real differences were between these 2 devices so I sent Sterling a question and they answered as follows: QUESTION "Why does the specs on the Sterling alternator to battery chargers say it can charge LiFePO4 batteries but in this video you say you need to use a battery to battery charger? Also if I already have a 3-way isolator can I just install am b2b or a2b between my isolator and my home LiFePO4 battery bank but not my truck AGM starter battery?" ANSWER "Reasons behind this are both complex and simple. The AB went through a redesign when lithium batteries were coming out into the world. We made the LiFePo4 setting suitable for the Voltages that we found to be most suitable, but the integral flaw to an AB and a lithium battery is actually in the hardware of the AB.

The AB does not have any current limiting potential, and as such can not limit the drain that the lithium battery has on the alternator. We can provide the correct voltages, but we can't limit that facet with an AB. It should be worth mentioning that we have catamaran manufacturers in South Africa who run our ABs directly onto lithium batteries and don't seem to have any issues at all. It's been put forward that we might be being overly cautious, but I'd rather be cautious with our customers than put their alternators or batteries at risk.

As for running the BB off of the isolator; sure, technically very possible. We have a number of clients who put isolation switches on the input line to the BB, and this would essentially be no different. So long as it can take the alternator feed off of your starter battery in some manner, it's willing to operate

-Ben"

 

[coachgeo]

one thing NOT added to these discussions much is alternator cooling.

 

[DJSmiley]

That's why I like the WCS B2B charger. I haven't seen it IRL, but it's specs, and the explanation movies from the manufacturer looks very promising to me.
It is expensive, but it looks like a really solid product, works with 12/24V, even works with different voltages (24V car system, 12V leasure setup, or the other way around).
Based on the things I've seen, it kicks ass over a Victron or similar.

Up to 60A, just as some competitors offer, but with some (imho very important) benefits:
- Current is regulated based on temperature. At +2 degree, a LFP doesn't like 60A charge. It needs to heat up first to accept such high currents. The WCS goes full power at 15 degrees or so, but at lower temps the current is reduced, and adjusted to the battery temp. If the battery heats up, current goes up.

Many people are aware of the charging options with regular LiFePO4 cells (don't charge), but at +1 it's not 'ready to fully go'. The optimum current is determined by the temperature, it's not a binary 1-0 switchover point!

Another major advantage: It has a secondary temperature sensor for the alternator. It lowers the output if the alternator gets too hot, instead of overloading. I really like that point of view
Especially in Europe, most vans are smaller. Especially the older ones have rather small alternators. If you take in consideration the power required to actually run the van itself, there might be not sufficient power left to charge at high amps.

And even if it were, most alternators can't run at 80+% of its rated capacity for long periods (depending on the temperature)

While driving on the highway, you might be good when running an alternator at high loads for longer periods, but if you're hitting a traffic jam, airfow is massivly decreased, thus lack of proper cooling is a serious risk.

https://www.wcs-mobiletechnik.de/

Their Youtube channel contains lots of interesting movies, including some showing their booster (In German)

https://www.youtube.com/channel/UCqEjC6N-cyBVzJrqHvAF-AQ

 

[coachgeo]

problem is 60a is childs play.. I have 115amp 24v charging available out of 150amp alternator and might upgrade to 570amp at a reasonable cost (could be free if I sell my existing alt)