backchannel: Alternator Supercharging video from Battle Born

[A response to this video]

I think BB is a reputable company that publishes useful and clear info. This video does not live up to their usual high standards.

1:09 you know everyone wants to go to these larger battery Banks 48volt battery Banks

Do they?

1:42 we were lucky enough to be able to put 800 watts of solar up there but you know that’s actually one of the bigger systems we put for solar um only able to bring in about 9 amps

The 9A in this reference appears to be solar charge controller at “48v” (51.2V for 16S LifePO4). In other words, ~**460.8W. Fair enough. Let’s put a pin in this for now.

1:54 speed um in conjunction with the intelligence batteries um you know this is a a whole new charging world for us and charging efficiency and the speed of

Is it a whole new charging world?

2:12 available but this kind of classification of RV typically the people are traveling you’re moving around so why don’t we just take some of that energy that we’re producing off of the alternator and put it into the battery Bank

That’s new whole new charging world? Charging the bank from alternator?

2:59 converter operates and now the converter’s got two different modes of operation the mode that we’re in right now because the vehicle’s not running is the 12volt support mode in 12volt support mode what’s happening is we’re actually running all the 12volt loads all the lights you see on right now they’re run off of the 12volt chassis battery and our system monitors that chassis battery and provides energy from our 48volt battery Bank to support

Not sure I see the value here.

3:33 now let’s look at the other mode of operation hey Dave fire it up so now with that ignition signal the system starts looking for the engine to be running looking for the starter battery voltage to raise because the vehicle’s running

You mean like every other DC-DC or relay that’s triggered by voltage?

3:51 mode where we’re charging from 12vt to 48v the max output that we could get on this converter is 3,000 Watts but we’re always having a limitation to what the size of the alternator is so we can easily program what that 12volt limitation is through the app what size Alternators on this B so we

Right, the charge rate needs to be comfortable for the alternator.

got a 220 amp alternator

Note: this is the high output alternator one can order on the Promaster. The stocker is 180A.

4:43 program it correctly if I set the amperage limit too high for this alternator the system actually realizes that as it kind of starts and stops the charging based on the input voltage raising and lowering

Yes, Voltage-sensing chargers have a cut-out voltage.

5:05 up right now where we don’t have a high idle kit on this van so right now we have it set at an extremely conservative 60 amps from the 12vt side

Pretty normal size for a DC-DC.

Notice this is 60A at 12v nominal*, or **720W. Yes, 720w from the alt > 480.8w from solar. BB and Boho may not have been trying to gaslight us an apples-to-oranges 9A vs 60A comparison, but an annotation on screen that said “9A @ 48V” would have been more truthful.

As it stands it makes it sound like the alt is making 667% more than the solar array, when it’s actually 50% more

but we’re comfortable going up to you know 50% of the alternator’s Max output with the converter so we’re happy to do maybe 110 amps yep yep coming off this hey Dave

This is the kind of thing that external alternators are great at: running alternators hard without overheating them. I think what’s happening is the WS500 isn’t actually regulating the alternator, but feeding that control to the 12v-48v converter. A decent idea, if it weren’t $3,000 (!!!).

5:33 van system you know everyone’s going after that really big battery Bank everyone wants to go 48 volt so now we’re bringing the components to Market that allow you to do that to do that safely and intelligently and

I suspect it has more to do with BB buying Wakespeed in 2022. The dog caught the car, now what does it do with it?

if you want a big battery bank got to be able to charge fast

I’d say if you want to charge fast by alternator then a secondary alt directly controlled by a Wakespeed (or similar) would do more for less money.

If one wanted to take this particular bi-directional approach the Sterling would do it for 1/4 the cost.