Fuso wont start...

[dwh]

The challenge is a BMS that would keep the cells charged from the truck alternator.

Not that big a deal. All the drop-in replacements have it. Better would be to fix the truck's voltage regulator. It just needs to charge to 14.5v or so and then drop to a float voltage below the resting voltage of the fully charged lithium.

Combine that with power from solar panels on the camper roof which has a totally different charge curve.

That's actually no problem at all. Just need a decent programmable solar charge controller. Again, charge to a certain voltage then drop to a low float voltage.

 

[gait]

If my alternator failed electrically tomorrow I could run my vehicle indefinitely from my roof top solar and house battery. Replacing energy for starting would take about 5 minutes. Biggest load would be headlights, about 16 amps on high beam.

When I connect alternator to house batteries in parallel with solar connection the solar is consumed preferentially because of the charger settings. I rarely need the backup of the alternator but if I do, since I'm always in the vehicle when the engine is running I disconnect alternator (and vehicle battery) from house battery when house approaches reasonably charged.

Just food for thought. It hadn't occurred to me previously that the alternator may be redundant.

 

[flossandfredsadventures]

Not that big a deal. All the drop-in replacements have it. Better would be to fix the truck's voltage regulator. It just needs to charge to 14.5v or so and then drop to a float voltage below the resting voltage of the fully charged lithium.




That's actually no problem at all. Just need a decent programmable solar charge controller. Again, charge to a certain voltage then drop to a low float voltage.

That was my understanding as well. Something like the Balmar MC-614 regulator which is both programmable and has a lithium charge profile. Even a cheap EPever Tracer MTTP solar regulator is programmable to suit lithium (but perhaps not as well as something from Victron). From what I've read these should be able to charge concurrently without adverse effects.

As for a BMS, for such a small pack I think I'd be happy to just run with something simple which would measure the cell voltages and trigger a 500A latching relay if they became unbalanced or under/overcharged. Something like this unit and its respective cell balancers - https://evparts.com.au/ev-power-bms/mcu-micro-08a.html

I hope to run separate starter and leisure packs that are both housed in the camper to protect from the unwelcome temperature extremes with a voltage sensing relay in between them. Total cost likely to be around A$700 for the cells, BMS and relay but a weight saving of about 50kg.

Please feel free to correct me if I've missed something or am incorrect somewhere as I'm not an expert and I'm only informed by Google!

 

[flossandfredsadventures]

I disconnect alternator

I know you've mentioned disconnecting before but do you do this via the regulator?

 

[gait]

I know you've mentioned disconnecting before but do you do this via the regulator?

a motorised isolator between vehicle and house batteries with a convenient toggle switch (with led that lights when isolator closed). I'm always near the vehicle when engine running and have no need to charge to 100%. It wasn't worth my time automating - I've just spent 6 months trip without need to alternator charge house.

There's a balancer from GNE that works differently to evparts.

 

[flossandfredsadventures]

There's a balancer from GNE

Yes, I prefer the balancers that don't function by wasting heat but I worry about that one and the high frequency tone that it emits. I'll probably be sitting on my batteries so I wonder if I would hear it? I chose to link the EV parts example simply because it had the relay wired in too for a reasonable price.

I do apologise if I've taken this thread too far off topic here.

 

[gait]

Yes, I prefer the balancers that don't function by wasting heat but I worry about that one and the high frequency tone that it emits. I'll probably be sitting on my batteries so I wonder if I would hear it? I chose to link the EV parts example simply because it had the relay wired in too for a reasonable price.

I do apologise if I've taken this thread too far off topic here.

I'm getting on a bit in years. When I originally installed for daughter in outside off grid battery box I could hear it clearly, but a couple of weeks ago I had to ask if it was whistling. Similarly with friend who has test rig in lounge who can just hear it but not when its surrounded by cardboard. We weren't sure if it was working, but there was a problem with the voltage monitoring and the cells were all within 3mV in the knee. I have a feeling the whistle is lower volume once balanced and the balancer has little to do.

 

[flossandfredsadventures]

I have a feeling the whistle is lower volume once balanced and the balancer has little to do.

That makes sense. They are very reasonably priced too. Thanks for the first hand report.

 

[SkiFreak]

The noise is very similar to my tinnitus, so sometimes it is hard to differentiate which is which.
As Gait mentioned, the noise is fairly easy to suppress. I currently have my balancer in the cardboard box it came in and that alone reduces the noise by about 50%.
If placed in a decent, soundproofed enclosure I fully expect that the noise will be virtually undetectable.

I too will be having my batteries inside the camper, so eliminating/reducing the noise has a high priority.

 

[SkiFreak]

I have a feeling the whistle is lower volume once balanced and the balancer has little to do.

That's what the doco indicates, but if I am honest, I cannot really hear any difference in noise level, whether the batteries are charging and doing their balance thing, or if they are balanced.
I should add... the noise is definitely noticeable, but it is not what I would consider loud, just a little annoying.