LiFePO4 'Starter' Batteries ???

[patrickparrott]

Based on Patrick's experience, it looks like stand-alone LFP starter batteries are not ready for prime time. It seems like the battery(ies) would need a DC-DC charger to buffer the alternator . . . and probably one of those Balmar modules.

You're correct about prime time, but only if the alternator regulation is not addressed. I suspect that the Balmar module is really just a sponge. Probably a capacitor bank. Similar to when lightning strikes, only on a much smaller scale.

 

[tpenfield]

You're correct about prime time, but only if the alternator regulation is not addressed. I suspect that the Balmar module is really just a sponge. Probably a capacitor bank. Similar to when lightning strikes, only on a much smaller scale.

Yes . . . one would think that the BMS in the LFP batteries could be modified so that it does a slow enough shut-off to give the electric field in the alternator time to collapse. Might not be much time is needed (1-2 seconds ?).

As you mentioned . . . I think the Balmar module puts enough capacitance in the circuit to dampen voltage spikes . . . or could be acting like a zener diode, so it gobbles the spike.

 

[wpns]

As you mentioned . . . I think the Balmar module puts enough capacitance in the circuit to dampen voltage spikes . . . or could be acting like a zener diode, so it gobbles the spike.

It's too expensive to buy one just to tear it apart or even characterize it and return it(*), but if it's a (20V) zener or equivalent, I'd be concerned about the long-term dissipation (does it heat up if you're running the alternator into just the APM?) and we still haven't solved the problem of using the BMS for charge regulation.

A drop-in starter battery would be more complex, and hence more expensive, than the battery manufacturers want to create, would need a custom BMS, an APM function, etc, and everyone's aiming for the low price point, not the perfect functionality and 8000-cycle 10-year warranty.

Good, Fast, Cheap, pick one?

(*) I don't do that kind of thing.

 

[patrickparrott]

Yes . . . one would think that the BMS in the LFP batteries could be modified so that it does a slow enough shut-off to give the electric field in the alternator time to collapse. Might not be much time is needed (1-2 seconds ?).

As you mentioned . . . I think the Balmar module puts enough capacitance in the circuit to dampen voltage spikes . . . or could be acting like a zener diode, so it gobbles the spike.

I don't know how much technical knowledge the Dakota customer service agent had but he did pickup right away on the BMS high shutoff limit causing the shutdowns and the manufacturing change that was done to correct the problem. He didn't say anything about adding more BMS response time. He then went to his manager on what to do about the warranty claim and came back with two options. #1.... return the battery and we will send you one with the manufacturing change or #2 purchase the Victron DC/DC Orion smart converter and install it on the boat. I chose the 1st option because my batteries are in the console with limited space, and I paid for a marine battery that was advertised for outboard motors. The replacement is being delivered today. I have tried to get them to look at the serial numbers first so that they will know for sure with no luck. If I can do without the Balmar module or the Victron converter I will be happier. I appreciate very much you and the others who have responded to my posts. I think that we are on to something that will produce a solution for those who have the same issue with lithium used for starter batteries on boats.

 

[patrickparrott]

It's too expensive to buy one just to tear it apart or even characterize it and return it(*), but if it's a (20V) zener or equivalent, I'd be concerned about the long-term dissipation (does it heat up if you're running the alternator into just the APM?) and we still haven't solved the problem of using the BMS for charge regulation.

A drop-in starter battery would be more complex, and hence more expensive, than the battery manufacturers want to create, would need a custom BMS, an APM function, etc, and everyone's aiming for the low price point, not the perfect functionality and 8000-cycle 10-year warranty.

Good, Fast, Cheap, pick one?

(*) I don't do that kind of thing.

I have started to purchase the SOK lithium batteries for my solar off-grid systems b/c they are not only Bluetooth, but they can be disassembled for repair or balancing.