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Daly BMS fail

Seacap

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Feb 13, 2020
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At least I think so. I am a newbie at this so bear with me. I installed a Daly 4s 3.2v 100A BMS on my 200A aluminum case cells. Just as I did this my 70A alternator failed due to worn out brushes. This caused a lot of consternation because of the timing ??. I replaced with a large case 120A alternator with a external smart regulator that uses alternator temp.

Anyways i kept experiencing voltage and current fluctuations. I would go to bed with my battery’s seemingly low at 13.06. Hen wake up in the morning at 13.20 with the reefer running all night. Then it didn’t seem to be getting a good charge. But I saw 50-60A at the beginning of the alternator startup. But I would end up with my batteries at13.15 after charging for two hours. So today I checked my current output and it was only 25A with the batteries sitting at 13.06. I disconnected the BMS and the out put into the batteries shot up to 60-70A. Kinda where I would expect from a big alternator. And all my voltages seem right now, and not fluctuating.

to me it seems like the BMS was wonky.
 
You mentioned a couple of things of concern.

LiFePO can suck a lot of current, Hooking your alternator directly to the LiFePO battery bank (with or without a BMS) can burn out your alternator. Your failure may not have been a coincidence in timing.

What is the charge profile for the external voltage regulator on the alternator? It is probably not set up for LiFePO4
 
You mentioned a couple of things of concern.

LiFePO can suck a lot of current, Hooking your alternator directly to the LiFePO battery bank (with or without a BMS) can burn out your alternator. Your failure may not have been a coincidence in timing.

What is the charge profile for the external voltage regulator on the alternator? It is probably not set up for LiFePO4

no, the brushes had burned up after 3200hrs. Confirmed by a repair tech. I have an external regulator that has a great charge profile for Lithium. And is recommended by the manufacturers, backed up by an alternator temp sensor that backs off output as temp increases.

The regulator bulks at 14.6, absorbes at 14.3 and floats at 13.3. It also has a force to float switch. So I can go to float at any time. Which I really like.
 
no, the brushes had burned up after 3200hrs. Confirmed by a repair tech. I have an external regulator that has a great charge profile for Lithium. And is recommended by the manufacturers, backed up by an alternator temp sensor that backs off output as temp increases.

The regulator bulks at 14.6, absorbes at 14.3 and floats at 13.3. It also has a force to float switch. So I can go to float at any time. Which I really like.
Which unit?
 
I use at balmar 614 an run alternator in small engine mode this gives me 50 percent power. Big alternators are best run at 50% power. Big alternator load can also wear out your bearings on crankshaft and water pump so I avoid running full outPut.
 
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