silerberend schreef :
WaltB schreef :
Bert65
LFP direct laden met dynamo. Geen dure regelaar nodig. Het enige dat nodig is om veilig met de dynamo LFP te laden is een stroombegrenzer en V-switch ( spannings relais) om bij bereiken van maximale LFP laadspaniing (bijv. 13.8V) het laden te stoppen. Dat bereik je met instelbare stroom begrenzer voor de veld spoel (rotator) van de dynamo (meestal 0-6A). Daarnaast misschien als extra veiligheid een thermostaat met sensor op de dynamo.
I would be careful listening to walt and ensure you get your own professional advice.
One thing he forgets to mention is Lifepo4 uses a BMS to regulate the cells. The BMS can cut charge to the battery. Tests have been done were an alternator was pushing charge to the lifepo4 when the bms cut off, this spiked voltages through the system of 80v+ in a 12v system, enough to fry most of your electronics.
Email from MHT Reader:
“RC,
The alternator for the Volvo MD2030 with 300 Amps lfp 14.6 max lasted a few hours. I believe BMS was switching on to off I to keep the lfp voltage to safe measure? Boat service replace alternator and it happens the second time? I now read your story on lfp and it explain to me why.”
Unfortunately the reader above learned the hard way. Ask yourself what happens when your alternator is in bulk charge, supplying all the current it can, and the internal BMS decides to “open circuit” or disconnect the battery from the boat? I’ll help out a bit here.
A) The alternator diodes, unless avalanche style, (rare in many existing marine alternators) but all Balmar alternators now use them, can be blown and the alternator can be rendered non-operable. Two years ago I did exactly this. Using the alternator test bench here at CMI the alternator was running at full bore charging an LFP battery. The “system” I set up had a .3A dummy load on, light bulb, to simulate a depth sounder. With the alternator running at full bore I disconnected the battery, just as an internal sealed BMS would do to protect the LFP cells. Poof went the alternator diodes and the light bulb! Worse yet the voltage transient I recorded on the “load bus” (think your navigation electronics) using a Fluke 289 was 87.2V. Ouch. Even if your alternator uses avalanche diodes, like Balmar’s do, the voltage at which they begin to protect the alternator is far too high for the vessels load bus equipment so you still need a way to protect against a load dump.
marinehowto.com/lifepo4-batteries-on-boats/ 
