Choosing LFP batteries for my conversion from AGM

[HeadedToTexas]

That is reassuring. Thank you.

 

[DDW]

On older chargers, without remote sense, you also need to be careful what voltage you set. It might look like 14.2 when charging at 20A but measure 14.8 when done. LA chemistry is pretty tolerant of sloppy regulation, LFP is not. A tenth or two in cables and connections makes a difference. I would measure the voltage at the battery terminal when it is full or nearly, very small current running in, and still in asborb phase. If it is less than that when charging early in the cycle then that's ok.

 

[HeadedToTexas]

The two batteries that are at “100%” show 14.12 and 14.16 volts on my handheld meter and are pulling less than 2 amps.

Does a red outline on individual cells in the Epoch app indicate balancing in progress?

 

[HeadedToTexas]

My main engine alternator is externally regulated with a Balmar MC-614. My plan is to switch its mode from whichever one it has been on since installed to LFP. Based on my readings, Balmar's default LFP profile is reasonable.

 

[Barking Sands]

The two batteries that are at “100%” show 14.12 and 14.16 volts on my handheld meter and are pulling less than 2 amps.

Does a red outline on individual cells in the Epoch app indicate balancing in progress?

correct.

 

[Delta Riverat]

Everything is looking good. Yes, the higher voltage batts will use less current, the lower, more. Keep 'em charging and they'll catch up. Parallel batts will self balance eventually.

 

[HeadedToTexas]

Amps went to zero and the charger went to standby. All batteries report 100%, but some cells still have red outlines. Now stay on the test bench for a few load cycles and recharges to 100%?

 

[Barking Sands]

If you want to. I'd probably do one more cycle and then slap em in the boat.

 

[SteveK]

Amps went to zero and the charger went to standby. All batteries report 100%, but some cells still have red outlines. Now stay on the test bench for a few load cycles and recharges to 100%?

If you have not already, log/record those cells to see if they repeat in future charges.
OMG, next I will be getting blue tooth.

 

[Marco Flamingo]

OMG, next I will be getting blue tooth.

I kind of wish I had Bluetooth on my Balmar regulator. I was in the ER on my hands and knees for over an hour programming my ancient Balmar using a little magnet and letting the regulator cycle through to make sure that the parameter I set was actually taken.

Print several copies of the Balmar cheat sheet off of MarineHowTo and keep the final edition (and some spares) in the log book. It is possible to not get it right the first (or second) time.

Can't be at the boat for awhile, so can't get eyes-on my Balmar settings. I remember I extended the initial startup from 1 second to 15 seconds. I can't imagine I'd ever be in a situation where 14 seconds was critical. 15 seconds and I know my engine has settled down.

I don't see some of the other Balmar settings for belt management and reduction of overall amps. Maybe on another page. Anyway, I also changed those parameters. My theory is that if I play nice with the belt and alt they will play nice with me.

I know that I lowered the max voltage. Stock setting of 14.8V (which is probably 14.9 before shutdown) won't do too much damage. 14.4V was enough for me. On my older Balmar, each lower voltage setting had to be at least 0.1V lower. Not sure that is true on the 614. I lowered the alt max temp to 90C. I removed the alternator batt temp sensor because each BMS has its own cutoff and I can read the battery temperatures from Bluetooth. What are the chances that a single battery temp sensor to the alternator would be on the right battery and the right terminal? I'll trust that to the BMS. I've monitored battery temperatures (of course) and have only seen a degree or two (F) rise after several hours of alt charging. The battery temp rise was probably mostly caused by rising engine room temp.

Time to move on to the next obsession.