Any Lithium gurus here?

[FeFanatic]

I have a pair of 100ah LifePo4 batteries that I want to install into my '03 Cougar. The history is that it came with lithium batteries already installed but they just didn't seem to charge like they should. I took them to the dealer and he replaced them without any issues. So, I put the batteries on the deck, hooked up the Minn Kota charger and it charged them to 83% and quit. Checking with a meter showed the batteries at 12.8 volts with the charger hooked up.

So, I had a Guest 3 bank charger that was in my crashed PII and tried it. No change. So, I discharged the batteries with a 2500 amp inverter to about 40% and tried to recharge them with the Guest. They went to 87 and 88% respectively. I took a little 6 amp lawn mower charger and topped them back off to 100% and they held for a couple of days.

Now is the weird part. I reinstalled the Guest leads and kept it plugged in to float the batteries and instead they drained the batteries back to 87% and show the voltage at 13.3 volts. I charged them back to 100% with the little charger and again they held for about 2 weeks.

Just to be sure I reinstalled the Guest leads again with it plugged in and the batteries started going back down.

So, with the Minn Kota not charging past 12.8 volts and the Guest going to 13.3 volts it seems these batteries won't get topped off with either charger.

What chargers are you using for your LifePo4 batteries.

Again, I have two 100ah batteries.

[catdude28]

In order to bring them to full charge you need a lithium capable charger. Examples of onboard chargers are the Noco Gen Pro and the Minn Kota PCL. The different lithium battery companies also make specific chargers for their lithium batteries. Some of the non lithium capable AGM chargers are also capable of charging lithiums on their selectable AGM setting, but will bring them to near full charge but not quite full. The Minn Kota PC is an example. You need to be careful and not use a charger with a profile that exceeds 14.4 volts. Really best to have a lithium capable charger with those expensive batteries.

[Bass_boat_boy]

I charge my lithiums with the minn kota pc charger on AGM setting and it charges that to 100%. Either get the pc charger or lithium specific charger. I'm happy with the MK PC charger.

[Louie]

The float charge and charging rate are pretty different charger to charger. I ended up buying a ionic for my ionics because I worried about the higher floating charge rates of a duel pro/ or noco. Yeah they will do it with success but for what I invested what's another few hundred for a good specific charger.

[Louie]

Heres some good info possibly specific to your batteries

https://www.power-sonic.com/blog/how-to-charge-lithium-iron-phosphate-lifepo4-batteries/