LiFePo4 charging.

[Igotknobblies]

I bought a small LiFePo4 battery for my motorbike. Its kick-start only and a 'total loss' set up so no alternator. The battery, a 12v 6Ah with on-board BMS is good for at least 8 hours ignition with 2 hours of lighting use too (all LED's). I bought an MPPT solar charge controller powered by a single 12v 40W panel. I googled fully charged voltage on this battery as being 14.4v. The Charge controller set to a max of 14.4v is showing just that, but my digital meter is showing 13.6v with charge leads in place. If I take the leads off the battery, voltage drops to 12.9, equating to 20%. Should I let the unit do its own thing?
Im loathe to leave unattended so checking every 10 mins as the surface is strong and its 1st charge since new. Any pointers please, especially for the charge controller as the translated Chinese instructions sound like 'pidgin' English!
Cheers, IGK

 

[Codlord]

Not sure I can answer but what make/model of solar charge controller is it? Is it specifically for Lithium or does it have a configurable LifePo4 charging profile?

I use a Victron solar controller for a Fogstar leisure battery and I just set it to the lithium profile and let it do it's thing. The manual says it does Absorption voltage of 14.2v and Float voltage of 13.2v.

Looking at another Fogstar I have here now which is not on a solar system or connected to anything (I just charge with a Noco Genius charger) it is charged to 100% and showing 13.3v.

So I would say 12.9v on a disconnected battery sounds "about" right.

 

[OldStock]

As above, the charge controller should have a mode forLiFePo4 to protect the battery and get the best life out of it.
Its not only about voltage, charge current, float voltage and charge method.

If the source you are using does not have a specific mode for LiFePo4, I'd consider getting something that does, as the battery is probably worth more than a solar charge controller.

 

[BTB 500]

Check the instructions for your solar charge controller - it's quite likely that an MPPT one is designed to be compatible with LiFePo4 batteries as well as lead/acid.

The battery has a BMS which should monitor/control charging to prevent the cells from being damaged or going out of balance. Again see what the instructions for that say about charging. Lead/acid chargers are very common and it may handle the profile from one of those anyway.

Regarding the voltage readout on the charge controller I have three older (quite basic) ones and they all over-read compared to a multimeter connected to the terminals!