RV inverter charger compatibility

[duaneb]

Newb here. I want to upgrade my AGM to lifepo4 100ah. My current RV built in 2019, it has an inverter charger PD4060K with a jumper for Lithium. The comments for this charger is that it charges at a constant 14.6V with no float.

Would this be a problem for current LiTime 100ah batteries? If so then I will research alternate inverter charges.

 

[Rocketman]

Yes, if you hold 14.6v into your Lithium batteries- it will be bad.

My favorite solution is to use a Victron Multiplus inverter/charger - lots of benefits.

But you need a charger that will go to float. (It needs bulk, absorbing and float modes). I like chargers that you can adjust the charging voltages - I feel 14.6v is too high and the float voltages on some non-adjustable seem too high as well.

 

[duaneb]

Thanks for the response. I called the PD manufacturer and they confirmed the constant 14.6V for their Lithium support. He indicated that the new LIFEPO4 BMS systems handle this. I also see Battleborn confirming that they support/sell this charger: “These units are designed to properly charge lithium iron phosphate batteries.”

First, does the PD manufacturer response make sense? Also, for the cheap brands, such as LiTime or Weize, does the BMS response apply?

 

[Rocketman]

14.6v / 4cells = 3.65v per cell.

That is the max you should charge a cell. That is 100% charged. That is also where the bms should cutoff.

Now does it go to float after either hitting 14.6v or staying there for 30min or so. If so that’s not bad (harder on the cells than my preference), but if it doesn’t drop to to 13.5-ish volts or turn off - that is really bad for the cells.

If it goes to float or turns off - it is a just fine charger…

In an RV, You want your Charger to be ok being plugged in for months at a time and not keeping the batteries at 14.6v the whole time.

Now I designed my system so I don’t need to charge to 100% - I aim to hit 95-ish% or so. There is not a lot of power in the last few tenths of a volt. I charge to 14.2 which is 3.55v per cell.

My hope is that my cells last longer.

 

[duaneb]

I ended up converting my AGM to a Litime 12V 100ah TM, with an Victron smart shunt, and upgrading my charger to the Victron smart IP22 12V 30 amp. This has been an education, and everything is working well so far.