Charging LiFePO4 Batteries

[grashley]

I have a Class A in my sig. I recently replaced my coach batteries with 2 200aH of LiFePO4 batteries from the FW we recently sold. They are working well, but... The PD9200 converter will not fully charge the batteries. The chassis alternator did no charging of the coach batteries on this past weekend trip. The half charged Li bank still provides more power than fully charged LA batteries.

I simply removed the 2 LA batteries and replaced them with the LI batteries. They are in a different location 2 feet away, but the wiring did not change. As I understand the factory wiring, the converter charges both coach and chassis batteries. The chassis engine should do the same, but I saw no charging happening on this last trip. If I replace the converter with a PD9300, Li compatible unit and simply swap them, will the higher voltage of the converter harm the chassis battery?

One other idea was to get a Li compatible charger (Battery charger) and connect to the Li batteries and plug it into 120 VAC. Would this damage the chassis battery?

Any other ideas or suggestions? I prefer asking how to do it instead of how to fix what I just blew up.

 

[Isaac-1]

An even simpler solution is to add the optional Charge Wizard pendant to your PD9200 and simply press the button on it when you want to fully charge your LiFePo4 batteries , I have been doing exactly that with my coach since switching to LiFePo4 in 2021, in my case it is 420AH of LiFePo4 with a PD9260 converter. LiFePo4 is perfectly happy sitting at partial state of charge for long periods of time, only occasionally needing to be fully charged.

The PD9200 series has 3 charging modes, labelled Boost, Float and Storage plus a 15 minute "equalizing" charge that is at the same voltage as Boost that runs every 20 hours. Boost operates at 14.4VDC for up to 4 hours, Float operates at 13.6VDC for I think 30 hours, then if no activity is detected it drops into "storage" mode at 13.2VDC. Given enough time operating in the 13.6VDC mode the PD9200 series converter will eventually get a LiFePo4 battery up to near 100% SOC (something over 95%), though the charge rate will be slower than if it were in the 14.4VDC mode. In the case of my 60 amp model, up until going over 95% SOC I will see around 25-29 amp charge rate in 13.6VDC mode and 55-59 amp charge rate if in 14.4VDC mode. With the 13.2VDC mode eventually settling around a 70% SOC charge state.

My standard operating plan is to use the charge wizard pendant button to bump it into 14.4V boost mode a day or two before I plan to travel, this fully tops up the battery (4 hours at 60 amps is up to 240AH of added charge to the battery bank, before it drops down to the 13.6VDC charge rate which will maintain it at something over 98% SOC). Though in my case I do also have alternator charging on the road, plus rooftop solar that keeps things maintained while traveling, but does nothing when the coach is in its enclosed storage shed.

p.s. I don't know how your system is setup to charge both the engine starting battery and the house battery from the converter, what I can say is there are some ways that this is ok with mixed LiFePo4 and Lead acid starting batteries, and some ways that this is bad. In my case the engine starting battery is maintained by a LSL Trik-L-Start maintainer (company that made them went out of business last year with the death of the owner)

 

[Camper2]

Isaac... I was planning to change out my PD9200 series for a 9300 series but since you posted the above I will save that $260 plus tax and use what I have. I do have the Charge Wizard pendant mounted on the wall also. Thanks for the info.

How will that setup work with generator charging?

 

[Isaac-1]

Every wiring setup is different, but mine works fine with my Onan KY 4000 generator, peak power draw from the PD9260 converter is under 1000 watts.

 

[John From Detroit]

Isaac... I was planning to change out my PD9200 series for a 9300 series but since you posted the above I will save that $260 plus tax and use what I have. I do have the Charge Wizard pendant mounted on the wall also. Thanks for the info.

How will that setup work with generator charging?

I have never done it and have no reason to try now days but I understand there is a way to "Adjust" the Wizard's voltage settings... I do know what it involves but not enough to do it without research. Basically you use a voltage "Divider" circuit (Couple of resistors) to fool it into thinking the voltage is other than what it is. Google should be able to find the data.

 

[Len and Jo]

An even simpler solution is to add the optional Charge Wizard pendant to your PD9200 and simply press the button on it when you want to fully charge your LiFePo4 batteries , I have been doing exactly that with my coach since switching to LiFePo4 in 2021, in my case it is 420AH of LiFePo4 with a PD9260 converter. LiFePo4 is perfectly happy sitting at partial state of charge for long periods of time, only occasionally needing to be fully charged.

The PD9200 series has 3 charging modes, labelled Boost, Float and Storage plus a 15 minute "equalizing" charge that is at the same voltage as Boost that runs every 20 hours. Boost operates at 14.4VDC for up to 4 hours, Float operates at 13.6VDC for I think 30 hours, then if no activity is detected it drops into "storage" mode at 13.2VDC. Given enough time operating in the 13.6VDC mode the PD9200 series converter will eventually get a LiFePo4 battery up to near 100% SOC (something over 95%), though the charge rate will be slower than if it were in the 14.4VDC mode. In the case of my 60 amp model, up until going over 95% SOC I will see around 25-29 amp charge rate in 13.6VDC mode and 55-59 amp charge rate if in 14.4VDC mode. With the 13.2VDC mode eventually settling around a 70% SOC charge state.

My standard operating plan is to use the charge wizard pendant button to bump it into 14.4V boost mode a day or two before I plan to travel, this fully tops up the battery (4 hours at 60 amps is up to 240AH of added charge to the battery bank, before it drops down to the 13.6VDC charge rate which will maintain it at something over 98% SOC). Though in my case I do also have alternator charging on the road, plus rooftop solar that keeps things maintained while traveling, but does nothing when the coach is in its enclosed storage shed.

p.s. I don't know how your system is setup to charge both the engine starting battery and the house battery from the converter, what I can say is there are some ways that this is ok with mixed LiFePo4 and Lead acid starting batteries, and some ways that this is bad. In my case the engine starting battery is maintained by a LSL Trik-L-Start maintainer (company that made them went out of business last year with the death of the owner)

I used this method (PD9245-pre lithium version) with two SOK 200Ah batteries for several years. It worked fine.

 

[grashley]

You may have just saved me some money!!