If I Charge Via AC, Should I Leave LiFePO4s On A Charger?

[Devin82m]

Hey everyone, I plan on making a 24 V Hand Truck system for backup power if our grid power goes out. I will eventually put a charge controller on it too to hook up to our panels.

Anyway, I was wonder if it's good practice or safe to keep my LiFePO4 cells on an AC charge to keep them topped off or if I should disconnect them from the charger every so often to let them self discharge some? This system will not be used often, probably only a handful of times per year, but I want to it charged and ready too. On the other hand I don't want to wear out the cells by charging them incorrectly. I don't have a charger, I was thinking of going with one of the Growatts all-in-ones, but also considered a Victron AC-DC charger, I have a Victron 15 amp Blue Smart Charger for 12 v, but know that won't work.

Thanks for any help or suggestions!

 

[snoobler]

Hey everyone, I plan on making a 24 V Hand Truck system for backup power if our grid power goes out. I will eventually put a charge controller on it too to hook up to our panels.

Anyway, I was wonder if it's good practice or safe to keep my LiFePO4 cells on an AC charge to keep them topped off or if I should disconnect them from the charger every so often to let them self discharge some? This system will not be used often, probably only a handful of times per year, but I want to it charged and ready too. On the other hand I don't want to wear out the cells by charging them incorrectly. I don't have a charger, I was thinking of going with one of the Growatts all-in-ones, but also considered a Victron AC-DC charger, I have a Victron 15 amp Blue Smart Charger for 12 v, but know that won't work.

Thanks for any help or suggestions!

Absolutely not safe or a good idea. LFP should be at 40-50% SoC to prevent deterioration when stored at high SoC.

This is one reason why LFP is not a good solution for "standby" power, i.e., power that is only needed infrequently.

LFP advantages manifest in their high cycle life. When you don't cycle them, their cycle life advantage carries a penalty - they degrade just sitting there at high SoC.

 

[Devin82m]

Absolutely not safe or a good idea. LFP should be at 40-50% SoC to prevent deterioration when stored at high SoC.

This is one reason why LFP is not a good solution for "standby" power, i.e., power that is only needed infrequently.

LFP advantages manifest in their high cycle life. When you don't cycle them, their cycle life advantage carries a penalty - they degrade just sitting there at high SoC.

Lol! Well then why are so many people building systems like that, including Will? I mean is the only valid use of LFP batteries to use it in a golf cart or solar power system? I'm not being sarcastic or anything, you're just the only person I've ever seen say something like that. I mean I have a small 10 ah pack I built a couple years ago for ham radio and have only used it maybe 3 times, so is it going to die early?

I just don't see the point of all this if the batteries can't be used for something like this. I mean the only other thing I plan on doing is eventually setting up a whole house solar power system, but that's potentially years down the road and I've had some of you tell me not to mix and match brands or ages of cells, so I can't buy a few here or there.

This is really confusing and disappointing to tell the truth. I don't have tens of thousands to dump on a full system that I would need. I mean I would probably need a 12Kw system based on some basic estimates I've done in the past, and that doesn't include my new shop I'm building that will have a welder, plasma cutter, and other large machines in it....

 

[Devin82m]

I mean I guess I could use it to power electronics on my office all the time and keep the all-in-one connected to AC for charging. But I would think that would kill the batteries a lot faster with all the charge cycles from every day all day use.