Is opportunity charging better for LiFePo4?

I’ve given up on AGM batteries in my GEMs. I currently have a 2016 and a 2024 with a pair of 48 volt 100Ah batteries in each of them connected in parallel. It gives me almost 80 miles of range but I live on an island that’s about 7 miles long so I probably shouldn’t be putting it on charge every night when I still have 80% capacity remaining. I know the AGMs wanted to be topped off every night but I’m not sure about these batteries. There are EV chargers at the restaurants and beaches here so my question is, should I just use the local charge points when I go out to eat and shop and not worry about topping off at home every night? I realize the BMS protects the batteries from overcharging but I cringe when I see the cells top out at 3.68v when I think 3.65v is full. Seems the batteries would be better off with occasional charging and keeping it midrange as long as the cells stay balanced.
Thoughts?

I would cringe too! That does sound a little high.
What charger are you using and is it set for this battery?
What settings do you have in the BMS? Perhaps they should be reviewed?
What does the maker of your battery say about this?

The 2016 has the original Delta Q charger and the car BMS is programmed for an AGM distance pack. I’ve got about a year and a half on those batteries and they’re doing great. Lasting longer than the stock AGMs and a lot less money. ($759 times 2).
The 2024 has the original Lester charger and this car comes with an Acuity battery monitor. I’m able to adjust some limited battery settings so that the car SOC matches the battery SOC so everything works like original. That charger also thinks it’s charging AGMs.
The batteries are rated as 51.2v with a 58.4 charging voltage. The stock chargers seem to agree with this and I assume that the battery BMS must kick in to end the charging when it’s full.
They seem to charge at 54 volts for most of the cycle and only get to 58.4 volts at the end for 4 or 5 minutes and the cells climb from 3.50 to 3.65 pretty quickly with little amperage.
The only other important specs I was paying attention to were 200amp continuous discharge (times 2 is plenty for any GEM).
I can’t imagine this setup isn’t getting a little more popular so I’m wondering how it’s working out for others.

I watched this real scientific sounding guy that had done a lot of studies on the chemistry and he said to charge them to 3.46. so that’s what I set my BMS to. I’m using a solar panel to charge mine I’m in Arizona so it trickle charges all day.

You are better off not topping them off all the time. I charge mine once a week or so. I let mine get to 20-30% and then charge. Lithium hates being stored fully charged

So when you charge them, do you go all the way? And how high do the cells go to? Are you using stock charger?
My E4 sits around sometimes for weeks so I keep it around 50%.
The E2 is out every day. I plug in at the free EV charging stations when we go out to eat or to the beach. I’m just thinking of never topping off again unless I ever see a cell get out of balance.
I’m still tinkering with the Acuity unit to see if I can prevent the Lester charger from straying a bit above the 58.4 mark.

2024 E4. I run a performance setup. 63v 310ah. Set the lester to charge higher. In you case dont worry about it getting to 58+ volts. Lester does a low amp equalization charge when finishing. Won’t hurt your batteries at all. The key for you is not getting them that high all the time .LFP cells only come out of balance at the very top end or bottom end, shouldn’t be an issue. Charge them when they got to 50% or less. At that rate they will have thousands of life cycles and will wear out from age before cycling out.

Thanks. My plan going forward will be occasional charging and just keeping it in the middle. Not too high and not too low. Don’t think I’ll ever miss lead batteries.

Just curious, but I thought GEM’s were 72? I picked up an old 2002 2-seater, but haven’t had time to work on it. I’m building a Lithium battery pack for my Club Car 6-seater now. If this works I’ll probably build a set for the GEM.

Original “classic” Gem cars (2000 to 2015) are 72v class.
Actual V range is somewhere around 68v low to 85v high.

New generation Gem cars (2016 and up) are 48v class.

Please design accordingly.

Cool. Thanks. I’m just getting into the GEMs.

Joe

Dont throw too much money at it. The 2000-2004 have many design shortcomings.

Some members here at, one time, did a lot with theirs, but at end of the day, the design fails were still there.

You can only polish a turd so much.

Thanks for the heads up. I think I’ve picked up some of that already. I’ll try to get it running and learn something. I’ll then keep my eyes out for a newer model. I really wanted a 4-seater, but this popped up at a golf cart dealer and I bought it. Plus they delivered it to me. The charger they included was worth quite a bit by itself. Obviously, the onboard charger was bad. That may have been the beginning of those troubles you mentioned. I’m sure you’ll hear more from me when I get fully into it.

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The problems with the 1st generation gems go beyond the under dash blue smoke generator.

  • barakes, or lack thereof
  • suspension, hehheh
  • steering, all the way down to how the column is mounted…

There is more, but you’ll figure it out.

PS LMK if you want to donate it to science. @AssyRequired and i have to someday drag one out to the desert and use it for a drive-by shooting range and ill see if i can get my friend who is a licensed blaster to blow it into a million bits

Thanks, and that sounds like fun! I may have to have a demolition day my self. No deserts in GA but lots of open farm land.

Any possibity of getting your hands on an old peterbuilt or mack truck? Smokey and the Bandit was set in Georgia i think?

“Move on over Bandit, the Snowman is commin through…”

Plenty of those around here. And, yes it was filmed here for the most part. 10-4

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