2005 GEM E2 Lithium Conversion

Hello all,
I have purchased a 2005 e2 and it’s in need of batteries. I’ve been reading a lot of good post here about converting to lithium so that’s the route I’m taking.

Here’s the specs:

Charger: Quick Charge, model: OB7210 currently set to “Deep-cycle wet and maintain”
Controller: Seems to be stock GE T3, Catalog#: IC3645SR7A353T3
Motor: 7.5 HP “Blue” D&D Motor Systems, Model: 170-501-0002B
DC to DC converter: Sure Power, Model: 71030i
Batteries: An old mess of different flooded lead acid
Gears: Spicer DANA 012AS107 0613-00249 : 10.35:1

I’m interested in lithium with a BMS. I messaged @Inwo to see if he has some to sell.

It seems I might be able to send out the charger to convert to a lifepo4 profile, but I’m wondering if this charger is as good as a DeltaQ and would a Delta be a better match with a BMS?.

I would like to get more range vs speed.

Anything else I should consider?

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For range you need a double set of lifepo4. Mine are 200wh/cell.
50 cell is is 10kwh. Near a Bolt 12kwh.
I do have a few Bolts left if budget allows.

I do not recommended bms for lifepo4, except for watching cell levels.
I can include indicating shunt balance boards for not a lot of money.

I’m looking for 25-30 miles. Is that something the green cells could do at 5kwh? It’s fairly flat here with a few short hills.

I had that charger and it worked fine up to a max voltage of 91V I believe it was. The only other issue was that it would time out on a long charge and I’d have to unplug and restart. Not a big deal usually. I swapped it out to get to 96V. I would use that charger until you’re all up and running and IF you decide you want more voltage, upgrade at that point. Dave is the man to get you what you need for sure. We have a different view on the BMS though. I started with a BT one and it worked good for shutting my charger off at the desired setting but I found that it actually was drawing down one of my cells and I would have to manually top balance them all regularly to get that cell back in sync. I got to where I was just using it to control the charger and then would unplug it to prevent leakage. I"ve since built a simple Arduino circuit that allows me to set my max charge and control the charger. Haven’t had any imbalance since. I’m not convinced the BMS is needed with the Volt batteries but that’s a debate that will rage on forever.

I only rate them at 20 miles. Some have reported more.
Nice thing about lithium is short charge cycles are fine. Plug it in for a few minutes or hours. Doesn’t matter.
Charger gains about 4 miles per hour. Twice that with two chargers.

That makes sense. I will plan on getting my current charger set to lithium.
@inwo I’ll contact you about those batteries.

This is very exciting. I have done a much smaller project using 80 A123 batteries for an electric bike. I can get a good 20 miles out of that. I think I could live with 20 miles, and maybe a bit more with a charge on the go.

I’m also wondering if I can fix the speedometer without limiting top speed. The 2 poles on the motor are making the MPH output half the actual speed. I might look into getting a programmer for that.

N8 you well love these green batteries . My Gem with 27 of them has a 30 miles plus range , the other Gem has 25 of them and i believe does 25+ miles . But the highest elevation in Naples is 36" , yes inches so to say its flat is and understatement . For improved range run tires @35psi and try to keep your speed below 35 mph . Also Gems hate weight so skinny friends are a plus .:grinning:

Ha! Thanks for the great advice!
I guess it’s time to lose some weight. :laughing:

Lithium conversion allows you the choice of keeping your larger friends, or not!


Looks like you have the parts before the batteries.
Probably won’t get far with one cell. :slight_smile:

I got the first box! Ha! No I’ll need the rest to get anywhere. Thanks for the quick ship. I’m excited to get her going. Should I be concerned with the fluid on the battery? It looked like it was rubbed down with Vaseline. I cleaned it up but just wondering if that’s normal.

Also do you have any info on the shunts. I found the website but I’m not seeing any instructions.

They were stored in mineral oil. Messy but harmless.
Shunts have + and - marked on them.
After batteries are installed put one on each cell with a second nut.
That’s it.

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Great, Thanks again @Inwo!

I’ll post some pictures of the progress soon.

Does anyone have a wiring diagram for the 2005?

Here are some pictures of the batteries and the install:

I’m working on the charge cycle. Currently the QuickCharge is set to “Deep cycle wet and shut off”. Seems to keep the voltage too high at the end so I have been monitoring and shutting it off manually. That temperature is from the side of the charger.

The batteries have stayed very balanced once the charger stops and throughout the discharge. I have measured about .02 V difference across all 25.

I haven’t done any long rides yet. Only about 8 miles so far.

I think I want a BMS to add low voltage cutoff protection, better charge management and more info about the battery state. I’m looking at different chargers too.

What do the balance board leds tell you? ie. volts per cell.
They come on about 3.6v. You may get by with the high voltage charging in no cell goes much over 3.7v.
They won’t be high long. Between the shunts and normal “drop back”.
If it does just add a cell or two. All the better. :slight_smile:

I better check my inventory. I love talking batteries, but testing and shipping has me burned out. Shelf is getting empty.
It’s hard to beat the green cells for price, fitment, safety, wide temperature range, and easy install.
A cheap voltmeter will give you lvc without the complexity of a bms.

just add a cell . 91v / 26 cells = 3.5v perfect. you well have a little more speed and range for $50 . Dont worry about low voltage cut off . Your gem will be a dog before you get them too low . I can be driving along and notice my gem starting to get sluggish , i have run it down to shut off for testing . cells were 2.5v+ .


hi, new here. not sure how to contact you regarding the cells, are you still selling them?