2002 E825 vs. Yamaha G29

I just got my hands on a E825 - Friends of ours had it sitting in the garage for the last 8 years or so.
I’m trying to wrap my mind around all these battery options and $$$ to get it back on the road.

The E825 cosmetically seems to be in like new condition - The batteries stamped 2008 are junk.

My yamaha is/was about to be moved from NY to FL and become our fun vehicle for beach and cruisin around town. And now the E825 comes along. I figure I’ll get the GEM going and let the wife pick.

I took a bunch of pictures of what is currently on the E825 - turns out our friends had a need for speed
( the previous owners, two left over hippies in their late 70’s had did some modifications.
Janet tells me it did 40mph, I’m thinking yeah right, what ever. Nancy her life partner has since passed away and held all the secrets to the Gem mods.

I’m seeing a modified charger with a GEM 4 Fun sticker on it. set up for AGM batteries.
and blue motor with a GEM Ride 4 Fun sticker - and a business card from Joe Gallardo

and looks like bigger wheels and tires 195/60 R14
I’m not sure if there is truth to the 40mph claim on 6 batteries .
I dont know if anything was done to override the factory speed limit

I done a few nights of heavy reading on this forum trying to get up to speed with the lingo. I’ve made some progress but still choking it all down.

What I’d like is 35-40mph and 50+ mile range.

I see Lifepo batteries maybe 26-28 cells to bump up the voltage and 120ah to 170ah

I’ll upload some more pics since its all new to me and I’d rather you guys confirm everything visually.

Thank you in advance for everyone’s help in getting this GEM back on the road -

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Welcome to the madness. Be sure to run the VIN at nhtsa.gov and see if the parking brake and DC converter recalls have been performed. (Can’t tell in your pictures). If open, Polaris will complete for free.

Thanks for that tip. I’ll check it out.

For now all I can do is sit in the drivers seat and make electric motor sounds. makes me think of the kids in the ChittyChitty Bang Bang movie I watched as a kid.

Keep the Yamaha for the beach, GEM’s are useless in the sand.


Don’t worry the beach in Florida is hard packed like driving on asphalt. It open to all vehicles.
Just like Daytona Beach. You could push a wheelchair down it.

Got my eye on these cells.

The 120 or 125 are not rated at 300amp surge
I thought Inwo or lithiumgod mentioned in a post that we should be looking for 300 surge capacity

The 176 size is rated at 350 surge

But I’m thinking by bumping up the voltage to 86v or higher will cut down on the required amp draw. Right?

Also will my current charger be able to charge the lifepo and at higher voltage?

The 300a capacity is a good start. The lfp from China are so cheap that there is not a good reason to cut corners on c rating.
25 cells is a good number. The early gems won’t run much higher voltage.
You will most likely need a new charger. You can try charging with anything to see how it goes. The bms will protect battery.

I’m was trying to buy cells in the USA
I feel like The China stuff will never get here

Do you have any Batteries your putting together?

Yes, but not for that kind of money. In the next couple days I will have 82v 22s 90ah new batteries.
24x16x7 110lbs.
Shown with 400a jk active balance bluetooth bms. Ready to drop in.
Most are pre-Sold. About 4 left as of today.

What do you feel my range and speed would be with your pack?
I dont mind spending a little more for a better battery. After all the battery is the life blood of these cars

The first sample went to a Gem in nj. And reported 30-40 mile range.
40 follows my 200wh/mile rule of thumb.
Speed depends on many factors, but this battery will make it run like it would with full charge, all the time.


I have an original 2005 with lead batteries, what would I need other than your setup to convert and what kind of money are we talking? I do have your MM.

Our location is flat, no hills and top speed is only 35 per road signs.


Nothing else needed. This battery is ready to go. Connect the two Gem battery cables.
Ideally, reprogram your charger, but 86v will charge to ~80% capacity. Iirc @LithiumGods found a lead profile that went higher than that. It really make little difference as the bms controls high voltage cut-off.
This one is $3,000. New in box.


What is physical size?

Any idea on what I can do with my lead acid batteries?

Wife is hesitant, will you be doing more after this round?

Metal recyclers will buy your old lead batteries, sell them on Craigslist or just donate them to an auto parts store.

If you have one good one, save it to run a light bar or high power stereo.

24x16x8 inches. 120lb.

This is a one time purchase for me.
I will try to get more but never know when they are available…

Dave, it fits perfect!

Just mocking it up. I Cut a quick piece of plywood and shimmed it up off the frame with a scrap of 2x4.
I still have some room to go higher. Probably go another 1” and that will will give plenty of room over the A-arm.

For wiring. Looks like positive from the battery will go straight to the fuse before the magnetic switch.
And the negative will go straight to the B- side of the controller.
Every wire is orange on this thing and I’m not seeing much of anything marked pos. Or neg.

Yes, negative being the Anderson plug from bms.
Bms may or may not have the outputs turned on. Go to “control” set both to “on”.
Pw is 123456
Pairing is 1234

Nothing wrong with that. I mounted the batteries for my gem1400 on marine plywood sprayed with flexseal.