Lithium upgrade Next generation (and update on version 1)

Four years ago i did the first leaf cell / gem conversion ( hard to believe it was that long ago) somewhere on the old site the details exist . Since it hadn’t been done there was no info available so i had to start from scratch . First i looked at all the different lithium cells that were available and their chemistry , then the what would be required to put it all together ( charging , programming of controller , fit , battery meter , weight …After dozens of hours on research i decided on the leaf cells .

one of the hardest things was deciding what voltages to charge and discharge to , not a lot of info available .

so i finally went for it , the results exceeded my expectations .the cart got real fast ( 40 + mph with a stock 5hp motor) , range was low 20 miles @ 35mph cruise and acceleration/ handling was a blast .If Porsche made a gem , this would be it .

After a few years i noticed range started dropping , after some testing it had become apparent the cells were losing capacity. i had read that nissan was having problems with them in hot climates and i live in south florida so they saw hot a lot . Also they were being charged to 4.13v , below their maximum but as later discovered a long term voltage that would reduce their capacity . so Nissan made some changes and produced a cell that is refereed to as the Alligator cell because of the casing . Got a set of those , dropped charge voltage to 4.08 ran those for 2 years . same thing happened . Now i’m run my stuff hard so that probably contributed to it . this pack is still in my gem and runs well , range has just dropped to about 14 miles again at about 35+ mph . The good news is that after all of these years the cells have stayed balanced within 1/100 of a volt ( i dont use a bms) ., after the initial lose of range they seem to have stabilized . i still love this conversion and would recommend it . Gm uses the same Chemistry in their cells but uses a water cooled thermal management system in their cars . plus they undercharge the batteries and as they age increase to charge voltage to retain mileage . this combo has kept owners happy but in our installations will probably have similar results as Nissan.

here are some tips:
keep max cell voltage to 4.05v , 4.0v if you can . try to keep them as cool as possible . dont use 2011/ 2012 cells if possible . if you need more range just do a double pack.

So 4 years later i started looking for the next generation update and found LTO (because of inwo)

Lithium Titanate is an amazing chemistry , you can :

charge an entire pack in 10 minutes
it is highly stable and wont catch on fire if over charged
can be rapidly discharged
can be discharged down to zero volts and left there without damage (this is a big one because multiple people have accidentally over discharged their gel or lithium packs and ruined them , expensive mistake)
has a 25+ year storage life
estimated to have 20,000 discharge cycles @100 dod

nothing else comes close.

the disadvantages are:
a little heavier then other lithium
lower cell voltage so you need more cells
they are expensive

and they’re used in commercial applications and not usually available to the public, until Dave came along .

so Dave got his hands on a bunch of test cells last year and sent me some , i tested them and knew this was it . But i didn’t react quick enough and couldn’t get all that was needed . A few months ago Dave came across some more of them and these were new . so we bought them all, 8 pallets worth, some 53ah and some 11ah.

These come in pouch form so you have to design a way to make them into a battery ( nowhere nears as easy as a leaf conversion) This is what we are doing right now , Dave has come up with couple of prototypes and they work awesome . I am currently trying to make to create a simpler version.(out doing Dave is not an easy thing to do )

hopefully this week i will receive the parts i need and will start assembly . will post some pictures shortly and update as we go.


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thanks for this info will soon start my lithium convert on gem e2
i will use 2015 64Ah Nissan Leaf Battery


12v 100ah shown.
Also works as 24v 50ah. 3 pcs for a small gem pack.

Is that what the bms/charger is for?
How many cells?

Anyone want to follow Mike’s lead, act fast.
I sold out >1000 pcs in two weeks.:sunglasses:
I’m out of 53ah cells.
I do have a dozen 24v 65ah potted batteries however.
Have to wait for Mikes testing.
If he finds that 72v 30s is enough, 3 of these will do a gem.
About $2500 Range.
If not, he could make a 2s add-on kit.


I’m coming up on a year with my 22 cell 2012 lithium conversion. They are working great, I have noticed that maybe the run time is decreasing, but the GEM is liking the extra voltage. I charge 22 cells to 91.4 Volts. I do not use a BMS, but monitor the cells frequently. The run time is not so bad that I would be interested in switching to a $2500 pouch type Lithium Titanate bank, but I will be keeping an eye on how others are doing.

your doing great . the shunt motors love voltage . when people ask me how a stock 5hp motor can out perform a 7.5hp motor , i tell them higher voltage . 91v makes your gem fast . grant is now pushing , i think , 100v . he says his gem is a rocket.

this is one of the things i like about lto . each cell has 2.3v . so you can keep adding cells to get the ultimate voltage you want .

fyi , if you haven’t been in a gem over 85v you dont know what your missing!

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yes first 48volt car are now ready it was charger did stop me but now it repaired.
so now i can start with gem i will use 10 or 11 leaf cell

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here are some pictures of the individual cells and one of the module i am assembling .

cleaning the tabs , coating with anti corrosion grease , then clipping them together . putt one bolt thru one clip for voltage monitoring or bms .

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From what you described the gem can handle over bolting up to 100v. In that case adding another 12v to a stock gem would be an awesome upgrade. Has anyone done a 96v lead acid gem?
Your lithium build sounds awesome. Thanks for posting details, I enjoyed learning about the different automotive cell performance.

I think I did the first 88 volt lithium upgrade. Charging to 100 volts.
Since then I’ve been encouraging someone to test the addition of a 6v or 12v battery to stock Gem.
No takers yet! Certainly not without risk.
The only fatality so far, due to high voltage, is the heater element.
There are ways around that issue too. As all my vehicles are now lithium powered, I have no incentive for more testing with lead.

If I were to do it:
Leave everything stock. Including charger.
Add 6v or 12v to controller only. Ie. connect in series with B+ terminal to controller.
Add a single charger for auxiliary battery.

This will only add voltage to motor circuits. Controller will be spoofed to accept high voltage, as it senses voltage levels thru pins 1, 2, and 17.
Main contactor coil, heater, and other electronics will not see high voltage.
Only the controller mosfets and capacitors will, and I believe they are the same as the 96v model.

I have never tried this. Based on my opinion only. Certainly many risks involved to Gem and limb.

I do know several who over-volted with lithium successfully.
The controller will protect itself from over acceleration by shutting down when you smash petal to floor. This could be a danger in traffic and controller should be programmed to slow things down.
Ask Grantwest for his opinion on performance versus risk.

Kinghappy was nice enough to supply me with a few more cells for testing, and I sent him some hardware to test. I sold 1k in two weeks. Have none left for myself.:disappointed_relieved:
Here are some pictures of the 24v 12s battery I’m building with them.
This is not as hard as it looks. We have all the parts sourced. Know what fits in what.
Soon to be tested on the road.
The large terminals were the last piece of the puzzle. We imported 100 of them. enough to do many Gem conversions. Other parts are off the shelf.
LTO batteries are limited. Mike has the only supply in the country, and less than 1/2 price.
We will both be here to help with conversions.
Can’t speak for Mike, but I’m betting he will make the first brave innovator one heck of a deal.


Michael, notice the final terminal design.
The first pictures were a fail. Would not fit properly in ammo box.
Terminals were turned 90 degrees, facing up.
All four bolts going thru hdpe plastic sheets used as compression plates.
Rock solid with no stress on foil tabs.
These 12" x 12" 3/8" sheets are available from Zoro. A great company with free shipping.
Menards has them in 4x8 sheets for less money, but this is so convenient.

Only thing needed is a foam, rtv, or resin base to support pouches from bottom.
Just an 1/8" or so.
Do you have plans, or nothing needed?

I just purchased a 2002 Gem needing batteries. I’d like to do this conversion and willing to be a test vehicle. I just emailed the seller on eBay whom i assume is Dave or Mike here?

should finish my install this week . been really busy and haven’t had much free time . i have 6 of the black modules that inwo posted pictures of arrving in about a week . i m going to hook those up in a gem and test . will keep everyone posted .

That’s me.
If you can wait for Mike’s test, the LTO may be a good choice. I have 15 24v modules here now.
Check out dimensions and specs. Altairnano | 24V 70ah battery module | battery 24v
The Chevy Volt conversions are Gem tested.
Four 12s modules fit and can be configured for 80v or 90v easily. Ryan has tested both.
I prefer a BMS, if for nothing else, peace of mind. BMS-24 displays all 24 cell condition at a glance.
I make wiring harness and accessories to make the Volt conversions work.

Just spoke with Inwo through eBay about the conversion. I want to do this and will follow Ryan and the rest.

Info from Altairnano:

Hello Dave,

Thank you for your interest in Altairnano’s technology. Altairnano’s 24V 50Ah
modules are based on our nano lithium titanate chemistry which allows for high
power rating, fast charge and discharges, as well as a very high cycle life.
When paired with a development kit it provides a test bed for the evaluation and
application of advanced lithium-ion battery technology for prototypes, new
application development, and for improving performance and reducing cost for
existing applications. The cost of a standard kit which includes the Connection
and Control Unit, Wiring, Battery Management System, and one 24V 50ah module is
$5,000 USD. Additional modules for series operation can be purchase at $3,000
per module.

If you are interested in discussing this further please feel free to contact me.

Best Regards,

Ok great. We just talked via ebay and responded. Glad to make the connection with you. I can wait, I pick up my GEM next week.

i have been really busy and haven’t had time until now to finish this project . i decided to start with 33 cells . 11 cells per case . a 12th cell will fit in each one so it could go higher. landed up doing two different end terminal setups .one comes out the top and one comes out the side , will have to see which i prefer . the cases fit nicely under the seat with no modifications , might eventually put them under the rear cover to free up space under the rear seat . starting with the Deltaq charger set to gels to see how it does . this build was much harder then the leaf builds someone would have to have a good electrical knowledge to build this from scratch .

should have test results tomorrow

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