High Voltage Gem car

I have not shared my latest hobby in a while. It’s building lithium power packs. They can be used for Power walls (home back up power) Electric boats, Gem Cars, Mega Stereo battery’s ect you name it. It starts by getting battery’s out of crashed / wrecked electric cars.
This is a pallet of lithium battery’s

Once I get the battery’s I can make them into what ever size and voltage configuration I want. For this project I started with a 20 cell battery pack that’s a 12Kw system. This is going into a Gem car so this battery is gonna be 82-86 volts

You can see the battery’s are module and you can stack them together to make what ever you want as far as voltage or amp hrs. Once the battery’s are all linked together they can be wired and configured. Additional monitoring wires need to be added for balancing and charging.

Final assembly and then it can be installed.

Here is what it looks like installed.

This 12Kw system makes for a Great fast reliable long range car. The cars normal voltage is 72-volts so bumping the cars up to 82 volts gives the car a bit of a performance bump. Each cell is 4.1 volts and the car had 20 Cells. 4.1 volts x 20 is a 82volt pack. I was able to split a smaller 8 cell pack into 2 sections. Each section is 4 Cells and has a total of 16 volts.

So this new battery was prepped. A battery terminal and charge and monitoring leeds were added.

Then it’s installed

Now the system is up at 99volts. The stock electronics needed to be hacked to allow higher voltage and becides the cars Heater (that can’t take 99 volts) all the electronics are happy. Here is a shot of the BMS (battery monitor system) you can see in the right hand side 99volts.

The new system is awesome. The Extra voltage wakes these things up big time.

I have built and shipped a few turn key systems and it’s cool to see what people are using these for.

BTW shout out to the company “ship a pallet” aka (pro ship) makes shipping heavy delicate items like this a snap. It only cost $250 to ship this battery to KC got their in 3 days

G- I’m getting a 2019 Polaris ranger ev that has lead acid and would be interested in converting to lithium. I would have no idea where to begin is this something you could help with?

Yup that’s right up my alley. I would need the Rangers voltage 48 or 72. And then the size of the battery compartment we are dealing with. And then it’s about how big of a pack you would like? (How much range) your looking for and I could source that battery’s build a pack, configure it get a charger programmed and get a BMS all wired in and programmed. I could ship you a full assembled battery pack. All you would do is install the pack and hook Pos to Pos and Ned to neg and your done.

That would be pretty awesome- are you in Tulloch? I’m close to Modesto. The Polaris is 48v not sure the ah what would you estimate all that costing?

Yes I’m at Tulloch so your close.
BMS $350
Charger $350
Battery’s $2000-$4000 depending on how much range/power your looking for. The smaller the pack the cheeper it is. Typical Flooded Lead Acid packs have a life of 3-5 years that’s about 300-500 charge/discharge cycles. Lithium has a 5000 Charger / discharge life span. So yes they cost more but they last longer then your gonna need. My advice is if your gonna keep this Ranger get the biggest pack you can afford.

awesome hobby there has to be a ton of people thankful you took your time to figure this out! Sounds like it makes sense for me to make the transition when my batteries are closer to toast which could be a year if we're looking at 300 charge cycles. Btw who did your garage floor coating? I have a thread for custom home upgragdes and need to find a better solution than home depot offers i can do myself or an elite solution i can hire out.

also do you have any gem cars for sale? I know my brother wants a 4 seater, doesn't have to be pimped out

That's so cool G

My orignal Gem got a 24 cell Lithium upgrade, this car flys.

I have a buddy that has a great 2002 4 seater it runs but it’s fixer upper he is only asking $1000 email me if your Intrested. The car is in Pleasanton.

that's cool G!

All Electric cruiser boat comming soon!!!!!

Green For St Patty’s

X3

LED light Bars

Daylight

You interested in selling one of those?

All these cars are sold/spoken for. I do deal with cars. Only downside is the cars I build are pretty expencieve. If you don’t need a long range fast cart then my cars are not worth it. Plenty of other short range cars for 1/2 of what I sell myn for. 7-10k of what I sell cars for is made up of the Battery/BMS/Charger. Most people don’t need a 16kw Cart.

Could I pay you to complete a lithium conversion on my existing GEM?

The Early cars do not convert well. The problem is the Early cars have the suspension set up for the weight of the heavy Flooded lead acid battery’s. When you remove the weight from the Early cars and install the light weight lithium the shocks just don’t work. They lock fully out and the car literally bounces down the road. Un driveable, and dangerous. That’s why I went back with the Air Ride shocks on my old gem. And that’s a whole nother project. The newer cars are so much better set up for lithium. And in my opinion if your gonna spend the money for a lithium conversion you wanna do it in a car that will hold its value. I take the cars down to nothing and replace all the bushings and shocks so they don’t squeak and creek, New Motor, New Speed controller, New Charger.

What years do you recommend?

2008 and newer

Thanks, appreciate the advice.

Grant, have you done any more with the home/powerwall type application?

Besides building them no. Just built them and the people used them for their own applications . What are u looking to do?

Building a home with pv and will need storage... doesn't seem like there's much out there commercially to complete with Tesla...

Yup. Tesla has got the power wall market right now. How many Kw do you need.

I could build & Ship you a Chevy Volt or Chevy Spark or Chevy Bolt Power wall system. My Gem is 14kw. Not Sure how much power you would need. Most power walls are in the 20kw range. Tesla’s power wall 2 is 13kw and it’s 6k. I can do it for less then 1/2 that price. A entire Bolt pack is 60 Kw. Thats right about the same size battery pack Tesla puts in its shortest range car 65Kw. I would go with the bolt for its size and shape (it’s flat) the battery’s are LG brand, so it mounts on a wall nice. Solar controllers and inverters are another subject. So let me know how much power you need I’ll get you a price.

Architect and consultsnt are still working on the system design and I’m trying to get my head wrapped around the whole thing. PV system will likely be around 15-20kw. Early proposal had roughed in 5 powerwalls but that may have been based more on the output of 3.3kw than the storage? Heading into the actual design phase soon so I should know more and will reach out. Thanks!

Grant what do you consider long range and high speed ? im looking at a 10 mile round trip and need to go AFAP , 35+ . I've got a street legal golf cart gas right now that maxes at 25 and it feels to slow on the road. (these roads are 25 and 35 mph speed limit) BTW , i came on here looking for the gem car post and boom! thank you!

Getting a golf cart to do 40 Mph you need to do some serious Mods. Getting a golf Cart to do 40 and make it feel like it dosent wanna flip over and kill you FORGET IT. Example taller wheels. Bigger Gears, High Speed motor, the list go’s on and on. Your cart has a Tire and wheel size that was made to Maximize your electric motors Highest RPM. So I’m sure your golf carts top RPM is in Sync with your motors Near Max RPM. This has to do with your cars Gear Raito in the transmission. You start making that motor spin faster with more Voltage and BOOM! I have heard horror story’s of motors locking up in High speed carts & people getting thrown threw the Plexiglass window. Now with $ anything is possible you can mod the heck out of them, but in My opinion trying to make a golf cart do 40Mph for 10 miles straight. Is like putting a wake boarding tower on a JET SKI. Sure it can be done but WHY they have much better ways to get it done.

That said a Golf Cart is a 100 times better rig for golfing. Gems and Thinks suck. But for covering longer distances at high speeds in the NEV ( neighborhood electric vehicle) category you ain’t gonna beat a Gem.

Last week I got my Gem going 54 Mph took my hands off the wheel the thing drives straight as a arrow. Get a Golf Cart going 30mph a white knuckle experience.

Crap I just re read your post You have a gas motor. But the Gear Ratio & Chassis & suspension designs limitations still exist. I hate to say it but I don’t have any good advice for Modding your golf cart except for just throwing Lott’s of money at it. For $6-7k you can buy a used all electric Fiat 500e take the doors off it and you have a 100Mph golf cart with AC and all the bells and whistles.

Haha !! Thanks Grant ! Totally agree on the speed / safety. That’s why i Was thinking of sellIng the cart and getting a gem instead . Thanks

Newer gems are overbuilt. They can go 50MPH with no drama. When Polaris took over and grafted a Polaris Ranger UTV front end of 2013+ Gems they became more then capable. That’s when they crossed over to a suspension platform with large disk brakes and nice big round A Arms and Shocks and tie rods.
Compare this front end to what’s under your golf cart.

Here is a typical Gem car ride.