Understanding lithium for Gems

Thanks. I’ll hold off on purchasing the LifePO4s until I hear from you about the Honda.
It looks like it’d be about $1k to ship the Teslas to my address, and that’s the only thing holding me back.

I’ll need a new charger to go with the Tesla or Honda as well, correct? Do you sell those too?

I’m sure we can get you that telsa battery delivered for way less than 1k. If that’s what’s holding you up. We have a shipper we’ve been working with. As long as your a little flexible with the dates.

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Thanks @Erniea15!!

@Inwo - I’d love to order the smaller Tesla set from you, but George is leaving for the west coast on Friday, and I’m not sure if that’s enough time for you to custom build.

Also, I’m sure you know this already, but the battery compartment has these slanted bars that reduce the usable space. Do you know if the batteries will fit and can you share the dimensions?

I’ve also measured from the back to the front, and it’s about 2" shorter than the batteries which I may be able to work with, and 14" wide.

I’m afraid not. It’s on the back burner until some other projects are done,
The one I have is 40" long which would extend to the rear axle, or poke through the front of the rear seat a couple inches.
I think the height and width are ok.

Ah, okay. I will let George know.
I will reserve the smaller Tesla batteries then and wait until you’re able to get to it (hopefully not too long!)
Can send you a deposit if you’d like, so let me know. Thanks

A smaller one is not a done deal as it requires 2 cuts and more waste.
As long as I know you want it, I can start planning. Remember, I have a Honda coming in this week.

If someone wants the 24s Tesla, George can pick it up tonight. Delivery when he’s in the area. He gets all over the country.
Mn. to Washington this weekend.

Dave, I’m very tempted because of the huge jump in range…

Not sure what I would do with the large volt pack (22s2p ?) that you installed though…

And then there is that 96v delta-q you modified that I have sitting.

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Clock may have run out this trip. He said later tonight he’d be passing by. 6pm is late for me. :slight_smile:

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No worries my friend.

I am fairly serious, although I feel I really should actually plan the next steps better. I’m kind of passing the point where spontaneous engineering is viable…

Did you receive the Honda batteries? Not sure how they compare to the Teslas - perhaps shorter range?

In any case, I am definitely set on buying a set from you so let me know. Thanks!

Yes, I did.
Does not look promising. All are 44 volt 12s, so can only assemble high voltage Gem batteries from them.
Have not measured them, but specs suggest <30ah.
On the plus side, very nice package. Same size as E-Golf physically.
image

It will take at least 4 modules to supply enough current and 60ah.
6 modules = 88 volts 90ah (not yet measured) 3p24s at cell level. 3p2s at module level.
$250/module includes pigtail (on order)

Thanks for your response! What does this all mean for someone not so technically inclined?

“High Voltage” - more oomph but at the cost of …? Feel like there was a bit of a negative undertone. Will i need a new controller?

“90 ah” - think that means much shorter range compared to the tesla batteries?

“3p24s at cell level. 3p2s at module level.” - no idea :grinning_face_with_smiling_eyes:

High voltage pushes everything to the limit. Many have done it, but not for everyone.
3p24s means 3 cells in parallel for 3 times the ah. 24 cells in series. 24 times the cell voltage of 3v to 4.2v. 3.7v nominal.
Tesla is 225ah. Honda is less than 30ah I believe. Testing one now.
It would take all 14 Honda modules to equal the Tesla battery.

I’m not a fan of connecting modules in parallel, but no other choice, and it’s common when using Volt batteries.

I have a different opinion than Inwo when it comes to high voltage. But know Dave is way smarter than me so… We have been running Gems up to 97v for years, to the best of my knowledge it has not caused any break downs. the Dc converters are rated this high so shouldn’t be a problem. That leaves controller and motor. When voltage is higher amperage becomes lower, Amps is what causes heat, heat is hard on motors and controllers. Assume you are cruising at 35mph, Your motor will be using a certain amount of watts. Formula is Watts=Amps x Volts. So if your volts are higher your amps are lower. Should be better for it.

But reality is your Gem will be Much quicker and faster. And if you race it around it will take its toll. I drive mine like it is a Porsche, Tires don’t last as long. But that is the price of performance.

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FYI @grantwest has run even higher voltage. I think he tried 100v. I found no improvement above 96v so that is where I run them.

What would be involved in using these batteries, is connecting 2, 3, or even 4 in parallel.
Positive to positive- negative to negative. Ah rating adds. 30-60-90 etc.
Then the pigtails shown above are connected pin to pin. A terminal srip should work good for that. That will connect each of the 12 internal cells in parallel and lock them together voltage wise.
These modules are small, light weight, and should be easy to fit.
The only downside is wiring multiple sections together.

IMO, use the Tesla. If there is any possible way to fit it. Even if it sticks out 2 inches through the front of the back seat.
Or if it can be raised enough to go over axle, and modify the spat.
image

Wish I had a classic car here. I’d find a way! :slight_smile:

Thanks Inwo.

I really don’t like the idea of it sticking out through the front of the back seat.
My Gem is primarily used as a golf cart, so the 40" long battery will stick out too far in the back and eat into the area where the golf bag stand sits.

What’s the verdict on the custom Tesla battery you had mentioned? I don’t mind (may actually prefer) the higher voltage Honda batteries, but the installation seems more complicated and your comment about connecting them in parallel bugs me.

I’ll primarily use the car as a golf cart and to drive around in our development (many hills), so don’t need the super long range that the 40" Tesla batteries will bring.

I’m happy to make a deposit, so let me know.

It will be a while before I find the time to build another battery.
Sorry to keep you waiting.
@Erniea15 may be able to help you with some Volt modules.
Nothing else for now.
I’ll post a picture when I get a Honda battery together.