Navitas AC & 72V Leaf Li-Ion hunting cart

[Sampras1977]

So this is my first cart rebuild. I tried to read as much as I could on the forum before this post.

I got two Precedent 2016 with bad batteries but otherwise in fine condition. Plan to make hunting buggies out of them for our gravel roads with some what hilly conditions. Will upgrade to 23" tyres, 6" liftkit, backseat and other goodies.

I will use the 5kw Navitas controller and AC motor package. Will need to find myself something like 500amp 72V solenoid to go with it.

For powerplant I found a 2015 Leaf pack with 25k miles on them from a salvaged crasched car (paid about $2500). Out of the 48 modules I plan to use 18 on each cart in a 9s2p config (module) which should be same thing as 18s4p (cell). Should have 120ah on 72v (8,6Kwh) available with a nice range. Each module can deliver 100A continous if I am not mistaken, so that should be 200A continous from the pack, that's likely all the juice this AC motor and controller needs on 72V.

Of course I plan to use a BMS with external solenoid to keep the thing from exploding... if possible...

To get started I wanted to get your mighty minds feedback on the best configuration of modules and BMS. Should I opt for two packs of 9 modules in a 9s1p config, or one large pack of 18 modules in a 9s2p config? One large pack mean 4 cells in parallell and monitored together I assume. Maybe this is a bit risky?

If I split it in two battery packs I assume I need two separate BMS but I have a lighter and more manageable battery. I assume I could use the same solenoids so that both packs shut down if either BMS feels there is something funny going on.

Other suggestions or if you think any of this is a bad idea, feel free to chip in.

Thanks for an awsome forum and all the knowledge you guys share. I am very grateful.

[Sampras1977]

Ok so I have decided to put all modules in one pack, two modules in parallell, to increase capacity and peak power. Since the Navitas setup can handle anything from 48-74v I am thinking to use 18 cells/9 modules in series for 18x4=72v in one pack (total 18 modules with two in parrallell).

Then I have enough battery modules for two more packs of 14 modules configured 7 in series and 2 in parrallel for a total pack voltage of 56V. Should be interesting to see performance difference with Navitas AC controller and motor.

I will fabricate the enclosures out of 5mm aluminum screwed together since I cant weld. I am thinking i should line the case with a glued down foam mat used in cars. I also would prefer a tight lid to keep dust out over time. I am not sure if I should put the BMS inside the box or not.

I got all the internals of the Leaf battery box included with the modules, I should be able to reuse some of the bus bars etc. Including pictures.

Here are the chinese parts I am considering:

Charger: https://www.aliexpress.com/item/4000...c00R6z34K&mp=1

BMS: https://www.aliexpress.com/item/3282...c00R6z34K&mp=1

Capacity meter: https://www.aliexpress.com/item/4000...c00R6z34K&mp=1

Any thought are apprecaited!

[st91ang]

Thanks for sharing Sampras. I'm also doing a Navitas 72V build and am rolling with my own LiFePo4 battery build but I'm still figuring out the charger. How do you like yours? I was thinking of finding one with more amperage but yours seems low cost and if you like it then I may change my mind.

Justin

[HogKiller]

I heard AC carts make a whine noise when running. That would be a deal breaker for a hunting cart for me.

[Danimal1228]

Sampras1977, any update? I am doing a Navitas AC conversion on my EzGo Shuttle 6 and will also be doing leaf lithium modules. I can't decide if its better to put packs in series for higher voltage (72v) / lower Ah or to parallel 2 packs thus resulting in lower voltage (48v) yet higher Ah.

Thoughts?