Basic Nissan Leaf 7 module Lithium setup with Generic Chinese BMS

[cowsgonemadd3]

I have been reading a bunch of pages but I had a quick question. What's the average price for a basic build like this out the door charger and all parts? My cart needs a new set of batteries and a good set of US batteries will run me around $850.

I don't need 50 miles of range so a lithium pack of 7 cells would be fine. We average less than 10 miles max driving per day. I suspect that won't change.

I already have an upgraded navitas 440 controller and upgraded motor.

[DaveTM]

Originally Posted by cowsgonemadd3

I have been reading a bunch of pages but I had a quick question. What's the average price for a basic build like this out the door charger and all parts? My cart needs a new set of batteries and a good set of US batteries will run me around $850.

I don't need 50 miles of range so a lithium pack of 7 cells would be fine. We average less than 10 miles max driving per day. I suspect that won't change.

I already have an upgraded navitas 440 controller and upgraded motor.

[cowsgonemadd3]

Do you believe it is worth double the cost of new US batteries to go DIY lithium?

[Pat911]

If you can afford it, without a shadow of a doubt. Significant performance upgrade as well as little to no maintenance, faster charging, longer life, reduced weight, the list goes on.

[Volt_Ampere]

Not to mention that they should last at least 2X as long so the cost is similar to FLA in the long run.

[fstop]

Originally Posted by DaveTM

Lots of creative solutions in this thread!
FWIW, I'd consider deleting the plywood cost and think about having a sealed steel firebox fabricated to contain all of this in the event of a failure, especially if the cart stays in your garage and your garage is part of your home. Both of my LifePo4 packs have been enclosed like this, and my opinion is that it is a wise line of defense for LifePo4 packs and likely even more so for DIY Leaf packs such as this.
So I'd add that cost in to the list, and while I realize we're talking Leaf cells here, if anyone is comparing costs between DIY and manufactured packs I'd also consider what your time may be worth.

[DaveTM]

Originally Posted by fstop

Lots of creative solutions in this thread!
FWIW, I'd consider deleting the plywood cost and think about having a sealed steel firebox fabricated to contain all of this in the event of a failure, especially if the cart stays in your garage and your garage is part of your home.

How do you keep the pack cool when you are charging it? Wouldn't a sealed firebox raise the charging temp more?

[Pat911]

Lithium cells do not warm up much during charging, If they do, you may have bad cells and that should be investigated. Having said that, a metal box will dissipate heat much better than a plywood one.

[fstop]

Never had any heat issues - no surfaces of the box on my old RoyPow or current 72v ever even get warm.

I think the main thing is to prevent oxygen from getting to a potential combustion event, and obviously steel can hold out under a situation like that longer than wood or other combustible material.

I've noticed that all terminals, screws, etc. that go through or into the case are all sealed with black silicone (high heat resistance) to prevent feeding a potential failure with any additional oxygen.

BMS units can and do fail, cells can and do fail (and I'd think ones that are 8-10 years old and you have no history on may be more likely to do so) so this is a good way I think to hedge your bet in case of such an occurrence.

[Volt_Ampere]

Lithium will burn without oxygen. It is very difficult to contain a Lithium fire in a large battery and it is very difficult to put the fire out. The pressure will rupture a sealed box - not good. The BMS is a backup in case the charger fails during charging. It serves other purposes but that is the primary one when it comes to reducing fire risk to an acceptable level. Our lives are now full of lithium batteries.