DIY 101 - 14 cell Nissan Leaf lithium pack

[Pat911]

Hi,

10 modules is correct for a 72v pack, giving a fully charged voltage of 84v. Your 72v controller will certainly be ok with 84v.

Cheers
Pat.

[bmuh]

Originally Posted by Volt_Ampere

You can certainly run 9 "modules" which is 18 cells which will give you a max of about 72V. It will run less than that most of the time. (more like 68V) 10 modules will give you a max of about 80V which might be too much for your controller. I would check on that and if it's not too much, then go with 10 modules.

Ok cool. Thanks for the quick reply!!

[bmuh]

Originally Posted by Pat911

Hi,

10 modules is correct for a 72v pack, giving a fully charged voltage of 84v. Your 72v controller will certainly be ok with 84v.

Cheers
Pat.

Thank you!

[bmuh]

So I’ve decided to start with a 14 module pack first until I understand better what’s needed to step it up to 72v. I have the packs ordered (eBay) and now I’m looking for a solution for BMS, charging and protection. In the two years that have past since this thread was started, ZEVA has stopped stocking most of the products I saw the OP using. But honestly, with the hit my wallet just took on the battery purchase, I’m hoping to complete this build without much more cost, but with the possibility to grow to a 20s pack if desired. Assuming the cost isn’t too much higher. Lol

Simplicity is important to me because I share the cart with my wife and daughter. I need the ability for them to just plug an extension cord where the factory charger port is (club car precedent) and walk away. If that isn’t something that’s possible with a 72v build, then it isn’t worth it to me.

With that said, what components would you all recommend to complete this build considering what is available these days?

Ben

[Pat911]

Hi Ben,

The “Cheap Chinese” BMS’s available on AliExpress are very good, especially the ones manufactured by JBD. JBD BMS’s are used in many (most) off the shelf lithium packs, whether they be 12v, 48v or 72v.

I’m assuming you’re still going with Leaf cells so for 48v you will need a 14s BMS, for 72v a 20s BMS is required. (If you’ve since changed to LiFePO4, let us know as it will be different).

There are some expandable BMS’s (10s-20s or similar) but it’s best to get a dedicated BMS, either 14s or 20s so upgrading to 72v will mean a new BMS.

Cheers
Pat.

[bmuh]

Thank you for getting back to me Pat.

I see the 14s JBD BMS on the site. Does it matter if the ad says it’s for 80-120 amps? Is that for the charge current, or is that the current when driving? Also, are these easily programmed without an external screen like I’ve seen for others?

I ordered 14 Leaf modules. Aren’t those LiFePO4?

Which charger would you recommend?

How about the high and low voltage cut? When I ordered my navitas conversion I also ordered and installed a Curtis Albright 350a solenoid (model SU280). This should suffice, right?

Thanks again,
Ben

[Volt_Ampere]

Leaf modules are not LiFePO4 chemistry. They are LiMn2O4 with LiNiO2 from the spec sheet. (at least the older modules I have)

[Pat911]

LiFePO4 has a nominal voltage of 3.2v, As Volt_Ampare states, Leaf Cells are different with 3.7v nominal.

A 48v leaf pack has 14 cells, LiFeOP4 has 16.

80A is ok if you don’t pass the discharge current through the BMS but you’ll need a way of disconnecting the load under low voltage conditions. See here…..

https://www.buggiesgonewild.com/showthread.php?t=160302

Cheers
Pat.

[Volt_Ampere]

I don't recommend running the motor current through the BMS. Use relays to disconnect the pack under low voltage condition and use the controller to limit the max current to safe levels. Good cells like the Leaf cells can handle the high starting currents no problem. I think I have my max current set in the Alltrax at 350 amps and I never hit that in the logs I have made running at full throttle from dead stopped on level ground.

[bmuh]

Thank you both. So I’ll order the BMS from the site suggested.

How do I set up my pack to disconnect with relays in the event of low voltage?

Ben