Basic Nissan Leaf 7 module Lithium setup with Generic Chinese BMS

[Sergio]

There are lots of ways to create a box to protect the pack, but if You are building a 7 module pack I think the $60 box from TechDirect saves a lot of fabrication time:

[molfpedal]

I used clear Lexan. Unbreakable. And easily drilled without cracking. Also used in the cart tub as a water shield from the rear wheels

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[DaveTM]

Lexan is good stuff.....and pretty indestructible. I have a piece that is my roof. I've covered it with camo vinyl stick on sheet. I've smacked and whacked a lot of low hanging small tree limbs and this stuff just doesn't break!!

[yensidcamper]

Glad to say batteries are on the way! BMS on the way and I have 90% of the other needed items. I'll be working on this for the next month and a half around my work and travel plans.

A couple of questions as i continue to educate myself, do the BMS wires have to be the same length? I have noticed from reading this forum on several builds they have not been kept the same length.

Sergio, it appears you have a fuse on the positive battery cable attached to the stud. If so, what size fuse? How do you determine this fuse size? I see many builds use a 400 amp fuse.

Thanks again for all the guidance.

[Sergio]

You should try to get the BMS tap wires reasonably within the same length since you are trying to keep the cells balanced to a few hundredths of a volt of each other.

Make sure each tap wire is also properly crimped to the ring terminal.

The fuse is the original that came with the Alltrax controller, I think it is a 300 amp.

Those fuses are slow blow and will not open until more than twice that current, the main purpose is to isolate the pack in case of a short.

[Volt_Ampere]

BMS voltage sense wire length is not critical as there is no current draw on them when the voltages are being measured. (at least there should not be) My own design BMS does not sense voltage during balancing when the BMS is drawing an amp through the sense wire. It turns off balancing for a second to measure the voltage during balancing.

[_ogre]

while i'll probably never convert to lithium (new fla last yr) i just read thru this whole thread, today. the knowledge on this forum is amazing. sergio has answered every question very thoroughly, posted schematics and diagrams. volt_ampere kicked in when needed. you guys are pretty amazing, as is this forum

[cmysstailights]

Originally Posted by gn386

[emoji106]+1 on Drew his work is sweet! He did these for me. He also does covers but my aluminum covers came from elsewhere. Don't mind some of the temp stuff I did to get charging/testing on bench.

Thanks, that looks sweet. Might have to hit you up for info on splitting the pack

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[yensidcamper]

7 Leaf Batteries arrived today. I realized I need a more precise multimeter as mine only measures to one decimal place. I don't want to spend the kind of money a Fluke would cost so does anyone have a good recommendation for a meter below $100?

All but 2 cells measured 3.9v and one fluctuated to 3.8 and the other to 4.0. What do you guys think, should I go ahead and parallel these to balance or wait till I get a better meter for a better reading?

I got a good deal on these from Tech Direct. I think because they all have the bracket on them. I have seen several pictures where packs have at least one of these brackets. I don't think it will interfere with anything.

While I wait on the box and buss bars, which I ordered, separately, I will pick up the 5/16 all thread tomorrow and bundle them together. I think this should be fine without any end plates since they are Gen 2. I understand those only have to be held at the corners. Right????

The BMS is due mid June from China even though it has already left China via plane on June 2nd, it just hasn't landed in this country yet according to the tracking info Aliexpress shares.

I have begun wiring the HV and LV relays in the box. Moving slowly but that is fine if I can have completed by July 15th I will be a happy camper.

Anyone see anything amiss or have any suggestions at this point. Thanks to all who contribute you have inspired me to try this build.

[DaveTM]

I would wire 'em up to balance for now. It can't hurt to let them self-balance. Wire 'em up as I did in the pic below.....but don't forget (as I did in the pic below).....and I did a few days later.....to wire all the middle terminals together.

The wire I used was a light gauge......but I left 'em wired up for a few weeks while waiting for the other "stuff" to come.