Lithium Woes - How to avoid house fires!

[Goliath]

I specifically chose this system for the BMS. It's supposed to cut off the cart in a low voltage situation, but still have an "emergency reserve" to drive another mile or so, after generating a warning.

But, I'm guessing my BMS was the cause of failure, as it should have shut off WAY before the 5+ volts the damaged cell attained. Having been in the auto service industry for over 30 years, I can say I've seen my share of factory defective parts, this is just the first time I've had such an in-your-face experience.

My recommendation to new lithium installers (aside from using the LiFePO4 cells) would be to incorporate a foam surround in the battery box at both the top and bottom, as in the picture I've attached. If I hadn't done that, either the battery box would have failed, adjacent cells damaged, or the cell itself would have burst out the top for lack of space.

If multiple cells in the same row fail, however, there may not be enough space for expansion. Another idea would be to make the battery box expandable, for the unlikely event of BMS/cell failures.

[BobBoyce]

And 18650 cells go into thermal runaway failure on a nearly daily basis worldwide. Whiskers growing in cells puncturing seperators when cells are stored fully charged, is just one failure mode that is on the rise due to manufacturers (mostly in china) cutting corners to cut costs.

I was impressed with how the leaf cells handled that failure.

[Goliath]

Scary about the 18650s.
I've got several devices that use them, and a few large bluetooth speakers that have banks of them.

[cmcnice]

Originally Posted by Goliath

I got the 72 AH 48v kit.
I bought it in January, as they have an end-of-year sale every year and it is $250 off the regular price.

I paid about $2,200 for everything, which is very reasonable for a complete system, and I've read good things about the LithiumBoost system.

I've heard the price went up a little, but that could just be a rumor. You can email Tsipi (Sam's wife) and she's pretty quick to reply with a quote.

I don't endorse their system, as I haven't used it yet.
I will say that so far, they have been excellent at communication, and the owner is sending me a whole new BMS and 5 new cells for that row.
As long as they follow through, I would do business with again.

An interesting aspect of their system, which I'm not sure other systems have, is their management of power cutoff. What I mean is that they have a proprietary harness that comes off the BMS that goes to the ignition switch. There are two other wires that go to the original ignition wiring. When the BMS detects the batteries are getting low enough to do damage, the BMS sounds an audible alarm. If kept driving too long, the BMS takes control and cuts off the cart. After that, there's some kind of mode to re-enable the cart for another mile or so, but it's designed to prevent an under-volt situation.

Not sure if that's present in other BMS systems, but thought it was handy.
.

Goliath- Interesting and informative experience, thanks for sharing. I've been communicating with Lithium Boost about the 36V system as well and likely going to get it. Have you gotten it up and running yet with the new cells?

Couple other questions was hoping someone can help me with -- Other than mileage and driving time is there any advantage the larger Ahr systems? my current cart is lead cell 36V powered, doesn't that mean I can't get larger battery pack without changing the motor etc? Any answers are appreciated. Thanks.

[Goliath]

I just received the replacement cells and BMS last weekend. I've got the cells back in the box, and the BMS mounted, but haven't wired it yet.

I should have it wired by the weekend.

Before you buy, you may want to see if you can run that motor on 48v.
You'll get more speed out of it.

The larger amp hour rating will help with distance mostly.

[cmcnice]

Originally Posted by Goliath

I just received the replacement cells and BMS last weekend. I've got the cells back in the box, and the BMS mounted, but haven't wired it yet.

I should have it wired by the weekend.

Before you buy, you may want to see if you can run that motor on 48v.
You'll get more speed out of it.

The larger amp hour rating will help with distance mostly.

Sounds good. Can you share your wiring experience (what did you have to get that not come from Lithium Boost) and specifics to your box build and mounting? Want t get everything I need before everything arrives. Appreciated.

[Goliath]

You first need to decide if you're going to stay with 36v, or go to 48v, then pick the amp hour rating of your kit.

The 72Ah cells are a different size than the 100Ah.

[BobBoyce]

Originally Posted by Goliath

You first need to decide if you're going to stay with 36v, or go to 48v, then pick the amp hour rating of your kit.

The 72Ah cells are a different size than the 100Ah.

The new 2018 Leaf pack modules are double the height and are heavier. A single module is now 112.6 AH nominal and 14.4V nominal if wired 2p4s.

[cmcnice]

Originally Posted by Goliath

You first need to decide if you're going to stay with 36v, or go to 48v, then pick the amp hour rating of your kit.



The 72Ah cells are a different size than the 100Ah.

I decided on the 36V/60ah system which is 11 cells.


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