School me on Lithium please

[MyCousinVinnie]

What's the ideal range for cell min and max of the Nissan Leaf? As in what do you (NCPW and DaveTM) have your range set at for battery longevity? I think I've seen 4.15 to 3.2??

[DaveTM]

My LV cell minimum is 3.14\cell or 44V-pack. Max HV is 4.07\cell or 57.0V-pack.

[MCJEFE]

Based on my driving and charging habits I think that I'll be adjusting the charger cutoff voltage and LV disconnect. I'm finding that most of the time I am only using the top 1/2 of the battery and seldom get down into the bottom 1/4 and have only needed to go below 52v a couple of times. Since it's recommended that Leaf cells be charged to 80% for maximum life I'll be moving my voltage parameters.

FWIW here is a Leaf discharge curve that I doctored up with my current settings. Right now I charge to 58.4 (4.17) and my LV disconnect is set at 47.8 (3.42). I'm thinking that I will adjust them to something around 57.4 (4.1) and 45.5 (3.25) for my LV disconnect.

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[NCPW]

Originally Posted by MyCousinVinnie

What's the ideal range for cell min and max of the Nissan Leaf? As in what do you (NCPW and DaveTM) have your range set at for battery longevity? I think I've seen 4.15 to 3.2??

With my single pack (7 Leaf modules), I charge to 4.17v/c, with the balance set to 4.14v/c which has my pack settling at 57.8V when fully charge. I have my LV set to 3.17v to give myself enough buffer to limp back home if ever needed. I think I've only reached the LV cutoff maybe twice. I've been getting 22-25 miles out my pack with mild driving (i.e. Not stomping on the go-pedal and cruising at 15 mph).

If I had a double pack like MCJEFE; I'd probably charge to a lower voltage because I'd have all the range I'd ever need. With a single pack, I want to get the most out of it that I can with hurting the cells.

[ab46501]

I'm still looking at AZlithium's site and their pre-built packs. The only Nissan leaf kits they have right now are from a 2014. They also have a kit from 2018 Chevy volt kit and from a 2018 Honda clarity.

I've read up mostly on the leaf packs so far and have seen some info on the volt. Has anyone used or does anyone have thoughts about the Honda batteries? The price point is a little better on them and the listing says the car they came from had less than 1000 miles so that made me interested.

[bronsonj]

I have Chevy Volt. The batteries are nice in that they are the correct width to fit inside your current battery tray. The difficulty is getting the 14S part. I am using 14S Chevy Volt cells in my Ezgo.

I put a 12S and 6S together which makes an 18S. Then I created the electrical connection at the 14th cell leaving a 14S and a 4S. The 4S is nice because it means I can use that as a separate battery for radio and lights...

There are other lith batteries available. i bought 60ah Bosch cells from a Fiat 500e for my sons 20v power wheels conversion... There are many options available. The key is to find something you feel comfortable using and at a price you like. Spend an evening cruising ebay and you can find Ford cells/Fiat (Bosch) cells/Honda/Chevy and Nissan.

Just remember lithium hates overcharge, undercharge and heat.

[ab46501]

So basically in auto batteries lithium is lithium...... it just depends on the number of cells as to how they can be set up?

[MCJEFE]

Originally Posted by ab46501

So basically in auto batteries lithium is lithium...... it just depends on the number of cells as to how they can be set up?

This is not necessarily true. There's several different types and configurations out there and you need to research what you are getting before you buy. But the most common auto batteries use a pouch configuration with a nominal voltage of 3.7v per cell and a 3.0v min and 4.2v max.

https://batteryuniversity.com/learn/...ased_batteries

https://batteryuniversity.com/learn/...of_lithium_ion

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[DaveTM]

Mcjeffe's comments and links are spot on.

Also, remember that the "power source" is just that. The controller doesn't care where the power is coming from, nor does the motor.

However, too many Volts will toast a controller or motor.

It's important to think of the Lithium pack as it's own "monster." You have to be diligent in feeding and using this monster. BMS systems go a long way to keep your monster from getting too much juice.....and from preventing it from loosing to much juice.

The cell balancing is a very important part of the BMS as well. Remember that the charger is just "one dumb" unit that will put out the volts\amps to charge the entire battery pack. The charger doesn't care if cells are out of balance.....it just charges until the pack says I'm full.....based upon the parameters set in the charger.

[bronsonj]

As stated there are differences in lithium chemistry. Many auto lithium packs use lithium manganese cells or Lithium Cobalt Manganese cells. The Chevy Volt and Nissan Leaf both have 3.7v nominal with 4.2v max and 3.0 min. Both can be configured to use with a BMS, the Chevy has balance leads you wire to where the Nissan has taps you wire to. Both will get you where you need to be.

It'd be a bit exciting to do a new conversion now though because of the other cells that are available. The Bosch cells from Fiat really strike my interest... My neighbor wants to convert and we'll have that discussion tonight. The bosch cells offer a pretty good capacity for the $ too. Last I looked the Ford cells were a little expensive in the used market but they were 26ah cells that you could parallel easily as they had a physical structure vaguely similar to the Nissan cells. You could parallel/series them to your hearts content to get what you wanted.

So there are many options, far more now than before. No, not all are the same although many use similar chemistry. A little time cruising Battery University can help immensely.