On 9/24/2021 2:13 PM, joeaverage@frontiernet.net wrote:

Perhaps the next time I need batteries - I can consider used EV lithium batteries. I'm not against continuing to use lead-acid.

This weekend I'll do as you detailed and charge them individually and then test with the hydrometer.

Chris

Definitely do the math when the time comes. I converted mine to lithium last winter. I got barely used lithium ion batteries from batteryhookup. They are batteries used in BMW i3 cars. They had modules that are 5 cells in series, so 2 of these works great for the ET. You need a Battery Management System to use these safely. You need a different charger. It has to shut off when the batteries are near full charge. trickle / float is not good for LION. You have to also decide how to power the winch and the lights, since tapping a lithium pack like they originally did is a big no-no.

Once I got the thing working, I got a second set of the same cells, and paralleled the for more AH. I have about 2200 watt hours of electricity in my batteries.

As far as how it runs, it's almost like it's plugged into unlimited power. The voltage only drops from 40V to 36 near the end of a discharge. (I have the BMS set to cut out before going low enough to really stress the cells, same on the top, as this extends the life.) Even when nearing the low point, I can be running in 4th gear flat out, switch on the mower, and feel no glitch from the inrush surge drawing down the batteries, not even a flicker in the lights. This was even when I was running only one pair of these batteries.

If you ever put a set of brand new fully charged set of LA in an ET, and go out mowing, etc, you notice how it runs... And then gradually slows down until they are depleted. With the LION, it's like that first 15 minutes the entire time. [unless you set the BMS too low, and get them near zero]

I did have to add some dead weight in the back battery box, since they are so much lighter and smaller than the lead acid.

LION vs LA -

much higher cycle life. Also, shallower cycles greatly increases cycle life. - The main reason [along with run time] I decided to double up.
Deeper cycles - in that with LA, you really can only get about half the AH out of a LA at the currents drawn by mowing.

LA any state other than fully charged accelerates their demise. As long as LION are not over discharged, it doesn't matter much.

No acid eating away the steel. And the concrete floor!

I also have pictures of a lot of this.

Dave