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. Emoji
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
_______________________________________________
Elec-trak mailing list
Elec-trak cosmos phy tufts edu
https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak