This is a repost from
I've been charging the batteries in Buttercup (4 @ 12V x 17AH) in two strings of two. (in the background at http://www.austinev.org/evalbum/822)
Four months ago, I started with a set of four new PowerSonic 12018 batteries.
I had set it up so that each 24V charger would be plugged into one half of the battery pack individually. My hope was that, if there were any differences between the two chargers, by randomly plugging them in, the differences would average out. Over time, the chargers were left plugged into their respective sockets on the pack, and just unplugged from the mains when I needed to use the scoot.
Four months later, Pack voltage falls off after about 4AH of use. After the voltage falls off, the voltages under load are as follows:
It sure looks like charger B has cooked the batteries. I can't believe that two batteries failed at the same time.
I'm doing voltage cutoff measurements right now. I'll "report back" if I learn anything else.
.... (time passes) ....
By my WattsUp meter, I did capacity tests and charge profile tests. ALL batteries had lost capacity: Batts #1 & 2 were around 10AH (14AH expected at given discharge rate), and #3 & 4 were around 4AH, and thus collapsing on the normal short commute.
In the charge profile, they charged at a constant 1.5A until 28.9V (14.45/battery), then switched to constant voltage (mostly). When voltage reached 28.97V (+-.03V) they fell back all the way ... to 28.03V (14.01V/battery) and held it at that voltage until I stopped measuring at eight hours. About one full AH more was pumped through the batteries.
Both bricks were within .02 volts of each other. The cutoff voltages are different than noted in the 2404 literature (SPEC2404S.022701). I checked the WattsUp against a Fluke voltmeter and was within .03V in the range near 24V.
My Vector "quad charger" floats batteries at 13.1V/cell, with periodic "float charge" periods of 13.7V (every few hours, for 10 minutes or so).
Right now, I'm not using the Soneil's at all. While the charge rate was within the published max for PowerSonic batteries, the float voltage was a few hundredths above maximum.
I have recieved no response from Soneil: their published e-mail address is not valid, and they have not responded to the "feedback form" I filled out at their website.
Remaining challenges: 1) Get a response from Soneil, and 2) see if there is some way I can continue to use the bricks.