Soneil 2404S's cooked my batteries :(

4 replies [Last post]
Joined: 12/01/2006
Points: 712


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

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:

Charger A:
#1 11.8
#2 11.6

Charger B:
#3 8.6
#4 9.2

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.


charger-profile.txt3.56 KB

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Joined: 11/17/2006
Points: 23
The problem is the 14 volt

The problem is the 14 volt float voltage, it should be closer to 13.5-13.65. 14 volts will boil off the electrolyte unless the batteries are really cold. The charger can still be used you its just that now you cant leave it on after theyre done charging be sure to take it off when the batteries are done charging. You could try squeezing some more life out of the batteries if you add some distilled water.

Gman's picture
Joined: 11/20/2006
Points: 1720
The problem is the 14 volt

Which is correct?
Re: Soneil 2404S's cooked my batteries :(
Batteries are probably not "cooked" but sulfated.

You need to charge them more aggressively occasionally. Bring them up
to 15 volts and hold them there for two or three hours. If the
capacity increases on the next cycle, do it again. Keep doing it
until you get no increase in capacity.

You should do an aggressive 15 volt charge like this on a regular
basis. Perhaps once per week if you drive the vehicle every day.

I like to use a timer and a 2 amp, 15 volt Toshiba laptop
power supply for this type charge.

Until latter,


Peace Out,

Joined: 11/17/2006
Points: 23
I disagree. Sulfation is

I disagree. Sulfation is caused by leaving a lead acid battery in a discharged condition. Sulfate is normal and occurs when the battery discharges, overtime it can form a sort of insulating blanket that impedes the normal functioning of the battery. I believe this is caused by the sulfate forming larger crystals with reduced surface area but i could be wrong. As long as he didnt abuse the batterys the 14.45 volt charge should be enough to get rid of the majority of sulfation. What you said about pulling the 15 volt charge is common procedure for flooded batterys where slight overcharge is not a problem. This serves two functions first a form of forced battery balancing, a 12 volt battery is made up of six cells that can become unbalanced just like any other series battery. A forced overcharge (equalization charge i believe its called) makes sure all the cells start off on the same plate, the gassing that occurs also helps knock some loose sulfate that wont turn back into acid and lead off the lead plates. The cells that end up with an overcharge dont suffer too badly but they do boil off water that must be replaced, not a problem with flooded cells,but not too many people are convinced that you can add water to sealed batterys. Not to say that pulling the battery up to 15 volts every once in a while isnt a bad idea. It helps to balance cells that you otherwise couldnt have and also helps to knock sulfation off the battery. It becomes a balance between death due to drying up the battery and consistently abusing a certain cell like everybodys scared of doing with ni-cd and li-ion packs. It should be done with caution in sealed batterys.
The 14 volt float charge on the other hand i know for a fact will cause gassing, leave it on there for 8 hours every day, welll you have the results. I once had a large trolling motor battery in my bedroom to power a car audio system i had set up as my stereo (i know i know), i had the charger set up constant current voltage limited, i spent a long time trying to find a good float voltage. I found it to be 13.68 in the summer and 13.63 in the winter. Turns out due to heating and air conditioning my room was colder in the summer than in the winter and i made up for just until i didnt hear any more bubbles coming from the filler caps. The battery lived for one and a half years before i moved to france.

Joined: 12/01/2006
Points: 712

Hee hee, there's zero chance it was sulphation.

As My subject line said, the Soneil's cooked my batteries. In fact, I tried adding about 2CC/cell of distilled water, but it made little difference.

I am very disappointed in Soneil, however.

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