After struggling for weeks on the road with a funky charging setup I arrived at a mail drop and picked up my new ebay 24v charger for my ice machine.Fool that I am, I did not check the soc on the 2 12v batteries before hooking up the new charger. I was excited to test it! But I canvtell you that they were at similar but not the same soc, and maybe around 12.5v.Should I run the charger till it shuts off, or will that overcharge one battery?I can top off as needed with my hokey 12v setup later tonight, but would love to get some aH in the batteries before then, using this new charger.PS: After being plugged in for a while, I read 26.97 across the two batteries. That seems low for charger output... but is about the same per battery as I was getting on my other (12v) charger. I have not yet had a chance to compare my meter's readings with another voltmeter, so everything is speculative, but it gives plausible readings when I am checking soc.

I would run it as is. What is the voltage of each battery while charging?

looks like 13.5 volts its in float.

smkettner, that was a brilliant idea! I'd checked them while charging, after about 45 mins, and they were at 13.52 and 13.24, approx. Now, after over an hour, they are 13.54 and 13.51. So it looks like they are balancing out? They are pulling 2.5amps for the pair, so not floating but maybe pretty close to full. If this ebay charger is good ;)

They may balance out, but series batteries (at least mine) were never very good at that.

At that voltage it is easy. If they were sharing 30 volts one might get equalized. If you always use them and charge them in series they should be fine.

'Nother dorky charger question | Good Sam Community

29 Replies

2oldman
Explorer II
Jul 06, 2016
I've been searching for the different amperage thing, but not easy to find. It does make sense though, that there would be less energy returned to the charging source because energy is consumed in the battery.

Perhaps someone has a more technical take on this.
Naio
Explorer II
Jul 06, 2016
Oh, thanks, Mr Wiz!
MrWizard
Moderator
Jul 06, 2016
When in doubt of a clamp on reading
Flip the meter over.. Right.. Left, effectively reversing current flow thru the meter
And test again
If the numbers are different avg them
Example
1.5 one way 3.0 the other way true reading is probably 2.25

It reads 0.75 high or low depending on current follow direction thru meter
Naio
Explorer II
Jul 06, 2016
Clamp-on. And it, too, is under scrutiny!

It's hard to find where the problem is in a system when I am not certain of any of the tools.
time2roll
Nomad
Jul 06, 2016
Series ammeter or clamp-on? Otherwise the current in a series circuit is equal in all parts. The method of measurement needs to be questioned.

15.2 seems high for a gel. I would charge separate. Test them for a bit but it might be getting close to trade-in time.
2oldman
Explorer II
Jul 06, 2016
Naio wrote:
Thanks, 2oldman.

So, why was it later so much higher on the neg wire, with charger still going?
I may have misspoken. I better look this up before stepping in it too much deeper.
Naio
Explorer II
Jul 06, 2016
Thanks, 2oldman.

So, why was it later so much higher on the neg wire, with charger still going?
Almot
Explorer III
Jul 06, 2016
smkettner wrote:
45 x .01 = .45?

Yes :)
2oldman
Explorer II
Jul 06, 2016
Naio wrote:
Pos wire read 3.85 amps and neg (on the other battery, of course) reads 1.72.
I'll take a stab at that.

I hope understand your question correctly. Electricity flows from - to +, and it's flowing through batteries, doing work, therefore the process of battery charging 'eats' amperes.

How's that? EDIT: actually in rereading this it doesn't make sense because the + should be less
Naio
Explorer II
Jul 06, 2016
After about 90 minutes top charge, charger still running:

0.33amps pos wire
2.47amps neg wire
15.2v one battery
13.90v other battery
27.90v across the two.

That 15 scared me so I unplugged the charger.

Mex, these two batteries are if equal age, about 9 years. I am trying to figure out if battery/s or charger are wonky, so I bought a new charger, but now I am not sure if the new charger's auto shutoff works properly.