Can i wire my D3100s in parallel and charge them like that, or will i have to do each one by itself?

Shouldn't be a problem! Just make sure they are grounded to the same point.

i do them 1 at a time my self

Is this before being installed? If so follow Jon's advice and do them individually.

Are you using the XS Power 1005 charger? If you are and you are going to charge them together you can bump the charger up to the 25amp setting, since you are charging 2 D3100s at the same time. If you charge them individual, then just charge them at the 15amp setting.

No i am not using XS Power 1500 Charger, i borrowed my neighbors charger.

So would i just put it on slow charge and leave it charging the batt over night?

How do i check to see if its done charging?

ttt

it would help to know if it is a special/specific charger. Mine has a light that says full charge, and a needle to show what "percent" the battery is charged. Have you checked out the charger at all?

There is no way possible to tell you how to charge your battery from the info you have listed. Is it an AGM battery charger? What amperage does it charge at? What voltage does it charge at? Does it have different stages of charge?

The batteries should be charged at 14.4V and 15amps is the optimal charge rate. A volt meter will be your best bet to see if the charger will work for you or not.

If it has 12v AGM setting put it on that and if it has a button to choose sizes I would put it to medium to large battery and make sure it doesn't go past 15v.

Edited September 21, 201014 yr by crunkjuice1

actually, my agm charger has gone over 16v before but it does it to excite the battery.

If it's REALLY cold outside or discharged bout 30% or more, it will raise it's voltage between 15.7-16.5v for just a few seconds then drop back to 14.7v solid til it's done.

It's nothing to worry about. I've done that for a whole year and the batts have never got warm or warped or anything abnormal and still read 13.16v when fully charged.