Good Choice for Dual Battery?

[jread]

Hey is this a good choice as a second battery to attach an inverter to in my car?

 

We get lots of them at my work and they should be in decent shape since I believe they get replaced based on a time period and not actual wear.

 

Not super versed in what kind of battery I need but assuming 12v is 12v? This one seems to have a pretty good ah rating and is gel!

 

I also have one of those fancy desulfating chargers so I should be able to push some life back into it.

 

[DaveT]

looks like a 12V, by the cell dividers showing through the plastic, and the vents.

 

It won't hurt to put a charger on it, see what it does.

 

The charge voltage on these is a bit lower than a car battery, and they are more sensitive to overcharge.

 

I ran a deep cycle marine battery in my car while I was building my house.  Ran an inverter for power.  Found that even by only drawing about half the AH capacity every other day, the alternator would not keep it charged even with 1Hr of driving every day.

I had to attach a line powered charger every night when I got home from the house.

[DaveT]

Other general deep cycle battery stuff.

Deeper cycles shortens life. 

Lead acid battery life is typically 5 years.  Under ideal conditions.  End of life is usually something like 70% of rated capacity.

Once you get past this, the self discharge rate climbs, and the capacity drops more and more rapidly.

This is not reversible.

 

You can likely look up the detailed spec sheets for the battery online on the manufacturer's website.

[jread]

Sounds like it won't do any damage so I'm going to go for it! It will be a second battery so its not going to leave me stranded. Was considering the maxima alternator upgrade people were talking about so maybe something newer would keep up!

Found the spec sheet pretty easy http://www.unitedpb.com/documents/power/broadband%20gel.pdf

Worth a shot.

[DaveT]

From the data sheet, the maximum charge rate is 96/4 = 24 Amps.

 

Maximum charging voltage = 13.8V

 

I would not parallel it with a car battery.  It should have a separate charge controller.

 

If you decide to just wire it in parallel, measure the current that will flow between the batteries with the car off.  Be aware, it could be moderately high.

 

It's ok to parallel identical type size and age batteries.  Not so good for combinations.  One will never fully charge, or one will get too much overcharge.  Both cases are not good for the batteries.

[jread]

Ah so likely not a great idea maybe I should find something more similar to my battery. We get tons of different stuff in just figured this would be a good call based on the method they use to replace them. Now that I understand what I'm looking for I'll be able to find something closer. Charge controllers seem pretty expensive!

[DaveT]

You could try paralleling 2 of the batteries from the shop, preferably from the same group / machine or whatever they came out of, so they are in the same state of age and cycle life.

[jread]

These ones are too big to fit and I've got a fairly good AGM in it right now.

I'll have to put more thought in, may just run the inverter on the main battery for a while as it has an automatic shut off at 10.5v. Will only be using it on long hauls anyways but would be cool to run the stereo ect for a bit longer with a backup.