Batteries

I am looking to replace my second battery in the truck as my old deep cycle expanded and ruptured. Is there any reason these shouldn't be good for the job:

http://pages.ebay.com/link/?nav=item.view&alt=web&id=281608886214

I appreciate they are second hand but for the price it seems worth a punt and give the dimensions they could be a very useful shape for squirrelling away in the back of the ute.

If it is a 12V battery (these are) then it will work, no question about that.

Your only risk here is pretty much what the seller states. Telling you the voltage without loading the battery is pretty meaningless. You don't really know what the life expectancy of a second hand battery is going to be. Could be great, could already be dead.

If your previous battery expanded and ruptured, I would definitely also take a good hard look at your charging system.

^ As above.

The AG12V100F is 33Kg - it's fairly typical for that sort of capacity. It's an odd shape compared to normal batteries and you'll have to custom-make the tray, but otherwise kernel's right on the money, in particular with your charging system - I'd be concerned about it.

I suspect the problem with the old battery is that it was a deep cycle gel filled battery and I charged it with a regular battery charger because it had been discharged completely flat. I have been told since that I shouldn't use an "ordinary" charge and need a charger specific to the deep cycle batteries. Is that true?

Thanks for the advice on the battery. I was planning to hook up my fridge to the battery and test the charge with that hooked on to it to see if it drops appreciably but to be honest for $100 I'm willing to take a chance

Gels are different to other batteries (of any type) because of how the electrolyte is stored. Other batteries use a liquid - so if you overcharge the battery, any bubbles forming simply pop and the liquid takes its place against the surface of the cell plate again.

In gel batteries, overcharging them still forms bubbles, but it's a bubble in jelly - it doesn't pop, it doesn't go anywhere. It simply lifts the electrolyte away from the plate and it's all over for that cell.

So yes, chargers are different for gel batteries - they limit the charging voltage to around 14.1V tops (chargers can normally hit 15V without any drama, some will push out to 16V to "equalise" the battery cells).

Cheers Tony...... And damn, I was hope my mate was wrong and it wasn't my own stupid fault ;0)

Tony, wonder if I might ask some further advice. Before I go and kill my repllacement battery is this charger ok to use with the below linked battery?





http://en.naradapower.com/Products/SLA/battdata/pdffiles/ACME.F/12NDF100.pdf

Also, it doesn't seem to mention one way or the other in the manual, but I presume this battery would need to be stored upright and couldn't be payed on its side in the tray of the ute

According to the spec sheet for that battery, it's an AGM. Orientation doesn't really matter, nothing's going to spill. You can also charge it with that charger - it might only be a 10A charger but that's fine, my C-Tek is only 7A and does the job just fine. AGMs can be charged at C/3 usually - which means capacity divided by 3. In this battery's case, 100/3 = 33A per hour, so your charger is only 1/3rd of that = safe. A spiral wound AGM can handle C/2, but they're easy to spot and the Narada battery you've got ain't one!

So what you have is good to go.

cheers Tony, I'd hate to blow two batteries up in quick succession.

The only thing to be concerned about is if that charger never gets into 'float' mode. 3-stage battery chargers supply power in 3 different ways:

Bulk charging: pumps in the amps. This is where the majority of charging takes place.

Absorption: this is where the battery is "topped off" - amps are reduced and voltage is held fairly steadily in the mid-to-high 14s. This allows the battery to come to full charge without fizzing the electrolyte away.

Float: This will charge the last 1-2% and maintain a fully charged battery. Volts are dropped to around 13.2V and held there. Amps are greatly reduced.

If your charger doesn't enter this last stage, and holds the voltage high, it will boil the electrolyte away - it's unlikely to happen unless the charger has a fault.