what has happened to my batteries?

Joined: 29 Aug 2005 Location: western shitney

i have 2 deep cycle batteries (100AH) that came from a UPS system.
i have been using them to start the zook ocassionaly, run the odd 12v drill or 12v fluro when working on cars and thats about it..
the last time i used one of them was on Australia day to start/run the zook while we cut it up (so we could move it around) and it worked fine..
they havnt been used since, but now i went to start the pajero with one of them and nothing... Confused

so i tried the other one and it was the same Mad

out comes the multimeter to check the voltage and they were 12.4 and 12.8v

so i got a 55w globe from a spotty to see how they are and they would light up but slowly.

so im wondering what has happened to them???
i didnt leave them sitting on the concrete or anything but now they seem stuffed cussing

Joined: 29 Aug 2005 Location: western shitney

anyone got any suggestions???

Joined: 07 Aug 2003 Location: Townsville

Tried charging them lately???? Most batteries will self discharge over time (anywhere from 3 months to 2 yrs) to reach an unusable level of charge.

Joined: 29 Aug 2005 Location: western shitney

it was only 6-8 weeks since i used them last...
i got one on charge with 2A going into it.. and the other one is hooked up to a solar panel so its only getting charged during the day.

the thing thats making me wonder is the voltage.

Joined: 07 Aug 2003 Location: Townsville

j-top paj wrote:

it was only 6-8 weeks since i used them last...
i got one on charge with 2A going into it.. and the other one is hooked up to a solar panel so its only getting charged during the day.

the thing thats making me wonder is the voltage.

Voltage indicates one of two things, they are flat, or both of them have a dead cell in them. I'm still leaning towards flat.... 2 amp charge is barely a trickle charge with that sort of A/H battery.

Get a decent 5-10 amp charger onto them and leave them for at least a day, or take them to an autoeleccy to get them tested and charged.

Joined: 29 Aug 2005 Location: western shitney

2A has been on them for a week. i was thinking a slower charge would work better than higher

Joined: 07 Aug 2003 Location: Townsville

j-top paj wrote:

2A has been on them for a week. i was thinking a slower charge would work better than higher

Not necessarily, you need to "burn off" some of the crud on the plates (even with AGM's) with a higher current. Most deep cycle batteries prefer a C/10 charge (ie 100 ah/10 = 10 amp) over about 15 hours to achieve this

Joined: 29 Aug 2005 Location: western shitney

looks like il have to use the bigger charger then..
i have a 100A charger i could use but i think that might be a bit much Laughing

Joined: 07 Aug 2003 Location: Townsville

j-top paj wrote:

looks like il have to use the bigger charger then..
i have a 100A charger i could use but i think that might be a bit much Laughing

It should nbe OK to use the 100 amp charger as the battery will only accept a certain amount of charge depending on the voltage. Keep an eye on the battery voltage for the first 30 mins or so and then after about 2-3 hours. If you have a spare ammeter put it in line to measure the inrush current, ideally about 10 amp or so for you battery after the first 10-15 mins.

Joined: 29 Aug 2005 Location: western shitney

id just set it to 13.8v and see how much it takes. i dont think it would take more than 10a i hope.
the reason i used the 2A one is that i didnt have to worry about it overcharging it at all.
il check it in the morning and if they arent any better after a week on charge then il bring them inside and hook them up to the big charger.

only problem is its under my bed and the terminals are hard to get to Crying or Very sad

Joined: 29 Aug 2005 Location: western shitney

well after a week on slow charge they are still stuffed Crying or Very sad

i connected them to the 100A one and set it to 14.5V but it would only take .300a

so what to do next before they go in the bin Confused

Joined: 11 Jan 2004 Location: Adelaide

I'd get feral with them - short them (VERY briefly) to see what happens. Preferably outside, in a well ventilated area, near a hose/shower, with some safety glasses on.

PM me before you try this, so I can come back and remove the evidence - coronial enquiries can be so time consuming. Wink

Joined: 29 Aug 2005 Location: western shitney

already tried that Twisted Evil

i did it when the paj wouldnt start.
i wanted to make sure the jumper leads had a good connection on the battery.
they struggle to supply a few amps

when i put a load on them (55W spotty) the voltage drops to 2-4V depending on which battery it is