12v Gel batteries

[Brett]

Morning all, I have just been digging my way through my shed this morning and have come across two 12v 31AH gel batteries from my wifes wheelchair including the gel cell battery charger. The wheelchair is no more due to my wifes changing circumstances but I forgot that I kept the batteries from it before throwing the chair away. My question to you is whether or not the batteries are suitable for use with my Skywatcher 130p az goto and also how I can charge the batteries with the charger. I ask this because the charger originally plugged into the control console on the wheelchair and not directly to the batteries. I have looked at the charger and there appears to be a - and + cable terminating at a three pin socket with the third pin being bridged to the positive terminal. I suspect I can just connect positive to positive and negative to negative on the battery but would like to be sure rather than blow myself up. I hope someone on here has experience with these batteries and any help would be much appreciated.

Thanks

Brett

[Merlin66]

First of all, I'm glad you wife doesn't need the wheelchair any more.

The batteries sound absolutely great for driving telescopes/ dew heaters etc etc. I've used 20Ah gel cells for the past few years with 100% success.

I assume you are correct re the charger outputs. I use a separate triple stage electronic charger, but they should all be the same.

Is there any rating shown on the charger?

Shouldn't do any harm to try it, just connect positive to positive, negative to negative and switch on!!!

Ken

[Brett]

Hi Ken, thanks for the reply. I have some pics if its any help........

http://www.flickr.com/photos/46804947@N08/4504760599/

http://www.flickr.com/photos/46804947@N08/4505393224/in/photostream/

http://www.flickr.com/photos/46804947@N08/4504754401/in/photostream/

http://www.flickr.com/photos/46804947@N08/4505398794/in/photostream/

Sorry about the links but I cant seem to get them to upload to the site

I hope its suitable as I have two batteries I can use, one for the mount and the other to use with the power inverter for the laptop.

Thanks

Brett

[Merlin66]

Your batteries are obviously bigger than mine!

The charger looks very similar to the one I have, so I'd just connect it up, get the batteries charged and off you go.

Ken

[Brett]

Hi Ken, I have a horrible feeling the batteries are capput. Ive connected them up but I don't see a charge light. They have been in storage for a year or so and im beginning to wonder if this has ruined the plates inside. Other than this there could be a loose connection within the charger itself as i don't seem to detect any output, could this be down to the charger not detecting a source to charge if the batteries are dead ? Could you possibly check your chargers output to see if this is the case

Another thing I forgot to mention is the fact that the charger is 24v, I have wired the batteries in series as they would have been in the chair when charging. Will the batteries once separated still be 12v when charged or will they be 24v ? Sorry for the dumb questions Im so so confused when it comes to electrics.

Thanks

Brett

[Merlin66]

Connecting them in series is the right thing to do with a 24V charger. When charged they will both be 12V.

I've just put the multimeter on my charger... with no battery connected I get no reading!

With the battery connected I get around 13.6V and the charger light comes on....

Can you measure the voltage across the batteries when the charger is connected?

I can lend you my charger if you want to try it out. Drop me a PM.

I'm in Cobham.

Ken

[Brett]

Hi Ken thats very kind of you, a friend of mine has a charger that will do both lead acid and gel batteries so I will give this a go tomorrow. Ive read up that gel batteries only have a life of 2 years or less if not maintained properly so im not feeling to optimistic to be honest. I have just found a 17ah lead acid battery that seems to be accepting a charge from a different charger so fingers crossed

Ah "I've just put the multimeter on my charger... with no battery connected I get no reading!" I wonder if the charger needs a little input from the battery before it switches its charge circuit on ? If this is the case then would it be possible to introduce some voltage from the 17ah battery ?

Apologies for all the Qs:icon_scratch:

Thanks

Brett

[Brett]

Hi Ken thats very kind of you, a friend of mine has a charger that will do both lead acid and gel batteries so I will give this a go tomorrow. Ive read up that gel batteries only have a life of 2 years or less if not maintained properly so im not feeling to optimistic to be honest. I have just found a 17ah lead acid battery that seems to be accepting a charge from a different charger so fingers crossed

Ah "I've just put the multimeter on my charger... with no battery connected I get no reading!" I wonder if the charger needs a little input from the battery before it switches its charge circuit on ? If this is the case then would it be possible to introduce some voltage from the 17ah battery ?

Apologies for all the Qs:icon_scratch:

Thanks

Brett

Update:

I have just given one gel battery a small 5 min charge with my standard charger and then connected it to the gel charger. This time I got a response from the charger which was three flashing lights (fault), I think this is down to there being only one 12v battery and the charger being 24v. Im going to give the second gel battery a small charge then wire them in series to provide 24v back to the gel charger and see what happens. Things don't look so bad after all:hello2:

Brett

[Brett]

Finally charging properly, thanks for the help Ken. No more leads trailing down the garden waiting to be tripped over