Help with SLA battery

Wurkkos

webley445

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Nov 16, 2001
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Not really flahslight related, hoping this is the appropriate forum.

I have two 12v/7amp selaed lead acid batteries. I want to use it for a small ham radio amplifier that runs on 12v.
But the batts I got are drained or near drained. Just wondering what I need to do , if at all possible, to get them up and running.

Would either one of these chargers work to get them back up on par?
http://www.batteriesplus.com/pc-34553-34553-WK12V1000.aspx

http://www.batteriesplus.com/pc-36126-36126-DBT021-0123.aspx

Hate to seem stupid about it all, but not sure if you can look at it like you would as charging and maintaining simple nihm cells or auto batteries, or if there are any special precautions or guidelines that have to be followed because they are SLA.
these are the mall black rectangular batts, maker name says "MK Powered".
 

yo6ial

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Aug 17, 2007
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Brasov / Romania
What did you mean by "drained or near drained"?

Because those Sealed (and then some) Lead Acid batteries
leak electrolyte in form of electrolyzed hydrogen and water/acid vapor.
Head and plain ol' regular usage drys 'em up in about an year or two.
...and keeping no charge whatsoever...
IF this is not the case and those cells are still wet (and hold a charge)
get them topped up with anty 0.1C (one 10'th of cell capacity) SLA/VRLA charger at hand.

I just can't get to the pages you linked so... can't say nothing about those (i presume) chargers, but any dedicated charger will do as long as you follow it's instructions and it delivers adequate current.
Automatic chargers that disconnect the battery when full (and not trickle charge them) will save you from a lot of headaches ;)
Also constant current charging will get the most cycles from those SLAs.

I used to hike with a 7Ah SLA in my backpack too, a while ago, until i made a pretty nice (for my shoulders) decision: a 4 series/4 parallel 8x 18650 li-ion cells pack. Storing a neat 4.4Ah (60.. and some watts) in less than 300 grams of it.

Nowadays these cells cost at about $4 each with integrated protection and, for any ham, serializing 4 pieces to a handy or a PA is child-play ;)

There are bigger cells on the market, storing up to 10Ah per cell (13600 size? i guess... i might be wrong) and there is a lot of power for a local uhf contest made from the peak of the mountain with a small setup .

Hope all my misspellings, up there, gives you some useful thoughts...

Cheers and 73's from Alex, YO6IAL .
 

webley445

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I got the batteries from work, I don't know how long they were sitting around.
I meant dranined as in power due to the low reading I got with the voltmeter.
 

VidPro

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yes either one of them will work great.
chances are good from your description though that the cells will not have much usable power. Gell cells do not like being left at low discharge levels for time, and do not handle many very deep discharges. they are good for UPSes and Emergency lights because they stay float charged very carefull charge level, and dont get used much.

like YO6AIL said, you would be much better off with some 11,000ma ni-mh cells , and they even have accupower Low self discharge versions of these, they are lighter and would give you much better runtimes and longevity, and wont mind being discharged up and down. with a LSD version of them they will hold thier charge for long times.

GELL:
SLA and the size and type your talking about is probably a GEL cell, gell cells dont leak acid all over the place, they leak a goopy gel if ever, they dont dry out, they split the containment , bubbles form in the electrolyte gel which expands the gel from airation.
WET:
they are not like wet cell motorcycle batteries or car batteries at all. normal wet batteries can bubble up the hydrogen and oxygen, out of the containment, and the "no maintance" verisons of them have water recovery systems that dont work very well, THEY can dry out, but dont split the containers, gell cells have completly different issues.

because you dont want these bubbles gathering in the gell, the SLA or GELL cell lead acid battery should not be overcharged ever. any charger you get should make sure that it peaks at a certian voltage and floats or stops.
from the SALES bs those will probably do that just fine, and are ok rates either of them for charging.
just check the peak voltages that are reached.
testing :
if the voltage doesnt rise to around 14V charged , and it seems about 2V low, then a dead cell might exist, and the batteries should be recycled or you will have splitting problems. usually a gell cell dies pretty evenly, so occurances of shorted cell items are not likley at all.
Chargers like these will not taper down in charge rate IF there are bad cells, and that can cause problems even at the lower rates these things run at.
If things were ever heating up unusually at charge, you would check the voltage, see that it is not taking a charge, and terminate the use of the battery.

SLA = Sealed Lead Acid , they usually stay sealed, but the containment can still split given overcharges, or when it is bad and being charged.

i would probably choose the Werker myself, if i didnt already just use a simple voltage regulation, off a transformer.
 
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webley445

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I was told on a ham radio forum to forget using these, they are probably shot. thinking perhaps it would be best not to cheap out on this and just be rid of it to avoid the time and trouble.
Regardless I appreciate the help.
 
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