Whats with these cheap 12v 7ah SLA's??

[Flashanator]

Ripped a fairly new 12v 7ah SLA out of a new 10MCP torch & noticed it was slightly lighter in weight then the older 7ah ones.

at 350mah, it only takes 4-6hrs to charge but it doesn't give good runtime.

maybe its damaged & not charging properly?

I want to try a diff charger. Is charging at 1.2ah ok?

I heard some guy charging them off car battery's in 15-20mins?? (not shore exactly how) :sick2: Wouldn't that screw it up in the first go?


thx

 

[Sabrewolf]

Ripped a fairly new 12v 7ah SLA out of a new 10MCP torch & noticed it was slightly lighter in weight then the older 7ah ones.

at 350mah, it only takes 4-6hrs to charge but it doesn't give good runtime.

maybe its damaged & not charging properly?

I want to try a diff charger. Is charging at 1.2ah ok?

I heard some guy charging them off car battery's in 15-20mins?? (not shore exactly how) :sick2: Wouldn't that screw it up in the first go?


thx

I actually have 4 of them puppies in parallel in my trunk as a second
battery pack for running the "Toys" in my car when i dont want to
drain the main starting battery. They are on a Marine style 1-2-Both
switch.

To answer your question... Yes, you Can charge them in your car,
with the engine running of course
Just connect it to your cig lighter socket, pending it is 10ah fused or
higher. Otherwise goes your fuse!
Robert M.

 

[Illum]

Theres quite a few jumpstarter manuals around here that does not recommend connecting 12V cells directly to other 12V cells to charge them [in the jump starters case, using the DC-DC charge cord]. Supposedly the unregulated "bumps" caused by the converter reacting to the alternators rpm fluctuations is quite damaging to batteries that require a stable charging current.

I would personally prefer to charge my Lead-Acids using a dedicated charger and would only charge cells using the "battery bridging/jump starting" technique as a last resort...stuff like a dead car battery

The heavier part could be a sign that you might have two batteries onyour hands, that is...two 6V 7AH SLAs connected in series, where the "heavy" part comes in being that the battery your holding contains two containers.

 

[Wok]

You may have the AGM style of SLAs...downunder the original Gel technology is been replaced. Advertised as SLA/AGMs. The float voltage & charging regime has changed in line with AGM rules which means replacement of older units using Gel type needs research.

 

[Fallingwater]

SLAs can't be recharged in 20 minutes. The lead-acid chemistry requires rather long charging times, especially if you want to be kind to your batteries and have them last.

 

[Aussie Cheese]

i disagree

You may have the AGM style of SLAs...downunder the original Gel technology is been replaced. Advertised as SLA/AGMs. The float voltage & charging regime has changed in line with AGM rules which means replacement of older units using Gel type needs research.

 

[Flashanator]

thanks for the replys people.

 

[Flashanator]

The 350mah charger I got seems to be the problem. It only takes about 5-7hrs to charge a 7ah SLA & then the batt isn't fully charged.


Can I charge at 1.2ah? Thats what i use for 12ah sla.

 

[Fallingwater]

That's a bit high for a SLA. I seem to remember they want a 1/10C charge current, while 1.2A is about 1/6C in your case.

 

[Turak]

The general rule for calculating the charge rate for almost any common Lead Acid Battery is charging rate = 20% of the Batterys overall capacity. Do not confuse the actual battery capacity with its 'cranking amps' or 'cold cranking amp rating', they ARE NOT the same.

For example I have a Deep Cycle Pro Cell 31DC marine battery which is a 145Ah battery rated at 810 CA (cranking amps) or 650 CCA (cold cranking amps). The 20% rate would be calculated against the 145Ah rating.

This is typically used more for 'wet' Lead Acid batteries (batteries with liquid in them and removeable vent caps), but can also be applied to Gell cells and AGM/SLA type batteries as well.

For the battery you specified, If you calculate it out... 7A x 20% = 1.4A
(The 20% estimated charging rate is usually on the conservative side)

The best thing to do though is to either just look at the AGM/SLA battery case or go get the spec sheet for the battery. Typically the maximum charging rate is printed right on the case. If not, I would recommend looking for the spec sheet for the battery on the manufacturers web site.

For example the following link is to a Rhino brand 12v 7Ah AGM/SLA battery.

http://www.ragebattery.com/pdf/SLA-7-12.pdf

According to the spec sheet for the above, the maximum charging current for this particular battery is 2.1A.

See the 20% rate is on the conservative side when compared to the actual spec sheet.

 

[jerry i h]

SLAs can't be recharged in 20 minutes. The lead-acid chemistry requires rather long charging times, especially if you want to be kind to your batteries and have them last.

I dunno. We have an electric forklift at work (I forget what the battery capacity is; dumb me, I am the one who researched/purchased it...:ironic. We have 2 chargers: a trickle that takes overnight or the weekend, and a fast charger that takes one hour (maybe 2; I would have to ask the driver). I was warned by the vendor that it would be better to use the trickle, inasmuchas it would extend battery life a little. They use both, with nary a problem, as far as I know.

 

[jerry i h]

The 350mah charger I got seems to be the problem. It only takes about 5-7hrs to charge a 7ah SLA & then the batt isn't fully charged...

Wait, just a doggone second here. According to my calcutator, 350mAh at 80% efficiency charging 7AH would take 25 hours, NOT 5 or 7 hours. Am I missing something?

 

[Flashanator]

what I meant was after 5-7hrs the small 350mah charger is saying my 7ah is fully charged, But yer, when you do the math its not possible, need 20hrs+ & proof is that my batt isn't fully charged is it gives poor runtimes.

So my small 350mah charger must be not working properly, which sucks as I hardly use it. Isn't that the way with most tech gizmos.:sick2:

 

[Fallingwater]

I dunno. We have an electric forklift at work (I forget what the battery capacity is; dumb me, I am the one who researched/purchased it...). We have 2 chargers: a trickle that takes overnight or the weekend, and a fast charger that takes one hour (maybe 2; I would have to ask the driver). I was warned by the vendor that it would be better to use the trickle, inasmuchas it would extend battery life a little. They use both, with nary a problem, as far as I know.

The forklift most likely runs from flooded lead acid batteries, not sealed ones. And there are, I think, special lead-acid batteries made to withstand quicker charge and discharge, though I've no idea if they are only flooded or not.

Since the original poster's battery is cheap, however, it's a safe bet it's of the ordinary, slow-charge kind.