SLA batteries

Submitted: Friday, Jul 29, 2005 at 19:52
ThreadID: 25166 Views:3505 Replies:6 FollowUps:5
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I've just bought a second hand 80w solar panel, 20 amp regulator along with a Chinese 100 ah SLA battery. I already have a 110 a/h AGM battery under the bonnet with a Redarc system. First of all, are SLA batteries silmilar to AGMs and can they be connected in series (together) thus giving a discharge of half the rate that I'd otherwise get if they were used seperately? Applications would be mainly 70L Waeco Fridge and some lighting in the caravan. Other times I'd be using it with the tent/Waeco. Main question, I suppose, is what are SLA batteries (pros/cons etc)
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Reply By: Grungle - Friday, Jul 29, 2005 at 19:59

Friday, Jul 29, 2005 at 19:59
Fiirstly don't connect them in series as then you would have 24V. Connect in parallel for 12V but double the capacity (if both batteries are the same). A SLA battery is not an AGM. Not even similar. A SLA is just a flooded battery that is sealed to a certain extent (maintenance free). They should not be coupled with AGM's but can be coupled with other 'flooded' batteries.
AnswerID: 122767

Follow Up By: BenSpoon - Monday, Aug 01, 2005 at 22:12

Monday, Aug 01, 2005 at 22:12
Grungle- can you say this for certain? I got a number of 150Ah SLA's off exide and I was told by their Aus distributor they were AGM's...... I am certainly in no place to argue, as I know as much about these batteries as I do the mating habits of a blue arsed fly.
FollowupID: 378315

Reply By: Steve - Friday, Jul 29, 2005 at 20:08

Friday, Jul 29, 2005 at 20:08
so if I want to slow the discharge rate down, connect in parallel with my cranking battery (keeping an eye on the discharge rate so as not to discharge my cranker too much)? I was thinking of running caravan lights of the SLA and my Waeco off the AGM/Redarc system under the bonnet. If I keep an eye on the discharge rate of both batteries I could switch the solar to wherever it is needed the most.
AnswerID: 122769

Reply By: Mainey (WA) - Friday, Jul 29, 2005 at 23:12

Friday, Jul 29, 2005 at 23:12
Same answer, ...No, don’t wire them together (in parallel) in an attempt to gain extra A/H.
Yes, it can be done, but it is only a short term usable proposition, as one will kill the other, the Sealed Lead Acid and AGM batteries charge at very different rates.

May I suggest:
Take your 110 A/h AGM out of the Aux situation with the Redarc as it is no good there either, as has been posted previously, and put it into the caravan, power it direct from the 80w solar panel via the regulator.
I would then connect the AGM to the 100 A/h SLA battery via a 50amp Anderson plug at the bumper connection, using the largest cable that will fit into the Anderson plug to avoid voltage drop back to the AGM battery.

Put the 100 A/h SLA in the Aux position with the Redarc, they will work fine now.
AnswerID: 122813

Reply By: Nick - Saturday, Jul 30, 2005 at 00:31

Saturday, Jul 30, 2005 at 00:31

Before you reconfigure your system, read Collyn Rivers comments in PostID 25021 about AGMs and wet cells in parallel with Redarc isolator. He has a different view and I believe he knows what he is talking about.
AnswerID: 122822

Follow Up By: Nick - Saturday, Jul 30, 2005 at 01:10

Saturday, Jul 30, 2005 at 01:10

By the way, in answer to your original post, I think SLA refers to either AGM or gel type batteries, so your Chinese SLA could well be an AGM. I think others are wrongly assuming SLA refers to low/no maintenance wet cell batteries. Best check it out.

FollowupID: 377998

Follow Up By: Grungle - Saturday, Jul 30, 2005 at 08:38

Saturday, Jul 30, 2005 at 08:38
SLA batteries should not be confused with AGM or Gel batteries. They are a maintenance free Seal Lead Acid battery used in applications such as portable power supplies and UPS systems. Do a search on the net for more info.

Regardless of what battery you have people should contact the manufacturer of the batteries to get a spec sheet that lists the charging profiles/voltages and maintenance schedule for that make and model battery. Other information such as paralleling them can also be obtained. This is the best way to design a setup that will maximise battery life.
FollowupID: 378008

Follow Up By: Nick - Saturday, Jul 30, 2005 at 09:07

Saturday, Jul 30, 2005 at 09:07

I did search the net and rightly or wrongly the acronyms SLA and AGM are often mentioned together for the same battery. I'm just saying this may be the case for Steve
FollowupID: 378011

Reply By: Steve - Saturday, Jul 30, 2005 at 17:47

Saturday, Jul 30, 2005 at 17:47
Thanks for the input guys. OK, it appears the SLA is a sealed gel type battery and yes, does charge much slower than an AGM. It is also a "shallow" cycle as opposed to deep cycle battery as I understand it and doesn't like much discharge at all. So, Mainey (bear with me mate, I think I'm missing something) wouldn't it be better to put the SLA in the van just to keep the lights going and not discharge much and keep the AGM where it is to run the fridge bearing in mind I don't always have the van but also camp under good ole canvas. Actually, I've only got this bloody SLA cos it was in the bundle with the solar panel and regulator in a local classified. Doesn't look that practical for these purposes. I read Collyn's post and have had a couple of his books for a while and haven't seen much reference to SLA batteries or any reason not to couple AGMs with Redarc. Please put me right if I'm wrong.

btw, my AGM/Redarc also goes to an Anderson plug on the rear bumper, which connects it's male partner on the van which in turn, turns me lights on. So to speak. So all I need is a shortish cable from the battery (SLA?) in van boot with female Anderson to connect to van plug, aided by solar whilst my AGM is kept going by the alternator and feeds the fridge. phew.......
AnswerID: 122900

Reply By: Mike DiD - Saturday, Aug 13, 2005 at 23:49

Saturday, Aug 13, 2005 at 23:49
SLA generally refers to batteries used for Alarms or Uninteruptible Power Supplies and these are Gel.

These standby batteries are generally Deep-Cycle but Gel (and Wetcell and AGM)can have the plates designed as Deep-Cycle or Starting.
AnswerID: 125066

Follow Up By: Mainey (WA) - Monday, Aug 15, 2005 at 18:40

Monday, Aug 15, 2005 at 18:40
My understanding is;
S L A stands for; Sealed Lead Acid

it can be a starter battery or a Deep Cycle battery, depending on configuration, density and size of the lead plates

if it's; a Sealed battery
if it's; a Lead plated battery (or lead/calcium etc)
if it's; filled with Acid

Then it's a S L A battery

Very basically
Wet cell batteries have 6 cells with caps where you can add water to replenish the acid.
Gel batteries are Sealed and with Lead plates (generally) and Gel in place of liquid forming the acid
AGM batteries are a different system again with many thiner lead plates each divided by a glass fibre matting material
FollowupID: 380042

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