SLA batteries

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.

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.

Steve,
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.

Steve

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.

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.......

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.