Problem with lipo4 is lots of bits require changing, costs money even though the batteries are very good, without changing any solar control units or chargers the lead carbons are a drop in exchange, these can be bought on line ebay or maybe with a link from this site.
The problem you'll encounter with going lead carbon is the limit charge rate of some particularly that 115ah leoch jobbie that you often link to Trev. Can't recall exactly but I think the maximum charge rate is just over 20A, you'll exceed that with your fat cable and HD relay system that you're using at the moment.
Ok so Trev has his own charge system, it's basically a split charge relay setup BUT he's cabled from the alternator to his leisure battery with very heavy cables, this means he'll be charging at somewhere around whatever the alternator can supply, because of this higher current flow his SCR is a very high current relay.
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I don't have one Merlin but is it worth getting this as I'm never going to be a big user/Ok so Trev has his own charge system, it's basically a split charge relay setup BUT he's cabled from the alternator to his leisure battery with very heavy cables, this means he'll be charging at somewhere around whatever the alternator can supply, because of this higher current flow his SCR is a very high current relay.
Those Carbons have a maximum charge current, if you download the tech spec and zoom in on the label on the top of the battery image you'll see 24A max charge current. I've got an idea that this has now changed to 22 but I could be wrong. Yes it's naughty that they don't openly state this in the literature and you have to wait until the battery arrives before you find out
A normal MH charge system comprises of thinner cables than what Trev's using and also there are smaller fuses, PCB tracks connectors and probably other relays etc too, this all increases wiring resistance and that resistance limits the charge current. The maximum current will vary from van to van because of all of the variables re cabling etc but obviously you have your DC clamp meter so you'll be able to check it, it will be highly when the battery is fully discharged and then the current will drop off as the battery charges up, probably won't exceed 20A anyway.
Sorry to be the harbinger of bad news but please don't shoot the messenger
No the alt which also charges the starter battery will throttle back as they do, anyway i will have 2 lez and one starter from a 70/90 ah altanator.
Absolutely, essential IMHO. Harry has done quite a lot of searching for a reasonable one at the right price but I don't know which one he when for and if it's arrived yet.
So here's that close up from their tech spec PDF
Yes, if you're going to use one in your setup then you'll need to check the current and limit it by adding some additional resistance, I'd just add a length of 2.5mm T&E mains cable, you'd have to experiment with the actual length but remember current will be higher when the battery is deeply discharged.
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Will look into that, meentime the old truck batts are holding up well, mind you i dont hammer them as only ever stay one overnight at a time, some lights ph charging and maybe a we bit of tv.
Personally I'd get a more suitable battery rather than trying to modify your van to suit. When you get a reply from Tayna why not ask them about other LC batteries without the current limitation?