How much converter/charger is really needed?

pianotuna wrote:
Bobbo,


What Mex is saying is that if you have shore power for charging, converter size doesn't matter much. If, on the other hand, a generator is being run, a device capable of high amperage charging is of benefit, and worth an upgrade.

Bobbo wrote:

OP here. When I am able to understand Mex's posts, I learn a lot. When, like this one, I don't have a clue what he is saying, I just go on and don't worry about it.

Except if you want to meet the 20% minimum charging rate on AGMs that Mex insists upon. A 45 amper is 20% of 225 AH. What if your bank is bigger than that?

I do my recharge on shore power when I get home, but I still have to meet the 20% minimum. (on 450 AH) The voltage is no problem with my adjustable voltage chargers.

I have to split the bank to get the parts down to where my converter is at least 20% of the larger part, a 250AH 8D AGM. So I need at least 50 amps for that. (spec max is 100 amps for that battery but Mex says ignore that spec. Doesn't matter, I can't run a 100 amper with my 2200 gen or on shore power at the house-pops breaker--so I use a 75 amper for that one.

The other part is two 100s in parallel so I need at least 40 amps to do the pair. Rated max is 27 each or 54, but Mex says to ignore that. If I do go with that spec, I am boxed in between 40 and 54 amps to do them. I use a 55 amper as it happens. Mex is saying I could use the 75 on them too.

( The problem is when driving home and the batts get some recharge from alternator charging and solar. Easy to get home with the batts high enough in SOC that they will not accept 20% amps. So now you can't meet the 20% rule. Now what?---discharge them till they will and now recharge them? Before leaving for home, disconnect alternator charging and solar? BTDT.---I find that 20% rule to be a real PITA, but I do follow it grudgingly.

Anyway, if the OP stays with Wets, he can do the low amp but proper voltage thing on shore power, but not with AGMs and a 45 amper unless he has 225AH or less of a bank. I think he could do that with a pair of those Trojan T-105-AGMs at 217AH.

https://www.trojanbattery.com/product/t105-agm/?_vsrefdom=adwords&gclid=EAIaIQobChMIk7aswufM3gIVD8pkCh2lmwtkEAAYASAAEgKR8vD_BwE