Charger size

[witzgall]

Hi all;

I am contemplating the installation of a charger on our boat. Right now, we have one Optima 55ah dual purpose battery for the engine. The house bacnk is one Trojan 1275 Battery, 150 ah, and I may be adding a second as well. This would mean a 300 ah house bank

So what size charger do I need for the two scenarios? I don't really need high rate charging, but something that will keep them topped of when at the dock.

Thanks,
Chris

[Rhosyn Mor]

Without too much info I would think a 10A charger would be just fine, its not a big bank.

[btrayfors]

Get an Iota 30A or 45A charger, with the IQ-4 smart-charge option (internal or external) and don't look back. Either will handle your needs handily. Since there's not much difference in price, I'd go for the 45A model which will handle your forseeable needs.

Top-of-the line stuff, great technology which few other battery chargers have, GREAT prices, and they'll keep your battery bank in good condition over the years.

You can find them on eBay or elsewhere. JackRabbit Marine has them, as does Industrial Supply and others. I have two (45A and 55A models) and they're terrific in applications on the boat and in my ham shack.

Bill

[By Invitation]

General rule of thumb - ideally your charger should be 25% of your house bank ah. If you want to be able to equalize your batteries, you need a decent charger. I would think a 30 amp would be fine but a 10 I think is too small.

[witzgall]

OK. SO if for now we decided to add a small solar panel to keep things topped off, instead of the charger, what size might be appropriate?

Chris

[By Invitation]

"small solar panel to keep things topped off"

I wish you luck with this one. There is a reason most cruising boats have huge panels. I have a very nice solar calculation program if you are interested I can email it to you. It calculates the entire charging and discharge cycle relative to the rotation of our planet and the sun. You will be surprised large a panel you really need.

I would recommend the charger first.

[David M]

I would leave the solar panel out of the equation of determining what size battery charger you need because sometimes you will be using one and sometimes the other to keep your batteries topped off. As was already mentioned, a smart 30A charger would work fine. As far as the solar cells go, get as many as you can afford and as many as you have space for. I don't know your typical daily amp-hour usage or your peak usage in watts, so thats as specific as I can get.

David