Battery charging advice

[jen1722terry]

Hi CDers,

We have a battery charging question:

Our house bank is two AGMs wired together in parellel. This type of battery needs extra charging with our portable smart charger to extend battery life.

We just had an electrician on board for our solar controller and he said we could charge them both similtaineously
without disconnecting them. Is this true?

Should the battery switch be "off" for all batteries when we're charging?

The batteries are Odyssey AGMs and a bit finicky with their charging needs.

Jenn and Terry

Any advice would be most appreciated

[Sea Hunt Video]

Hello Jennifer and Terry:

Thank you for posting these questions. I was getting ready to post similar questions.

I have two batteries -starter and house. Both are Delco Deep Cycle M27MF maintenance free AGMs that I purchased in November 2011 Sadly, because of medical issues I have not been able to keep them charged while S/V Bali Ha'i has been siting on a Triad trailer in my driveway. Both batteries are basically "dead".

I have given thought to trying to "resurrect" them and have bought a WM battery charger for that purpose.

I will look forward to responses to your questions to see what I can do with my AGMs.

[Paul D.]

I don't think it should matter whether the battery switch is on of off for charging the batteries. What does matter though is using a charger able to be set to charge AGMs. They require a specific charging regimen. Most newer marine AC chargers should have a mode for AGMs. I would first make sure that, a. your charger has an AGM setting or is designed to charge AGMs somehow and b. if you are charging them together in parallel that they are the same age batteries and about the same state of charge.

A call in to someone like Ham Ferris at Hamilton Ferris Power Products may be really helpful. Good luck.

[Sea Hunt Video]

Jennifer and Terry:

I found this website that provides information on charging battery banks in parallel and series. it also provides what appear to be simplified diagrams of charging setups, etc.

http://www.batterytender.com/connecting-chargers

I have NO IDEA if the information is accurate or not. Hopefully, someone will post after looking at the above thread to let us know if the website appears to offer accurate information.

[jen1722terry]

thanks to all for the sage advice.

Yes, we do have an Odyssey smart charger designed specifically for our Odyssey AGM batteries. So we'll try charging the two house batteries in parallel and see if the charger completes the full reconditioning cycle.

Thanks again.

Jenn and Terry

[Boyd]

If your solar controller is wired directly to the batteries (my preference) with a fuse on the red wire from the controller, then the battery switch position will affect the system in the following way:

Assuming you have a simple on/off switch. If you have a 1/2/all/off switch its a bit more complex. Repost if that's the situation

If the switch is off, then all charging power goes to the batteries. Theoretically all house loads are not powered. The likely exception would be bilge pumps which are typically wired directly to the batteries with their own separate fuses.

If the switch is on then any house loads that are on (controlled by the panel breakers) will be powered by the solar controller and or battery if the sun is down. For instance if you leave the fridge running in this example, much of the solar load will go to running it and little to the batteries. If the sun goes down the fridge will be powered exclusively by the batteries.

Should in the unlikely event your solar controller is wired to the switch, if the switch is off your not charging your batteries.

Batteries wired in parallel will both charge from the single source feeding them. One battery might see a bit higher charge voltage due to resistance in longer wires, corroded connections, etc. If the wiring is all good then they see almost the same charging voltage.

Hope this helps.

Boyd
s/v Cat-A-Tonic
Prout 34
Fort Lauderdale, Fl.