Adding a Second House Battery

Sadey · Post by **Sadey** » July 9th, 2019, 9:35 am

I have a total of four batteries, 3 starting and 1 house. It seems I'm asking to much of my new AGM house battery so I might add one more house battery. Is it as simple as securing a second battery properly, wiring + to + and - to- from the current house battery? I have an 80amp charger for the current house battery so is that enough and will it charge both with the simple wiring I laid out above? I have an additional 30amp charger for the starting batteries that I'm sure is isolated to those only.

Cooler · Post by **Cooler** » July 9th, 2019, 10:22 am

Hey Sadey! Electrical is not my forte, but I may see a mechanic today that would know. If I see him, I'll check it out. Are you guys still in Sister Bay? I drove through by car last Friday, on my way to Ellison Bay. Was going to stop and find you, but the traffic was horrible and there was 0 parking spaces. If you are looking to do a cruise, come over to Menominee Thursday. I will be there after 2PM, staying that night. My slip is D-3. 8-)

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Sadey · Post by **Sadey** » July 9th, 2019, 11:26 am

I would really appreciate you asking the mechanic. Thank you! We were in and out all day so even if you had stopped by I'm not sure we would have been there. We leave here Monday the 15th and have two be back in Racine by that Thursday. We were kicking around hitting Menominee. If we do I will send you a PM I or look for you at D3.

bud37 · Post by **bud37** » July 9th, 2019, 12:21 pm

I don't see any reason that won't work fine.....there is enough charger. Just get a second battery exactly like the first, size/Ah etc.

One thing , connect the pos+ to the boat from one battery and the neg- to the boat from the other....you have created one bank here from two batteries and important to take and give power evenly across the bank.

Sadey · Post by **Sadey** » July 9th, 2019, 3:13 pm

Just to clarify, from the currently mounted house battery using the proper gauge wire I run a positive wire from positive to the positive of the new battery and the same from the negative side of the current battery to the negative side of the new battery? Two batteries = one bank?

bud37 · Post by **bud37** » July 9th, 2019, 7:39 pm

Sadey wrote:Qr Bbpost Just to clarify, from the currently mounted house battery using the proper gauge wire I run a positive wire from positive to the positive of the new battery and the same from the negative side of the current battery to the negative side of the new battery? Two batteries = one bank?

You got it..... :down:

.....that one bank will now be 12volts but twice the Ah......you have created one big battery in effect.....

Sadey · Post by **Sadey** » July 9th, 2019, 7:50 pm

Got it thanks bud37!!

Post by **Viper** » July 10th, 2019, 10:29 pm

Yes in simple terms that's how it works. The more complicated consideration is wire gauge based on a bank's current out capacity but you're probably fine just adding one additional battery. Install a new battery that is the same spec as the existing one. How old is the existing battery?

Sadey · Post by **Sadey** » July 10th, 2019, 11:40 pm

The current house battery is about three weeks old.

Post by **Viper** » July 11th, 2019, 6:48 am

You're fine. What you don't want to do is add an additional battery to a bank that has much older batteries. They should all be the same spec and the very close to the same age. I trust all the different banks your charger is charging are all AGM and that the charger is set to an AGM charging spec?

Adding a Second House Battery

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