what is my house bank capacity? - SailNet Community
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what is my house bank capacity?

One of my winter projects is to replace charger. I understand that I should size the charger based on ~10% of the capacity of the house bank. But thinking about it I realized that I don't really know the capacity of my house bank.

My 12v house bank consists of 4 Exide GC-110 golf cart batteries.

The specs for the GC-110 are:
- 220 Amps
- 6 volts
- Amp Hours (20 hr. rate): 186
- Minutes at 75 amps: 110
- RC Minutes: 390

so, for the purposes of sizing the charger, which value should use for the capacity of each batt?

Also I'm assuming that I'd multiply that capacity by two for the total capacity (a pair of batts in series, the two pairs in parallel)

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Re: what is my house bank capacity?

I think you're on the right track.

Two batteries in series will increase the volts and two batteries (or battery banks) in parallel increase the Ah's.

Daniel
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Re: what is my house bank capacity?

Each battery is therefore specified to be charged at 18.6 Amperes. Because, presumably, you have two 12 Volt banks to charge both banks in parallel would require a 37.2 Ampere charger. The reality is that you will only see these charge currents if the batteries are quite discharged, and then only for a short time. So buying a 40 Ampere charger may not be worth the expense and all. Ten or twenty would be fine by me.

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Re: what is my house bank capacity?

You have 440AH @ 12Vdc.

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Re: what is my house bank capacity?

Quote:
Originally Posted by bristol299bob View Post
One of my winter projects is to replace charger. I understand that I should size the charger based on ~10% of the capacity of the house bank. But thinking about it I realized that I don't really know the capacity of my house bank.

My 12v house bank consists of 4 Exide GC-110 golf cart batteries.

The specs for the GC-110 are:
- 220 Amps
- 6 volts
- Amp Hours (20 hr. rate): 186
- Minutes at 75 amps: 110
- RC Minutes: 390

so, for the purposes of sizing the charger, which value should use for the capacity of each batt?

Also I'm assuming that I'd multiply that capacity by two for the total capacity (a pair of batts in series, the two pairs in parallel)
Four Exide GC-110's in series>parallel is a 372Ah bank for the as new rating.. The Ah capacity is your 20 hour rate on the battery plate or spec sheet. 186 X 2 = 372.

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Re: what is my house bank capacity?

Is there any disadvantage (other than excess cost) to going up a size on the charger?

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Re: what is my house bank capacity?

Quote:
Originally Posted by bristol299bob View Post

The specs for the GC-110 are:
- 220 Amps

- Amp Hours (20 hr. rate): 186

so, for the purposes of sizing the charger, which value should use for the capacity of each batt?
Is it 220 [email protected] 20 hr rate, or 186 [email protected] 20 hour rate? What rate is the 220 measured from?

20 hour rate is usually considered standard, so 186 X 2 = 372 AH.

Divide by two because you shouldn't deplete below 50%, in order to avoid damaging the batteries.

When you batteries are tied together into a bank, think of them a single battery. During bulk charging, you want to be able to deliver 25% of charge amps to the battery. For example, if you have 200 AH of capacity, you want to be able to feed in 50 amps. Your dealing with flooded batteries, so you don't need the crazy high amperage of a AGM, for example. 25% is a good number for flooded batteries. They won't accept much more. If you want to charge faster, go with AGM.

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Re: what is my house bank capacity?

Quote:
Originally Posted by miatapaul View Post
Is there any disadvantage (other than excess cost) to going up a size on the charger?
No disadvantage. The batteries determine the acceptance, not the charger.

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Re: what is my house bank capacity?

Quote:
Originally Posted by mitiempo View Post
No disadvantage. The batteries determine the acceptance, not the charger.
thanks, that is helpful. I figured as much, just did not want to make a huge mistake. I can get a deal on a larger charger, and figure I will eventually have a bigger bank, so might as well get it now rather than replace it later.

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