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AngeW · 12-08-2016, 04:36

we are replacing our house battery bank, as five years on our old AGMs are on their last legs. We've ordered 3 AGMs - Exide Dual with 240 amps. Problem is only two have arrived with the third not coming for about a month. The amps from two batteries (480 amps) will be just under our current house battery bank 498 amps).

Is there any reason why we shouldn't put the first two in now and add a third in a few weeks?

thanks for your help

Ange

SteveInMD · 12-08-2016, 05:12

I seriously doubt a few weeks is going to make any noticeable difference in their life span of 5 to 8 years. If you are really worried about it, treat the two you have well at least until the third one is installed. No discharges below 50% of the rated amp hours!

**HappyMdRSailor** · 12-08-2016, 05:35

Quote:

Originally Posted by SteveInMD

I seriously doubt a few weeks is going to make any noticeable difference in their life span of 5 to 8 years. If you are really worried about it, treat the two you have well at least until the third one is installed. No discharges below 50% of the rated amp hours!

I'm no battery expert, but tend to agree with Steve here...

SteveInMD · 12-08-2016, 05:37

Perhaps I should clarify... It is best for all of the batteries to be the same age. Basically the chemistry going on inside the battery slowly changes over time (sulfation, etc.) However this typically means you should not mix batteries that a number of years old with a new battery. I would have a hard time believing that a few weeks difference is going to make any real difference, especially if you can keep the two you have on a modern battery charger as much as reasonably possible. If you do need to disconnect from power (like to go sailing) be sure to recharge before reaching 50% of the amp hours rating. This assumes you have a battery monitoring system that tells you amp hours used. If not you should get one. This is far more important than a few weeks difference in battery age.

AngeW · 12-08-2016, 06:59

Quote:

Originally Posted by SteveInMD

Perhaps I should clarify... It is best for all of the batteries to be the same age. Basically the chemistry going on inside the battery slowly changes over time (sulfation, etc.) However this typically means you should not mix batteries that a number of years old with a new battery. I would have a hard time believing that a few weeks difference is going to make any real difference, especially if you can keep the two you have on a modern battery charger as much as reasonably possible. If you do need to disconnect from power (like to go sailing) be sure to recharge before reaching 50% of the amp hours rating. This assumes you have a battery monitoring system that tells you amp hours used. If not you should get one. This is far more important than a few weeks difference in battery age.

Thanks for this Steve, I was hoping that was the case. It does appear they may have located a third battery for us - in spite of the whole country (Greece) going on holiday. Appreciate your thoughts re battery monitoring system, we have one for solar, but not overall amp hours used. Will investigate

appreciated, Ange