Determining Battery capacity

[PDReynolds]

Hi All

I am just installing my Victron Battery monitor and part of the setup requires me to determine my battery capacity. I am monitoring my 2 house batteries"SRM-4D.

What is my total A hour capacity of these in parallel? Is it 200 Ah times 2?

 

[centerline]

Hi All

I am just installing my Victron Battery monitor and part of the setup requires me to determine my battery capacity. I am monitoring my 2 house batteries"SRM-4D.

What is my total A hour capacity of these in parallel? Is it 200 Ah times 2?

if they are 12v batteries, the answer is yes....

2 6v batteries will not double the amperage... it will if you are using them in a 6v system, but not if you are putting them in series to create 12v....

 

[Dan Hill]

If they are rated 200ah each then yes your ah capacity is 400. But, this is when they are brand new. If they have been treated properly through their life so far I would deduct maybe up to 5% capacity per year of usage and start there. 1 year previous usage = 380, 2 years = 360, etc. Another method is to apply a 5 amp load for close to 80 hours but who's got time for that!

I'm sure there are more scientific ways to calculate this and I'm positive others will provide.

Good luck!

 

[mitiempo]

Hi All

I am just installing my Victron Battery monitor and part of the setup requires me to determine my battery capacity. I am monitoring my 2 house batteries"SRM-4D.

What is my total A hour capacity of these in parallel? Is it 200 Ah times 2?

Correct, in parallel the AH is doubled and voltage stays the same.

The batteries you have are not 200 AH batteries however, and are not true deep cycle either. Their specs do not show AH measured at the 20 hour rate. The specs are shown at the bottom of the first group at this link: http://www.interstatebatteries.com/cs_estore/content/product_info/marine_f.asp

I would guess the are somewhere around 140 - 150 AH each.

 

[rgranger]

I just took four old deep cycle batteries to AutoZone (last week). They advertised free battery testing and a $5 rebate on recycled batteries. These batteries were left in some old boats that I had purchased to restore (a hobby of mine). Anyway, three were still good. The interesting thing is... the battery testing device told me the remaining Ah and the cold cranking capacity. Not sure I understand how it works but... That is one way for you to get your answer and it is fast and free.