Posts: 7Registered Users
I have a house in Mexico off the grid with 6-8 hours of sun.Right now I have 24 volts system with 8 KC-130 solar panels (2 groups of 4) running to a MX-60 controler and a Outback inverter with 12 crown golfcart batteries(3 groups of 4). I also have a Bogart2020 meter and a Outback "mate"
I am Up-grading now to 12 Surrette S530 (400amp) each. So, I think I am going from around 600amp/hour bank to a 1200amp/hour bank? is that correct and.
1. will I have enough solar panel current to support the new batteries?
(My house is used maybe 4 days in a 10 day peroid with little load)
2. Will I have to reprogram my Bogart2020 meter for the new amp/hour?
3. Will I have to program the MX-60?

thanks khinphx

khinphx,

You only need to post the question once--we are not too strict about which forum (general solar, vs new user questions).

Regarding solar to battery ratio:

8*130 watts / 2*17 volts = ~31 amps of charging current

Your battery are 6 volt--so it will be 3 strings of 4 batteries each or in AH:

3 strings * 400 amp*hour = 1,200 AH of battery (at 24 volts)

31 amps / 1,200 AH = 2.6% rate of charge...

Normally, to achieve good equalization (once per month, or whatever the battery vendor recommends), somewhere around 5%-13% charge to capacity ratio is recommended.

Your solution would be to have 2x the number of panels, 1/2 the number of batteries, or plan on using a generator once a month to perform equalization...

Normally, having too Large [not small] of battery bank is not a great idea--it takes a long time to recharge them. But, if your home's load is not very large, and you are using it 4 out of 10 days--it will probably work (with generator use for equalization).

Is your current battery bank getting properly recharged in your current setup? Did the current battery set last or are you replacing it because they died too soon? Are you keeping your batteries above 75% state of charge (prevent sulfite hardening--if you discharge below 75% SOC, it will probably take too long to recharge just using the solar panels--especially during winter without using the generator)?

Are you planning on more loads/full time living in the near future and sizing the battery bank now and plan on more solar panels/generator time in the future?

-Bill

PS: Sorry, about the other questions:

Yes, you will need to reprogram the "2020" meter for Battery AH capacity (see manual).

You may need to program the MX 60 to better match the recommended charging voltages for the Surrette--again, read their documentation and update the MX 60 as needed (settings may be close enough though--depending on how the MX 60 was originally configured).
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Posts: 7Registered Users

The present batteries are working fine and "float" at about 2:00pm the next after the night before use. In the morning after a lot of night use down to 78%- 80% and then recharges great.
I have line on the Surretts S530 Brand new for a "cant pass up" deal.

Fixed my previous post--wrote small when I should have written Large.

If you get the new batteries, it is generally not a good idea to put them in parallel with your existing "old" battery bank (especially if the batteries are difference AH capacity/model/vendor)... Something is not going to charge correctly or draw down evenly and cause early life failure of one or the other batteries in your mixed bank.

So--you will probably need to find a new home for the old batteries.

Also watch your "water usage"... If the new batteries are not using any distilled water month after month, they probably are not getting enough charging. Check once in a while with a good Hydrometer to make sure that everything is charging OK.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Posts: 7Registered Users

I am going to pass on the golf cart batteries to a friend that all ready has the same. I will watch the water usage and I will Equilize as recomended by Surrette.
Thanks for the help and sorry about posting in the wrong section. <first timer>