Battery Price Solution

Re: Battery Price Solution

Oh boy... A can'o worms set of questions.

Yes, AGM batteries are about the as close to "perfect" that you can get with Lead Acid Batteries (clean, freeze resistant, more efficient, no water to add, usually do not outgas during normal operation, can be mounted on side, etc.).

And Gel Batteries should not usually be considered for solar pv/deep cycle applications (too easy to damage with high charging currents/voltages).

The downside for AGM is they are, roughly, 2x the cost of flooded cell batteries, may only last 1/2 as long as high end flooded cell batteries.

True deep cycle batteries (with thick plates) tend to last/cycle longer.

Forklift type batteries, can last 15-20 years, but are (typically) less efficient and use more distilled water.

I believe in keeping parallel battery strings to a minimum (ideally 1 series string of cells; 2-3 maximum parallel strings--difficult to share current, a bad cell can take out the other strings, plus you need extra wiring/fuses/breakers per string for safety). So, it is not the 2/4/6/12 volt per battery that is really the question, it is the AH rating of the cells and your ability to move them (a 2 volt 300 lb cell vs a 12 volt 300lb cell, the 2 volt cell will have 6x the AH rating, so fewer parallel strings needed).

-Bill

Re: Battery Price Solution

A little light bedtime reading:

Deep Cycle Battery FAQ
www.batteryfaq.org

And the Walmart, as others have said, may be great for a short term (3-5 year) battery bank setup. Let you get some real world experience without a 10-20+ year commitment (and not even knowing your loads yet for new construction).

The issue seems to be, buy 2x larger battery bank and the battery bank may last 2.1x longer. Buy 2x more expensive high end batteries, and they may last 2x longer.

So far, from what I have seen, the big issue is the number of years between change out... Having to replace batteries every 5 years vs every 10-15+ years may be really nice. As is only limping along on a degraded bank every 10-15 years vs every 5 with small/cheap bank.

But, in the end, if this is your first trip into solar/at this home/facility... Buying smaller/less expensive battery bank and beating it up a bit to see how much power/fuel/etc. you use--then with your new found/hard won knowledge--Go out and buy the "ultimate" battery bank/array upgraded/etc. as needed).

We are, in general, a pretty cheap group of guys here and try to answer questions on the best use of money. But--everyone has their own needs and situations--And why we just don't point to one "Off Grid Configuration Post" for all the newbie questions.

There is rarely one "optimum answer" in this field.

-Bill