I have (4) 6 volt 230ah golf cart batteries for our solar system. A friend gave me (2) new 6 volt 210ah golf cart batteries. Can I add those to my current system being they're different amp hour rating?
Depends... How old are your Batteries? have you ever measured their Internal Resistance? Are they basically the same Size? (Plate Dimentions) ...... or just buy 2 more identical to your friends, and put them ALL IN SERIES, and move to 48Vdc for a Bank Voltage...
The 4 batteries are two years old and have been well maintained, check water frequently and they're always full. Adding. 2 more sounds like the way to go. How do I check internal resistance and what am I looking for? B
Actually, that take some Specialized Equipment, but in general, Batteries in Parallel, are not a Good idea, UNLESS they are exactly the same, to start with, and even then, they will tend to conform to the lowest of the group, and die from there... I run Three Strings of L16HDs @24 Vdc for 1200 AmpHours of Capacity, and the Bank I have now was NEW 3 weeks ago... The previous Bank finally Died after 10 Years, with only 20% Capaity the last 6 Months... What I should have done is bought 4 More, and jumped up to Two Strings in Parallel @ 48 Vdc... but I couldn't afford the last four Batteries this year...
Thanks for the information. Probably pick up 2 more to match, with the shorter days coming I could use a little more capacity
VERY well said ^^^^^^^^^^^^^^^^^^^^^^^ And So true ! Changing Voltages works well for real true Classics , Kids & the B17 system on charge controllers , as for inverters , they are what has locked in the set system voltage !! Sloth
Batteries in a bank, no matter how they are arranged, are going to vary moments after installing them ,it's just the nature of things. My bank is switched along with all other components as well . Each component (includes series paired 6 volt batteries =12 volts) is on a 3 position switch. Center off , or off line, Up is for testing voltage,, Down is for adding into the system. Every thing is fused. Make no mistake ,fuses pay off big. I have 6 volt golf cart batteries some are over 5-6 years old and just about to the end of their life cycle. they are pared and tested in pairs @12 volts , however If , when I see a decline in the bank , I isolate the weak one and reconnect the strong one to another 6 volt that is already paired, and that pair has a boost. that's one- 6 in series with 2 -6's paired. In my system I have lights that are 6 volt, so I have independent lines fed from any 6 volt battery I choose to serve the system. I've never had a problem. Solar is such a steady charge ,that if there are discrepancies in the system, it all works out . I have varying size solar panels, as well as a wind mill, as well as grid tied battery charger, and 6500 watt diesel generator. . These all make contribution . With proper diodes in place, nothing back feeds to lesser components . Be it batteries or solar panels or wind mill they will all vary in their values , just as there are variations in sunlight and age and so on . I don't stress over these things , The only concern I have generally is a battery with a dead cell , "That" does/can waste energy an otherwise good cell would absorb.
Main Battery Bank... 3 Strings of 4 L16HDs in parallel for 1200AmpHours @ 24Vdc feeding a Trace 4024 Inverter/Charger.... New Sept 2017....
