[RE-wrenches] Strings and series of batteries

[Jeff Yago]

Boy, this string on strings and series of strings is starting to string into a very long list of string related emails!

We also avoid multiple strings of batteries, but sometimes this is required to get the right combination of system voltage and amp-hour capacity.  We also agree that 3 or more strings is not good, and we have seen many cases where one string stays much less charged than the other strings on older systems as terminals corrode and individual battery cell conditions start to go south.  

However, for safety reasons we install a catastrophic in-line fuse in each separate string that is sized to help prevent a "melt-down" when one string tries to dump into another string that has a failed battery or shorted cell.   Not sure how fail-safe this is and would not protect against small amp flows between strings due to battery temperature differences, but feel its better than nothing.   

I also point out that for remote off-grid installations you sometimes have to use smaller and easier to handle L-16 size batteries, as its hard to pack in several one-ton tray batteries with no roads using a gater, so this means you still need multiple strings of batteries in parallel.

Jeff Yago

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