Low voltage alarm

[BigAl.NZ]

Originally Posted by markcouz

Depends if you want to submit your result to a scientific journal or just find out how your batteries are doing. Using a constant load will give a slightly variable current which is more than good enough for an estimate of battery condition.

In your case you are looking at about 18amps, which is about 200w load.

Thanks - when you say in my case are you referring to my fictional 220Ah battery or the actual setup detailed in the first post of this thread?

I ask because my theoretical example I calculated 11Ah.

[markcouz]

Your 360Ah bank would require an 18Ah load to carry out the test.

[BigAl.NZ]

Originally Posted by sailorboy1

I suspect your batteries aren't getting fully charged and you are much less than 90% (like at maybe only 60%). Start getting your batteries fully charged.

Btw - I have my alarm also set at 12.2V. It only goes off if running a big load off the inverter. Like my toaster or microwave.

Do you still use TE105s? They FLA?

I think I will be up for new batteries but the location of our compartment means either AGM or GEL. We have GEL now so was looking at the TE35.

If there is no need for a sealed box I could look at the TE105s. So cheap and well known.

[BigAl.NZ]

A footnote to this thread:

I had the batteries tested 3 times by a local guy (capacity test).

Twice they lasted 67 minutes, the third time they only lasted 10 minutes. He could not explain the two different results (anyone?), but the conclusion was they are stuffed.

[markcouz]

So this is a simple analogy that I use to explain common battery issues to my clients, feel free to skip if you like.

You can think of batteries as a bucket of water that silt up over time. You can always fill (fully charge) the bucket, but the amount of water available will be reduced depending on the level of silt.

Your batteries are about 90% silt!

I guess that at some stage you have had a single cell failure (as in 1 of the 3 2v cells in a 6v battery has failed), as you have 2 batteries in parallel and you apply 14v across them to charge you are applying 14v across 5 cells and not 6 - this would cause the 5 good cells to be overcharged and be damaged as a result.

I would recommend replacing all the batteries, but if you have budget constraints you could ask your local guy to do a load test on each 6v battery individually and see if there aren't at least some that are serviceable.

You would require access to a 6v charger so that each battery could be charged correctly without being influenced by a faulty battery in series. Discharge each cell through the same DC load after charging and measure the result in Ah. That would give you reasonable info as to the condition of each.

Good luck

[markcouz]

Correction:

... as you have 2 batteries in series...