Let them sit unloaded for a while, test the Voltages on & off loads (I use a motor as a load) see which batteries to remove, etc, etc.
I had eight 12V 7AH Sealed Lead Acid in parallel, all but one were secondhand, from old computer UPS's.
They're all wired with same-length connectors to the MPPT controllers battery output bus. (like it describes [url=http://www.smartgauge.co.uk/batt_con.htmlhere[/url] in section 3)
Anyway, there is a small Voltmeter permanently connected across the whole stack, telling me the average Voltage, which read 12.7
So, I thought this was a bit strange, seeing as I hadn't used them for a month or so and that the panel on the other wall, connected between the solar panel and charge controller read 15V 5A.
Where's this 75 Watts going I wondered?
So I began to pull all the red cables off the terminal posts, came to a pair of batteries and thought f**! that, they're hot.
Yes, the pair I removed took over an hour to cool down, one was beginning to bulge as I've seen so very often.
There's a lesson here somewhere - OK, I know mixing old and new (or weak and strong) is not a good idea, but never realised how hot they could get.
Actually, we had a power cut this morning and I was just after another battery to replace my internet modem's UPS inside, but that gave me a good excuse to do this "test".
I will replace the wooden board they are sitting on for a plastic tray, in case I get any leakage from splitting, which would not be good for whatever is on the bench below...
I had eight 12V 7AH Sealed Lead Acid in parallel, all but one were secondhand, from old computer UPS's.
They're all wired with same-length connectors to the MPPT controllers battery output bus. (like it describes [url=http://www.smartgauge.co.uk/batt_con.htmlhere[/url] in section 3)
Anyway, there is a small Voltmeter permanently connected across the whole stack, telling me the average Voltage, which read 12.7
So, I thought this was a bit strange, seeing as I hadn't used them for a month or so and that the panel on the other wall, connected between the solar panel and charge controller read 15V 5A.
Where's this 75 Watts going I wondered?
So I began to pull all the red cables off the terminal posts, came to a pair of batteries and thought f**! that, they're hot.
Yes, the pair I removed took over an hour to cool down, one was beginning to bulge as I've seen so very often.
There's a lesson here somewhere - OK, I know mixing old and new (or weak and strong) is not a good idea, but never realised how hot they could get.
Actually, we had a power cut this morning and I was just after another battery to replace my internet modem's UPS inside, but that gave me a good excuse to do this "test".
I will replace the wooden board they are sitting on for a plastic tray, in case I get any leakage from splitting, which would not be good for whatever is on the bench below...
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