Solar Cluster: Remember kids, over-discharge protection matters!

So, yesterday I had this idea of building an IC storage unit to solve a problem I was facing with the storage of IC tubes, and to solve an identical problem faced at HSBNE.

It turned out to be a longish project, and by 11:30PM, I had gotten far, but still had a bit of work to do.  Rather than slog it out overnight, I thought I’d head home and resume it the next day.  Instead of carting the lot home, and back again, I decided to leave my bicycle trailer with all the project gear and my laptop, stashed at HSBNE’s wood shop.

By the time I had closed up the shop and gotten going, it was after midnight.  That said, the hour of day was a blessing: there was practically no traffic, so I road on the road most of the way, including the notorious Kingsford-Smith Drive.  I made it home in record time: 1 hour, 20 minutes.  A record that stood until later this morning coming the other way, doing the run in 1:10.

I was exhausted, and was thinking about bed, but wheeling the bicycle up the drive way and opening the garage door, I caught a whiff.  What’s that smell?  Sulphur??

Remember last post I had battery trouble, so isolated the crook battery and left the “good” one connected?

The charger was going flat chat, and the battery case was hot!  I took no chances, I switched the charger off at the wall and yanked the connection to the battery wiring harness.  I grabbed some chemical handling gloves and heaved the battery case out.  Yep, that battery was steaming!  Literally!

This was the last thing I wanted to deal with at nearly 2AM on a Sunday morning.  I did have two new batteries, but hadn’t yet installed them.  I swapped the one I had pulled out last fortnight, and put in one of the new ones.  I wanted to give them a maintenance charge before letting them loose on the cluster.

The other dud battery posed a risk though, with the battery so hot and under high pressure, there was a good chance that it could rupture if it hadn’t already.  A shower of sulphuric acid was not something I wanted.

I decided there was nothing running on the cluster that I needed until I got up later today, so left the whole kit off, figuring I’d wait for that battery to cool down.

5AM, I woke up, checked the battery, still warm.  Playing it safe, I dusted off the 40A switchmode PSU I had originally used to power the Redarc controller, and plugged it directly into the cluster, bypassing the batteries and controller.  That would at least get the system up.

This evening, I get home (getting a lift), and sure enough, the battery has cooled down, so I swap it out with another of the new batteries.  One of the new batteries is charging from the mains now, and I’ll do the second tomorrow.

See if you can pick out which one is which…