The rabid VRLA

I didn’t know that lead-acid batteries were susceptible to rabies, but the cracked battery I found in an APC UPS a while ago certainly seems to know better! After sitting untouched on my bench for about a week, it’s without doubt enlightened me on the subject!

That's definitely not normal VRLA drool, son.

It looks like something that you'd find in the movie "Aliens".

Of course, there is a proper, scientific explanation to this (I doubt the rabies virus thrives in sulphuric acid and lead). That is that the highly contaminated, cracked cell is leaking a lot of current and is being discharged by only sitting. When you discharge a lead-acid battery, you essentially combine the acid in the electrolyte with the lead on the plates, creating lead sulphate. It normally collects evenly along the sides of the plates, but since a wall is missing, nothing prevents it from forming on the edge of the plates as well, growing up in the air.

As if APC batteries weren’t bad enough already

Upon hauling home a failed APC Back-UPS RS 1500VA (BR1500I) and cracking it open in the shop, I was greeted by a new sort of battery failure:

The battery casing has a very large crack in it.

Yes, the plastic casing on one of the batteries has cracked – and it isn’t even just a minor crack; about 80% of the end wall of the cell can be bent up with a screwdriver.

Amazingly, the cell is still working. The battery was charged at a decent 12,6V when I measured it. The ESR of the cell, however, is not as healthy. It would barely power the UPS when idle.

This is how it looked when I pulled the battery pack out.

The crack reaches around all the way. The plastic is only attached at the top.

I very much doubt that this has anything to do with the UPS itself, it seems far more likely to be a manufacturing defect on the battery. The UPS charges the batteries normally, and the other battery in the pack shows no signs of abnormal wear, not even swelling.

I think this is a quite serious issue indeed. If a consumer was to remove the battery pack, oblivious to the potentially corrosive contents of the battery cells, someone could get seriously hurt.