[TriLUG] reason not to mix batteries in UPS

[Joseph Mack NA3T via TriLUG]

My UPS started beeping, so I replaced the batteries. There were two banks 
of 4 12V7AH SLAs. The banks were

o 4 Duracells from Batteries Plus

o 4 PowerStars (presumably some generic brand) from Amazon. (about 25% 
cheaper than the Duracells)

The PowerStars were hot and the plastic cases bulged out and had melted 
together (all four coming out of the UPS as one block), but miraculously 
weren't leaking.

One of the Duracells leaked and badly corroded the contacting F2 lug.

I don't give either brand good marks here.

I assume the PowerStars failed first, but the circuitry which detects a 
failed battery gave a pass, as the Duracells were still accepting charge. 
Presumably the PowerStars then got beaten to death, getting hot, till the 
Duracells failed and the circuitry declared the batteries dead.

I assume if the batteries has been from the same manufacturer, they would 
have all failed about the same time and the batteries wouldn't have got 
hot.

Joe

-- 
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
Don't upgrade a working machine - it won't work any
better - it could work worse; it may not work at all.
Homepage http://www.austintek.com/ It's GNU/Linux!