Monday, July 4, 2011

Things To Fix

Back about 2003 or 2004, I bought an Orion Telescopes Dynamo Power Station to power my telescope drives.  This is essentially a sealed lead-acid battery with an integrated charger and flashlight, similar (although with less storage capacity) than this one.  This was after an unfortunate accident with trying to cheap out and use a motorcycle battery in a box.  It spilled in the back of the Corvette one evening, damaging the carpet.

It worked great--but when the clouds finally cleared long enough in the last few days to again use a telescope, I discovered that it would not recharge.  The LED saying "NEEDS CHARGING" would not clear.  This is not a surprise; no rechargeable battery lasts forever.  I was expecting to find that the replacement battery would be either:

1. Hard to remove from this unit.

2. Hard to find a replacement.

It turned out that while it was a mild hassle disassembling the unit to get out the sealed lead-acid battery, it was really not difficult to find a replacement.  I called up Batteries Plus in Boise, and they had an exact replacement in stock: same dimensions, 12 VDC, 7 amp-hour, just like the original.  Even better: for a couple dollars more ($34.95) they had a 9 amp-hour battery with the same dimensions.  This made it possible for me to get this operational again the same day, and I was able to use my telescope this evening.

1 comment:

Nicholas said...

7Ah SLAs are very common; they are used in a lot of smaller UPSes (and as you discovered, other products too).

If you let the terminal voltage drop below about 11.5V then (like wet cell batteries) the plates sulphate up and the battery is pretty quickly toast. Make sure to charge any lead-acid batteries you own at least once every two months or so even if you don't use them to prevent this.

You can sometimes recover sulphated lead-acid batteries with a battery "zapper" but apparently it doesn't work with the gelled electrolyte types. The zapper relies on bursts of high voltage to flake the sulphate off and this eventually redissolves in the water to form sulphuric acid. If the electrolyte is gelled then that process won't work.