HSx External Cache Battery (ECB) renewal


It seems that any used HSx ECB unit you buy is going to have shot cells. That's because the cells turn to mush if the voltage drops too low, which they're going to do when not hooked up to a system. Even in a running system they don't seem to last more than a couple of years. You'll know they're bad if the LED blinks all the time, and your controller complains endlessly about low cache battery voltage. Here is how to fix a dead backup battery unit for about $16 and some hack work.





Here is the part number on the internal unit. I guess you could buy one of these and spend a lot of money!






OK, we're cheap, let's fix the one we have. First, take the battery unit out of the SBB carrier by removing the two screws on the side. Then take the inner unit apart as shown.





Here is what it looks like out of its shell. Remove the indicated hardware to take it apart.







Here is what you get when you take it apart. Make sure not to short anything in the process, OK?







Here is what you get after you slice off the shrink wrap.







Here is another part number to chase if you don't like hacking your own like this.






Getting the stick apart at this point requires some careful prying apart, because the cells are glued to each other, and the end insulators are glued to the cells, with silicone sealer. I ended up doing some slicing with a single edge razor blade to get it started; they were too firmly stuck otherwise. But you really really don't want to have the razor blade hit both battery terminals at once, so be careful out there! Even a mushy dead cell probably still has some major amps on tap.





Here is how the cells are wired together.






Desolder the wiring connections. Save the short wire and the insulator piece. Go buy yourself some new batteries. I got mine for under $8 each here: http://www.gotbatteries.com/ProductPage.asp?ProductNum=37L142S1
You can find the specs from the manufacturer here: http://www.enersysreservepower.com/cyc_b.asp
Once you have the new cells, you need to bend down the tabs on them the same way as on the old ones.





Here are the new cells. Bend down all 4 tabs as shown.







I'm usually anal about rebuilding stuff, but here is how I got my shrinkwrap to be as thin as the original. Ugh, right?







Put it all back together, plug it into your cache cable, and no more blinky LED!