Sunday, October 25, 2015

1344 Cycles - Still Going But...

The Winston Battery pack has soldiered on.  It has long surpassed the life of the AGM lead acid batteries and even the Deka Solar gel batteries, which gave up the fight at about 850 cycles on my solar system.

There is an odd thing though about these Winston Battery cells.  They create a bit of a smell sometimes.  The theory was that they are high pressure valve regulated and unless abused would never vent anything.  They'd be perfect for use indoors.

The truth didn't quite work like that.  The detailed instructions for them suggested that you should install them upright (just in case the valves open and some liquid electrolyte comes out).  Luckily, I did so, as the first set of cells I had suffered some kind of 'event' a while ago and I noticed some small crystal deposit on the tops of five cell vents.

Some time later, after talking with the supplier and Winston Battery, they offered to send me replacement cells.  I actually used these as a backup battery, in case the originals gave up.  I considered putting the suspect cells out to pasture but wanted to see if they would live out their life or actually die (hopefully not doing anything overtly incendiary!)

When taking the battery pack apart to see if anything had happened in the terminals, a couple of the cells had gotten some corrosion in the copper threads that increased the cell resistance in the string of cells.  But after some careful cleaning and re-assembly, the battery resistance balance was restored (all cells showing roughly equal series resistance).

The only thing I have noticed since is that the old battery pack gives off an odour sometimes when charging and oddly, when discharging to low levels.  A kind of sweet smell.  I tried putting balloons over the vent caps but no gas was ever released (that I could collect).  The patio door has a trickle air vent over it, and this seems enough to dispel the odour after a while.

I started using the spare battery pack as a second battery last winter.  It was completely separate from the main battery and I used the mains charger and the old spare 1kW inverter on it to get some extra storage for the winter.

But finally this summer, I took the plunge and wired the new battery in parallel with the old one after bottom balancing them together (so that they both reach 'empty' state at the same time).  This will make for an interesting experiment in itself, as the old battery had some 1200 cycles on it and was joined by a pack with barely 20 cycles on the clock.

I needed a strong oak coffee table to take the weight of the new battery, which sits above the old one on the floor below.