Originally posted 2/16/2013
I’ve been exploring my muse of late, not to mention doing my accursed income taxes for this year, so blog posts here have taken a hit. But who can be diligent out here? Accuweather says it’s 75 today, but my digital thermo says it’s 80, while my “analog” mercury classic says it’s 81. Sunny, very thin, high clouds, a warm breeze… Perfection. I’m acclimatized here, I guess – I have to put on a long-sleeved shirt when it drops to 70! What’s up with that? I see Algonquin, IL, my home base, reads 17 & 7 for today. Sheesh!
If you were down here, would you be toiling away? Didn’t think so. Where’s that cabana girl with my drink?
Going strictly by gut feel, the office batteries seem to drop voltage under load more quickly than they used to, but once they sit and recover, the voltage pops right back up where it should be. I picked up some heavy duty electrical connectors yesterday and may install them in the parallel wires linking the four batteries, so I will have the ability to electrically separate them for individual voltage checks. It’s just a way to see whether one battery is any worse off than the others. With them all linked together like they are now, they tend to equalize each other to the worst one, and will all read exactly the same voltage. Right now, the only way to electrically isolate anything is to unfasten connections at the battery terminals. Some of them hold up to seven wires each, so doing it this way is both a serious nuisance and fairly dangerous. All the terminals are fully exposed and quite close to each other, so a flopping wire can easily cause some excitement real quick! These aren’t little 9V cells that you stick on your tongue to see if they still have a charge. At best, they can instantly destroy a terminal or connector in a heartbeat, with lots of amusing sparks. Try shorting out your car battery, and you’ll see what I mean.
AGM batteries, like all batteries, tend to sulphate over time and lose capacity. Battery life for these is helped by limiting usage to just 20% on a daily basis, which I’m doing. That means if you have 420 Ah of power available, you should repeatedly use only 84Ah before recharging. Not much! You’re free to use up to 210Ah if you must, but battery life is trimmed off greatly if done regularly. Sulfation is combated by the solar controller, which raises charging voltage once a month to try to get it off the plates inside the battery. I do have a battery charger that desulphates full-time, but that’s a 120V device – not an option out here. I’ll be researching little gizmos that use the battery’s own power to desulphate.
Why the obsession over sulphation? It’s far and away the top reason why batteries fail over time. A high capacity solar setup uses lots of batteries. In my case, I have no external storage for them and must keep them inside, which means I’m limited to AGM cells. which normally don’t vent acid vapor. Good! But at about $300 each, one becomes motivated to make them last as long as possible.
AGMs can take quite a bit of punishment. They also like faster charge rates than I can give them. That will limit lifespan as well. Still, like my “save every nickel” budget/expense challenge to live mobile, it will be interesting (to me) to see how long I can keep each of the three separate battery packs going. The bottom limit is supposed to be about a year and a half. Watching usage and trying to limit sulphation should get them into the six-year-plus zone, so a little obsession over boring old batteries can pay off big-time in the long run, and the longer the better!