On Saturday 11 August 2007, Tim wrote: >On Sat, 2007-08-11 at 16:46 -0400, Bob Goodwin wrote: >> I installed two new SLA batteries two days ago and judging from the >> voltage across the terminals it was charging. I would have to remove >> the case to measure battery voltage which ought to be near 27 volts by >> this time I would think. > >My preference for checking that batteries are charging is measuring the >current going to them, rather than voltage. But that's not always >practical, heavy charge can be quite a few amps, and it may drop down to >just a few milliamps when (almost) done. That's quite a range to cover >with just one meter. > In some cases, just a few milliamps can still be excessive Tim. I recall years ago when I was doing the KXNE-TV transmitter site for Nebraska ETV, the batteries that started the Cummins 335 powered standby generator required replacement, so I went to Norfolk and picked up a pair of 225AH 12 volt batteries like you see in the average truck tractor. They came dry and I had to wet them, and charge them. My personal criteria, and its worked very well for 55 some years for me, is that a lead-acid battery is fully charged when it begins to outgas. We had a 'trickle charger' for them that was actually a 10 amp model. I wound up with a 12,000 ohm 2 watt as the trickle limiter before those batteries quit gassing. Going by the SG & holding it at around 1.265, 6 years later I'd added water once & not much then, a pint or less for all 12 cells. 6 years later, and given that there was a block heater on it, it was still only a half a second of cranking maximum cuz that puppy fired on the first cylinder to come to tdc even in 20 below weather. Bigger incandescent lamps never went fully dark on a power failure. That was 1977 when I left, and if my successor has cared for those batteries as well as I did, those same batteries may well still be sitting there ready to turn that Cummins wrong side out or start it, which being entirely up to the Cummins. >-- >(This box runs FC5, my others run FC4 & FC6, in case that's > important to the thread.) > >Don't send private replies to my address, the mailbox is ignored. >I read messages from the public lists. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Nothing shortens a journey so pleasantly as an account of misfortunes at which the hearer is permitted to laugh. -- Quentin Crisp
