When charging battery (acid)with a 10 amp charger is it preferable to disconnect battery or leave connected? I charge battery 12 hours. Thanks, Don
-
-
Re: Charging battery.
you mean leave it connected in the car? you could I allways disconnet it though. -
Re: Charging battery.
As long as there is no more than the usual handful of milliamps draw when connected, it doesn't make any difference, but 12 hours on a 10 amp charger is way more than necessary unless the battery is dead. That's 120 amp hours, which is about double the 62 or so amp-hour capacity of the battery.
The amp setting on a charger is really a voltage adjustment - the higher the amp setting the higher the applied voltage and the higher the minimum current flow when the battery is charged to peak voltage - about 12.6 volts at room temperature.
Most modern chargers have an ammeter, and when the charge rate drops to a minimum and won't go any lower, the battery is fully charged. On my 6/2 amp charger the battery is fully charged when the meter drops to two amps on the 6 amp setting and zero at the 2 amp setting. At the 2 two amp setting the battery can't be "overcharged and barely so on the six amp setting.
If the ammeter doesn't reach the normal minimim for the setting in a reasonable amount of time the battery may have a shorted cell.
I charge my batteries once a month or before driving if it's been more than a week since they were last driven or charged. At the six amp setting about two hours is all that's required if the car hasn't been driven or the battery charged in the last month.
DukeComment
-
Re: Charging battery.
Thanks Duke, You answered my ? . Also other charging facts that are important. I think my charger has a cut off when fully charged, but since charger is over 20 years old who knows. DonComment
-
Re: Charging battery.
Don,
I have had very good success using the small Battery Tenders in my vehicles as they are only driven infrequently. Have used them for many years and they will not overcharge a battery but you can let the car sit for 6 months and it starts immediately when you turn the key.
Something you may want to consider.
Kurt Bunting # 26406Comment
-
Re: Charging battery.
"I charge my batteries once a month or before driving if it's been more than a week since they were last driven or charged."
How come? Won't the generator/alternator sufficiently charge the battery after the drive?Comment
-
Re: Charging battery.
A modern "maintenance free" battery self-discharges about one percent per day at room temperature. This is if it's disconnected with no parasitic load. (An old fashioned maintenance type battery self discharge rate is about 3 percent per day.) So .99**30 = .739. The modern battery has lost about a quarter of its chemical energy in 30 days.
The engine will probably start, and even assuming you drive it long enough to fully charge the battery, if you keep repeating this regimen, the battery will develop permanent sulfation on the plates that will soon keep it from attaining a full energy charge no matter how much you charge it. An "old fashioned" maintenance type has lost 60 percent of it's energy in 30 days and may not crank the engine fast enough or long enough to start. Repeat this a handful of times times and poof - you'll be shopping for a new battery.
The result of consistently placing a heavy cranking load on a partially discharged battery is short life. If you maintain a typical inexpensive modern lead-acid battery in infrequently driven vehicles as I do, the nominal life is about 7-8 years and my record is 11 years.
But be cautioned that if you kill an older battery by doing something stupid like leaving the dome light on for a few days (Yeah, I get "stuck on stupid" sometimes like everyone else!) then you might as well go get a new battery even if you can bring the old one back to life - because an older battery won't last very long after a severe discharge.
It's worth considering a "deep cycle" marine type battery for Corvettes that see infrequent service as they are more tolerant of deep discharges and the vintage Corvette Group 24 size is a common size for marine applications.
DukeComment
-
Add-on
I agree 100% with what Duke says. Different battery technology tolerates discharge differently. NiCad batteries 'love' to be cycled periodically through their charge profile and 'hate' being constantly left on a charger. You actually extend their life cycle by letting them run down and charging them back up!
Lead acid technology has the opposite profile. It loves to be kept up to charge and doesn't tolerate well being fully depleted of charge. That's why mfgr's have a 'deep discharge' design for marine applications (battery is left unused for long periods of time, like winter storage).
Last, heavy battery discharge is the Achilles' Heel of many of the aftermarket, drop-in, solid-state ignition systems. All have a lower threshold where there's insufficient voltage to during engine cranking for the SS ignition module to turn on and fire the engine. So, if you've replaced points & condensor with one of these, it's always a good idea to charge the battery after several weeks of disuse before trying to start the car!Comment
Comment