[AT] Batteries charged backwards.
Dean VP
deanvp at att.net
Thu Feb 13 14:39:26 PST 2020
Very few if any load testers that we shade tree mechanics own are capable of being used as a constant load. I know mine can only be used for a few seconds on a fully charged battery or it will over heat. I don't know how many ohms the coil has but I suspect to properly load a 12v battery for a test one would want to draw at least 50 amps momentarily. Power = VxI.... 12 x 50 = 600 watts. That is a lot of watts to dissipate in a small air coil. Possibly short duration loads will eventually draw the battery down.
.
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On Wed, Feb 12, 2020 at 2:08 PM, szabelski at wildblue.net<szabelski at wildblue.net> wrote: When connected in parallel, the current being put through the batteries will
split between the two, with most of the current going through the good
battery and the dead battery only getting a portion of the current. The dead
battery will have a higher internal resistance and will limit the current.
When jumping a dead battery you are limited as to how much current your car
alternator will provide. Your alternator is only rated for so mush output
and your running car is using some of that. That’s why it sometimes help to
turn off all lights, radio, etc. on the running vehicle when jumping a
really dead battery. It’s also good the turn off all the lights, radio, etc
on the dead vehicle so that whatever your providing is going to go to the
battery and starter of the dead vehicle. Sometimes people will rev the
engine thinking that they’re getting significantly more lower out of the
alternator (double??). This is not the case, you are limited.
When your vehicle is running, the alternator puts out about 14V after a
start, then, once the battery is charged back up, the output should drop to
12V for running whatever is turned on. At that point your battery is
basically in idle mode, unless the alternator can’t carry the total load,
then it tries to make up the difference.
Carl
Carl
----- Original Message -----
From: Thomas Martin <tmartin at xtra.co.nz>
To: Antique Tractor Email Discussion Group <at at lists.antique-tractor.com>
Sent: Wed, 12 Feb 2020 14:47:29 -0500 (EST)
Subject: Re: [AT] Batteries charged backwards.
Stephen
Well it appears you do not understand the difference between connecting in
series and parallel.
When you jump start a vehicle, one connects in parallel, the current from
the jumper battery does
not have any affect on the the dead battery.
Tom.
> On 13 February 2020 at 07:52 Stephen Offiler <soffiler at gmail.com> wrote:
>
> I wouldn't purposely put 50 amps into a totally dead battery if I
> didn't have to, but then we have the example cited by others, the
> jump-start. Who-knows how many amps will flow; limited only by the
> internal resistance of the batteries and the cables & connections. I
> don't think many people appreciate that a jump-start is actually sort of a
> hail-Mary maneuver. If you didn't need to get the car/truck/tractor
> started ASAP, the smart move is to charge the battery slowly and
> correctly. People are going to chime in and say "I've been jump-starting
> my entire life and never had a problem!" OK. Me too. But the issue here
> is that it's impossible to know how much you might have shortened the life
> of that battery by hitting it with that big uncontrolled amperage surge.
> In Cecil Bearden's case, he's not stuck in a field or a parking lot or
> whatever. He has the opportunity to do it right. And that definitely does
> NOT include hitting it with a giant surge.
>
> SO
>
>
> On Wed, Feb 12, 2020 at 1:08 PM Thomas Martin < tmartin at xtra.co.nz
> mailto:tmartin at xtra.co.nz > wrote:
>
> > >
> > Surely US battery chargers have adjustable amperage?
> >
> > I thought it was a given that you wouldn't put 50 amps into a
> > dead battery...
> >
> > Tom
> >
> > > > > On 13 February 2020 at 03:14 Stephen Offiler <
> > soffiler at gmail.com mailto:soffiler at gmail.com > wrote:
> > >
> > > Hold on. A completely dead 12V battery connected to a
> > > good 12V battery is going to cause very large current to flow into the
> > > dead one. This is not a good idea.
> > >
> > > SO
> > >
> > >
> > > On Wed, Feb 12, 2020 at 9:08 AM < szabelski at wildblue.net
> > > mailto:szabelski at wildblue.net > wrote:
> > >
> > > > > > > Cecil,
> > > >
> > > > I agree with completely discharging the batteries
> > > > and then putting the batteries in parallel one at a time with a good
> > > > 12V battery. The batteries will try to equalize when in parallel.
> > > > When you drain the battery, take the load off and let the battery
> > > > sit for a while, then put the load back on and drain some more.
> > > >
> > > > You should use a battery charger that has a trickle
> > > > charge feature. This puts a full charge into the battery at first,
> > > > then drops down to a small charge to top the battery off. You may
> > > > have to do this several times and should leave the charger on for at
> > > > least one full day. Don’t rush the job.
> > > >
> > > > You can also check that each cell is good by taking
> > > > a reading between each cell. A bad cell will indicate a lower charge
> > > > then the others. Do this with every recharge attempt and note if you’re
> > > > making any progress.
> > > >
> > > > Don’t know if you’ve ever gone on-line to look for
> > > > videos on bringing dead batteries back to life, but their are some
> > > > that show how to drain a battery, rinse it out, then refill and
> > > > recharge. They appear to work out quite well, but I can’t swear by
> > > > them since I’ve never done anything like this myself.
> > > >
> > > > Good luck!
> > > >
> > > > Carl
> > > > ----- Original Message -----
> > > > From: Thomas Martin < tmartin at xtra.co.nz
> > > > mailto:tmartin at xtra.co.nz >
> > > > To: Antique Tractor Email Discussion Group <
> > > > at at lists.antique-tractor.com mailto:at at lists.antique-tractor.com >
> > > > Sent: Wed, 12 Feb 2020 00:24:36 -0500 (EST)
> > > > Subject: Re: [AT] Batteries charged backwards.
> > > >
> > > > Hi Cecil
> > > > I consulted a very good friend on the other-side of
> > > > the isle.
> > > > Tony is auto-electrician, of vast car, truck &
> > > > tractor experience.
> > > > He says you MUST discharge the batteries, separately
> > > > with a bulb.
> > > > They need to completely discharged. No measurable
> > > > voltage.
> > > > Then one battery at a time needs to be placed in
> > > > parallel with another
> > > > fully charged 12v battery, they then need to be
> > > > connected to a 12v
> > > > charger...
> > > >
> > > > Tom
> > > >
> > > > > On 12 February 2020 at 15:31 Cecil Bearden <
> > > > crbearden at copper.net mailto:crbearden at copper.net > wrote:
> > > > >
> > > > >
> > > > >
> > > > > > I had 2 group 31 batteries out of the tractor
> > > > that were completely
> > > > > > dead. I hooked them up in series and connected
> > > > my 24Vcharger to them
> > > > > > as It was handy and I wanted to charge both.
> > > > After a couple of days I
> > > > > > checked them and found that I had hooked the
> > > > charger backwards. I
> > > > > > hooked a couple of incandescent headlights to
> > > > drain the battery, but
> > > > > > after 3 days they won't light up the headlights,
> > > > but they still have a
> > > > > > lot of spark when shorted with cables.. A guy
> > > > at my battery shop said
> > > > > > I should hook up a 6volt light to them and use
> > > > that to run them
> > > > > > down.... At $100/ea, I need to try to save
> > > > these...
> > > > > > Cecil
> > > > > _______________________________________________
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