[AT] Batteries charged backwards.
Cecil Bearden
crbearden at copper.net
Sat Feb 15 06:50:25 PST 2020
Steve:
When I looked a the lamps there was no light seen. Maybe they were
still drawing current, The battery is still "hot"when shorted across the
terminals. I need to do something in the next 3 days as I don't want
these batteries to freeze.
Cecil
On 2/15/2020 8:18 AM, Stephen Offiler wrote:
> Mathematically correct, but bear in mind the entire explanation is
> predicated upon your stated assumption, that both 6V and 12V lamps are
> rated at the same wattage. I agree, and in fact I mentioned this
> myself, somewhere wayyyyy up there in this thread. Also, if you have
> two of the 12V lamps in parallel (which I believe Cecil mentioned back
> there at square One) that's going to do the same thing, double the
> current draw. Which option is easier depends on what you have laying
> around: do you have a couple of 12V headlamps, or do you have a single
> 6V lamp that is rated a similar wattage as one of those?
>
> SO
>
> On Sat, Feb 15, 2020 at 8:38 AM <deanvp at att.net
> <mailto:deanvp at att.net>> wrote:
>
> Cecil, let me try to explain why going to the 6v light helps
> discharge the battery faster. I think your statement of “…. would
> not discharge the battery” should really be phrased as it takes
> too long to discharge the battery. Lets assume that the 12V lamp
> and the 6 V lamp are designed to produce 60 Watts. The 12V lamp
> then uses 5 Amps but the 6V lamp uses 10 Amps to produce the same
> power. So the resistance of the 6V lamp will be half of the 12V
> lamp. Or looking at it another way, the resistance of the 12V
> lamp is 2.5 ohms and the 6V lamp is 1.25 ohms. Now lets assume
> the 12 V battery has been discharged to 1.25 volts and needs to be
> pulled down further. The 12 V lamp will only draw a ½ Amp and
> slowly draw less but the 6V lamp will draw 1 Amp initially and
> slowly get less. The 6 Volt lamp will discharge the battery twice
> as fast at this lower voltage which one could not do at the 12V
> starting voltage because it would burn out the 6V lamp. As the
> battery discharges a lower resistance is needed to keep the
> discharge rate at a reasonable rate. As the battery voltage drops
> the discharge rate drops with it unless the attached resistance
> is lower. A 12 V lamp would take much longer to fully discharge
> the battery. That is why the 6V lamp is used after the battery has
> dropped below 6V. Just plain old math. It takes a really long
> time to get to a true “0” V. It just takes longer with a 12V Lamp
> vs a 6V lamp.
>
> Dean VP
>
> Apache Junction, AZ
>
> *From:*AT <at-bounces at lists.antique-tractor.com
> <mailto:at-bounces at lists.antique-tractor.com>> *On Behalf Of
> *Cecil Bearden
> *Sent:* Thursday, February 13, 2020 7:37 AM
> *To:* at at lists.antique-tractor.com
> <mailto:at at lists.antique-tractor.com>
> *Subject:* Re: [AT] Batteries charged backwards.
>
> The problem I cannot understand is why, when I connected 2
> incandescent headlights in parallel to the battery it would not
> discharge the battery completely. My battery supplier told me to
> then use a 6 volt light. I have seriously thought about just
> hooking both in series and then using them as power for arc
> welding. A welding rod would discharge them quickly and
> completely. Welding can be done using batteries as power...
> I charge my batteries outside for safety. These are sealed
> batteries.
> Cecil
>
> On 2/13/2020 8:28 AM, Stephen Offiler wrote:
>
> I do not have ADD, although I am starting to wonder what
> personal issues you might have, Thomas. And no, the point of
> this exercise is not to reverse the polarity, The point is to
> make the best possible attempt to recover two batteries that
> have been accidentally reverse-charged. That involves much
> more than reversing the polarity. There's a right way and a
> lot of wrong ways to tackle each of the steps. Discharge.
> Repolarize. Recharge.
>
> SO
>
> On Thu, Feb 13, 2020 at 9:08 AM Thomas Martin
> <tmartin at xtra.co.nz <mailto:tmartin at xtra.co.nz>> wrote:
>
> Do you have ADD? The point of this exercise is to reverse
> the polarity of a battery.
>
> On 13 February 2020 at 23:15 Stephen Offiler
> <soffiler at gmail.com <mailto:soffiler at gmail.com>> wrote:
>
> For some actual information on lead-acid charging, try
> this:
>
> https://batteryuniversity.com/learn/article/charging_the_lead_acid_battery
>
>
> On Thu, Feb 13, 2020 at 3:49 AM Thomas Martin <
> tmartin at xtra.co.nz <mailto:tmartin at xtra.co.nz>> wrote:
>
> Hi Dean
>
> After the dead battery is connected to the charged
> 12v battery in parallel, a battery charger is
> connected, (the charged battery
>
> is there only to dictate the polarity), and
> charging can commence.
>
> Tom
>
> On 13 February 2020 at 20:41 deanvp at att.net
> <mailto:deanvp at att.net> wrote:
>
> Tom,
>
> Could you explain this a little further. If
> the current from the jumper battery does not
> have any effect(affect) on the dead battery
> how does it charge it up?
>
> Dean VP
>
> Apache Junction, AZ
>
> *From:* AT
> <at-bounces at lists.antique-tractor.com
> <mailto:at-bounces at lists.antique-tractor.com>>
> *On Behalf Of *Thomas Martin
> *Sent:* Wednesday, February 12, 2020 12:47 PM
> *To:* Antique Tractor Email Discussion Group
> <at at lists.antique-tractor.com
> <mailto:at at lists.antique-tractor.com>>
> *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
> <mailto: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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