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Charger needed to revive 18 aH Lead Acid Batteries

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nuckolls.bob(at)aeroelect
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Posted: Thu Aug 30, 2012 4:54 am Post subject: Charger needed to revive 18 aH Lead Acid Batteries

At 06:22 PM 8/29/2012, you wrote:


<rparigor(at)suffolk.lib.ny.us>



Hi Group



I have a task to try and revive some 18 aH 12 volt sealed AGM 

batteries that weigh in at ~ 14.5 pounds.



The charger that was being used on them begins at a 3.5aH charger, 

then slows down a bit and peaks ~ 14.2/3 then goes to 13.7 float.



After a while, I don't know if from letting discharge too much or for 

too long, or the 3.5 aH is a bit too fast, but what happens is the 

batteries although they peak and go to float, they really don't take 

too much of a charge and have a very low capacity.



   How long does the charger stay in a top-off mode? 3.5

   amps charge is okay. But the absorption charge should

   sustain at 14.7 or so until the charge acceptance current

   of the battery is 100 mA or less.



http://tinyurl.com/9s7kpww



I have a 900mA Yuasa motorcycle charger, that does a little better.



Now what I did find works really well, is using the fool cheapest of 

cheap battery chargers I gave away with the 9aH batteries I sold on 

AeroElectric.



   Do you have a way to measure and plot the performance

   of your charger. Also a way to measure real capacity

   as a result of that charging protocol? One of these

   West Mountain Radio analyzers can be used to both plot

   charger performance -AND- confirm the battery's acceptance

   of charge.



That charger is nothing more than a 500mA transformer that supplies a 

constant 500mA current, then the circuit just looks for 15.4/5 and 

turns off. Now mind you it can take not hours, but days to reach that 

magic 15.4/5 number, and some batteries can not be revived, but most 

can. Then I found that if I take two of these batteries and parallel 

them and let the poor 500mA charger reach 15.4/5, it gets about as 

good as it gets so far.



   Yes, the higher trip point is well into the range

   recommended for absorption charging . . . perhaps

   a bit high but certainly high enough.



I think that the longer elevated voltage is perhaps desulfating??



   Don't know if it's a sulfation problem at all,

   just a quirk of the chemistry. Those two batteries

   I bought from you have been subjected to a couple

   of charge/discharge cycles using just a Battery

   Tender and they seem to be taking on a full load

   of watt-seconds.



   Just for grins, I'll do a cap-check on one and then

   do a manual, constant current charge that guarantees

   sufficient dwell at absorption voltages and repeat the

   cap-check.



   There's a number of exemplar smart-charger profiles at:



http://tinyurl.com/9t6t8x8



   in particular, take a look at this curve plotted on

   a Schumacher 1562A



http://tinyurl.com/945zdog



   it seems to be doing the right things in accordance

   with contemporary wisdom



   The Battery Tender Jr has the right moves too,

   but not as defined. That's what I use to charge

   and maintain a stack of test batteries here in

   my shop.



   Battery Minders behaved like this when I

   tested them



http://tinyurl.com/9paguuy



   Little or no absorption dwell, very low end

   of charge trip point. I used to have a couple

   but after doing these tests, I relegated them

   to maintaining a fully charged battery only.

   Gave them away to family members for keep batteries

   in garden tractors and seldom used vehicles topped

   off . . . but cautioned against expectations for

   getting the battery up to 100%. It would probably

   pump it up to a value that would start the engine.

   Once the lawn was mowed, the machine's normal recharging

   protocols would probably top off the battery where

   the Battery Minder would be useful for maintaining

   that condition.



I have a constant current 2 aH charger, and if I let it go much over 

14.4 the batteries make a minor bubbling noise that I don't like too 

much and figure if I let it go it will begin venting? I let it go 2 

hours but the 500mA charge brought back more capacity.



Sorry for the long winded explain, what I need:



I need a consistent source for a fairly inexpensive charger that can 

help revive these batteries.



I looked at Walmart, they have a 1.5 amp charger that peaks too low.



   Is this the 1562 or it's offspring? I'm surprised

   that it wouldn't behave much as the version I

   tested some years ago. Schumacher is the BigDaddy

   of battery charging tools. If anyone should know

   how to do it right, it should be them.



   I'll do a looksee to find out if the Battery Tender

   falls short of top-off when used as a stand-alone

   charger-maintainer.



   I thought the short answer to your question would

   be to pick up a Schumacher 1562 or current

   replacement at Walmart. Do you have one of these

   in hand? You could mail it to me and I can run some

   plots on it.

   Bob . . .

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rparigoris

Joined: 24 Nov 2009
Posts: 805

Posted: Thu Aug 30, 2012 9:16 am Post subject: Re: Charger needed to revive 18 aH Lead Acid Batteries

Hi Bob



Thx. for the reply.



The chargers being used are Chargetek 3 stage chargers:

http://www.chargetek.com/resources/battery-charger-basics/



I didn't measure it, but the link says it turns off at between 1/100C and 1/50C, so on a 17aH battery that is between 170 and 340mAs.



What is the amp draw that you need to drop below for the Schumacher 1562A to drop out of absorption rate and go to float with a 17aH battery?



If it's 100mAs or less that may just be the ticket to success.



Is there a way to adjust this point to allow it to stay in absorb for a longer time?



Thx.

Ron Parigoris

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nuckolls.bob(at)aeroelect
Guest

Posted: Thu Aug 30, 2012 12:32 pm Post subject: Charger needed to revive 18 aH Lead Acid Batteries

At 12:16 PM 8/30/2012, you wrote:


<rparigor(at)suffolk.lib.ny.us>



Hi Bob



Thx. for the reply.



The chargers being used are Chargetek 3 stage chargers:

http://www.chargetek.com/resources/battery-charger-basics/



I didn't measure it, but the link says it turns off at between 1/100C 

and 1/50C, so on a 17aH battery that is between 170 and 340mAs.

         Hmmmm . . . okay. I seem to recall that Skip

         Koss talked about recharge currents below 100

         mA for terminating an absorption cycle on really

         big batteries like the 30-50 a.h. aircraft batteries

         we used at HBC. Kicking off that high seems a

         bit 'light'.

What is the amp draw that you need to drop below for the Schumacher 

1562A to drop out of absorption rate and go to float with a 17aH battery?



         Have no idea. Never measured it. Don't know how

         critical it is. Given that the Schumacher product

         stayed in a absorption mode for a significant time

         suggested that a righteous absorption charge was

         being delivered. I don't have any 1562's around

         to measure. I could put one of your Chargetek

         machines on a DAS and find out where they are

         calibrated.



If it's 100mAs or less that may just be the ticket to success.



         Yes.



         Just for grins, I took one of the 12a.h. batteries I

         bought from you that has been on a Battery Tender

         for the last several days (green light on, in maintenance

         mode. Fooey, didn't read the float voltage first) and

         hooked it to a 14.6v power supply. Charge current jumped

         to 300mA and over the next 12 minutes it fell to 100mA.

         Putting a crayon to the numbers suggests that the battery

         is 12 a.h. x 12v x 3600 s/hr ~ 500,000 watt-seconds

         at full charge. The little boost on the bench put in 200

         mA average for 12 min for 0.2 x 14 x 720 ~ 2000 watt-seconds

         or less than 0.5% of capacity. Hence I deduce (1) that the

         Battery Tender did indeed return and support this battery

        to 100% of rated capacity and (2) an end of absorption cycle

         value of 100mA is not an unreasonable calibration point.



         It would be interesting to plot an absorption cycle for

         energy the battery takes on after recharge current drops

         below 300mA . . . I'm guessing that it's probably less than

         1% of rated capacity . . . but don't know without measuring.



Is there a way to adjust this point to allow it to stay in absorb for 

a longer time?



         Haven't had a 1562 (or replacement) apart to find out.

         But even if the EOAC termination value is higher, I'm

         not convinced that you're going to loose much. We could

         set up the experiment and find out.

   Bob . . .

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nuckolls.bob(at)aeroelect
Guest

Posted: Fri Aug 31, 2012 8:12 am Post subject: Charger needed to revive 18 aH Lead Acid Batteries

At 06:22 PM 8/29/2012, you wrote:

 	  Quote: 	
		  

<rparigor(at)suffolk.lib.ny.us>



Hi Group



I have a task to try and revive some 18 aH 12 volt sealed AGM 

batteries that weigh in at ~ 14.5 pounds.



The charger that was being used on them begins at a 3.5aH charger, 

then slows down a bit and peaks ~ 14.2/3 then goes to 13.7 float.


	


         Pursuing another train of thought: It is

         possible that the batteries have suffered

         so degradation of performance due to combinations

         of age, conditions of storage, or even manufacturing

         quality.



         Skip Koss has related Concorde's techniques for

         recovering what appears to be a totally trashed

         battery. The process includes things like application

         of 24v on a 12v battery until recharge currents

         rise above some established value followed by

         a couple deep charge/discharge cycles. He

         said this process may well flog the horse back

         to some demonstration of life . . . but you

         never get back to 100% even if the battery

         is young.



         There's a mil-spec requirement for being able

         to recover a badly discharged battery . . .

         like a dead-short on it for a week before

         the recovery process is applied. Capacity

         tests measure proportion of chemistry still

         active . . . and there are some failures that

         cannot be recovered with outside stimulus.



         Bob . . .

 	  Quote: 	
		  After a while, I don't know if from letting discharge too much or 

for too long, or the 3.5 aH is a bit too fast, but what happens is 

the batteries although they peak and go to float, they really don't 

take too much of a charge and have a very low capacity.



I have a 900mA Yuasa motorcycle charger, that does a little better.



Now what I did find works really well, is using the fool cheapest of 

cheap battery chargers I gave away with the 9aH batteries I sold on 

AeroElestric.



That charger is nothing more than a 500mA transformer that supplies 

a constant 500mA current, then the circuit just looks for 15.4/5 and 

turns off. Now mind you it can take not hours, but days to reach 

that magic 15.4/5 number, and some batteries can not be revived, but 

most can. Then I found that if I take two of these batteries and 

parallel them and let the poor 500mA charger reach 15.4/5, it gets 

about as good as it gets so far.



I think that the longer elevated voltage is perhaps desulfating??



I have a constant current 2 aH charger, and if I let it go much over 

14.4 the batteries make a minor bubbling noise that I don't like too 

much and figure if I let it go it will begin venting? I let it go 2 

hours but the 500mA charge brought back more capacity.



Sorry for the long winded explain, what I need:



I need a consistent source for a fairly inexpensive charger that can 

help revive these batteries.



I looked at Walmart, they have a 1.5 amp charger that peaks too low.



Any ideas?



Thanking you in advance

Ron Parigoris





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=382105#382105



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   Bob . . .

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