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Pulse charging?
By Hank, Section Homebrewed Electricity Posted on Wed Apr 7th, 2004 at 01:48:30 PM MST
Can Pulse charging damage a Battery?

I acquired 4 8D batteries that were used for emergency power at a local hospital. They replace batteries every 3 years.
Three of batteries had an indicated voltage of 12.65 volts and one was at 12.46 volts.
I put the weaker battery on a normal charger,10 amp for several hours then I proceeded to pulse charge it using 110 v AC with a 24 uf cap as per the latest schematic. Amp meter indicated I was putting in about 1 amp. Well this battery has gone south real quick. The voltage drops down to 10.5 volts overnight (off the charger)from about 13.8 volts. One cell was weak to begin with (borderline) now it seems to have gone dead or shorted out.
Any one else have any similar experiences? Comments really appreciated,
Thanks,
Hank

Pulse charging? | 13 comments (13 topical, 0 editorial)

Re: Pulse charging? (none / 0) (#1)
by franknbuger on Wed Apr 7th, 2004 at 06:22:22 PM MST
(User Info)

Hello! I could be wrong, but I thought the way to charge was,if you took the electric out of a battery fast it needed to be put back fast.And if the battery was used slowly it needed to be charged back up slowly.Like an auto when you use the starter,the alternator put it back up fast then trickles of to a slow charge.Aren't they using the pluse chargers to try and bring back a sulfated battery?I was thinking of building a pluser myself, now maybe i wont. Please Advise.
Frankenbuger

Re: Pulse charging? (none / 0) (#2)
by Hank on Wed Apr 7th, 2004 at 08:16:37 PM MST
(User Info)

Hi Frankenbuger,

I'm not the guy to ask about pulse chargers as this was my first attempt at it. I guess they work as you can buy commercial units.
I think in recharging batteries you put more current into them initially then back off as they near full charge regardless of how they were discharged. I could be wrong on this though.
Regardless 10 amps into an 8D battery (225 ampHr)is not a lot and the charger cuts back on current as the battery charges up.
What I suspect happened is that these batteries were sulfated pretty bad and by charging them up some of the sulfate could have peeled off and shorted the cell. Such is life I guess!

I would not let this discourage you from building a pulse charger. I for one think they work and this was just an unfortunate case. Can't expect every salvaged battery to turn out good now can you?

Good luck and hope others with more experience chime in,
Hank

[ Parent ]

Re: Pulse charging? (none / 0) (#3)
by nothing to lose (nothingtolose175 at yahoo.com) on Wed Apr 7th, 2004 at 09:55:33 PM MST
(User Info)

Yep, can't expect to bring back all scrap batteries :)

I got a wierd one though. I scored some used trojan 360amp hour 6volts. Wire 2 in for 12v and pulse charged. first set is 6.37 or so each now (12.7? for pair) and holding while just sitting a few days. Second set, one was at about 3v and other at 2.5 or so. After pulsing a few times, better one is at 4.9 I think but the 2v dropped to .45v ???
Say what?
Yeh, it dropped to less than 1/2 a volt. Ok I did a fast bulk charge on the 2 then and I got it up to around 4 volt, but after checking it a bit it was dropping .01 volts fast enough to check my watch with, using a digital meter. I'll see what it is in the morning I geuss. One cell has a scummy film for some reason, so that one might be shot but at least something to play with for awhile.

My pulse charger is a retail battery charger, 2/10/20/40 amp charger and battery reconditoner and 100 amp booster starter, all 12v though. I have another normal type charger that has a 6V setting. I might try just a normal charge on that wierd battery and see what happens.

In general I don't think pulse charging will hurt one. My first night with the trojan 6volts I connected them wrong and pulse charged the 2 wired for six volts instead of 12volts as I had intended. Didn't seem to hurt them any far as I can tell.

I need more pulsers now, will have to try and learn to read those schematics and build one. I have a ton of 12v deep cycles and about 10 trojan 360amp 6volts now and really want to pulse them all for a few days each, but this one or 2 at a time will take months :(

.
.
nothing to lose

Spelin and tpying are my strong points, not electronics.

Re: Pulse charging? (none / 0) (#4)
by bob g on Wed Apr 7th, 2004 at 10:07:19 PM MST
(User Info)

this is just my opinion based on a few hundred hours of research from the manufactures of lead acid batteries.

i dont think the pulse charger idea is a bad thing to try and bring back a battery from the edge.... but...

i would certainly not use one on a new battery until a lot more research has been done.

according to all the experts in battery manufacture there is no conclusive evidence supporting that pulse charging is better than more common steady rate methods.

also there is some debate as to whether or not the pulsing causes shedding at higher voltage levels, if this is so then the sulfates may never be broken down and returned to the acid as designed and active material may be lost from the plates.

personally i would like to see some thorough testing done on several batteries by at least a couple of independent sources, using double blind testing.

i will likely build a pulser for rejuvenating tired cells, but at this point i will not risk new or known good cells to this sort of charging.

just my opinion for what it is worth

bob g

Re: Pulse charging? (none / 0) (#7)
by TomW on Thu Apr 8th, 2004 at 07:22:54 AM MST
(User Info)

bob;

Did you run across any references to pulse charging sealed batteries? My sealed battery guru is JimU and he seems to think that doing this to SLA or AGM batteries will probably kill them something to do with crystalization. Flooded batteries are a whole different animal however.

Pretty common on this site for some process to be proposed and folks grab onto it without proper research then run into problems because they only looked at a small piece of the whole picture. There is a major difference between sealed batteries, flooded batteries and the whole spectrum of other types and what works for one may not work for others.

Just thoughts from here.

Cheers.

TomW

"Education consists mainly of what we have unlearned."--Mark Twain
[ Parent ]

Re: Pulse charging? (none / 0) (#9)
by monte350c on Thu Apr 8th, 2004 at 03:12:17 PM MST
(User Info)

Hi Tom,

Though this doesn't specifically answer the pulse charge question, it's a doc I found useful for a recent product development project for work using SLA batteries:

http://www.panasonic.com/industrial/battery/oem/images/pdf/Panasonic_VRLA_ChargingMethods.pdf

The page that is on has some other useful info, links near the page bottom:

http://www.panasonic.com/industrial/battery/oem/chem/seal/index.html

They're not the same as flooded batteries, some of those docs give some interesting info about the chemistry inside too.

Not sure if this will be of any use or not, but it makes for a good read at least!

Ted.

[ Parent ]

Re: Pulse charging? (none / 0) (#10)
by bob g on Fri Apr 9th, 2004 at 12:25:59 AM MST
(User Info)

Tom:

i didnt really look into the pulse charge thing as it relates to gell cell, sla's etc.
as i am looking to use flooded cells myself.

i do know that most of the battery engineers are a bit leary of using pulse charging on good cells, they comment on the possibility of shedding (which may lead to shorted plates) if you use too high a voltage, but they don't say how high is too high.

There is also some consensus as to just using a higher than normal constant DC voltage to break down the sulfation, but warn that the battery has to be closely monitored for thermal runaway.

personally i think that pulse charging is ok, in moderation, and closely monitored, on problem cells that are not up to snuff. i figure what have you got to loose if all else fails.

i have found several references to eliminate sulfation by dumping the cells, and adding fresh distilled water, and charging at as high a rate as possible without over heating or over gassing the cells, to break down the sulfation and return it to the water. i guess you monitor the water for a rise in specific gravity, and when there is no longer a rise, charge for approx another 3 hours. then refill with fresh electrolite at the proper spec. gravity. then finish charging as needed.

The way i figure it for my system and use, i plan on using conventional charging methods, with higher rates of charge from a SOC of 60% to 90%. i plan on cycleing them within this range and once a week top them off at a lower rate to desulfate them and keep them in top order.

they also say to keep good records, and when the batteries get to about 80% capacity they are near the end of their life. This is when i plan on doing the rinse,regemin and follow with pulse charging if needed to extend the battery useful life if possible for other uses within the system.

i like everyone here on the board would like to try the pulse charge scheme to recover some of my batteries after they are starting to give up in the main circuit.
if i can extend the useful life/capacity of the retired batteries a couple of years i figure it to be a worthwhile project.

one thing causes me some concern though reguarding the use of pulse charging on good cells, and that is why arent the battery manufactures embraceing it? i could understand a conspiracy if the only manufactures were from here in america without any foreign competition, but with batteries comeing from all corners of the globe a conspiracy doesnt seem likely to me. Would seem to me that if it was a good thing on good cells competition in the manufacturing sector would have brought this technology out long ago.

as we all know just because pulse chargers are manufactured (commercially), doesnt necessarily mean they are "all that", but rather may have uses in particular situation. Kind of like the Yugo, while it was manufactured it certainly wasn't all that! It did fill purpose i suppose, but just because something is built and marketed doesn't necessarily make it a good product.

i figure if no one does it, (testing that is) i plan on trying it out and will do testing to see if pulse charging is actually better at recovering tired cells as opposed to methods the engineers claim are just as effective. we shall see :)

bob g

[ Parent ]

Re: Pulse charging? (none / 0) (#11)
by kell on Fri Apr 9th, 2004 at 06:47:41 AM MST
(User Info)

How do you dispose of used electrolyte? It has lead in it.

[ Parent ]

Re: Pulse charging? (none / 0) (#12)
by bob g on Fri Apr 9th, 2004 at 09:43:40 AM MST
(User Info)

not sure of the correct answer here, except maybe paying a recycler to take it, but this is my plan.

let it settle out and syphon off as much of the clear liquid as possible, and neutralize it with baking soda.

save the remnant with all the lead flakes and return it to my battery cores before they are turned in for recycleing.

any other idea's

bob g

[ Parent ]

Re: Pulse charging? (none / 0) (#13)
by charged on Sat Apr 10th, 2004 at 04:54:04 AM MST
(User Info)

It adds a bit of snap to iced tea.

[ Parent ]

Re: Pulse charging? (none / 0) (#5)
by Jerry on Wed Apr 7th, 2004 at 11:45:12 PM MST
(User Info) http://www.dplusv.com/Photo-03.html

Hi Hank

The info on that scimatic says for evey 24 UF 1 amp of current will flow.

So your rite on there. The D8 batteries are prety big. I don't think 1 amp will have much effect.

I've been using 420 UF at 660 volt AC motor run capacitors. This is six 70 UF caps in perelell.

I'm using an 1800 watt variac. I can set the voltage or amperage from 0 to 20 amps, voltage upto 150 v.

I've been pulse charging/desulfate the big batteries at 10 amps or around 88 volts for the caps I'm using.

I've done some small garden tractor batteries. They take about 2 to 3 days. The big golf cart batteries I'm pulsing may take a week or longer.

I've been pulsing this golf cart batteries 2 and half days now and the SG has gone from 0 to about the middle of the gage.

Checking the SG is very important. It'll give you an idea of chemical condition.

At 10 amps batteries realy get to bubling and the fumes are strong so best do this outside.

I'm doing a low volt version with a transformer at 30 volts, 10 amps and 1,000 UF. It seems to work as well as the high volt version but much safer.

Keep up the good work. Collectively we'll figure out how the idea works. I know it works. I'm using a battery that came from the scrap heep in my van every day. It was a 2 volt, dried up, dirty piece of &&^%:+?$% that came out of the @&^%$ pile and now it works good every day.

Its true you can't savem all but a few here and there is nice.

JK TAS Jerry

Airheads Page

Re: Pulse charging? (none / 0) (#6)
by nelson on Thu Apr 8th, 2004 at 05:24:44 AM MST
(User Info)

A guy in Fargo, ND has 700 Trojan's 12V 30XHS.
General Duty Deep Cycle Batteries. They are
new, but a couple years old.
I bought 15 for 40.00 each. When charged they are
12.6, but had SG that varied alot.
I bought a Model BD-2 Battery Desulphator 10-60 VDC 50 MA.
After 5-7 days each battery SG all came back. I
found that if you discharge these batteries down to 10
volts, recharge them up a few times they get stronger.

Battery Desulphators work Great, takes to long "tho!

Re: Pulse charging? (none / 0) (#8)
by Curtludwig on Thu Apr 8th, 2004 at 01:39:11 PM MST
(User Info)

I got 4 little 6v 10ah batteries out of a professional video power pack for nothing. When I got them they'd take up to about 4v each. I got a solargizer desulfator and using nothing but the the power of the sun and the magic of the solargizer the first test battery will charge all the way up to 6v but then hold at something like 5v. Its taken something like a month of good sun to get there but I'm gaining and the price is right! The solargizer was like $10 on eBay.

[ Parent ]

Pulse charging? | 13 comments (13 topical, 0 editorial)

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