Charging old batteries

[cranetruck]

Yesterday, I installed the two 6TMF batteries I got from Medlog at Aberdeen.

The Chargetek 500 is handling it from now on and after 18 hours it is still in "Bulk charge" mode with measured voltages of 13.08 and 13.24 volts on them.
Both batteries were manufactured in 2000 and measured about 11.4 volts open circuit when installed.
Bulk charge means that a charging current of about 5 amps is applied. When 80% of battery capacity has been reached, it switches to "Absorption mode" until fully charged. Float charging is maintained continously after the batteries are fully charged.

PS. My only complaint is that I received Exide batteries, not Deka....

 

[cranetruck]

...after about 26 hours, both batteries show 13.8 volts plus or minus....red light still on. Should switch to constant voltage mode when 14.6 volts is reached.
Just checked it, now after 36 hours, they read 14.29 and 14.40.

 

[Rattlehead]

Looks like you might have some good batteries. Have you ever put an equalization charge on a lead acid battery? It is pretty common in the literature for the care and feeding of batteries in a solar/wind power storage system. Charge controllers typically have a button on them to activate an equalization charge, which basically charges them at 15.5v for an hour. Afterwards which you need to check the water level.

I have a sweet power supply that I got on ebay, it has voltage and current limit settings from 0-36v at 0-20A, or 36-70v at 0-10A. I use this to do an equalization charge once a year on the 6TLs in the deuce. I don't do this on the maintenance free batteries because they aren't designed to open up to add water.

 

[cranetruck]

That is what this charger does, it addresses each battery separately and the end result should be two identically charged batteries. You may notice that the voltages are approaching the same level. Just checked them and they are now 9 mV apart, 14.34 and 14.43 respectively.
I'll keep posting the results.

 

[Rattlehead]

No, I mean a deliberate overcharge of 15.5v, and limited current. It is supposed to equalize the individual cells in each battery.

Here's some info found on a quick search

http://energy.ece.uiuc.edu/Balog/images/intelec02.pdf

 

[cranetruck]

Thanks, need to do my homework.
Looking over the article, the first task will be to define the terms used, "series strings", "pack", "cell", "monoblock" and the meaning of "battery" here....

Okay, tell me how "Stage 1" below differs from an equalization charge, please.

 

[cranetruck]

Battery voltages are now 14.37 and 14.45, so they have stabilized and the charger should be in "Stage 2", which is the constant voltage phase.....

 

[cranetruck]

Some time during the night the charger switched to "Stage 3" Float mode. The voltages are now 13.16 and 13.19 on the batteries and the light is green.
Keeping the charger plugged in will hold the batteries at full charge.
This concludes this little experiment/demonstration. The batteries are over 8 years old with an unknown history, so it'll be interesting to see how much longer they will hold up.

 

[Rattlehead]

Okay, tell me how "Stage 1" below differs from an equalization charge, please.

About 1 volt

I'm not an expert on batteries, I have only picked up a few things while reading about alternative energy systems. All of the literature discusses this periodic overcharge as a means of ensuring each individual battery cell is fully charged. All of the better charge controllers have this as a built-in feature as well.

So if 2.4v/cell indicates a full charge, what if you have one cell that is 2.5 and one that is 2.3? The average shows the battery fully charged (14.4v for 6 cells), but the 2.3v cell is not. The thinking is that, with potentially varying health of each cell, a forced overcharge can bring all of them up to 100%. We know the benefit of charging each 12v battery in a 24v string separately. It is the same principle of battery health, just a different way of getting there because we don't have access to each cell in the battery.

They also mention a benefit of stirring the electrolyte by the boiling, which I think ours get stirred up enough while driving alone.

This overcharge may not be as helpful for the duty cycle of vehicle batteries vs ones that get heavily deep cycled and recharged, and sometimes the recharges aren't to 100% before the next deep cycle. I don't know. But if I have to check the electrolyte level in my expensive batteries anyways, it doesn't take much longer to throw an hour long overcharge into them once/yr.

 

[Boatcarpenter]

Speaking of batteries, what is the cause of the whitish/greenish growth that occurs on battery terminals occaisionally?
BC

 

[emr]

In my opinion when over charging for one hour U are desulphating them, thats the difference if any , but than i suspect Bjorns charger is de sulphating also, just alot safer, and more controlled , taking the human out of the deal,over heating the bats is one way of doing it, ive seen a big charger for that for sale by me but its 600 bucks..but the human has to do constant temp checks...I love this bat info, i think they will last a while depending on just how sulphated they were to start, if somebody kept em charged most of there life they will do fine, maybe a loss of cranking time? how much ? in good temps and a good truck may be a no problem thing ,would love to see em crank a similer truck next to each other one with new bats, and rate whats worth while,,, and that all depends on the extent of sulphation warped plates etc, but since they came up that charger is doing its job for sure...Randy

 

[cranetruck]

It's not over yet....

Cranked the engine, which started as usual within seconds and ran the truck for approx 45 minutes.
Turned on the Chargetek again and it spent an hour or so in constant voltage mode and switched to float charge. So far so good.

Cranked the engine again, which started even quicker this time, ran truck for 1/2 hour and shut down.

Again, turned on the Chargetek, but this time it didn't get out of constant voltage mode, not after six hours and acid was bubbling out of the vents.....I disconnected the Chargetek.

Today, a day later I checked the open circuit voltages and they were both 12.80 volts.
At least one reference I found stated that if the open circuit voltage didn't agree with the specific gravity, then the plates were sulfated.....
So, checking specific gravity, I recorded readings from 1.110 to 1.225, with battery #1 having a delta of 70 points and #2 a delta of 120 points.
Conclusion: Batteries are sulfated, won't take a charge and are no good...
After all they are 8 years old. Didn't cost me much, but it was a lesson. Wonder if the Dekas would have fared any better....

PS. Because of the almost instant starting of the engine, it wasn't much of a capacity test for the batteries. Also, I checked the specific gravity of a new battery, which was fully charged to make sure the hydrometer wasn't off.

 

[mangus580]

Conclusion: Batteries are sulfated, won't take a charge and are no good...

Isnt this where the desulfation type chargers (ie Solargizers) come into play?

 

[cranetruck]

Too late here and sulfation can be prevented by keeping batteries charged at all times. From what I read, sulfation is only a problem when the battery voltage drops below 12.4.

 

[DanMartin]

After reading this thread, I decided to go with the Chargetek 500. Ordered on Monday...had it on Tuesday (wow, fast shipping...turns out batterystuff.com is in Grants Pass, Or...just down I5 from here). Installed yesterday and is working great. I mounted mine behind the passenger seat in the deuce on the rear wall of the cab to keep it out of the elements.

Nice unit...$99...cheaper than new batteries. I like how it charges/maintains both batteries individually.

 

[mangus580]

Too late here and sulfation can be prevented by keeping batteries charged at all times. From what I read, sulfation is only a problem when the battery voltage drops below 12.4.

Interesting, I had the impression they reversed the process.

 

[Recovry4x4]

I've got many dead 6TLs. One day I'll spend the money and buy some EDTA and try the chemical desulfating process.

 

[HillBilly]

Hi all! With great risk of sounding like an idiot. The batts I pulled say they were shipped Sep 2004 and in both batts the cells are all submerged. I also have a dual voltage 6/12 multi-amp 2/40/250 for the 12V side. Here's the idiot part! I have tried to charge them @ 2 amps for 24 hrs they quickly return to there voltages that I tested b4 I ever put the charger on which BTW is 10.5 and 7 volts. I don't want to put them on a 40 amp charge til I got some input from you folks first. Time? Should I buy a tester for Specific Grav?
Scrap em and save up 4 new?

I also did some callin around to see if there were any shops, batt places, parts stores to see if pehaps some one might desulphate and charge them 4 me. Since I am a MV newbie. Only one guy knew what desulphate was (salesman from an industrial/commercial batt shop) and he said it is useless to do this because the positive and negative plates were seperate and coated with some type of polymer. I am an electrican by trade and know that poly is an insulator so is this horse pucky? He also said that old batts 20 years + did not have the coating and that all new batts do. Think he is tryin to make a sale or are the people @ batterystuff.com peddling snake oil?

here are picks of batts and charger.

 

[cranetruck]

This is how I understand it, de-sulfating devices are good while the battery still has enough capacity to be used on a vehicle.
It's better to keep the battery charged at all times from square one and not having to worry about sulfate build-up in the first place.
A specific gravity measuring device, hydrometer, is cheap (approx $5.00) at your local NAPA and will tell you if the battery is servicable or not. A difference of more than 50 points between the cells means that the battery is on its way to the scrap heap.
As stated in one of the posts above, if the open circuit voltage shows a fully charged battery, but the specific gravity indicates a low charge (capacity), then you have a sulfate problem.

Solargizers should not be confused with "smart" chargers.

I'd like to see a solar powered "smart" charger........meanwhile, I'll keep my Chargetek plugged in. The green light tells me that the batteries are ready and the starting system won't be exposed to damaging unservicable batteries.

To continue the above story, I removed the old 6TMFs and installed two fresh commercial batteries (for now) and the charger stayed in "constant voltage" mode for less than 5 minutes before switching to "float" mode. The specific gravity indicates that the batteries are fully charged as does the open circuit voltage.