How Long To Charge The Batteries?

[dabtl]

I got started this morning for the North Texas Fair Parade fairly early. I was hauling politicians rather than riding with V V A 920.

I removed the cargo cover and cleared the bed of the vehicle. When I went to start it I kind of noticed I had forgotten to turn the power off a few days earlier. Ooops! No battery charge apparently. I grabbed the slave cables and jumped it off with the other deuce.

It started up around 8:30 AM and ran until 11:30 AM or so. I did not shut it off at any point. First, I have no clue how long it would take to charge the batteries and second, I was not sure if the starter relay change would solve the hot start problem I had.

It seems replacing the starter relay solved the hot start problem and the batteries turn the starter rapidly now.

So, all knowing Guru's, are the batteries charged now or should I drive it more to full charge them?

 

[jasonjc]

Best bet would be to use a chager on them one at a time over night.

 

[broman78]

If you are at the house turn it off, cause you have a way of jumping the vehicle. If you have a charger hook it up and do a trickle charge on the batteries tonight. I would think you would be good but I don't know.

 

[dabtl]

I have parked them side by side in case I have to jump it off again tomorrow. It appears the battery will spin the starter with ease now.

 

[jollyroger]

I am no expert but it sticks in my mind that you will reach about 90% capacity from full discharge in about 30 to 60 minutes under constant cruse type mode. it takes some time to "peak" the batteries. Others on the site will know for sure.

 

[zout]

best

You got er going
Best bet if you charge quickly you get what is called a surface charge - to really get a good charge - trickle charge them overnight to get what is called a deep charge.

 

[atankersdad]

You need to load test them with a meter after you fully charge them, That will tell you if one or both were killed. These batteries are very tough to kill if you keep them hydrated. Charge and test. Guessing will get you stranded.

 

[Keith_J]

The hotel load (lights, etc) is minimal. With a properly functioning 60 A alternator, you will get a 90% charge in 2 hours. Remember, the alternator puts out 60 A only when the engine is at least 1800 RPM and the voltage at the batteries is 24. As voltage climbs, current falls.

The batteries are about 80 Amp-hours in capacity. Look up Peukert's Law as it also applies to charging. Because the 24 volt system (nominal), CCA means much less, total capacity is the key.

 

[dabtl]

The hotel load (lights, etc) is minimal. With a properly functioning 60 A alternator, you will get a 90% charge in 2 hours. Remember, the alternator puts out 60 A only when the engine is at least 1800 RPM and the voltage at the batteries is 24. As voltage climbs, current falls.

The batteries are about 80 Amp-hours in capacity. Look up Peukert's Law as it also applies to charging. Because the 24 volt system (nominal), CCA means much less, total capacity is the key.

What does this mean in English?

 

[Keith_J]

What does this mean in English?

It takes more than 2 hours to fully charge dead batteries. There is no way to fully charge batteries quickly because as soon as you get the voltage over 28.8, the batteries generate hydrogen. Also, fully discharged batteries charged with the alternator can become over heated.

It is always best to top off the charge with a dedicated smart charger like a Deltran Battery Tender. It has 3 modes of charging, a current limited initial mode, then a lower current saturation mode and finally a trickle charge. Since it has a floating negative, you can hook one up to each battery without having to disconnect.

 

[dabtl]

OK, now I get it. I will pick one up tomorrow or Monday.

 

[Keith_J]

All good points TN Col. As batteries age, the lead sulfate which forms as a result of discharge form into a crystalline form which is very hard to revert to lead/lead oxide in the charging process. Most chargers, including the regulator on the alternator are just voltage regulators and these are not capable of reverting the lead sulfate. Given enough time, these formations of hard crystalline lead sulfate reduce capacity.

The old practice of dumping the electrolyte and replacing it with fresh can work but it won't fully recover a bad battery.

Now, on the use of a voltmeter...A battery fresh off a charger will read about 13.6 volts. This is because the charge is on the surface of the plates. After about 4 hours disconnected, this surface charge penetrates the plates and voltage should be 12.8.

Most hydrometers are too coarse, having 5-8 balls between dead and full charge. The ones I used in the Army were the Leica (the optics company) refractive, made for both battery and coolant testing. These have automatic temperature compensation.

Leica Duo-Chek

 

[Mark2X2]

dabtl,
We have an old displaced hillbilly that dose our alternator & starter work. He is insists that an alternator isn't a battery charger. If you have dead batteries fully charge them, if you install new batteries fully charge them before you install them. If you think your batteries at all questionable have them load tested at a shop with a modern load tester.
Last winter I had alternator trouble on my John Deere 653E, the batteries are JD "Strong Box" they were 23 months old. The regulator quite working and was over charging. Caught it right away, yanked the alternator brought to Harv. Installed the new rebuilt (145 amp Delco) lasted two days it quite charging popped the regulator, yanked it brought it back he fixed it. I swore up and down my batteries were good, I charged them, tested with a hydrometer, load tested with our old tester they were good. Two or three days later, burned up the stator, took it back he fixed it. Took my batteries to the JD dealer, put them on there tester they both failed. Got two new batteries, took them home, charged them, installed them the next day. Haven't had any trouble since.
Old Harv has some good hard earned knowledge. His theory when we have a stretch of -20 below 0 weather is. Go sit in the tavern and drink, you will spend less money then if you try to work. You burn up you starter trying to get it started, you jump it and get it going. Then your batteries are down, then you cook the alternator trying to charge dead batteries. So you spent a $1000 on new batteries, alternator & starter. Then working in real cold weather every thing else that was weak breaks. So it would have been cheaper to go on a good drunk.
Mark
M35A2 Deuce
M105A2 Trailer
M101A1 Trailer
3)Rokons

 

[nap159]

I was taught a way of de-sulfating batteries by my old wise grandfather. It's called the drop test. If you have a battery that seems to not take a charge. Pick up the battery and drop it on the grass a few times from about two feet high. Seems kind of barbaric but believe it or not IT WORKS!

 

[Keith_J]

I was taught a way of de-sulfating batteries by my old wise grandfather. It's called the drop test. If you have a battery that seems to not take a charge. Pick up the battery and drop it on the grass a few times from about two feet high. Seems kind of barbaric but believe it or not IT WORKS!

Actually, charging is the only way. Lead sulfate forms at both the cathode and anode plates during discharge, that is why the specific gravity drops as the sulfuric acid is converted to lead sulfate. Most batteries have dense-packed construction to protect against vibration and shock. In between the plates are separators of glass fiber.

Unless the battery corrodes the cell connectors or develops an internal short, most of the problems are due to formation of large crystals of lead sulfate which poorly conduct electricity, making the reversal to lead/lead oxide a much slower process.

To answer the question, measure the specific gravity. Full charge is 1.300. Full discharge is 1.000

 

[cranetruck]

Dabtl, follow Keith's advise....I have used the Chargetek 500 "battery maintainer" for years and it works great (lost one in a thunder storm/lightning strike once, but that's another story), made for dual 12-volt battery systems.
The optical battery tester may be found on ebay for about a 1/3 of the price, may not be Leica, but probably as accurate....

 

[cranetruck]

Don't forget to check the PS magazine section, still on the old site, which has lots of info on the battery care.

 

[dabtl]

I am headed to Northern Tool for a battery tender today.

 

[Speddmon]

I've been using a "battery tender" brand trickle charger on my motorcycle for years!! Ask any biker and they'll probably tell you they use one too. Without a tender you can expect about 3 good years from a bike battery. I've gotten 7 and 8 from my motorcycle batteries using the tender. It's the long winter storage that kills the bike batteries, but the battery tender really works good on them. I actually have one on my ATV now and my tractor as well.

 

[Keith_J]

I've been using a "battery tender" brand trickle charger on my motorcycle for years!! Ask any biker and they'll probably tell you they use one too. Without a tender you can expect about 3 good years from a bike battery. I've gotten 7 and 8 from my motorcycle batteries using the tender. It's the long winter storage that kills the bike batteries, but the battery tender really works good on them. I actually have one on my ATV now and my tractor as well.

Motorcycles are very hard on batteries because they typically have permanent magnet alternators with shunt-type voltage regulators. These alternators have low output at idle while the regulator must dump the excess voltage as heat with the engine at high speed. Automotive alternators have variable rotor current, controlled by the regulator.

Yes, regular use is critical. And sadly, most vehicles at DRMO have been without operation for months. This is why they rarely start. And also why Monday PMCS with operation of the engine until it reaches operation temperature is SOP in the Army.