806 Battery voltage vs amps

I've had my 806 diesel for about 27 years and gone through about 6, 6 volt batteries in that time. I use Epsom Salt in them about once a year. When they go out it's the same - I can charge them to 12.6 volts or a little higher, but they will only click the solenoid. I change them out, the new ones show a 12.6 volt charge at 100 % and kick the engine over for the next six or so years.

My brother also has an 806 diesel and in 12 years has gone through one set a year (2-6volts). We can charge each to 6 volts or the pair strapped to 12.6/12.8 volts and they won't do anything but click the solenoid. I know he has a problem with that tractor and he has put a trickle/solar job on it to keep the batteries up, but there's still a problem. New batteries kick it over, just like mine.

The question is when a battery charges to the 12.6/12.8 volt which is 100% on the charger, does that mean the battery is good and we should look else where for the problem? That voltage is on the old batteries going out that don't work and the new ones coming in that do.

Appreciate the help as always,

Bob

When a battery shows good voltage with no load, and you are sure it is fully charged, that is an indication of a high resistance connection somewhere inside the battery.

Next time that happens, try connecting the volt meter across the posts (go directly to the posts, not the cables), then apply a load, like the starter or headlights, etc. If the voltage drops to zero, or a significant drop, the battery is bad.

Open circuit voltage on a battery that has been on a charger can show it to be good and charged. Load testing is the real answer
for battery function. Test the voltage across the battery posts (not wire ends) while cranking. (be safe and in neutral, wheels
blocked). 10+ volts are needed. Not a flame, but i would not put Epsom Salt in a battery. Magnesium Sulfate adds a dissolved metal
and more uncontrolled sulfur in the electrolyte. Jim

Like minds. Jim

OK. That helps a lot Steve. The voltage reading doesn't tell the whole story, then. It may have grounded out plates or something like that apparently.

My brother lives quite a distance away, but I can tell him how to check that out. Not sure just why he goes through so many batteries. He must have something draining them. We put a test light in the ground circuit with the key and everything off. It didn't show anything there.

Thanks again, Bob

I just read your posts, Jim. Much appreciated.

That Epsom salt thing was in document from ISU. I read it a long time ago and have done that for years. May have to rethink it.

Thanks to both of you for all the help.

Bob

A test light will not show a small drain, not enough to light the bulb. I had a small drain on my Oliver. My multimeter has a 10 amp scale so I connected it in series with the ground cable. It showed a 50 milliamp current with everything off. PO had replaced the alternator with an internally regulated Delco and connected the wire from the amp light to the output stud in stead of the rectifier terminal. It charged OK but would drain the battery between uses.

I load tested a set of batteries that were 13 years old with a simple load tester. I had 12.5 volts. They would not start the truck. Then I load tested them with a digital tester and checked amps. They way less than half of rated amps. While you may have enough volts under load. Amps is also important

Hello Bob21 Martin,

A battery when fully charged should be 12.6 volts @ 80F. Your charging voltage should be 1 1/2 more volts
then the 12.6 volts. The new batteries work because they have 12.6 volts without the charger on them.
Taking a volt reading while the clicking is accuring is the best way to see where the voltage is dropping. Starting at
the battery terminals, and follow the plus side on the circuit. In your case the new batteries worked so
you found the problem,?

Guido.

I'll check that drain again with a multimeter. Thanks for that information.

The biggest problem I have is with my brother's 806 right now, but the explanations really help. I had always read about the voltage indicating the bad battery, but I knew when I had the voltage on mine I had to replace them to get going again.

I think he must have a small drain on that tractor less than my test light shows. I bet we can get to the bottom of this. He has a good tractor with an IH loader in great shape. I know he'd like the idea of saving money on batteries.

Appreciate the help, as always, Bob

Voltage can be produced by two plates in each cell that won't give you much of any amps to turn the starter. A new battery will give you the
same voltage reading with all the plates working inside but will also give you the amps you need.

Do away with your 6 volt batteries and put in one nice size 12 volt. This will eliminate your problem for ever. By doing this you also
eliminated two extra battery connections that can corrode and cause the same problem you're having. My dad had the same problem with his
Farmall 560 diesel. We installed a 12 volt battery and cured the problem.

When I worked in St. Louis we took all our 6 volt batteries that were hooked in series and replaced them with one 12 volt battery. We never
had any more problems after that.

100-200 amperes is a good range for smaller tractor starting requirements. Considering a static charge voltage of 12.75 (my 24/7/365 go-no go number) to put 10 volts ACROSS the
starter....input terminal to case of the starter, not frame of the tractor or anything else not physically part of the starter, with that voltage you only have 2.75 volts to spare. Taking worst
case which could be for a 100 hp diesel in the winter, a number of 200 amps, (12.75-10)/200 = 0.0125 ohms max. in the entire system....internal battery, interconnecting cables and
terminations, and starter windings and brushes. To tell you how small that resistance is, if you are using a Digital Multi Meter, go to the lowest ohm scale you have (200 probably) and
touch your leads together. My meter reads 0.4 ohms. Back in the days of the analog meter, like Simpson to name a popular brand, you could zero out that lead resistance but can't now.

A load test of your battery checks the cell/sulphate condition. If you can dial up 200 amps and the terminal voltage is still at 11v or above that's a go for me. Others surely have different
numbers.

Cables of adequate cross sectional area, like AWG size 0 or 00 are excellent; longer the run, larger the diameter required. All terminations need to be clean, bright, and tight....clean and
bright on the inside where the current flows.

Don't overlook the starter case to battery return lead in your system hygiene. I like to polish off a spot on the starter case, under a mounting bolt where the battery return lead touches
the case and the bolt holds it and the starter to the engine block.

Then that leaves brushes and armature conditions.
---------------
On 2ea 6v in series vs a single 12v or pair in parallel, the 2ea 6v in series is the worst option since all the circuit and battery resistances are in series and add up to restrict current flow
and starting ease.

This is how I do it and have successful results.

Thanks a lot for all the help and advice. Funny a couple of posts here mention the ground running to the starter. Mine does and his doesn't. His batteries are switched end to end with the ground hooked to the frame back by the column.

We'll change that for him. He had a ratty strap over that he's ordered a part for. That should help a lot. He has a little solar trickle charger that works, but the batteries still go down. That must be why he goes through so many batteries.

Appreciate all the help, as always, Bob

He's been looking into a single 12 volt for that tractor, too. That may solve a few problems.

Testing anything without placing it under load and stress reveals little usable data.
As simple as turning on every light, fan etc then measuring voltage will provide superior data .

(quoted from post at 12:10:39 01/07/17) Thanks a lot for all the help and advice. Funny a couple of posts here mention the ground running to the starter. Mine does and his doesn't. His batteries are switched end to end with the ground hooked to the frame back by the column.

We'll change that for him. He had a ratty strap over that he's ordered a part for. That should help a lot. He has a little solar trickle charger that works, but the batteries still go down. That must be why he goes through so many batteries.

Appreciate all the help, as always, Bob

Click to expand...

Connecting the "ground" which is the negative conductor to a starter mounting bolt eliminates several potential high resistance connections . It's just good policy and eliminates some future failures . I was surprised how much faster one of my tractors cranked just by adding one "ground cable".

Thanks buicKanddeere. That helps a lot. We'll get this going yet.

Bob