Basic charging question, I think.

[petebert]

Just bought a new house with 10 acres and a tractor was included in the deal. It's a Zetor Zebra but I think this is a general charging question so this forum would work.

I've been working on cars for years but am not familiar with how the deep cycle batteries work. I put the volt meter on the battery and it will show 12.2v. When I go to start it I get one crank before it clicks and now with the volt meter it shows 6-7v, let it sit for a few minutes and it will show 12.2 again.

So I jump start the tractor and put the volt meter on the battery terminals and it still shows 12.2, so could it be the alternator? The battery does appear to be old and at the point where they normally fail. I also tried turning the headlights on and voltage at the terminals dropped to 11.8.

 

[k0ua]

Well you are for sure not charging the battery with the tractor, so yes alternator is not working for you. The charging voltage should be at least 13.8 to 14.2 volts. The battery may be about gone now from lack of charging. Put the battery on a charger, check water level if it is that kind, repair/ replace alternator/regulator then decide if battery is going to make it or not and whether it needs to be replaced also.

James K0UA

 

[LD1]

Yep, something isnt charging it back up.

And 12.2V is a dead battery.

12.6-12.7v is 100%
12.4-12.5v is 75%
12.2-12.3v is only 50% charge

But it makes me wonder...does this thing even have a charging system. Because I question why it even has a deep cycle battery??

 

[petebert]

Well I assumed deep cycle because it says commercial/agricultural on it, is that not correct? It does have an alternator, I made sure of that. I keep forgetting to check the belt with the motor off but while running the belt flops around quite a bit. I'd never let a car belt run that loose and I have seen cars not charge just due to the belt.

 

[Gary Fowler]

I would first put a charger on the battery and see if it takes a charge (assuming that you have a battery charger). Alternately, set the belt tension same as you would for a car and jump start the tractor, let it run for an hour or so and see if it charges the battery. The battery might not take a charge even if the alternator is working properly. I recently had to replace a deep cycle battery on my boat that would not charge. It would show fully charged but then the voltage was less than 12 volts. You can also take the battery to just about any auto supply store and they can check it for you for no charge. If you have a digital multimeter you can check the output voltage on the alternator with the engine running also.
I would be more inclined to think that you have a bad battery than a bad alternator so work from that direction first prior to removing the alternator. As for the deep cycle battery: Could be that the previous owner put an old trolling motor battery in the tractor that no longer held a good charge for his boat or he may have just bought one as a replacement. They will work for starting battery also.

 

[jenkinsph]

Sounds like a lack of maintenance all the way around. I would start with the basics.

Check all fluids including checking for water in the sumps.
Check for loose bolts, bad wires, maypop hoses and tires.
Check steering joints, wheel play, brakes.
Most of this can be done while charging the battery. While the belt is loose I would check the water pump for play too.

For the specific problem, recharge battery and tighten or replace belt first then restart and test voltage again. I would expect to see about 14 volts when charging and running. Turn on the lights and see if it will maintain the charging voltage.


With a label showing commercial/agricultural it isn't a deep cycle but is likely just a generic battery. I would check out the overall tractor before spending any money, then if I was going to keep it put the largest capacity battery I could fit. If it doesn't maintain the charging voltage after tightening the belt you will need a new voltage regulator and alternator or depending on the type setup at least the alternator.

 

[jinman]

Well I assumed deep cycle because it says commercial/agricultural on it, is that not correct?

Petebert, I think "commercial/agricultural" means the batttery is ruggedized for rough use and may also have higher amp draw (larger internal plates) than regular auto starting batteries. Deep cycle batteries are meant to be charged up and then used until they are almost completely discharged because the equipment that uses them has no ability to charge them. The most common use may be electric trolling motors, but also many dump trailers have pumps running on deep cycle batteries. Normal starting batteries won't last long if they are discharged over 1/2 their capacity on a regular basis. Deep cycle batteries can do this over and over with few negative side effects. Since your tractor has an alternator, it should not need a deep cycle battery, but if it had one, it would be okay.

Are you reading the voltage from the battery right on the battery terminals or on the battery cable connector? If your battery terminals are dirty and you read on the cable, you will see a voltage drop under load. If you put your voltmeter lead into contact with the battery terminal itself, that will tell you for sure if it is the battery dropping or not.

 

[Soundguy]

I agree with jinman.. a deepcycle battery is not really for that type of application.. that tractor needs a working charging system.

soundguy

 

[petebert]

I tightened the belt and still no improvement. It has an internal regulator. I tried testing the voltage at the alternator and it bouncing all over. I've seen this on cars when the brushes wear out so the regulator is trying to compensate. I called my closest authorized parts dealer from the zetor website, about $350 before shipping!

 

[brin]

I tightened the belt and still no improvement. It has an internal regulator. I tried testing the voltage at the alternator and it bouncing all over. I've seen this on cars when the brushes wear out so the regulator is trying to compensate. I called my closest authorized parts dealer from the zetor website, about $350 before shipping!

You might want to take the alternator to a local re-builder ( an auto electric shop) in your area...much cheaper than buying a new one...that's what I do.