D4H charging problem

[gdutson]

Hey guys,

I have a new to me '92 D4H III LGP. Trying to find out why, at idle, I am getting a good 14.5 volts to the right side battery but only 11-12 volts to the left battery. Any suggestions for troubleshooting? Are these units a 24v system to the starter or just 12v with double the amperage?

Thanks for your help...

 

[Mquinista]

In this tractors electrics are of 24V nature as said above,
Usually Alternator output has to be soemewhere close to 28V, and the batteries should reflect that.
usually it does not spread evenly through the batteries even if one measure one by one.

To diagnose for problems in what batt concerns, check them disconected one by one and u can figure out condition of each one. Usually one goes bad and the system does not perform well.
Once u´re happy with the batt, conect them in series and check for voltage, engine off , +- 24V , engine on alternator charging at least 26,5( despite is a bad indication ) system is rated to run at 28V.

 

[gdutson]

In this tractors electrics are of 24V nature as said above,
Usually Alternator output has to be soemewhere close to 28V, and the batteries should reflect that.
usually it does not spread evenly through the batteries even if one measure one by one.

To diagnose for problems in what batt concerns, check them disconected one by one and u can figure out condition of each one. Usually one goes bad and the system does not perform well.
Once u´re happy with the batt, conect them in series and check for voltage, engine off , +- 24V , engine on alternator charging at least 26,5( despite is a bad indication ) system is rated to run at 28V.

Ok. Then I'll check for 24v at alternator (engine off) and 26v at alternator (engine running). If the batteries are connected in the dozer correctly, should I see 12v or 24v at each battery?

 

[Vetech63]

Ok. Then I'll check for 24v at alternator (engine off) and 26v at alternator (engine running). If the batteries are connected in the dozer correctly, should I see 12v or 24v at each battery?

You can measure both ways. Each battery will show 13-14 volts individually. Connected together and checked at the main positive and negative will show-27-28 volts on average.

 

[gdutson]

You can measure both ways. Each battery will show 13-14 volts individually. Connected together and checked at the main positive and negative will show-27-28 volts on average.

Great! Any idea where the "main positive and negative" point would be on this unit? The batteries are in separate compartments so I would like to locate where they interconnect to make it so the batteries are in series.

 

[Nige]

Try posting a Serial Number. Model year means nothing unfortunately.
You can have some parts illustrations and an electrical schematic.

Can you elaborate on how this problem started.? There's isn't a possibility that someone has installed a nominal 12v alternator on a machine with a 24v electrical system is there.?

 

[Delmer]

The main positive will show 24 volts to ground and be connected to the starter, the main negative will show O volts to ground and will be connected to ground, somewhere... the intermediate positive and negative terminals will be connected to each other, and show 12V to ground.

Check the battery voltage after sitting overnight, if one has a bad cell, then it will show under 11V and won't reach 14V unless it's charged for a long time, if ever. Also check for any connections to one battery and not the other, like 12v radio etc. That will drain the one, and it won't recharge properly because they're in series, they have to each take the same amps in when charging.

 

[gdutson]

Try posting a Serial Number. Model year means nothing unfortunately.
You can have some parts illustrations and an electrical schematic.

Can you elaborate on how this problem started.? There's isn't a possibility that someone has installed a nominal 12v alternator on a machine with a 24v electrical system is there.?

Sorry, I meant to do that in the beginning but forgot. The S/N is 9Gj00398. I don't know much about the history of the machine so anything is possible. I just got the machine home and am starting to go through it noticing the battery charging issue and also starting to troubleshoot the instrument cluster lights inop. Thx!

 

[gdutson]

The main positive will show 24 volts to ground and be connected to the starter, the main negative will show O volts to ground and will be connected to ground, somewhere... the intermediate positive and negative terminals will be connected to each other, and show 12V to ground.

Check the battery voltage after sitting overnight, if one has a bad cell, then it will show under 11V and won't reach 14V unless it's charged for a long time, if ever. Also check for any connections to one battery and not the other, like 12v radio etc. That will drain the one, and it won't recharge properly because they're in series, they have to each take the same amps in when charging.

So with a 12V charger it sounds like I need to disconnect the leads to the dozer and charge them individually...?

 

[Nige]

Sorry, I meant to do that in the beginning but forgot. The S/N is 9Gj00398. I

Schematic on the way. Check your messages.

@Delmer - see below. 109-OR is permanent Batt+, 403-GN goes to the alternator warning light and piggy-backs to the hourmeter.

 

[gdutson]

Go

Schematic on the way. Check your messages.

@Delmer - see below. 109-OR is permanent Batt+, 403-GN goes to the alternator warning light and piggy-backs to the hourmeter.

View attachment 301051

Got it! Thanks so much. Lots more connections test.

 

[Delmer]

So with a 12V charger it sounds like I need to disconnect the leads to the dozer and charge them individually...?

Depends. You don't have to disconnect anything if you have enough time to charge the batteries one at a time. You're really only worried about charging the low battery, if one is 12.6 or higher, it's charged good enough for our purposes.

If you want to use two 12V chargers at the same time it gets complicated, even one 12V charger I'd keep the charger insulated from the machine in case the output is grounded (when charging the 12-24V battery). Plastic smart chargers are usually insulated and you could use two at a time, but you wouldn't want to find out you're wrong the hard way.

 

[gdutson]

Depends. You don't have to disconnect anything if you have enough time to charge the batteries one at a time. You're really only worried about charging the low battery, if one is 12.6 or higher, it's charged good enough for our purposes.

If you want to use two 12V chargers at the same time it gets complicated, even one 12V charger I'd keep the charger insulated from the machine in case the output is grounded (when charging the 12-24V battery). Plastic smart chargers are usually insulated and you could use two at a time, but you wouldn't want to find out you're wrong the hard way.

Good to know. I'll go through the wiring diagram from Nige and do some voltage testing. Both batteries test good using our battery load tester. One is definitely not holding a charge for long though so it may be on its way out.

 

[Nige]

Both batteries test good using our battery load tester. One is definitely not holding a charge for long though

Surely those two statements are at odds with one another.? If the load tester says it's good then it should hold a charge. If it is not holding a charge then no way should the load tester say it's good.
Bad tester.? Bad battery.?
My 2c, YMMV.

 

[Mquinista]

HeHe , u´re so lost , lets try and help u...
Negative or Ground is any point in the metal structure, so basically every component is grounded to the main structure.
Some components like Alternator and Starter , are GWD by the structute and a Lead, the lead is to prevent shorts in GWD conection.

The battery is the storage , it serves only the purpose of starting the machine, nothing else. That´s why is possible that electrical components may not operate correctly without the 28V.

The battery has a Negative Lead conected to the structure, or it may have a lead to a main Negative Pole. wich in turn is conected to the main structure. ( only with the diagram one can ascertain that)

This is where your battery starts, this lead is conected to #1 Batery negative pole, the Positive pole of batt 1 is conected to the Negative pole of battery #2 wich in turn has his Positive pole Conected directly to the Starter, (nothing in beetween) a Thumb thick wire from POS on Battery to the starter. Alternator May or may not be conected directly to the same lead on the starter. Really depend on the installation.

i´ll atach a hand draw schematic of what it may look like, Diagrams u request to people in the forum, posting the machine Serial Number. They´l be glad to help.

 

[JD955SC]

Check and clean all connections and terminals

Make sure no aftermarket accessories are wired to one battery directly

Check your battery voltage at high idle. Older machines had regulators that function better at higher RPMs.

 

[Delmer]

Good to know. I'll go through the wiring diagram from Nige and do some voltage testing. Both batteries test good using our battery load tester. One is definitely not holding a charge for long though so it may be on its way out.

The battery tester is measuring cranking amps, not internal discharge, so it wouldn't surprise me if it tests good after charging, but drains sitting a day.

Disconnect the negative cable from each battery, the grounded one first, then the intermediate negative terminal, charge the batteries, let sit a day or two, if one goes flat then that's the problem, by flat I mean less than 12V. One bad cell (slow discharge) could explain all your issues.