JD 500A 24v charging system

[corcom]

I bought a used JD500A diesel backhoe around 20 years ago. Really nice machine. Other than regular maintenance, hose changes and etc. no real issues. Of course I don't use it much as well... The one issue is the system charging. To begin with, the wiring behind the front panel has decayed and so I dumbed the system down. I've got the starter hooked up. The only other thing hooked up was the alternator. However, it hasn't been charging for years... It's a 24v alternator (Motorola RA24JD902) landing on one of the 12v battery's neg terminal (two 12v batteries in series). There is a red and blue wire coming out of the regulator going to a plug on the harness. The blue wire broke and so I finally decided to try to figure out what's going on. With the engine running I tried measuring voltage from the regulator outputs to ground and got no reading on either the red or blue. Am I doing something wrong or is the regulator kaput?

 

[corcom]

I bought a used JD500A diesel backhoe around 20 years ago. Really nice machine. Other than regular maintenance, hose changes and etc. no real issues. Of course I don't use it much as well... The one issue is the system charging. To begin with, the wiring behind the front panel has decayed and so I dumbed the system down. I've got the starter hooked up. The only other thing hooked up was the alternator. However, it hasn't been charging for years... It's a 24v alternator (Motorola RA24JD902) landing on one of the 12v battery's neg terminal (two 12v batteries in series). There is a red and blue wire coming out of the regulator going to a plug on the harness. The blue wire broke and so I finally decided to try to figure out what's going on. With the engine running I tried measuring voltage from the regulator outputs to ground and got no reading on either the red or blue. Am I doing something wrong or is the regulator kaput?

 

[Tx Jim]

My advise from serving as a JD dealer service manager from 1976-1987 is to change your 500A electrical system from 24 volt to 12 volt. if you follow these instructions you will probably not get BALD from pulling your hair out.

 

[LouNY]

I switched my Dynahoe to 24 volts,
I used a 24 volt one wire alternator similar to this;https://www.amazon.com/DB-Electrical-ADR0154-Alternator-Universal/dp/B0081SBDCM/ref=pd_lpo_sbs_263_t_0?_encoding=UTF8&psc=1&refRID=Z658PJ5MXGHKM4Z8KY5Y
I just picked up my 12 volt lighting off of one battery.
My system is a negative ground so my alternator is wired to the starter hot lead.

 

[TBN Support]

:welcome:

Welcome to the forum!

I'm going to move this thread over to our John Deere section.

 

[corcom]

Thanks for responding Tx Jim. I guess it would be a lot simpler doing 12 volt. I don't use the backhoe often and not when it's below 50. Though I had to once get it started after a big snowfall and so rigged up a platform to aim a torpedo heater at the block for about half an hour... But otherwise I just need to crank the starter - that's it. Fuel gauge doesn't work - a dipstick works fine for me. The only rub is I'd have to switch out batteries (I'm assuming 2 sixes in series), alternator and starter?

 

[corcom]

Thanks Catherine!

 

[LittleBill21]

just wire the battery's in parallel no reason to switch them out

 

[corcom]

I missed the obvious! Thanks LittleBill21.

 

[beenthere]

Don't think Catherine noticed you already had a duplicate thread started in the JD Vintage tractor section.

 

[Tx Jim]

Welcome to TBN
I advise to change 24 volt elect system over to 12 volts & save yourself a lot of grief. I served as a JD dealer service manager from '74-'87 & I'll bet I understand the quirky JD 24 volt system much better than the average member of tractor discussion forums. Does your tractors electrical system have 2 large circuit breakers that were field installed that help keep wiring from shorting out & causing a fire?

 

[corcom]

Sorry about the muiltiple posts. This is my first time and I'm just figuring out how this works. Definitely haven't seen these breakers.

 

[Tx Jim]

I switched my Dynahoe to 24 volts,
I used a 24 volt one wire alternator similar to this;[
I just picked up my 12 volt lighting off of one battery.
My system is a negative ground so my alternator is wired to the starter hot lead.

On JD 24 volt system that I'm familiar with one can't successfully have elect accessories connected to just 1 battery as the batteries will not charge back up correctly IE the elect accessory load must be split equally between both batteries.

 

[TBN Support]

Sorry about the muiltiple posts. This is my first time and I'm just figuring out how this works. Definitely haven't seen these breakers.

No worries

I merged the two threads that had posts.