Voltage regulator not working

**Terryl** · 01-21-2023, 10:19 PM

Howdy all, well this is not a car problem but on my fork lift.

I have an old pre 1980's fork lift, it has a 6 cylinder in-line propane powered engine, I had trouble starting it, (slow cranking) so recharged the battery over night. It started fine and I used it for the day, went back a week later and the battery was dead again, hummmmm???

So checked out the battery and it was low, recharged it and it started fine, checked the battery voltage while running and it was the same as when it was off, hummmm.....

Checked the output of the alternator and it was zero volts, traced out the charging circuit and found out that the amp meter was dead,(12 volts on the input, zero volts on the output, internal shunt type) and had been for a long time, so the battery was never getting a charging voltage from the alternator, buy passed the alternator and I got charging voltage to the battery, the bad thing was it was at around 16 volts, (battery was fully charged) disconnected the charge wire to the battery and it jumped up to 35 volts. (approximately)

So thinking that the voltage regulator was bad, I went a got a new one, same problem.

So somehow the voltage regulator system is not working as it should, (new exact replacement voltage regulator) it should regulate to 13 to 14 volts then drop down, what it does is drift up in voltage as high as 17 volts, and before it burns something out I shut down.

So any ideas Guys and Gals ??? This one has me stumped....

**maird57** · 01-21-2023, 10:41 PM

Is the regulator a name brand or off shore?

**Terryl** · 01-21-2023, 11:15 PM

Brand name, got it from O'reilly auto supply, same exact one that was on it.

Standard Ignition 12 Volt Voltage Regulator - VR103

Code:

https://www.oreillyauto.com/detail/c/standard-ignition/standard-ignition-12-volt-voltage-regulator/std0/vr103?q=vr+103&pos=0

**maird57** · 01-21-2023, 11:43 PM

Also if a battery is not regularly used it could be sulfated and may cause an overcharging that the regulator can't handle. Very rare but could happen.

**Terryl** · 01-22-2023, 01:52 AM

Battery is about 2 years old, it takes a nice charge from my external battery charger, but without the onboard charging circuit working I might get 6 to 7 starts out of it before it wont crank.(or cranks very slow)

This is an old unit, it looks like someone replaced the old generator with an alternator,(online service manual for this unit shows a generator) but I can't get to the alternator to check the model number without a major tear down of the top frame, (seat, tank mount and safety cage) the alternator puts out 35 volts when I bypass the amp meter but I do not get regulation of the charge voltage, new amp meter is on order.

According to the service manual and on-line info everything looks to be wired right, but I have trouble wringing out the wire harness (hard to reach one side to the other) to see if there may have been something chewing on the wires.

**The Noof** · 01-22-2023, 02:01 AM

What brand of alternator Terry?Rather than just voltage do you have a way to check the ripple???If it's high voltage, it can be the rectifier related,charging high voltage ac.You must check the ripple too....dvom measured voltage only tells part of the story.

**Terryl** · 01-22-2023, 05:08 AM

I have no idea on the brand/type of alternator, all I can see is the back side of it, it's a major tear down of a lot of heavy stuff to get to it.

I bought this fork lift used,(from a used equipment dealer) but I wonder if someone just hacked the install of the alternator and it's never been working right to begin with, still digging through the wiring to see if there is something chewed up or not connected right.

**jets** · 01-22-2023, 05:23 AM

Terryl,

Test the voltage in AC mode with a DVM, might be the rectifier is bad or partially failed. Generator is DC output Alternator is AC output then rectified if my memory is working LOL. The rectifier is either built into the alternator or external. Have a look around for it.

**Terryl** · 01-22-2023, 06:10 AM

Here are some photos, the regulator has been replaced with the same brand and type, the alternator is unreachable without some major work.

Regulator.jpg

Alt.jpg

**dishuser** · 01-22-2023, 06:33 AM

IMO you're gonna have to dig

**runamok** · 01-22-2023, 07:49 AM

You can buy a one wire alternator .one wire from battery to alternator.no voltage regulator needed.i have one on my forklift it charges at a certain rpm

**Terryl** · 01-22-2023, 08:44 AM

I've put too much already into this, new voltage regulator and a new coil,(old one had a weak spark) and again to get to the alternator to replace it is major work.

**The Noof** · 01-22-2023, 02:56 PM

Terry:that is a Delco 10DN style alternator, & a Ford external regulator.As I stated before, CHECK THE RIPPLE!.If you don't know what it is, it's ac rather than dc current in the charge voltage, indicating a rectifier issue.A rectifier failure can result in high voltage output but it's ac, which is useless to a car battery.