D722 not charging. VR output low

[mrburt]

3 new voltage regulators; original, one warranty and one acquired independently.
All three VR outputs are 11.9 volts with no load; battery voltage when connected. Checked at max RPM.
Confirmed AC volts per spec from dynamo. Swapped dynamo leads.
Confirmed ground with meter and replaced ground wire.
Grounded VR case.
Confirmed 12v control input voltage when key is on.
All voltages checked at pigtail from VR on VR side of connector.
Confirmed glow plugs off when not in preheat.
Confirmed all battery connections/grounding, cleaned/bonded connections.
Performed charger repair cycle on battery.
Battery charges to 13.1 volts with Genius 10 charger.

Stored over night in an insulated but unheated garage.
Slow turn over. Barely started @ 12.33v.
Ran a tank of fuel out at full throttle voltage 12.36v. Possibly charged some but now battery is pretty warm for running for 2+ hours.
If the LED work light is on the voltage drops to 12.3v.
Only thing left is a weak battery or the fuel pump and/or SOV draw excessive current.

 

[GreensvilleJay]

Ideas...
1) do load test on battery ( what's it's CCA ? )
2) swap in a new/known good battery (biggest CCA that'll fit )[make SURE posts ARE correct orientation]
3) how cold is it
4) put ammeter between battery and regulator and SEE what the charge current actually is.
5) fan belt tight ( 1/2" deflection ?? )

 

[mrburt]

Ideas...
1) do load test on battery ( what's it's CCA ? )
2) swap in a new/known good battery (biggest CCA that'll fit )[make SURE posts ARE correct orientation]
3) how cold is it
4) put ammeter between battery and regulator and SEE what the charge current actually is.
5) fan belt tight ( 1/2" deflection ?? )

#1 is next step. It's 16 bolts to remove battery
#2 done but no diff on short run.
#3 32F
#4 not done yet but voltage is the same everywhere
#5 not loose.

 

[GreensvilleJay]

OK, kinda important.. as this is a 'dynamo', it's probably good for 12-14 amps max output, so have you any 'heavy' loads ,like lights ? on the mini exc.

ugh,16 bolts !!! Nobody's stealing that battery ! Best have a box of bandaids handy.

It could be a weak battery.

 

[North Idaho Wolfman]

What is the voltage at the Dynamo?

 

[mrburt]

#1 is next step. It's 16 bolts to remove battery
#2 done but no diff on short run.
#3 32F
#4 not done yet but voltage is the same everywhere
#5 not loose.

Bought a new battery. No change. Fully charged drained down to 12.25 while running at full throttle. Polarity correct.

 

[mrburt]

What is the voltage at the Dynamo?

Depends on RPM and load. Connected and at full RPM output is 20VAC as per the spec.
Swapped leads just for... no change
New battery no change.

OK, kinda important.. as this is a 'dynamo', it's probably good for 12-14 amps max output, so have you any 'heavy' loads ,like lights ? on the mini exc.

ugh,16 bolts !!! Nobody's stealing that battery ! Best have a box of bandaids handy.

It could be a weak battery.

Nothing but the fuel pump and SOV.
Glow plugs are a big drain but they cut off after start.
Replaced battery, no change.

 

[GreensvilleJay]

Yeesh, sounds like you've got a fairly large 'parasitic load' draining the battery and Dyno/reg can't keep up.

Would need to see the wiring diagram for specific help but IF you have an ammeter, pull a fuse, connect ammeter and new inline fuse in it's place. Check both 'key off' and 'running', record the numbers.
Obviously with key off, NO current ( amps ) should be the result. Add up the 'running' list, that's the total current(amps) being used.

 

[mrburt]

What is the voltage at the Dynamo?

Depends on RPM and load. Connected and at full RPM output is 20VAC as per the spec.
Swapped leads just for... no change
New battery no change.

 

[mrburt]

What is the voltage at the Dynamo?

One item that may have been missed above. If I pull the wire from the VR connector that goes to the battery, the charging output, it reads 11.9V with no load. Hooked up reads battery voltage. This would/should eliminate anything drawing the voltage down from excessive load. But I am not sure what the output would be under no load conditions.

 

[GreensvilleJay]

Would need to know the rectifier/regulator you're using but generally speaking they convert AC from the dynamo into pulsating DC, so reading with a meter won't give a 'nice' value.
If it's what I think it is, it maxes out at about 14 amps ( similar to a riding lawn mower )

Is the black wire from the regulator truly grounded back to the battery -ve? 'looks ok' doesn't do it, need to confirm. Simple ohmmeter test, one probe on -ve of battery, other on the rectifier's black wire. Yeah, I know, might need a trained octopus or 2 bandaids. but an important test. IF the rectifier is not grounded, it won't function properly.

if you post the part number of the rectifier ,I'll look it up online. Be nice if the wiring diagram could be posted. Long distance diagnosis is 'challenging', but easie rthan the 2 AM call I used to have to deal with !

 

[North Idaho Wolfman]

The only way your going to get a good dynamo test is you need to disconnect the dynamo and measure the voltage off the dynamo at full rpms.