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.