How long can I go after Alternator stops working w/four 12v batts? and diagnising/fixing 200amp hummer alt on LMTV

[aw113sgte]

Update about two batts use with no working alternator.

If it gets much below 40f.... and your batts are not brand new..... you need all four to make it 60 miles. Seems ever 5 to 10 degrees it goes colder you loose a lot of voltage. On 20f days with two batts.... the 30 mile drive home in the 60 mile trip I do... with headlights on and heater fan., the 12v batt hitsc 40% state of charge results are; can not back into my own parking space (takes several forward-n-backward off dead end to get turned into my spot) cause it pops into Neutral. If I turn off headlights.... it works fine..... so it for sure is a voltage thing.. thank god it is litterally @ my parking spot that this comes about. Granted Ive risked driving with headlights off in a few spots to get me that extra distance.

soooooo seems like ..... if you are in cold weather.. 4 batts is needed to have best chance at emergency No Alt. chargeing drive ability (approx 60 miles) . In the warm.... 50+.... your fine for 60 miles. 60f+.... probably good for 80 miles.

Wish me luck...... I dont want to drive this truck this much "yet.".. It$ breaking me. If times dont change soon I will have to abandon this whole dream, retirement living in LMTV camper, career change plans and give up- sell it all / come up with some other plan jLIKE SOON (Thanks Brandon.. can't afford both you and Murphy )

Did you mention headlight type? LED will draw far less power.

 

[Ronmar]

Did you mention headlight type? LED will draw far less power.

Oh yea, LEDs would be a fraction of the load… I totaled up wattage once and came up ~27A for all the lighting on a 1078. Its over 30A on a 1079…

 

[coachgeo]

Did you mention headlight type? LED will draw far less power.

good point. One is a 100w Halogen (was way less expensive than a heated LED to keep off snow when put it in 5+yrs ago)

 

[Ronmar]

100w is 7.7A all by itself

 

[Ronmar]

Ok, got around to load testing the 24v on my A0 this afternoon. 24v only feed to the cab with a blue sea amp meter and 100A shunt in that line.
ignition on 6A
start and idle still 6A. About the time the air tanks went over 66PSI and the buzzer stopped, it dropped to 3A. I dumped some air and reactivated the buzzer but the load stayed at 3A. There are 2 heaters, both temp activated, one on the primary filter and one on the air dryer. I no longer have one on my filter, so I suspect at 39deg, it was maybe cold enough to activate the dryer heater until it got enough hot air from the compressor to warm up the dryer enough to turn it off…

So idling, transmission in N N, and run solenoid, 3A. my gauges are now mechanical, i suspect a normal A0 would probably pull another half amp for gauges
Dryer heater 3A, I suspect the fuel bowl would also pull ~3A when active due to cold.
24-12 converter on, no change
neutral to D or R, no change
all my LED lights on +5.6A@24v, about 1/3 of what incandescents would pull. It will probably be close to 6A when all the habitat markers are installed
High beam +1.5A.
blower on high +7.4A
Wiper on high +2.1A

A little higher than I figured, and forgot all about the heaters, but Now we know…

 

[aw113sgte]

Ok, got around to load testing the 24v on my A0 this afternoon. 24v only feed to the cab with a blue sea amp meter and 100A shunt in that line.
ignition on 6A
start and idle still 6A. About the time the air tanks went over 66PSI and the buzzer stopped, it dropped to 3A. I dumped some air and reactivated the buzzer but the load stayed at 3A. There are 2 heaters, both temp activated, one on the primary filter and one on the air dryer. I no longer have one on my filter, so I suspect at 39deg, it was maybe cold enough to activate the dryer heater until it got enough hot air from the compressor to warm up the dryer enough to turn it off…

So idling, transmission in N N, and run solenoid, 3A. my gauges are now mechanical, i suspect a normal A0 would probably pull another half amp for gauges
Dryer heater 3A, I suspect the fuel bowl would also pull ~3A when active due to cold.
24-12 converter on, no change
neutral to D or R, no change
all my LED lights on +5.6A@24v, about 1/3 of what incandescents would pull. It will probably be close to 6A when all the habitat markers are installed
High beam +1.5A.
blower on high +7.4A
Wiper on high +2.1A

A little higher than I figured, and forgot all about the heaters, but Now we know…

Great info! I want to check my C7 at some point. So a shunt vs a clamp meter? Can you explain why (I have a clamp meter that can do DC and would obviously be easier the a shunt setup).

 

[Ronmar]

Great info! I want to check my C7 at some point. So a shunt vs a clamp meter? Can you explain why (I have a clamp meter that can do DC and would obviously be easier the a shunt setup).

I have the Blue Sea 1732 and shunt and a 1733 voltmeter for a solar rig, and don’t have a DC capable clamp-on a DC clamp should work fine and would be easier, but the shunt was simple enough

General said the C7 ECU was good for 1.1A, not sure what the MMDC/gauges pull, but i suspect not a lot. Perhaps maybe 2 more running amps total than my 3116? Maybe ~5A without anything else on for an A1/A1R?