Parasitic Draw

[williamh]

I think before everyone goes off the deep end on this guys poor truck , I’m sure you got a bleeder just killing 1 battery. Without disconnecting any of the battery’s I think you need a current sensing meter to see if there’s a drain. They come in different styles but something like this

hopefully with a lower amp reading to check the wires that are connected to the battery to find the draw. They make clamp on meters that read dc amperage at harbor freight. There isn’t too much other than the transmission or the alternator / regulator that’s always going to be pulling off the battery’s. The meter will help you identify the wire and the tag will tell you where it goes.

 

[FMFHMMWV]

Alright guys, I have an update. Id like to first express my gratitude for everyone's help with this issue. Any pf you that chimed in and need a couch to crash on in SD, You are welcome and Ill make you my crispy fat rib eye.

Update 1:
1. I disconnected all the peripheral circuits.
2. I tested for parasitic draw by disconnecting the negative terminal and testing under the 20A setting on my multimeter. I registered 0.00 draw. couldn't even believe it. nothing. even took out the sound system and nothing. no draw. every 30 seconds or so, Id register a 0.01 for 2 seconds or so and it would go back to 0.00.
3. so I drove it around for a few days.

Update 2:
I was casually driving the truck around town streets when the trans light went on and I couldnt shift out of first. I have neutral/reverse/park but noting about 1st or maybe second. immediately took it back to the house. parking it and tried to turn it of and restart it. Nothing. The batteries are dead.

Inferences: I don't have a parasitic draw but rather, something is either draining my batteries while i'm driving (short?) or im not charging them (bad generator or voltage regulator?)

Question for the team: How do I test the regulator and the generator?

 

[FMFHMMWV]

Switched off is not the same as disconnected, you need to disconnect EVERYTHING from the batteries and then start carefully re-connecting things until you find the problem.
You have to be careful with a dual voltage system, remove the ground cable from the rear battery and then try ether intentionally or through some failure to pull current from the 24V terminal and you reverse bias anything connected to the 12V tap (this BTW would only pull current from the front battery) as long as the ground cable is disconnected

Thank you for this information sir. as it turns out, I am draining both batteries, not just the front.

 

[FMFHMMWV]

I think before everyone goes off the deep end on this guys poor truck , I’m sure you got a bleeder just killing 1 battery. Without disconnecting any of the battery’s I think you need a current sensing meter to see if there’s a drain. They come in different styles but something like this View attachment 900494

hopefully with a lower amp reading to check the wires that are connected to the battery to find the draw. They make clamp on meters that read dc amperage at harbor freight. There isn’t too much other than the transmission or the alternator / regulator that’s always going to be pulling off the battery’s. The meter will help you identify the wire and the tag will tell you where it goes.

Thank you sir for this insight. I have since shifted my suspicion of the culprit. I think now that my batteries are either not getting charged due to a faulty regulator/generator. I am now respectfully requesting guidance on testing regulator and generator sir. everything has been working great for 3 years. kind of curious what is failing. thank you again for your help.

 

[Coug]

I don't recall seeing it mentioned, what alternator is in your truck? Knowing this will help us to be able to provide more specific troubleshooting, as a few things are different between the different types

Use a multimeter to check voltage at the batteries.
Then use the meter again at the alternator and see what the voltage is at the connections if it's any of the larger dual voltage systems.
I'm not as familiar with the 60 amp unit, but I believe it goes through the start box, so only works with it turned on.

Start the truck, let run for a minute or two, and check voltage again at both places. You should be seeing at least 28V.
You should be seeing same voltage at both places. If alternator is higher than the batteries, you have a bad wire or bad connection somewhere.

If you are seeing the same voltage (or maybe a little under due to glow plugs and cranking) as before you started the truck, then most likely culprit is a bad regulator. The 60 amp it's internal, the 100, 200, and 400 amp are external.


This should provide a basic idea of where the issue is at for more specific help afterwards.

 

[FMFHMMWV]

I don't recall seeing it mentioned, what alternator is in your truck? Knowing this will help us to be able to provide more specific troubleshooting, as a few things are different between the different types

Use a multimeter to check voltage at the batteries.
Then use the meter again at the alternator and see what the voltage is at the connections if it's any of the larger dual voltage systems.
I'm not as familiar with the 60 amp unit, but I believe it goes through the start box, so only works with it turned on.

Start the truck, let run for a minute or two, and check voltage again at both places. You should be seeing at least 28V.
You should be seeing same voltage at both places. If alternator is higher than the batteries, you have a bad wire or bad connection somewhere.

If you are seeing the same voltage (or maybe a little under due to glow plugs and cranking) as before you started the truck, then most likely culprit is a bad regulator. The 60 amp it's internal, the 100, 200, and 400 amp are external.


This should provide a basic idea of where the issue is at for more specific help afterwards.

Do you test at the large cable on the generator? And this should be 28v or greater?

 

[Coug]

Do you test at the large cable on the generator? And this should be 28v or greater?

Okay, time for a couple more questions.
Did the charging system on this truck ever work, or did you just recently acquire it and trying to sort everything out?

I'm asking because something here doesn't look right.

The N1225-1 alternator has an external voltage regulator bolted to the outside of the unit. Your pictures are not showing that regulator.
Not sure where the wires out of the sides of it are going, but if the regulator is remote mounted somewhere else on the truck, that is where you would be checking for output voltages.


This is what it normally looks like

Here is what it looks like installed in a truck (the pictures are a V-belt truck, but it's identical in a serpentine belt setup)

The yellow washer at the front is the 14V tap (should show same voltage as the rear battery)

The red wire cover is the 28V tap. That should be the same voltage as the batteries
Just under the red cover you see a shiny strap. That's the alternator ground strap. Mine was loose when I got my truck and that will cause issues.


Could you take a couple pictures of where all the wires coming out of the alternator are going to?

 

[FMFHMMWV]

Okay, time for a couple more questions.
Did the charging system on this truck ever work, or did you just recently acquire it and trying to sort everything out?

I'm asking because something here doesn't look right.

The N1225-1 alternator has an external voltage regulator bolted to the outside of the unit. Your pictures are not showing that regulator.
Not sure where the wires out of the sides of it are going, but if the regulator is remote mounted somewhere else on the truck, that is where you would be checking for output voltages.


This is what it normally looks like

Here is what it looks like installed in a truck (the pictures are a V-belt truck, but it's identical in a serpentine belt setup)

The yellow washer at the front is the 14V tap (should show same voltage as the rear battery)

The red wire cover is the 28V tap. That should be the same voltage as the batteries
Just under the red cover you see a shiny strap. That's the alternator ground strap. Mine was loose when I got my truck and that will cause issues.


Could you take a couple pictures of where all the wires coming out of the alternator are going to?

1. Yes the charging system did work on this rig for about 2.5 years.

2. You are correct sir, the regulator it remotely mounted.

3. Regulator: when the engine is off, the yellow post on regulator registers the same as rear battery.

4. Both batteries: When engine is off I register about 24v.

5. Generator: I have not tested it at the large terminal with thick black cable and red wire. Will also check groung

 

[Coug]

The manufacturer has a really good troubleshooting guide that will take you step through step to determine where the failure is at.
95% of the time it's the regulator.

https://www.ceniehoff.com/Documents/Ctrl_Hyperlink/TG17_uid252021123202.pdf

 

[FMFHMMWV]

Update:

Generator: testing at 18-25 and change with the truck running.

Regulator: testing at 10-12 and change with the truck running.

Will post videos of the tests.

 

[FMFHMMWV]

Update:

Generator: testing at 18-25 and change with the truck running.

Regulator: testing at 10-12 and change with the truck running.

Will post videos of the tests.

The regulator is 10-12 at the 14v post

 

[Coug]

Either alternator or regulator is bad.
If you understand how to use a multimeter, go through the tests in the PDF I linked in my last post. That will confirm for you which item is the failed one.
As I said before though, it's usually the regulator, but not always, so if you aren't familiar enough with following the test procedures, you could take the risk of buying a regulator and it will likely fix the issue, but there's still a chance it's the alternator itself.

 

[86humv]

The relay for the 4l80e trans behind battery box will sometimes stick closed with voltage going to your trans computer
with vehicle turned off.

 

[FMFHMMWV]

update:

1. both batteries together are at about 25v.
2. big red on the alternator is registering about 25v with truck on and running
3. 28v on regulator is registering about 25 with truck on/running.
4. accessory on the regulatory is registering about 12v with truck on/running.
5. 14v lug on regulator is registering about 12v with truck on/running.

 

[Milcommoguy]

Little con-fused... what is the test point for item 4 listed? Explain. I ask... what is the voltage on the ignition sense terminal at regulator with the switch in the RUN position? Next, model of regulator ?

Don't know about this parasitic drain, but differently not charging.

"Parasitic drain" sounds serious. Hope I don't catch one, CAMO

 

[FMFHMMWV]

So everyone was right it was the regulator. Underneath the epoxy was all cracked. I replaced it and bang...28volts all around. Can the n3118 work on the hmmwv?what other dual voltage units work on our trucks? Any upgrades? The new one is a n3135 from an 1151

 

[Coug]

So everyone was right it was the regulator. Underneath the epoxy was all cracked. I replaced it and bang...28volts all around. Can the n3118 work on the hmmwv?what other dual voltage units work on our trucks? Any upgrades? The new one is a n3135 from an 1151

The N3118 is for the 400 amp alternator, not the 200 amp, so no, you can't use it on the 200.


The 200 amp is considered the go to for the HMMWV. The 400 amp is only used for high power applications, like radio shelter carrier trucks or SECM trucks with things like electrical air compressor and huge inverter in them.

For the civilian world, the 400 just takes up a lot of space, is heavy, and a pain in the butt.

Earlier trucks used a 60 amp, but it was for the V belt systems only, and doesn't have a 12V tap and shouldn't be used for anything other than 3 speed trucks.
A few people have put civilian alternators into their HMMWVs, but had to add load balancers to the batter bank if they had 4 speed trucks that require the 12V feed to the transmission control module.

 

[FMFHMMWV]

The N3118 is for the 400 amp alternator, not the 200 amp, so no, you can't use it on the 200.


The 200 amp is considered the go to for the HMMWV. The 400 amp is only used for high power applications, like radio shelter carrier trucks or SECM trucks with things like electrical air compressor and huge inverter in them.

For the civilian world, the 400 just takes up a lot of space, is heavy, and a pain in the butt.

Earlier trucks used a 60 amp, but it was for the V belt systems only, and doesn't have a 12V tap and shouldn't be used for anything other than 3 speed trucks.
A few people have put civilian alternators into their HMMWVs, but had to add load balancers to the batter bank if they had 4 speed trucks that require the 12V feed to the transmission control module.

Thank you! This is great information. I think the civilian alternator idea could be something I would entertain in the future but would need guidance on the load balancers and voltage regulation.

 

[Coug]

Thank you! This is great information. I think the civilian alternator idea could be something I would entertain in the future but would need guidance on the load balancers and voltage regulation.

Voltage regulation is taken care of by the alternator.
Depending on what type of loads we're talking about, there are a couple different ways to balance them and have 12V out of them. Easiest way is a battery balancer plus a 24/12V converter.

Examples below

Balancer. This one places a slight load on the higher voltage of the two batteries to make sure they charge evenly.

Battery Balancer - Victron Energy

Equalize the state of charge of two series connected 12V batteries using the Battery Balancer. Find a Victron Energy dealer near you.

www.victronenergy.com

Converter. This one has a built in relay, so it can be wired into the electrical system to come on and turn off with the run switch. It can also be set up in parallel up to 5 units if it isn't big enough (it's still more output than the 12V tap on the dual voltage regulators)

Orion DC-DC Converters Non-isolated, High power - Victron Energy

Eliminate the need for a high current switch in the input wiring with the remote on/off connector on the Orion DC-DC Converter. Find a dealer near you.

www.victronenergy.com

I used Victron stuff as examples because it's very high quality equipment and NOT manufactured in China. I recently spoke with the primary dealer for my area and he became a dealer because he works on firetrucks and other emergency response vehicles. For his job price isn't a factor; only quality, and he got tired of dealing with all the cheap electrical modules the manufacturers of the trucks were installing, so he went on a search for the best quality electronics he could find for the electrical in the firetrucks, and Victron was the answer.
I also deal with some off grid inverter systems and other stuff, as well as RV conversion with battery banks, and everyone with Victron seems to love it.