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2 Questions: Block Heaters, and 12V/24V Jump Starting

biggdadd58

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Wheeling WV
1, Do these come with block heaters?

2, How does one jump start one if the system is 24 volt and regular vehicles are 12 volt.

OK 3 questions...

3, Is it easy to get a dedicated 12 volt side to run normal stuff?
 
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Jabba

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Indiana
Jabba

I'm not the expert...

1. I don't think so. (I'm going to look for one now that 4-Star says his has it...)
2. They make an umbilical to use from one HMMWV to another. I don't think you can jump one with a 12v car.
3. Some guys tap the batteries in the middle, and that yields 12v, but I think it can be problematic to your charging system. They make a 24v to 12v converter for just this purpose. I have one, and am in the process of installing it.

Jabba
 
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biggdadd58

New member
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Wheeling WV
How do you start one of the older diesels in extreme cold?

There has to be some way to jump start with a single car.

Advise more on the converter please?
I'm not the expert...

1. I don't think so. (I'm going to look for one now that 4-Star says his has it...)
2. They make an umbilical to use from one HMMWV to another. I don't think you can jump one with a 12v car.
3. Some guys tap the batteries in the middle, and that yields 12v, but I think it can be problematic to your charging system. They make a 24v to 12v converter for just this purpose. I have one, and am in the process of installing it.

Jabba
 

BLK HMMWV

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Buy a newer one with the 6.5 or 6.5 turbo running the 4l80. they have 200amp dual voltage alternators. Or upgrade an older one.
charge one battery at a time from a 12 volt source.
Install some kind of block heater.
I'm guessing the HMMWV's with the Arctic upgrades may have had something on them.
 

biggdadd58

New member
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Wheeling WV
Are you saying to upgrade just the alternator?

Charging one at a time is a given. I was asking what to do if you are out and need a jump to get back home.
Buy a newer one with the 6.5 or 6.5 turbo running the 4l80. they have 200amp dual voltage alternators. Or upgrade an older one.
charge one battery at a time from a 12 volt source.
Install some kind of block heater.
I'm guessing the HMMWV's with the Arctic upgrades may have had something on them.
 

Monkeyboyarmy

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Kingsville,Oh.
With a 12 volt system you can only jump 1 battery at a time on the 24 volt system. So you could jump one battery and let it charge for a while and then jump the second battery to see if it would start. Do not let the vehicles touch. Other than that you would need to jump it with another 24 volt system.
 

Wire Fox

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Indianapolis, Indiana
I'll add in my bits as well. No, the HMMWVs do not come with an electric block heater, oil pan heater, or radiator heater of any sort by spec. It's possible that one may have been added as a special requisition (or by private owner if you're not buying from GovPlanet), but don't count on this being there. They are equipped with a glow plug system that can get the engine started in most climate conditions. The military specification for extreme cold starting would involve the use of a specially-installed auxiliary heater kit that is fired up before starting the engine, allowing it to heat the engine and the cab before starting. These are very expensive and rather hard to come by unless you're just plain lucky, or decide to shop for your surplus HMMWV out of Alaska...

All that said, you can cheaply add heaters that plug into standard 120V AC at home. You can purchase a block heater for a standard civilian 6.2L/6.5L diesel engine, which installs by removing a freeze plug and then bolting the heater plug into place. Additionally [or in lieu of] the block heater plug, you can purchase stick-on pan heaters, which can be place on the transmission oil pan and engine oil pan. Each of these items is about $20-45, depending on who makes it, where you buy it, and the specific model you buy.

Next...the HMMWV can only be "instant jump-started" by another military vehicle operating at 24V. You'll do this with a heavy gauge cable known as a "slave cable" in military jargon, which plugs into the port on the front of the passenger seat base. Unfortunately due to the difference in voltages, there's no easy way to jump start your HMMWV off of a 12V vehicle, but it can be done. The key to this is understanding that the HMMWV uses two 12V batteries wired in series to create the necessary 24V for the system. The best option will be as others stated: charge one battery at a time and be as patient as you can be. Your backup if you only have one vehicle will be to try to identify what is the weakest battery...it may be possible that if you connect to only one of the batteries in the pair that it will be enough additional current available to help the HMMWV crank and start (I have done this successfully). If both batteries are evenly cooked...bring two vehicles (or two vehicle batteries) and two sets of jumper cables. Connect one vehicle/battery to each battery in your HMMWV and use that as your jump start. Be careful on all of these to observe the polarity and cable position in your HMMWV so that you do not accidentally connect both HMMWV batteries to any single battery or vehicle at the same time...the 24V from your HMMWV will likely damage any 12V vehicle if you make this mistake.

Last item: The best way to have reliable 12V available for accessories is to install a step-down converter to take the 24V output to 12V. This will ensure that the batteries discharge evenly and give you the longest, most reliable performance from your batteries. Another option is to use a load balancer (very expensive) and choose to tap off of a single 12V battery in the pair. With that, you'll have 12V available, plus the load balancer will monitor the batteries and ensure that any imbalance is correct via it's charging/discharging system for each battery. The compromise method, which is the method that the military had chosen, is to have a dual-voltage alternator. The main 24V system keeps the battery pair charged up, but there's a second output at 12V on the alternator's regulator that is installed to a single 12V battery in the pair. You will simply tap-off power from that same battery for your 12V accessories and that alternator will provide extra charge to that one battery to make up for the extra load demand.
 

BLK HMMWV

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I'm thinking you need to find a nice Civilian H1 version.
It's a 12 volt system so anyone can instantly jump start you in your group.
And more normal electronic accessories you may want to use will be easier to power up.
It will meet your first post requirements of being different.
Parts are more easily cross referenced and sourced.
More places can service it
 

TOBASH

Father, Surgeon, Cantankerous Grouch
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How do you start one of the older diesels in extreme cold?

There has to be some way to jump start with a single car.

Advise more on the converter please?
1) You live in West Virginia, so what do you consider to be extreme cold. I spend 14 years in the Canadian Prairies so extreme cold means minus 40 degrees C/F. Block heaters are easy to purchase and install as the engines are GM sourced.

2) I am upgrading my HMMWV to the newer style dual voltage alternator that supplies 12V and 24 Volt. Also, you can purchase 24 Volt portable jump starters and 24Volt battery chargers with jump-start option. The upgrade will cost around $1000.oo.

3) I am not a fan of power inverters, as they can blow out. Others may disagree. a 24 - 12 Volt power inverter is something you can purchase at Diesel truck service stations and on Fleabay and such.

4) I agree with BLK... If you want creature comforts and 12Volts buy a civilian model and don't waste your time. These vehicles are big and loud and noisy and fun, but they are NOT civilian H1's.
 

Action

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I just went out and verified that both of my blocks do have heaters in them. One is a 1996 GM block. The other is a 2007 GEP. The heaters are the middle plug on the driver side. Just above where the oil dipstick enters the pan.
 

lowell66dart

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The stick on pan heaters can be had at any of the places that sell tractor parts. Very common to use these on tractors.

IF you find yourself with low batteries lets be honest. There ain't gonna be another Humvee that will pull up to help. Then you need the stupid expensive slave cable. So the safest thing to do is take it slow. Disconnect the batteries in the Humvee. Now you charge one at a time with the jumper vehicle safely. This method will not make a bad day worse.
 

Action

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don't shut the engine off when you stop for lunch.
or carry a couple spare batteries on off roading trips. My first Humvee came with two smaller batteries I used to start it and get off the trailer.
 

Keith_J

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I jump charged a M35 Deuce with my 12 volt car. It can be done but only with discharged batteries. If the batteries are defective, you won't do it.

Now if you have two vehicles and two jumper cables, you can hook each battery to each vehicle, just make sure all three vehicles are not touching!! But chances are slim you will get enough current through this setup.

Current flows easiest through short and fat jumper cables. Nothing beats a set of 25 foot NATO cables for jump starting 24 volt military equipment.
 

Action

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Lets say you are out in thr middle of nowhere and your humvee wont start. Why wont it? Is the alternator dead? Or did you run your 12v stuff too long? You wont make it very far if the alternator is toast. You need a tow....
 

Keith_J

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Batteries fail far sooner than alternators. My general rule of thumb is replace batteries every 4 years and you won't be stranded. Alternators last 100k miles, your mileage may vary. This is why jump starting is still important.
 

ken

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My GEP 6.5 also came with a block heater. In the middle freeze plug on the drivers side.
 

snowtrac nome

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western alaska
the hmmwv will start reliably down to - 20 with good batterys and glow plugs. just look at my location This is how I know. if you are driving daily a block heater is a good thing more important is heating the atf. The 3l80 is just a turbo 400 with out park, the weak spot of the 400 is early front pump failures when started in the cold. To jump start with out a 24 volt system will require 2 vehicles and 2 sets of jumper cables.
 
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