HMMWV - Battery Issues


New member
Dallas, TX
I recently acquired a 1989 HMMWV M1038 from an individual. The batteries that were in the vehicle were completely dead so I took them to O'Reilly Auto Parts to swap them out with a new set. The vehicle started up and ran fine with no apparent electrical issues for a few days but then it quit starting up so I opened up the battery compartment and realized one of the negative terminals that was connected to the battery cable had severely melted. I removed the new batteries and took them back to O'Reilly where they replaced them with another new set. Then the same thing happened, the vehicle ran well for a few days and then quit working and to no surprise the same battery terminal had melted again. Any ideas what could be causing this? I have included a few photos for reference. I am a new humvee owner so still working on reading through all of the manuals and such so any guidance would be greatly appreciated!

Thank you,


Well-known member
Last time I saw something like that it was a bad connection at the terminal. All the amperage was trying to go through one small spot, causing it to melt.
It doesn't appear to be the battery's fault since you've replaced them a few times, I would try a different end for the cable.

Looking at the pictures, the clamp doesn't appear to be making good contact with the battery, the melted one looks like there is air space between the clamp and the terminal post. Either need to replace that cable end clamp, or use a cutter to make it properly round. Replacing is probably the better option here, then make sure there is no gaps between clamp and post.
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Well-known member
Steel Soldiers Supporter
San Jose, Ca
The negative and positive battery terminal clamps are different sizes and plenty of people don't realize that. Putting the wrong clamp on the wrong terminal leads to poor contact and excessive draw thru a small area. This is what causes hot spots and burning. The positive terminal is the larger of the two. They're done that way so you won't reverse connect the terminals. That said, you can still hammer a negative clamp onto a positive terminal or clamp a positive clamp on a negative terminal. This is called Bubba mechanics.
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Well-known member
Steel Soldiers Supporter
Metairie/La (N'awlins)
You are very fortunate O"reilly warrantied the batteries. In my parts selling days, Any terminal damage was an automatic voided warranty with most major brands. Those look like the universal cheapie terminal ends. I would try getting HD ones from NAPA in Belden or a HD parts store. They will have solder type or mechanical with different ones for postive and negative. A battery brush might clean up the ends slightly. When everything is working right, use some spray battery sealer on these ends with exposed wiring.


Active member
Steel Soldiers Supporter
Papalote, TX
I concur with getting the correct connectors, I am new to the HMMWV but have been kicking around with 24V military trucks for about 40 years, 24V is NOTHING like a 12V system, on a 12V system you get a poor connection it will not start, with a 24V system it will act JUST like an acetylene torch, pretty impressive as long as you are not paying the bill.
MAINTENANCE is extremely important!!!!!!!!!!!!
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