battery load testing

LDB · Feb 1, 2006

How exactly are batteries load tested? I think at least one of my batteries is subpar because after several hours of either driving or running the APU I can only go about 4 hours with the refrigerator, the computer and maybe one sleeper light on before the low voltage alarm sounds and shuts down the sleeper. I realize these aren't deep cycle batteries but with 4 of those huge batteries in the box I expect more than that. Also, where do you go for load testing them? I'm thinking maybe I should wait till I'm home again and go back to the dealer I got the truck from but wanted opinions from those more mechanically inclined than I am (read everyone).

Leo Bricker, owner trucks 3034, 4958
OOIDA 677319
73's K5LDB
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greg334 · Feb 1, 2006

Leo
Batteries are load tested by loading the battery and watching the drop in voltage across the poles for a few seconds. There are a few new machines out there that go though a few tests and give back accurate results but I have only seen one machine in my travels. I forget the percentage that the drop has to be to deem it a bad battery; I think each type of battery has different requirements for the drop in voltage. When I tested gel cells, I loaded the battery with 10 ohms (100 watt resister) and if it dropped below 10 volts, it was tossed.

Hope this helps.

davekc · Feb 1, 2006

If it is to just test the battery, you can get a quick free test at autozone. It will only identify whether the battery is any good. Dealer can do the same thing but why wait if you don't have to. If your truck wasn't under warranty, you might get charged by a dealer.

If it requires more tests beyond the battery, then you need a volt/amp meter. This will show the output from the truck, generator, and what is drawing from the battery, and how much. You may have a short in something you are running or something grounded improperly.
These tests will identify the problem.

Davekc
owner
21 years
PantherII
EO moderator

ATeam · Feb 1, 2006

My first choice would be Wal-Mart because of the easy truck access. To test your batteries individually, you'll need to disconnect them from each other. A load test machine is a simple device found in most places that sell batteries. It would be a simple matter for a Wal-Mart mechanic to wheel it out to your truck and do the test. If you disconnect the batteries yourself and have them uncovered for the test, you can probably get it done for a quarter hour labor at Wal-Mart. Wear safety glasses. Goggles are better still. Batteries can blow up if sparks occur near them. Best to unhook the ground cables on the end away from the batteries to stop current flow.

Refer Hauler · Feb 1, 2006

One reason you may experience a quicker than thought "Low Voltage Alarm" is that maybe not all 4 batteries are connected to the accessory circut. My truck also has 4 but only 2 supply the "hotel" with the other two isolated via circuit board for engine compartment use. Check with your dealer the KW's may have this feature built in also.

LDB · Feb 1, 2006

I talked to my dealer today. They are going to talk to engineering and see what they can learn. I'm going to wait until I get back home and have them look at it. It will be a warranty item. I'm pretty sure all 4 batteries work together on everything because if you order the refrigerator you must also order the 4 battery option rather than the 3 that are standard. I may look into getting another battery box and a couple of those glass mat batteries to run the sleeper.

Leo Bricker, owner trucks 3034, 4958
OOIDA 677319
73's K5LDB
Highway Watch Participant, Truckerbuddy
EO Forum Moderator 1+ Years of Service
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ATeam · Feb 2, 2006

Do you have a generator/APU on the truck? If so, there is a device that will automatically start the generator if battery voltage gets too low. That would eliminate the need to install additional batteries and their associated weight, cost, and maintenance over time.

LDB · Feb 2, 2006

I have a Willis APU and I am EXTREMELY satisfied with it. If I can get the truck low voltage level adjusted downward to match the Willis starting point the monitor function will do that. A less desirable alternative would be to raise the level on the APU to a point just above the truck cutoff but that will run the APU more often and I'm trying for less not more. I'm going to do more research on the glass mat batteries as well. They seem to be decades ahead of anything else and I want to know more about what they offer.

Leo Bricker, owner trucks 3034, 4958
OOIDA 677319
73's K5LDB
Highway Watch Participant, Truckerbuddy
EO Forum Moderator 1+ Years of Service
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Support the entire Constitution, not just the parts you like.

Broompilot · Feb 4, 2006

In my last business my life depended on deep cell batteries, A team is correct or try an Electronics store. I use to have a battery tester unhook all battery connections put red on red and black etc... it will read the strenght do this after you run them down some. Very low cost tool.

Anyway back to the batteries, I had the option of batteries and choose the deep cell and have never had a problem until after three days and to jump them does not hurt them at all. You live in a warm climate next set you should consider the deep cell and will probably only need three and not four. An Expert no, but this has been my expierence so far.