Batteries- new 8D30 on a 2005 International School Bus

This topic contains 5 replies and was last updated by patrick-slee 1 year ago
August 5th, 2011 1:18am


I have a 2005 International School Bus it use to have maintenance free batteries in it and never had any troubles with them. Now it has new 8D30

not maintenance free batteries in it that was put in a month ago and now they are already dead. The bus has been sitting not been driven. But the batteries are completly dead. Turns out the batteries were good, and the bus must have a draw somewhere. I looked around nothing was left on. Im not to sure the best way to find a draw, I disconected the negative terminals on both batteies, left the positive connected on both batteries, connected my test light to the bus Frame, and touched the test light to the negative terminal and it lite up strong. am i checking this correctly? Do you know a better way of checking for a draw, im stumped and cant seem to find where this draw is coming from, any advise is greatly appreciated.

August 5th, 2011 2:51am
You might check to see if the draw is coming from the alternator, and draining the battery. Disconnect the power wire off of alternator, and see if that stops the draw. other than that.. a heater or heater pump left on?
August 6th, 2011 1:02am
I'm with Brazeau on this, the first thing i'd be doing is disconnect the main charge wire from the alternator & see if that stops your problem.

There are a couple of ways to check for current draw, it depends on what equipment you have available to you.
August 7th, 2011 2:55pm
Your on the right track and brazeau is also.Obviously you have a test light avaliable to you so use that to track down your draw.What I do is the same as what your doing only I usually disconect the positive side and insert my test light in there in series.If it lights for a second and goes out then everything is o.k.-that brief lighting is from the altenator but it must go out.If the test light is still lit then you have a current draw.Now narrow down the circuit that has the draw by going to your fuse pannel and removing fuses till the test light goes out,whatever fuse that turns off the light is what circuit that has the draw.Also keep in mind that radios have a constant draw for the memory and clock but generally won't light a test light.Good luck.
August 28th, 2011 3:08am
I like to use a multimeter to diagnose parasitic current draw problems because then I know the magnitude of the current draw being measured. Inductive amp clamps work well also with no cables to disconnect. A multimeter will be inserted in series, either on the positive or negative side, just as you would with a test light. Start out with the multimeter set on the higher 10 amp setting and then move to the milliamp range if necessary. A 2005 bus is going to have an electronic engine and chassis so expect maybe 50-60 milliamp (0.05amp) from the ECMs for a normal current draw. Also, there may be a delay between the time you shut off the key and the time at which the ECM's power down fully. As suggested before, pull fuses until the current draw displayed on your multimeter disappears. To isolate the suspect circuit further, disconnect connectors on the suspect circuit until the current draw disappears. That will narrow down the problem to a specific component on a circuit.

I saw a bus problem once where the little light in the coin toll box next to the driver, up front, was staying on due to faulty wiring. Also, temperature controlled thermostats, such as that found on refrigerated cargo vans, can be tricky to troubleshoot because the parasitic current draw only occurs at night when it gets cold but disappears during the day when you're measuring the parasitic current draw. Glovebox lights are also common culprits.
November 4th, 2011 10:19pm
Had the same thing happen several years ago and I disconnected the negative battery cable and put a VOM in the circuit between the negative battery cable and the negative battery post. I then started to pull fuses or breakers until I saw that I no longer had a draw. This told me the circuit that was drawing down the battery. This will help you to narrow down where the problem is.

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