 Posted 4/13/2010 10:36:36 AM
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| Our department had battery problems with our first Tahoe, a 2007 PP model, where we were replacing batteries every 15 to 20 thousand miles. We were unsure what the draw down was being caused by but eventually we added a second battery with a Kussmaul Battery Isolator, Model #091-139-2-12. We routed all emergency equipment to the second battery but now we are only averaging about 12,000 miles before the second battery goes dead. We now have a second PP Tahoe, a 2009 model and we have already replaced the battery twice in it. It does not have the second battery yet and we need help diagnosing the problem. With all our equipment running we are probably drawing around 125 to 130 amps. If we turn off the emergency equipment and just run the computer, camera and radio we are probably drawing around 90 amps. Has anyone else had problems with the alternator output? All of our vehicles have the same equipment and we have not had any problems with the Crown Vic or the Charger batteries.
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Posted 4/13/2010 10:41:15 AM
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| What battery are you using? Also, What is your draw with the engine off and your radio, computer and video running. I may have an answer as I fought battery issues with ours.
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Posted 4/13/2010 12:44:05 PM
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| I misspoke about the 2009 model, the factory battery was just recently replaced at approximately 30,000 miles. We use Energizer batteries as a replacement and they have 700 CCA. The 2007 model had multiple factory (AC Delco) batteries fail before we switched to the Energizer. We have tried several different wiring options and in the 2007 model we have all the emergency equipment "key hot" except the computer. The video camera system is programmed to shut down after the engine has been off 30 minutes. In the 2009 model everything stays powered with the key off. We run 12 hour shifts and when officers get out of the vehicle at the end of the shift they power all the equipment down. We have the occassional incident where equipment is left on and a simple jump start solves the problem, but that is not what is happening here. One last note, while watching the volt meter on the 2009 model it appears while idling to only be putting out between 9 and 10 volts. If emergency equipment is turned on the idle boost takes over and the charge goes up to about 14 volts. Shouldn't it run around 12-14 volts all the time?
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Posted 4/13/2010 1:12:07 PM
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| We did have issues with our Delco batteries in that series on my 07' and had to replace four battereis before we got a good one. You should be able to verify that with a Delco rep. but you may have to drag it out of him as they do not volunteer that information. We did recieve warranty credit for the sub-par batteries. As far as your charging issue, 9-10 volts is too low. Check this with a good battery as a poor battery will confuse the ECM and it will misregulate the alternator. Also, check for bad conections in your primary electrical system as well as your installed emergency equipment. You didn't mention what your electrical draw was with your gear on and your engine off. Any idea? This needs to be checked right after turning the engine off and then monitoring for about 10 minutes so you can monitor the sequential shut down of vehicle systems by the ECM/BCM.
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Posted 4/13/2010 1:26:42 PM
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| I'll have to check on the battery draw with the engine off and I'll let you know. Regarding your 4 bad batteries, were they detected immediately or did they last a couple of months before having to be replaced? I'll be replacing the battery in the 2009 again and I'll watch the volt meter with a fresh battery to make sure it is charging properly. I have checked all the fleet TSB's and I cannot find anything about the alternator but that is the only thing in common with the two vehicles. When you consider that the 2007 has all the emergency equipment running off the second battery and now it only lasts maybe two months, it appears that the draw is more than the alternator output and it eventually kills the battery.
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Posted 4/13/2010 1:46:01 PM
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| Each of the four batteries went bad within 2-3 months.
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Posted 4/16/2010 2:02:48 PM
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| WE SWITCH TO ODDYSEY BATTERYS IN ARE 2008 TAHOE THE COST IS MORE BUT IT IS FOUR YEAR FULL REPLACEMENT WE DO GET ALTERNATOR NOISE ON ARE KENWOOD TWO WAY RADIO
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Posted 4/29/2010 9:32:02 PM
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stlcpk (4/13/2010)
Our department had battery problems with our first Tahoe, a 2007 PP model, where we were replacing batteries every 15 to 20 thousand miles. We were unsure what the draw down was being caused by but eventually we added a second battery with a Kussmaul Battery Isolator, Model #091-139-2-12. We routed all emergency equipment to the second battery but now we are only averaging about 12,000 miles before the second battery goes dead. We now have a second PP Tahoe, a 2009 model and we have already replaced the battery twice in it. It does not have the second battery yet and we need help diagnosing the problem. With all our equipment running we are probably drawing around 125 to 130 amps. If we turn off the emergency equipment and just run the computer, camera and radio we are probably drawing around 90 amps. Has anyone else had problems with the alternator output? All of our vehicles have the same equipment and we have not had any problems with the Crown Vic or the Charger batteries. A couple of things...... Are you replacing batteries in pairs? If you have one that is marginal and put a new battery with it, you will wreak havoc on your electrical system, i.e. alternator and regulator. Are your batteries both lead acid? Or are they spiral cell batteries? Have you checked the output voltage with a DMM as opposed to using the gauge on the dash, the factory gauge's a hit and miss for accuracy. I would recommend a Fluke DMM, and then let us know what the output is @ idle, @ idle with a load, @ speed 2000-2500 RPM's both with and without a load. If you have a continual load of 90 amps on your vehicle every day all the time, you have some other issues, the vehicle may use 25-35 amps to run. Are you guys using toaster ovens during your shift, because that is a lot of current to be running on a continual basis. After your basic tests in the various conditions specified above, we can determine a little better what's going on. And just an FYI, most vehicle alternators are not designed to charge two batteries, especially if they have been run dead. Every time you jump one that is dead, you warp the plates and start the sulfation process, i.e, less battery capacity. You may also want to check the state of health for your batteries since they seem to go dead after a short period of time. And lastly, what part of the country are you in, weather (temperature) will be a factor in battery capacity as well. Sorry to be so windy, I have had a touch of experience with people running batteries dead.
Do you want it right.... or right now.
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