akadeadeye Report post Posted August 16, 2011 I am sure I will get some good answers to this question. This concerns one of our toad vehicles. Yesterday morning I turned the key, barely a crank, then dead. Clock was dead, etc. Jumped the battery and took it to Auto Zone for testing. The vehicle is a 2008. Auto Zone man tested battery is good. 12.78v with no charge and 14.7 with the engine running. He ran further tests and said my starter was going out. Took it to dealer. They said starter was fine, alternator fine, battery bad. Confirmed 12.7v but had lost its cranking power. Rated for 615, but showed 360. I don't understand. How can the battery show good voltage but lose its cranking power? Don Share this post Link to post Share on other sites
wolfe10 Report post Posted August 16, 2011 Don, One of the best tests is the one you perform with a digital voltmeter with the battery installed in the coach (digital voltmeters start under $20 at Sears, Radio Shack, etc). With the battery fully charged, have someone use the key to start the coach. While cranking, check voltage at the battery and starter. If a big difference, check all connections for cleanliness and tightness. If voltage drops below 12.0 VDC at the battery while cranking with a fully charged battery, you have a bad battery, or starter. You will need an ammeter to determine which. Or a battery store who can load test your battery while applying the amp draw your starter should be drawing. If you have a battery boost/battery combine switch, use it and see if it makes a difference. Brett Share this post Link to post Share on other sites
Guest BillAdams Report post Posted August 16, 2011 You can also have the battery load tested. Frequently you will find that a battery can hold a full charge but as soon as a load is applied the battery will fail. This is just a more complex test than the one described by Brett and many battery resellers can perform this test. I usually just connect the voltage meter to my battery and check for good 12+ volts and then crank the engine. If you see the voltage fall sharply you have a bad battery. The increased voltage you are seeing with the engine running indicates that your alternator is good. What was going on in the hours before your dead battery? Just sitting? Being towed? Let the lights on? Sitting in the garage? Share this post Link to post Share on other sites
akadeadeye Report post Posted August 16, 2011 Bill, Fine one day, bad the next morning. I left nothing on. I did not do the voltage test to see if the voltage dropped while cranking but I ended up replacing the battery and all is fine now. Just a little disappointed that a 2008 battery on a Chevy Suburban is already dead. Don Share this post Link to post Share on other sites
Guest BillAdams Report post Posted August 16, 2011 Do not be surprised. That sounds about right for the cheap batteries used today by the auto companies. We like to replace our car battery with something from Wal-Mart which has a 3 year warranty. We recently took one in and they replaced it without question and we are now good for another 3 years (well, about 1.5 years by now). If the car won't start and the alternator is good it's my policy to replace the battery. It sounds like you did the right thing. Share this post Link to post Share on other sites
desertdeals69 Report post Posted August 17, 2011 Be sure to check battery voltage at the terminal of the battery, both positive and negative and not at the cable next to the battery. Share this post Link to post Share on other sites
rorr1821 Report post Posted August 17, 2011 I am sure I will get some good answers to this question. This concerns one of our toad vehicles. Yesterday morning I turned the key, barely a crank, then dead. Clock was dead, etc. Jumped the battery and took it to Auto Zone for testing. The vehicle is a 2008. Auto Zone man tested battery is good. 12.78v with no charge and 14.7 with the engine running. He ran further tests and said my starter was going out. Took it to dealer. They said starter was fine, alternator fine, battery bad. Confirmed 12.7v but had lost its cranking power. Rated for 615, but showed 360. I don't understand. How can the battery show good voltage but lose its cranking power? Don I had a similar situation on my Jeep which had a Auto Zone top rated battery. The battery was still under a full replacement warranty. When I went to crank the Jeep it would not turn over the engine. I disconnected the battery from the vehicle and put a charger on it for several hours. After it was charged I let it sit for a few hours to dissipate the surface charge and tested the volts which came to about 12.7 or 12.8 as I recall. I assumed I might have not turned something off so I cleaned the terminals and re-installed the battery, but it went dead again. So I went through the charge process again. However, this time I got out my hydrometer. The one I have reads the specific gravity. I checked each cell. I found one cell was very weak. Took the battery to Auto Zone and they load tested and it proved to be OK by their test. I told them it had a bad cell and to do a hydrometer test. The person said let me see receipt and then he gave me a new battery. I have had no more problems and this has been over year ago. My point is that one test is not necessarily conclusive when it comes to batteries. Ray Ray Share this post Link to post Share on other sites
HarveyWhite Report post Posted September 28, 2013 Battery's can get a loose plate if you jar it just right it will short and drain your battery. I had one on our toad like that-- one day fine next day no start. The dealer tested it and said all was OK. So the next stop was to buy a new battery replaced and have had no more problem. Share this post Link to post Share on other sites
