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Power Loss When Shutting Engine Off

I have a 2004 Honda Odyssey with 46K miles on it and a battery that is less than a year old.



After driving the vehicle for at least 10 minutes, I shut off the engine. Sometimes, the power is completely drained; I cannot use the power locks, clocks is blank, lights are off. Sometimes, the power is very low; the clock displays the time, but is dim.



Anyone care to take a crack at diagnosing this?

Check for tightness of all major electrical connections from the battery on back.
Also check and see what voltage the alternator is putting out when the engine is running. It should be between 13.8V and 14.6V or so. If it is less, then the battery is not getting charged. If it is more, then the battery is being damaged.
If those items check out as okay, then your battery probably has an internal defect.

Do you have to charge the battery? Does the car start when this happens?

First of all you need to check all the connections on the battery, make sure they are clean and tight. Make sure the ground cable on the engine block is clean and tight. If everything checks OK, then you need to have a complete electrical system check done, which means having the charging system checked and the battery tested.

Sorry, I should have mentioned that I do not have to charge the battery to get it to start up again.

If I wait from between 1 and 5 minutes, I get full power back. Also, it does not always happen. Just today, it occurred 2 out of 3 times that I started/stopped the vehicle.

I will check the things mentioned.

Thank you

Loose cables or bad ignition switch or relay.

look closely at the cables to and from the battery. is there any green corrosion aruond the end of the crimp on plugs, between the wire cover.

i would ensure the wires aren’t corroded from within.

and how many keys and stuff are hanging on the key ring? lots? sounds like a dumb question, but too much weight on the ignition switch can wear it out and cause problems like this.

Both battery terminals had green corrosion. I cleaned them both with instructions found on the Internet - with a battery terminal cleaner with a scrub brush. After cleaning both, the problem has not occurred since.

Thanks for the tips.