Just spent $800 on new alternator when my 2008 Odyssey broke down while on Va-ca in Utah. Battery charging warning light went on, slight electrical burn smell, battery drained. No power, car went into limp mode. Had it towed to nearby mechanic. Three days waiting for part.Replaced alternator and told me everything was cool. Only made it 50 miles after I picked it up. Same problem traveling through Mountain pass 6% grade with my wife and kids aboard, aarrrg!!. Had it towed again, anyone have any ideas?..only 5 days to make it 1500 miles back to work…
Did they replace the battery? How old is it?
I’m of little or no use on this one due to so many unknowns and the fact that you’re on the road with no tools or expertise.
There’s also the possibility that both the first and second alternator replacements were the results of a bad diagnosis. I have no idea as to how the diagnosis was arrived at.
How old is that battery? The point here being that a bad battery can take out alternators; IF those alternators were genuinely bad. I would hope that during any testing the actual alternator itself was tested to verify the failure as there are components that prevent a good alternator from charging.
My personal opinion is that a battery should always be tested during any electrical diagnosis; or crisis in your case.
Sincere sympathies for the predicament you’re in. Maybe someone else can weigh in on this. I could weigh in with a lot of things but it starts to become an overload; pun not intended.
He told me battery was ok, 2008 Odyssey. Sorry, new to car talk. Had it on radio while this was going on…
Any idea how old the battery is?
Yup. Now that you’re home again, take it to your own mechanic and let him diagnose the cause. Unfortunately, having a repair done while on a trip often results in continuing problems. There are a lot of shops out there who prey on… or perhaps I should say don’t have the usual intergrity towards… travelers.
Wish I was home, I am still in Utah held up in zero star hotel, 1st mechanic said battery is ok, it’s a few years old…waiting for 2nd mechanics opinion. Can bad battery spoil new alternator?
Yes. Alternators aren’t really designed to charge a battery up from nothing or near nothing. Doing so puts too much strain on them and can kill them, especially if the battery has a dead cell.
Sorry, I thought you were home.
Hopefully the new shop can properly diagnose the cause. It really needs to be done hands-on.
I know of no way a bad battery can damage an alternator.
I had something similar happen to me a coupe decades ago. I bought three or four alternators before a mechanic finally figured out it was a cable that connected to the alternator that was faulty, and would only act up when it got hot.
What you need is a competent automotive diagnostician, not someone whose troubleshooting skills amount to connecting a computer to your car and reading the codes. Try to find a mechanic who wears a white coat. 
Find another mechanic in the middle of nowhere?
…or a towing service that will take you and your vehicle to a competent automotive diagnostician.
Do you have the ability to find and check the fuse links in the underhood fuse box? There is a link (similar to a fuse) shown in the charging circuit that is rated at 120 amps. That’s a ton of current with current meaning heat.
It’s referred to a Fuse 22 if I remember correctly. You might eyeball that for any signs of obvious burning. A poor connection which can come and go due to burning can cause failure of the alt. to charge the battery or eventually it may fry the alternator.
Just curioius, but what part of Utah are you in? I know someone who knows someone out there who is not a mechanic but who is mechanically astute. This would be in far northern Utah.
Thanks, I am in Green river, I will bring up your ideas with mechanic who I am going to see shortly…
I would want to be at a dealership if I were on the road with a problem.
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None in the area, it seems.
Honda dealer 100 miles away in Grand Junction Colorado, tow would not go
there…Will stop by there when and if we get underway…
People are asking how old the battery is. We haven’t found out, yet.
If it’s the original or more than a few years old…
I’d have been considering hitching a ride, buying a battery and some cheap tools or jumper cables and catching a ride back.
It may even be cheaper than towing, unless insurance covers towing.
With the new battery installed (or “jumpered” in there), running without HVAC fan, radio, etcetera, the car would probably have another 50 or 100 mile range.
However, not everybody would do what I’d do…
CSA
2 years old…1st shop said it was ok…
This is what happens when a mechanic is too lazy to recharge the battery when replacing the alternator. The draw from a discharged battery can overheat the alternator especially when the vehicle demand is high because of air conditioner use. The newer the battery the greater the draw can be but the age of the battery is really not the issue.