Dealer's Plan to Address Battery Corrosion Just Doesn't Add Up

Dear Car Talk:

I have a 2017 Honda H-RV. The issue is that the positive battery terminal has "excessive corrosion." The dealer wants $1,500 to replace wiring and terminals.

I have cleaned the terminals but am waiting on the results. Is this a design flaw? I don't live right near the ocean. -- Mike

It sounds like your dealer has an "excessive boat payment" due, Mike.

I'm suspicious. The car is far too new to require any kind of wiring replacement. And if it does, you'd be justified in asking Honda to participate in the repair.

If you're getting corrosion on a battery terminal, it can be due to nothing more than time and the climate you live in. It could be a sign of a failing battery, if battery acid is escaping. Or, in rare cases, it can be due to an alternator that's overcharging, which is easier to accept than a dealer that's overcharging.

But none of those are $1,500 problems.

So, this is absolutely a case where you want a second opinion. Go to a mechanic you trust (search on if you don't have one) and ask him to look at it. Unless he sees an obvious problem, like a crack in the top of the battery casing, he should test the battery and charging system.

If the battery and alternator both test OK, then he should thoroughly clean the terminals for you. He can even hit them with some anti-corrosive spray. I used to hit my brother with that, but it didn't do much good.

Then drive the car for a month or two with clean terminals and check again for corrosion. If it's back, you can try replacing the battery. Most batteries last four to five years these days, so you might be due. But that's a $200 job. Even an alternator -- should you need one -- is a $500-$600 job. I honestly don't know how they're getting to $1,500.

If the charging system is fine and the car continues to operate well, but the corrosion keeps coming back, then you may just need to add an item to your seasonal chores, Mike: clean gutters, rake leaves, remove crust from battery terminals. Good luck.

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