Hi all. My Mom gave me her old Lexis, she stopped driving a while back. When I picked up the car I had to jump it. There was also corrosion on the battery terminal. A couple of weeks later the car wouldn’t start. I tried cleaning the corrosion and charging it, but long story short I purchased a brand new 7 year battery. I’ve been driving it all over town both during the day and at night. Last night it wouldn’t start the car. There was enough power to power the inside lights but not crank the engine. My roadside assistance people jumped it with no problems.
You can take it to a store that sells batteries and pay them to clean and test it. It may very well be the corrosion is the problem. Heavy corrosion will allow enough juice to light the lights, blow the horn, etc., but won’t allow enough to turn the starter.
You can clean it yourself, but there are some dangers involved and you could do more harm than good. The shop can also load test the batt. and tell you if it needs replacement.
If the corrosion is bad enough, you may need new cables.
It certainly sounds like the alternator’s not charging the battery.
Most “Do It Yourself” auto parts shops can test alternators, usually for free, on the hopes that you’ll buy a replacement alternator from them.
Other possibilities are the battery cables aren’t carrying the juice - corrosion on battery terminals is common, but if it’s bad enough, it can get into the joint between the wire itself and the terminal clamp and block current flow.
A fairly remote, but still possible problem is the new battery is bad. Pretty unlikely, but I include it for the sake of completeness.
Happily, replacing alternators and battery cables is usually pretty easy - I’d do the work for a friend or neighbor for a six-pack or some similar pittance. If you need to take it to a mechanic, well, it won’t be quite so cheap.
ETA: before replacing anything, get the alternator and battery checked out. There’s no point in replacing parts that aren’t bad.
OK as has been mentioned, the corrosion can get inside the cables and cause a voltage drop (resistance) so the battery never gets fully charged.
The alternator might be on its way out.
The new battery could be bad.
A competent technician can check all of these items plus a couple more in about 20 minutes or so.
Sears auto centers actually do a very impressive comprehensive electrical system diagnosis. I’m not sure what they charge for it, I observed it while warrantying a battery.
I love optimists.