As soon as it started getting down into the 30's at night here in the Hill Country, my rig started to turn over slowly. Then late last Friday evening it wouldn't turn over, only clatter. Cleaned all battery terminals, jumped it and it ran great the rest of the evening. Came home, hooked up battery charger and left it overnight. Next morning, no problem starting.

Over the weekend, recleaned terminal and checked fluid...none were low. Hooked up battery charger to each battery individually...and both eventually made it down to the 1-1.5 amp charge range. Ran all weekend long without a problem, but I noticed the voltmeter seemed to be riding a little closer to the 18 than usual, say in the 15-16v range.

Parked the pickup around 4:30pm Sunday, running and starting fine. Today at about 2pm, I went to run an errand...open door, interior lights blinking. Definitely no start. So much for making it to the UPS store on time. Pulled all battery cables cleaned again. I placed the battery charge first on the passenger side battery which started charging at the 5-6amp range, then within 30min or so, fell down to the 2amp range. Hooked up to driver side battery, also started at the 5-6amp range. After about 6 hours, it was down to the 1amp charge range. I've now moved the charger back to the passenger side, which is currently at 2amp charge and will leave it overnight.

Observation: both batteries are measuring in the 18+ volt range individually on a handheld digital voltmeter. Is this possible?

I went to Autozone and purchased a hygrometer to test each cell. Each battery has 1 cell that is 50%, at least one that is 100% while most were showing 75%.

While all was charging, I also discconnected, cleaned and reconnected the both ground cable connections and the connection to the starter.

I'm now confused. Should my batteries be at 18+ volts? Am I missing something?

 

18v on the batteries doesn't sound good. when I use to service batteries during a college job, the batteries should rest in the 12V range with the vehicle off. and you should have 13.5-14.5V (generally) with the vehicle charging the batteries while the engine is running. If you are at 18V something in your charging system is jacked. You are overcharging your batteries and killing them if I had to take a guess. Use your volt meter and check voltage at the terminals with the truck running. should be 13.5-14.5V. Haven't dug into my alternator but I'm pretty sure most if not all newer vehicles have the voltage regulator built into the alternator, so if the alt or volt reg is dead, you would probably just replace the alternator assembly all at once. Last time I saw a seperate regulator was on my 68 stang. Someone else may back me up or tell me I have no clue.
my $.02
Chad

 

Thanx for the info Chad. I appreciate it.

'68 'stang...I had one as well. Wish I had never sold it.

"Mustangs...their tough". Best part Machio ever played.

 

The voltage regulator is built into the alternator. With the condition that you described, it is over charging the batteries. I hate to be the berer of bad news but you need to replace the alt and the batteries.

 

Agree 100%.
The batteries may have been good a short while ago, but now they are fried from the alternator overcharging them.

 

Thanx for your feedback Jim and Dan. Alternator is off and going back to Autozone this morning. Purchased June '07 and has a limited Lifetime Warranty...so it should be a replacement issue. I wonder if they will do anything for me on the batteries, since it was the alternator that has fried the batteries.

 

probably not, most warranties nowadays do not cover equipment connected. but if you are loud enough to the right person, you may get something out of it. I'm no big fan of autozone, I don't buy anything from them but the basics like fluids and consumables. Any parts or seals come from other places. My exp has been o'reilly's is OK, but if I need it now and need it right, dig down in the pocket book and go to napa if they are open (lousy business hours). Your mileage may vary.

 

It depends on the management at Auto Zone. There are 2 in my area and one of them the manager is very helpful and wants the customers to be happy, the other one forget it. He is so miserable that I swear he hates himself. All you can do is ask and be insistant. Maybe they won't give you free batteries but maybe they'll knock something off of them for you.

Good Luck and let us know how you make out.

 

crosbo, that reminds me, what are the warranties on the batteries themselves. If you can't get new one's for free, pro-rating is better than a swift kick to the "you know what".

 

Took the alternator to AZ and it tested okay. I questioned how my batteries could both be at 18+ volts and the guy quickly offered to replace the alternator. The replacement will be here tomorrow.

I'm going to reinstall the current unit and test output voltage tonight. We'll see.

 

start the truck, yank the batteries off, and measure. it may be somewhat erratic, but at that point it's all alternator. may need to tell the dude at AZ to learn how to operate the machine. They have testing equipment for testing on the vehicle but it's easy enough to do with a DMM and accomplish most of the same functionality.

 

I wouldn't ever do that on an electronically controlled vehicle.
Otherwise you might end up buying a very expensive engine control unit.
Those batteries are there to buffer the alternator output.

 

I agree with Dan.. don't disconnect the batteries while running.. !

 

it will also burn up the alternator, i know b\c we replace one on are firetruck every 2 years at $1200, b\c someone shuts off the master switch before shutting off the eng. yes very pricey! you think they would learn but they don't!!

 

never thought the ecm would fry from just the alternator output. I can kinda see it though. Shop I use to work at fried an ECM on a Lexus cause it didn't like the memory keeper plugged into the cigarette lighter. I'll take your word on, use to work on the older cars. Guess I haven't pulled that trick in a while.

Chad