Battery Tender light vs Ammeter query
 

Battery Tender green light is on but ammeter shows alternator is charging full blast.

I Hadn't cranked Apatch up in a while so I decided to crank him up and run it for a while. Battery tender light on green. I ran elect fuel pump a little longer than I usually do and flooded carb. Wouldn't crank but engine turned over like it should. Green light still on though I had cranked it enough for it the red light on the BT to come on.

I left it for several hours, light still green when I tried again. Cranked right up but ammeter shows fully charging. I ran it "a pretty good while", long enough to where the ammeter should read "in the middle", neither charging or discharging. Light still green on Battery Tender.

I hope I am making myself clear here. Usually I crank it up and the light on the BT turns red and the ammeter shows it is charging just long enough to bring battery back up to full charge and and then drops back to the middle and the BT light shows green again.

I hooked up my other Battery Tender, No change.

I am still 6V positive ground.

Am I missing something here? I know I am getting old and partially "losing it", but not that much, I hope.

The battery is an Optima 6V Red Top. It has never given me any problems although it is getting some age on it.



All comments appreciated.

Re: Battery Tender light vs Ammeter query
 

Lawson. Your explanation is confusing to me. Are you leaving your battery charger (battery tender) connected to your truck battery while you are trying to crank or start the engine ? If so then you should not do that. Do you leave the battery charger still connected to the battery while your engine is running ? You should not do that either. The battery charger is for charging batteries only and not for testing charging systems on cars. If I have this wrong then I am sorry but please explain in more detail. Regards, Kevin.

Re: Battery Tender light vs Ammeter query
 

You can run an Optima too low and something happens it won't take a charge.
You have to connect it to a strong battery and charge it and it comes back to
life. I think that is the procedure. They also have a problem of the thin lead
plates under the terminal connection getting eaten away from acid fumes.
These thin connection can be eaten through but still touching. You can read
battery voltage but won't carry any amps. G.M.

Re: Battery Tender light vs Ammeter query
 

Kevin:

Hey, it's confusing to me too or I wouldn't be asking questions. LOL This is something that I've just noticed for the first time and it got me wondering.

Yes, I sometimes leave the BT connected when I crank it, and run it a while in place. Why should I not do that? I sometimes disconnect it and run it in place as well. It doesn't seem to hurt anything to leave it connected while cranking/running.

Just as a check, I will disconnect the BT and crank and run it and see if that makes any difference. I will report further after the test. No time to do that now.

Lawson

Re: Battery Tender light vs Ammeter query
 

Lawson, Your battery tender or charger has an output of maybe up to 10 amps or less depending on which model it is. Check the specifications of the one you have. When your starter motor is cranking your engine it is drawing anything from 150 to 250 amps out of the battery. If your tender is connected to the battery during this cranking cycle then also the starter is trying to draw power through the tender. The starter might be trying to draw say 80 amps through the tender which is way over its current capacity. Components inside the tender such as the rectifier or transformer were not designed to do that and damage may be the result. If your tender is still OK then you have been lucky. You should not do that. Regards, Kevin.

Re: Battery Tender light vs Ammeter query
 

Just to add to the above post. Some heavy duty battery chargers have sufficient current output of say around 200 amps for a brief time to be able to jump start a vehicle. These chargers are designed for that job and are made for that purpose. They cost a pretty penny as well. Regards, Kevin.

Re: Battery Tender light vs Ammeter query
 

I fried my Battery Tender that way, by leaving it hooked up while running the engine. Their customer service told me never to do that. Nevertheless, they are going to send me a new one because it was still under warranty. Best to unplug the Tender prior to starting the car.

Re: Battery Tender light vs Ammeter query
 

GM, The early optima batteries did have a problem with thin terminal connecting links to the plates but that was long ago and the fault has been rectified. That problem was also partly caused by having an optima on charge for longer than required and allowing it to gas for long periods. They are by far the best 6 volt battery available for old cars. Regards, Kevin.