I went for a drive yesterday in the Vette. About a 30 mile drive with speeds averaging between 35-50 mph. Before the trip, the battery tender was showing a solid green light, so it was in "float" mode. After the drive, I reconnected the tender and it charged for a while, then went to flashing green (80% or higher charge) and then to solid green "float" mode again, after a few hours. Is this normal? I am wondering if I have a battery problem, since I thought that the battery wouldn't discharge when driving. I bought the battery tender due to the battery going dead a few weeks ago, but the battery was fully recharged. Do you think what I'm experiencing is normal or do you think I've got a battery that is going bad?

 

Sounds normal to me. A car's alternator does not return a battery to 100% from what I have read on numerous sites by charger manufacturers and university professors discussing battery technology. The BT takes it to 100% and then does what it needs to ensure it stays there without overcharging.

 

your normal! what you describe is exactly how it should work. remember that it takes several minutes and miles at over 1500 rpm to get the battery re-charged from starting the engine, etc. I have always found some slight discharge on any battery I run for a while then hook back up to my battery tenders - motorcycle, generators, and yes, automobiles.

 

With my car after a ride (starting with a charged battery) it takes only a few minutes to show solid green when I hook up my tender...

Disclaimer: I have a Schumacher tender and drive a Z06! It takes about a minute to exit the shut down car and hook up the tender in the trunk that means the inside lights are on for a little while. Normally solid green in fewer than 5 minuets!

 

Thanks everyone for the quick response. Nice to know that what I'm experiencing is "normal".

 

another one who thinks a battery will charge in 30 mins

 

... also have a Schumacher on my regular 06 and that's exactly how it operates. Been that way for the past 3 years.....

 

"Originally Posted by IDSRVIT
I hooked up the battery tender directly to the battery but I've noticed that once the battery is charged 100% and then I drive the vette (distance doesn't seem to matter) and when I plug the battery tender back in it charges (red light stays solid) for 2-3 hours and then it hits the 80% charge stage (solid red / green flashing) for about 6-8 hours before it finally shows charged (solid green). Thought it was strange at first and possibly the battery tender itself so I took the one off my wife's '66 Mustang and the same thing occured."



Your battery wasn't discharged and really didn't need the length of charging it was getting when you plugged in the tender plus when you got home. It's just how the tender plus operates. If you don't like that you need to purchase a tender junior model which is about half the price of the plus.

I wrote this reply to the question above which is like yours:

You have noticed the diff between the original battery tender (non plus model) and battery tender junior compared to the battery tender plus.

The tender plus replaced the original tender which is not made any more.

The tender plus was brought out to be compatible with the AGM (absorbed glass matte) battery. Agm batteries require a longer recharge time as compared to regular flooded batteries like the car came with.

The tender plus has a modified absorption mode and timer algorithm added for the AGM. This means that after a flooded battery reaches 14.4 volts (where the original and JR model would go to green light float mode taking from 5 min to maybe an hour to get there) the plus model continues to charge at 14.4 volts with the green light flashing till the current drops below .1 amps or the timer times out in 6 to 8 hours or if the voltage never gets to 14.4 it times out at 72 hours.. The flooded battery does not need these extra hours of charging but since the plus must do the AGM's you get it anyway.

This is why I use the JR model. Its only .75a charge rate vs the 1.25a of the plus but it has no absorption mode and it does not give that 6 to 8 hours of unnecessary charging on my flooded lead acid battery.

 

Totally normal. The Battery Tender is not meant to charge the battery in seconds.

 

wbear

I just started using the Battery Tender Plus.. I know it is normal for it to spend the 6-8 hours charging. I would have gotten the Tender jr. had I known about the info you have posted.. Anyhoo.. I found out something by accident tonight.. After placing the Battery Tender on the Vette tonight and the DIC showing 14.4 volts and the Tender going through the full charge routine I started the Vette for a second.. When I looked at the Tender it now indicated it was in the trickle mode.. ya know.. solid green light. For whatever reason that may be a way to by-pass the AGM mode.. Whatcha think?

 

That is a good question. It may have been coincidence. Remember that the tender is not a booster and was never intended to be hooked to the battery when starting the engine so I probably wouldn't do that. Also putting a load on the tender during its charging cycles may cause voltage changes which could alter the timing of the cycles. When you open the door and cause the courtesy lights to come on or turn on the ign to read the voltage on the dic you are causing a load on the battery. If you want to accurately measure the charging voltage at various stages in the cycle I would use a volt meter at the battery instead of the dic.

The tender plus may not always stick to the 6-8 hours. The resting voltage of the battery when you hook it up and the amps vs volts when charging may sometimes alter the advertised cycles.

 

In addition to all of the above (with which I agree), remember that what the car thinks is 100% may be different from what the battery tender thinks is 100%. There can be, as used to say in the computer business, 'subtle definitional disagreements'.

Lead acid batteries give their best life when the charge is maintained over a narrow range near fully charged. Over charging, which should not occur with a battery tender, is counter-productive in keeping a battery from deterioration.

 

wbear

Thanks for this info.. I will not start the car with the tender connected.
I will let it do its thing. As long as the battery starts the car when i need it to.. I will be happy with my purchase of the Tender..

 

Can I ask why you guys are using the tenders? Are they really needed?

 

Many of us do not use our cars in the winter in the NE. We use tenders to keep our battery from dying when storing a car for multiple weeks without driving them. I personally may go 2-3 weeks without using my vette especially when I was flying all over the world in my last job. Keeping a tender on the battery assures than when we want to drive the car the battery is not dead.

 

I use the tender to keep the battery fresh for those times that it sits in the garage for weeks at a time. The older the battery gets the odds of a let down when you push that start button are greater the longer the vette sits idle.. I read somewhere.. It can take up to a half hour of driving to re-charge the battery that starting the car depletes. Any one else care to amplify?