Do you think my Battery Tender has gone bad? Dead battery.....

[Zack1978]

Hi everyone,
I have a 2011 Nissan Titan that stays in the garage for the winter months. I purchased the Titan brand new in 2011 and I had to take it to the dealer in 2012 for a recall. While my truck was at the dealer they did their "complimentary" check and the battery must have failed so they replaced it under warranty.
At this time, the battery from 2012 is still my truck and it was fine until a few days ago. The truck has just shy of 22,000 miles on it, so it is in the garage much of the time and it is always on a Battery Tender. I assume that being on the Battery Tender is what allowed the battery to survive as long as it has.
A few days ago I went to start the truck.......
The Battery Tender was on the truck and indicated that the battery was fully charged. I went to start the truck after I removed the Battery Tender and the battery was basically dead and it did not have enough power to start the truck. I used my Halo jump pack and it fired right up. I drove the truck for a bit and it did charge and I was able to restart it once without the help of the jump pack.
So why did the Battery Tender indicate that it was fully charged when it clearly was almost dead? Why was the truck able to charge it ? Do you think that my Battery Tender has gone bad?
And YES, I know that I need to buy a new battery!


Thank you

 

[JavierH19]

The charger knows the voltage but not the capacity. A bad battery can still charge and stay charged so the battery tender can't be faulted but once a load it put on it the voltage will tank. Get a new battery and measure the voltage then put the tender on it and see if it goes into charging mode. If it does and finishes check the voltage to see if it's where the tender will charge to. If not it's likely bad.

 

[Zack1978]

The charger knows the voltage but not the capacity. A bad battery can still charge and stay charged so the battery tender can't be faulted but once a load it put on it the voltage will tank. Get a new battery and measure the voltage then put the tender on it and see if it goes into charging mode. If it does and finishes check the voltage to see if it's where the tender will charge to. If not it's likely bad.

This make sense. I guess at this point I will wait until the spring to buy a new battery.

 

[oil pan 4]

Probably just get another of the same type of battery and call it good. Make sure the battery tender voltage is good and didnt burn up the battery. Should be about 13.5v.

 

[JHZR2]

I’ve had a battery tender overcharge because something went wonky in the controls. It would sit in the high 15v range.

 

[Eddie Hudson]

Try measuring the voltage with a VOM after sitting overnight. You might have a good battery but bad connections.

 

[ripcord]

Before you go jumping to conclusions, I would first clean and tighten the battery terminals very well. I just had to do that with my daughter's car after it sat for a week. I first thought battery had a bad cell because the voltage on the dash said 8.9 volts, but a multi-meter across the post said 12.5v. I had to really scrape and clean the posts and cable end to get it to work right.

 

[f355spider]

I’ve had a battery tender overcharge because something went wonky in the controls. It would sit in the high 15v range.

I had the opposite. Years ago I bought a used SureCharge wall wart battery tender at a garage sale for a few dollars. Took it home, connected to a good condition battery and it's charging voltage was like 12.9vts. It never went higher...tossed it in the garbage. Saved the ring mounts and battery clamps

 

[dubber09]

Do I understand it correctly that the battery is about 13 years old?
My first guess would be bad battery.

 

[Arc]

This make sense. I guess at this point I will wait until the spring to buy a new battery.

I've never had a battery last that long. Maybe 5 years max.

 

[JHZR2]

I had the opposite. Years ago I bought a used SureCharge wall wart battery tender at a garage sale for a few dollars. Took it home, connected to a good condition battery and it's charging voltage was like 12.9vts. It never went higher...tossed it in the garbage. Saved the ring mounts and battery clamps

Your scenario I could almost live with. A permanent float charge might not get the battery to a true 100% sod, but it will prevent sulfation. That’s the main phenomena I’m working to prevent. We aren’t talking safety critical UPS where a few seconds of runtime could be the difference between systems running and crashing. An SLI battery intrinsically lives a hard life, and vehicles with highest off state loads do a lot of the damage as they take the batteries rapidly off of 100%. But if you can make it electrochemically unfavorable to create sulfate, that’s a decent situation.

Not saying your charger should have broken to that state though…

 

[RaymondP]

Time for a new battery. Christmas present to self/car? You have done well with your current one. At this time without replacing the battery you have a good chance of getting stranded. Well worth avoiding the associated hassle should this very likely event happen again. Gives you a chance to shop without being in a crisis. Good luck.

 

[Zack1978]

Time for a new battery. Christmas present to self/car? You have done well with your current one. At this time without replacing the battery you have a good chance of getting stranded. Well worth avoiding the associated hassle should this very likely event happen again. Gives you a chance to shop without being in a crisis. Good luck.

I know I need a new battery. The question is more about my Battery Tender, why did it indicate that the battery was fully charged when it fact it wasn't. And why did some run time on the truck charge the battery? Why didn't the tender charge it?

 

[Zack1978]

Do I understand it correctly that the battery is about 13 years old?
My first guess would be bad battery.

Yes, I know the battery is old and needs to be replaced. I am more interested in why the Battery Tender didn't keep it charged enough to start the truck when the tender indicated that it was fully charged. Why did the battery seemingly charge when the truck was running?

 

[dubber09]

I think the tender has logic built in that determines when battery is charged based on voltage. Battery voltage can get high enough to trick it showing fully charged but there is no capacity in the battery. Charging battery when in car and engine running has different logic that keeps charging to 'fill' battery. That's the best I can explain.
I know tenders/maintainers are popular since you don't need to disconnect battery to 'charge' it but I have no trust in them and never had one but a proper charger with manual modes selection per battery type and charging current. It does require disconnecting battery from car to prevent potential car electronics damage during charging thou.