Tugboat 996

The weather here has been warm for a few weeks and the salt has been washed off of the roads. My GT3 has been on a battery tender for a few months and the gauge on the tender shows that the battery is fully charged. So, I have taken the car out for a 30 minute spin and when I plug it back into the tender it shows that it is drained, but charges back up in an hour. I am assuming that it just needs a new battery. Agree?

johnsopa

Depending on the amp rating of your charger it may be ok.

Use noco 1a through 5a chargers and they usually take a few minutes to 30 mins to go back to fully green.

If you open the door while the cars are on a tender the charger goes all the way down to the lowest state then slowly goes back up.

I think the best way to diagnose battery health is to have a battery place hook up one of the testers

maybe try this too. After getting back from a drive, let the car sit for awhile then turn on the ignition to see what the voltage shows on the display. Mine usually show 12.2-12.4V before I crank. If you’re at 12v or below before cranking then you probably need a new battery.

Maverick787

Very Normal assume it’s a CTEK, my McLaren 2016 675LT was on the original battery when I sold in 2022 and it did the same. My Speedster does the same on the Porsche charger since I bought it home new in 2020 and the battery is fine.

Tugboat 996

Thanks...it is a Porsche brand charger. It maintains the battery just fine and there are no signs that anything is wrong. Only when I come back from a drive, it shows that the battery is low.

Maverick787

‘Yes, I have the same one ……I believe it’s made by CTEX and Porsche slapped a logo on it. I unplugged it for 10 seconds, and it went to level once I plugged it back in and cycled back to full in seconds.

johnsopa

I suggest switching to NOCO chargers. They have profiles for regular lead acid batteries, AGM (which most of us have I think) and lithium batteries. We used to have CTEK for everything but I’ve migrated to NOCO for motorcycles, cars, tractors etc. the only thing I prefer about CTEK was the connector which is easier to plug in.

Antigravity

No,do not assume anything is wrong with your battery or charge yet. When you first put maintainers/chargers they will usually go through a very short test of the battery to see the voltage and it’s probably just going through its motions and then realizing it’s fully charged after it put some energy into the battery. With the GT3 and other Porsches, if the battery is low, it will definitely throw flags because they have rear wheel steering and electric power steering so if the voltage is low on the battery they throw flags immediately so that is when you will know if your batteries actually low as far as the car system seeing a battery that is faulty, has not been charged, or is not been holding a charge well

Tugboat 996

Thanks everyone. I tried it out yesterday and the same thing happened. When I brought the car back and plugged it in it was on the lowest reading and took 30 minutes to get back to the highest,, No issues while driving.

racer959

I have my battery tender for 10 years and it does exactly the same thing. Its normal.