Took my SVR in for its annual inspection and I forgot that as they access the OBD port I need to disconnect the battery afterwards to reset the modules and stop the power drain issue

I put the car on the CTEK trickle charger a couple of days afterwards. But when I came to start it today battery is totally flat even though it's still on the ctek

Has anyone measured the rate of power drain when the modules don't shut down properly? Is it possible that the rate of drain is faster than the rate of trickle charge? I've disconnected the battery from the car and put the battery alone on ctek so hopefully that will fix it...

I guess thinking about it, the power drain issue kills the battery in 1-2 days and it takes a day to fully trickle charge so it's prob pretty close. The ctek had a red error light on it so perhaps it tried to charge and couldn't get the battery level up so it stopped?

Any thoughts welcome. Hoping I haven't killed the battery (it's was down at 6V but does seem to be going up again...)

 

Some trickle chargers won't work unless the battery has a minimum voltage on it. I don't know about CTEK units but Battery Tenders won't charge if the voltage is too low.

 

I think CTEKs struggle with no-voltage starts, too.

 

When using a tender can you clip to posts underhood or in trunk to batt? Or will either work?

 

I don't have a permanent tender hooked up. I use a big CTEK unit with the terminals under the hood for winter storage. Been Doing this for three years without an issue.

 

So to hook to car is it red to red black to black? Or black to another groundiing point? And are our factory batteries lead acic or agm?

 

The under the hood terminals have one with a red cover. The other is a silver post that is a ground you connect the black lead from the charger to.

If you connect to the battery red to positive terminal, black to negative terminal on battery or to ground.

I believe the stock battery is an AGM type.

 

Yes - my stock is a H7A AGM battery with Jag logo on it

And yes - just black to black and red to red is fine. Or black to another grounding point if easier

I hooked the ctek red to red battery terminal clamp and black to a nearby body grounded screw. Fitted the ctek socket into the inside of the trunk so I just plug the connector into the socket and close the trunk when I'm leaving it for a few days or more
V easy to do

It also has a green, amber, red set of lights that gives a v rough approximation of how well charged the battery is

Battery charged back up to 12.8V on the ctek once battery was disconnected from the car. Started and ran fine this evening. So hopefully I saved the battery

But a warning that the trickle charger either can't keep up with that power drain when modules aren't shutting down properly. Or it thinks the battery is failing as it doesn't get to full charge and turns itself off. Either way trickle charger isn't enough to avoid the OBD issue - still need to disconnect and reconnect battery to reset the modules. For me that means each year after State inspection

 

Thanks guys! I didnt use one last winter but I plan on it this year.