PSA - Don't use a Battery Tender Jr. on your Z
 

Hello everyone. Just got off the phone with Deltran who makes the Battery Tender smart trickle chargers. These are the chargers I've seen recommended for people storing their car over the winter. I store my Z for about 3 months every winter and the last 2 years I have hooked up a Battery Tender Jr. to my battery. The first year after storage this way I went to start the car and it started very rough - like the battery barely had enough voltage. However I checked the battery later after driving it and it appeared fine so I just forgot about it.

Last year I again stored my Z with the Battery Tender Jr. connected. This time something odd happened. I store my car at a relative's house and asked him to check up on the tender every once in a while. He reported back that the Battery Tender Jr. was always flashing the green light. This indicates that the battery is >80% charged but not fully charged yet. All winter long it was flashing green and I didn't have access to the car so I didn't worry about it too much. When I went to pick up my Z in the spring, the battery was totally dead. Nothing. I had to jump charge it for a long time, probably about 30 minutes before it had enough charge to start up.

At this point I thought my battery was probably just old and nearing the end of its life (although that seems strange since it's only a 2009). I also tried searching the forums and google for anyone who had problems like this and I didn't come up with anything conclusive. Nor did I find any information from Deltran that said there would be an issue with a Battery Tender Jr. on a sports car. I had the battery tested after driving it for a while and sure enough the battery was fine and didn't need to be replaced, so I started to suspect the charger was at fault.

Fast forward to this winter and I just put my car into storage a couple weeks ago. The same thing is happening again. The charger is just blinking green again and never lights solid. I called up Deltran and told them the situation and they told me right away that the problem is that you can't use a Battery Tender Jr. on a sports car. They said cars like the Z have very high parasitic draw and this basically confuses the algorithm in the Tender Jr. and it can't keep up with all the electronics in the Z. They said I would need a Battery Tender Plus since it charges at a higher current. I had suspected as much, but until now I couldn't find any information confirming my suspicions.

TL;DR: Don't use a Battery Tender Jr. on your 370Z because it can't keep up with the high parasitic draw on the battery from the Z's electronics. It will make your battery die during winter storage and probably shorten the life of your battery over time. Spend the few extra dollars on the Tender Plus instead.

been using battery tender on my G for the last 7yrs, Z for the last 4yrs with no issue. :D

this one:

http://www.amazon.com/Battery-Tender...battery+tender

i would check your car for abnormal parasitic draw before blaiming it on the battery tender.

:iagree:

Or get the battery tested. If it's a 2009, and it's now 2013, that's a pretty good run from a battery. I never had a problem with my Battery Tender Jr. And it seems odd that the solution from the manufacturer is "The cheap one won't work. The expensive one will. You should buy the expensive one."

my G is 2004 and factory battery. :icon17: my G is less polluting than a f-king prius.

Wow. Probably climate related. I get three years out of a battery. It's like clockwork.

yah, im not in a super hot climate and dont drive the car in really hot weather anyway since i only motor them on weekend motrnings. :D i do add distilled water though when needed.

You're right. The heat will kill em!

There's nothing on my car drawing unnecessary power and the intelligent key battery is pulled as well so the car isn't communicating with the key. Car is stock and nothing is plugged into the adapter ports. There's really nothing it could be and the battery tested solid. I'm still going with the manufacturer on this one. Otherwise what would I even do? I'm not buying a new battery because there's nothing wrong with the current battery. I agree it sounds convenient for the manufacturer to recommend the more expensive model, but the Plus charges at twice the current so it makes perfect sense. She also told me how to troubleshoot the Tender Jr. to make sure it isn't defective (which I did, and it isn't) but she said that won't matter because the Tender Jr. wasn't designed for sports cars. If you guys don't want to listen to me that's fine, but I'm going on my third winter now and I'm sick of having a dead battery in the spring on a relatively new car. It may be 2013 now but I bought the car in fall 11 with only 4K miles. There's no way the battery should be dead this fast.

I bought the BT plus for my Harley's years ago (sold both a few yeras ago) and now use it between my vette, Z and lawn tractor over the winters. No problems ever. The BT junior has a charge rate of 0.75 AH vice 1.25 AH for the plus. It should keep any battery charged. Maybe the BT jr is faulty?

Then the BT Jr died. It's a bad unit if I had to guess.

have them send you a replacement battery tender jr and see. i'd unplug the battery from the car to do this test as well.

you shouldnt have to unplug the battery from the car though when using battery tender.

Long Term Parking
 

I would be more concerned about letting a 370Z sit for 3 months over battery issues.

:confused:

In places that snow, it's very common for people to put their sports cars away after snow starts falling and take them out again in spring. Did I misread your post somehow?

I had to replace my 2009 battery already too. I never used the charger but never checked the fluid level either, and it was low. Tons of heat on track days coupled without maintenance = new battery for me.