Can you connect the trickle charger at the hot post in the engine bay instead of at the battery?

 

Yup, do it all the time. Works fine.

 

Sweet, thank you Bob.

I'm going to Sears tonight to pick one up. My new Porsche battery somehow discharged over the winter (disconnected) and I want to leave it charging for a week.

 

Afshin,

A cheap "trickle charger" can and will overcharge the battery if left on too long. A "battery maintainer" will not. The difference is that a trickle charger continues to charge the battery, while a maintainer automatically cuts off when the battery is charged.

Most new chargers will automatically cut off, so just be sure that you buy one that does so. Cheap ones may not...

 

Yes.

 

If it's completely discharged, you might want to put it on a bigger charger overnight and then after it's fully charged put it on a trickle charger. The trickle charger will probably not be able to completely charge up a dead battery.

Also, car batteries, unlike marine batteries, don't typically like to be completely discharged so once you've charged it back up check the battery voltage and cell to cell voltages because you may have lost a cell or two.

Also, if you can, check the water level before you start charging it. Make sure the water level in all the cells are filled up to the bottom lip and ONLY USE distilled water.

Good luck.

 

After reading Wally's post, I realized that I assumed that you were talking about using a battery maintainer. A normal trickle charger might charge up a dead battery. A battery maintainer will not. Sorry for the confusion.

 

http://www.amazon.com/Battery-Tender.../dp/B00068XCQU

Attach the ring terminals to the battery posts and snake the connector out and up by the rear ground point. Then you can put the trickle charger on when needed. Many people have made more elegant/convenient hardwired connections but you may not want to modify the car irreversibly.

 

Thanks for the advice guys. It's odd, the fluid levels are exactly right, just above the min level. The battery didn't completey discharge over the winter but it was low enough that it didn't have enough juice to get the car started after the long winter. It did turn over a bunch of times and as soon as I noticed it was drawing down I stopped. I jumped the car and took it for a drive to get some charge on it. It did start fine later but I want to get it fully charged using a battery charger.

I hope I didn't make a $170 mistake by driving the car yesterday, I'll find out soon enough I guess.

Rob I've contemplated adding wires to the battery, I know many run the wires through the hole at the bottom of the battery box. I'll have to wait and see how things go. I know the car doesn't have a current draw, this is definitely battery related.

 

Here's my maintainer setup. Using a high frequency (switching) charger/maintainer. It's a three stage charger, but this one is only good for indoors. Some are water proof, all are made in factories in China.

http://www.batteryuniversity.com/partone-13.htm

 

Afshin--

The latest Schumacher maintainer I have from Wal-Mart is a 'smart' maintainer. It tests the rate of charge needed to build voltage and adjusts. Less than $25 at the Wal-Mart I visited. It will not charge a battery that has been run way down though; On hookup, it looks for some minimum terminal voltage before it starts charging.

If/when I have a battery that's been run way down, I top the cells with distilled water and use a larger charger to bring it back most of the way. I have a very vintage 6amp stupid charger for this duty. I monitor the terminal voltage during charging, and stop when it goes over 14 or so. Then the smart maintainer goes on for the finishing touches.

I also monitor specific gravity of the fluid after the battery has had a chance to rest some after charging. If it's low and the battery open-circuit voltage is OK (12.5 or so) it's a sign that the battery is on its way out. The specific gravity test should be part of the annual maintenance/inspection process, in my opinion. A battery that doesn't hold a charge will kill an alternator and strain the rest of the equipment in the car with either too-low and sometimes too-high voltages.

I made a short harness connector for it that lives permanently in the front corner of the fender under the hood. The wiring is hidden up inside the fender, with just the little two-pin connector sticking its nose out, wrapped with the harness for the fan controller. Positive wire has a ring terminal and is in the stack on the jump post. The negative attaches to the body with a smaller ring terminal, at the ground point right next to the top of the AC condenser. I used a common ATC fuse holder lead for the positive end with a 10A fuse to protect the wiring. Use requires the hood up on the latch so it's hard to forget to disconnect it, but the car cover still fits on it while stored.

 

And I know the car does have a current draw... it may not be a big one but it is always there.

Even if its perfect it will be at about 15mA. Given you probably have a 75Ah battery (when new) then you'd have a meaningful impact on charge (difficulty starting) by probably about 10-12 weeks (best case) under real life conditions. Seems it may have been sitting this long...

Alan

 

I should know better than to make a comment like that. I know the car does have a natural draw but to clarify, it's not above and beyond the norm.

Since the battery was taken out of the car I know nothing was drawing on it while it sat so the only explanation is that the cold temperatures dropped it's CCA over the winter and it never recovered to the point were it would start the car. That's my theory at this point...and I hope I'm right otherwise that new $170 Porsche battery is a piece of junk!

Bob thank you for the description, that is very helpful.

 

+1 on using a battery maintainer on the hot post. I use it during the summer driving season and also while the car is stored during the winter. Easy to connect and disconnect. "Wouldn't leave home without it."

 

Afshin,
I've used the Schumacher maintainer for about 12-13 years now to maintain the battery. I even leave it plugged in all winter while in hibernation and it always starts first shot in the spring. I attached it to the battery terminals in the spare wheel well and place it next to the spare (Arrow). Attach a 6 foot extention cord and every day when I come home , plug her in. I am on only my second battery in 14 years . The extension cord tucks under the hatch rug when not in use. I swear by it!