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View Full Version : one PC925 is NOT enough



kismetcapitan
November 22nd, 2011, 01:42
I said I would add a second if running off of just one PC925 would fail me. It did. One PC925 is good for three starts in a row, as I discovered. Not trusting the weak starting of one PC925, I found a shop that had them in stock. Went to pick it up, then started the car, drove across the street, turned off the car to fuel up. The pump wasn't working, so I started the car again, moved to another pump...turned out the gas station was out of premium. Tried to start the car, FAIL.

So that was three starts without giving the battery time to recharge, and in a situation that would normally be encountered (I was not "testing" the battery, I was just going about my business!).

I was very lucky to have A: had the car prewired for a second PC925 and B: that I was out buying a battery, instead of out, say, running errands. I was saved by pulling out the second battery wiring and connecting the new PC925. It was still miserable to fiddle with connecting screw terminals by hand in the dark and cold by cellphone light.

One PC925 works if you start the car, and start a decently long commute. For short trips within a city, it starts to strain. And if you have to move your car a couple times, say, in a parking lot or moving to different pumps in a gas station, then you're toast. I also found that various warning beeps would go off for a couple seconds while starting until the car came up to voltage.

Two are working just fine. And with one tucked in each corner storage area of the trunk, they're invisible, and I have eliminated the stock battery location.

4everRS
November 22nd, 2011, 03:52
Keep us updated! Have to say I am a little disappointed. I was hoping that it was going to work great with one. I have my water/meth system in the drivers side corner, and won't be giving it up anytime soon. I would love to get rid of the lump in the trunk, but need good cold cranking for MN winters.

lswing
November 22nd, 2011, 03:55
Standard daily driving for 4 months on mine, never an issue. I guess I could try and start the car over and over, but maybe there is something causing your lack of charge, alternator?

It's been about 40 here the last few weeks, not really cold I suppose...

kismetcapitan
November 22nd, 2011, 04:29
have never had any electrical issues. It could be that my battery connections or ground points are not ideal, but the installer was not a car shop, but a leading car stereo shop - one that does a lot of competitions. They're very familiar with multi-battery installs and the basics of grounding, like getting clean metal-to-metal contact, etc.

The two PC925s seem to be outperforming the one big Interstate battery I had replaced, and it's pretty chilly here in Ann Arbor.

hahnmgh63
November 22nd, 2011, 05:54
Been using my PC925T for almost 3 years with no problems. Have used it with temps down into the mid 20's. I wonder if you have a bad or old battery?

kismetcapitan
November 22nd, 2011, 16:14
both batteries were purchased new, so in theory one might have been a dud? Although it worked just fine when given enough charging time; maybe just five minutes of driving?

In any event, the car started quite powerfully with the two PC925s this morning and it was around freezing, parked outside all night. Although I may not have realized any battery weight savings, I've gotten rid of the trunk battery without having to convert the spare wheel well. So you can have your cake and eat it too.

Or...decide to reduce weight by ditching the spare, which I have. If a can of fix-a-flat is all RS owners got in Europe, I think I can live without the spare. In 26 years of driving, I've never run into a problem where fix-a-flat or a puncture kit didn't save the day - I always took that route instead of jacking up the car and throwing on the spare. Of course, this is when I'll probably encounter that one in a million catastrophic tire failure...

ben916
November 22nd, 2011, 16:45
on the topic of the "spare" tire: has anyone ever used it?!?!?
I have heard some horror stories on some other sites where the spare doesn't inflate properly or the "widow maker" jack is non-operational...

kismetcapitan
November 22nd, 2011, 19:03
when I get back home after Thanksgiving, I'm going to inflate that thing for shits and giggles; it's just the weirdest spare I've ever seen and I've got to give it a go :)

lswing
November 23rd, 2011, 03:13
I hear ya, it's a damn nice spare, mines never been used, got to check it out...

kismetcapitan
November 23rd, 2011, 06:06
and fwiw, two PC925s are better than the single mammoth Interstate they replaced. I'll put up pics of the installation when this damned rain stops.

aussie rs6
November 23rd, 2011, 07:52
on the topic of the "spare" tire: has anyone ever used it?!?!?
I have heard some horror stories on some other sites where the spare doesn't inflate properly or the "widow maker" jack is non-operational...

Even our local audi stealer tech, said get rid of the rs6 factory jack and buy the factory jack provided for the Allroad- a lot safer.