Stefan

Hello all,

I just had a rebuilt alternator put in my car as the old one wasn't charging any longer.

My question is, is the rebuilt working properly???

Normally I'm getting the 13.5-13.8 volts expected at the battery terminals when it's idling or I'm driving. BUT ... when I load up by turning on all lights, fans, radio (stock) and defroster, it drops down to 124-12.9 range at idle and not a whole lot higher at speed. I was under the impression that it should be at least 13.5 or so at all times.

Anyone have any input or experiences?

Thanks!

Jaak Lepson

Stefan ... sounds like you need to replace both your positive and negative battery cables and clean up the grounds. I had mine replaced and what a difference it makes! Even my dash lights are brite!!!

The part (cables) cost about $275 CDN from dealer's in T.O. and may take oven an hour to replace.

Jaak Lepson:

Stefan

Thanks Jaak! I was wondering if the cables might be an issue. I know my dashlights are so dim (even on full brightness) that I can barely read the digits.

Any strange things to watch for or tips when replacing the cables? I wonder if even cleaning the contact points at the other from the battery might make a difference.

DAR951

You might try a "user name" search for "Iceshark" on this forum for the hands down best replacement cables going... There are a bunch of Rennlisters that will swear to the quality as well as the remarkable difference they make with many "things electrical" on our aging cars. He can also answer any specific questions you might have re. your charging system.

By the way, dim dashlights are in all likelyhood a different problem... corroded reflective surface is a chronic problem with the 944 instrument cluster. there are some DIY fixes or new reflectors are available from places like 944 Online (www.944online.com)

Stefan

Thanks Dar! I already contacted iceshark and have some prices for his cables. Sounds like I should go with his as opposed to factory according to the folks here.

Another project for next summer I guess. It's too cold to mess with now i my unheated garage.

IceShark

Stefan, if you are going to get the cables from me you probably should do it sooner rather than later. I may not be doing this next spring.

And it would be hard to duplicate them for the same cost unless your labor is worth zero. Even just getting the same quality parts would be hard to do on a one-off basis.

Jaak Lepson

Stephan ... you should do as Iceshark says and get it done soon. Cleaning the battery cable contacts don't help as the wire it's self is bad. It does take a while (used my buddies P-Car garage to do it ) and it will make a big difference.

Now when I drive at night the gauge shows around 14 V all the time. Also, is the cooling duct in place that feeds air to the altinator? If it's missing you will be back at it again.

Jaak Lepson

krickmann

I'm sorry Dan, you didn't get a copy of the memorandum? Yeaaah...well, all of us on the board have decided you have to keep satisfying our electrical needs and that you can't quit making your light cannons, wiring harnesses, etc. Yeaah... and while we're at it, you need to come up with new stuff. Are you sure you didn't get that memorandum? I'll send you a copy of the memorandum.

IceShark

Jaak is right. I didn't want to post all the reasons why my cables are better. But Porsche used bare copper terminals and poor strand count automotive style wiring. The terminals are just crimped on. What happens is that corrosion walks up the crimp interface between wire and terminal.

I use tinned copper terminals (able to resist corrosion better than bare copper), crimp them on, then solder the joint to create a molecular bond, then seal the whole works up with glue lined heat shrink and electrical silicone. That joint will last longer than you will.

Other improvements are a fuse in the alternator cable and the positive cables covered in fireproof fiberglass sleeve. And heavier cable.

It is quite a bit better than the stock wiring.



Memo? I'll help guys out for awhile, but there has to be an end to it.

Stefan

Yes, my air cooling duct is in place. I saw the mechanic put it on when he swapped out the alternator.

Like I said, my gauge sits at 14V unless I turn on everything electrical in the car and then it falls to 12.5 or so. To me it sounded like the alternator not being able to generate enough.

Thanks for listing the differences in your cables vs. porsche. I'm not impressed with the electrical work overall in this car.

Stefan

I asked my mechanic what his opinion was and he said that a drop to 12.9V on full load is normal and that he's never had to change the +ve battery cable in one of these cars, sometimes the gnd, but not even that very often.

Does anyone know a good test to check the continuity of the gnd cable or +ve? Simple put an ohmeter on both ends and see how low the resistance is? How low should it be on a good one?

Iceshark's cables sound like a great idea, but after alll the money I've recently spent on car repairs, I'd rather not add to it unless I have to.

Jaak, which mechanic do you use? Can I borrow his garage sometime?

IceShark

Stefan, there is also an ambient heat issue on alternator output. The hotter the temp the lower the output. Though you are not exactly in Arizona in the summer when they hit nearly 120*F.

What is "full load" to drive output down to 12.9v? If you get both radiator fans, inside fan, rear defrost, both window motors, all lighting, sound system hitting hard on bass, cigarette lighter, etc. going at once, then 12.9v would certainly be possible. You are drawing more than the alternator can put out.

Print this off to use for resistance values and your measurement tests:

http://www.vandenhul.nl/artpap/awg.htm

It is a nice chart as it has both AWG and metric cross section. Your main cables are going to be 35mm square, so a tad over #2 AWG.

Your mechanic hasn't been around too long to make such a stupid statement about the positives. Just ask Perry951 or the general board on what happens to the cable insulation and the results when the car bursts into flames. There are two fire fears among those that actually know these cars: fuel line over headers, positive battery cable short.

Jaak Lepson

Stefan ... you have PM!

Jaak Lepson

Jim 944S

Stefan:

Get a new mechanic!!!

When I replaced my original wire with Dan's kit I found my originals to be riddled with cracks!

What appeared to be solid insulation, when bent slightly, revealed deep concentric cracks that exposed the bare copper wire! Must have looked like an aurora borealis under the hood when starting.

Certainly a candidate for self-immolation. I consider myself very lucky to not have had a major fire, and urge all of you to check out and replace any questionable wiring or contacts.

Jim 1987 944S

IceShark

Jim is correct. The plastic/rubber insulation doesn't stand up too well after so many years of close by heat cycling. It is rather shocking. All you have to do is pull the cable off, flex, and look at it.

I cover the positives with fireproof fiberglass sleeve. I'm pretty sure they will stand the test of time. But you can ask an aerospace engineer what he thinks. A few have the cables.