Bad Alternator/Optima advice...

[KFC911]

I had the 911 out today for a long extended drive (limited driving during the winter months) and put her back on the Xtreme tender at the end of the day. The tender indicated 25% initially and though I didn't break out the multimeter to check with the car running, I'm assuming the worst. I'll diagnose and make a plan (rebuild, replace, etc.) later, but I've got so many projects going on, spring has sprung, and I just don't want to tackle it for a few months. Is there any harm in continuing to drive her (shorter periods but alway up to temp), but not down that low (say down to 75%), and then always going on the tender when garaged?

[James Brown]

Is the alt light on?

[KFC911]

No it wasn't James...I've always assumed the alt light was a go/no go for the alt/fan turning. Is it related to the alt's output too? I haven't even done basic research on threads I've read over the years, but will later. I'll get a multimeter reading from the battery with the car running tomorrow. Thanks!

[Joe Bob]

The battery may be salvageable.....

Charge it fully, should read 12.5-12.8 at rest.

Start the engine, 13.0-13.5 at idle
13.5-14.0 at 2500 rpms

Anything under 13 while running your alt is toast.

[KFC911]

I'm sure the battery's fine...took no time to return to 100% (via tender)...I'll probably get those readings later on today, and proceed accordingly. Assuming the alt IS toast...would occasionally driving it for several months regularly going from 100>75>100% be risking the Optima? Obviously, that's not ideal, but I JUST don't want her "down completely" right now if I don't have too...thanks!

[James Brown]

Read the voltage at the battery with the engine running around 1000 rpm and see what you get. A new battery, no matter what brand it is will die if the Alt. is not charging.

[brads911sc]

I wouldnt drive with a bad alternator/voltage reg... that is a sure way to kill your battery...

[Joe Bob]

The light is part of the charging circuit. It could be as simple as replacing it.

[KFC911]

Originally Posted by Joe Bob

....
Charge it fully, should read 12.5-12.8 at rest.

Start the engine, 13.0-13.5 at idle
13.5-14.0 at 2500 rpms
.

"IDIOT LIGHTS" - and how I despise them...wait for the movie! Thank you all for your suggestions and advice and I apologize for not doing some basic diagnostics before starting this thread. It would appear that the only "problem" I have is an Xtreme tender with a row of LEDs indicating 25/50/75/100% charged. Their primary purpose seems to be giving an owner a mild heart attack thus causing them to post needlessly on car forums . After driving around a bit today, I did some checking...both at idle and 2K rpms, my alt output seems just fine (a bit high, 13.9 at idle...no biggie I assume). Then checked the battery, fully charged...all is well. Hooked up the Xtreme...indicates 75% for a bit then 100%.

Thank you all!

signed..."the boy who cried wolf"

[vracer]

I don't know how knowledgeable you are, but are you aware that these alternator-regulators are noted for failing INTERMITTENTLY to the high side, 15+V?

[KFC911]

Originally Posted by vracer

I don't know how knowledgeable you are, but are you aware that these alternator-regulators are noted for failing INTERMITTENTLY to the high side, 15+V?

You're not going to insult my "lack of intelligence" one bit, and I welcome any & all comments. I'm going to do some reading, but in the meantime, no I wasn't. I'm definitely going to keep an eye on things with the multimeter, but with the several readings I did today, I saw no indication of that. I based my assement on the tender's "idiot lights" simply due to the fact I put a fully charged battery on and it indicated 75%, then 100. I realize an 'intermittent problem" will NEVER happen when one wants to diagnose it however . Thanks!

[Joe Bob]

13.9 isn't out of line....could be a result of a high idle when cold. When you start getting over 15v you can fry things. Not just the battery.

That's why I always recommend replacing the crappy clocks with a head temp and voltmeter.

You really should do a read at 2500 rpms or more and do a few times. Bad VRs can be spiky as mentioned above.

BTW, the stoopid LEDs are there to entertain not edumecate. Pretty sparkly thingies are for the mullet-headed MOPAR guys.

[James Brown]

Ok sounds fine now go out and drive!

[KFC911]

Originally Posted by Joe Bob

...You really should do a read at 2500 rpms or more and do a few times. Bad VRs can be spiky as mentioned above.

Thanks, I will do that. At 2k, the output was 14. I'll do some more checking over the next few day at 2500+ and see what develops. Question...If I go on a long extended drive, then return home, I'm assuming the battery would be overcharged a bit if the VR is going. I think black tape is still the solution here since I don't have a mullet

[KFC911]

Originally Posted by James Brown

Ok sounds fine now go out and drive!

Believe me I will...spring has sprung, and I was afraid my baby would miss it...thanks!

[James Brown]

Heres a good mod, remove the oil quantity gage and put in a voltmeter from Palo Alto Speedometer. Looks like it belongs there and you can always monitor the charging system. mine runs around 14.3 volts most of the time. You just have to check the oil quantity manually, but you do that anyway, right?

[KFC911]

Originally Posted by James Brown

Heres a good mod, remove the oil quantity gage and put in a voltmeter from Palo Alto Speedometer. Looks like it belongs there and you can always monitor the charging system. mine runs around 14.3 volts most of the time. You just have to check the oil quantity manually, but you do that anyway, right?

Excellent idea! My oil level gauge (worthless as you indicate) is also on my gas guage however...rut roh! No problemo, when I'm driving the 911, I don't care what time is staring back at me...bye bye clock ! I checked their site and will give them a call. Thanks!

[vracer]

I think the dancin' fool, JB has it nailed. I have a factory option volt meter in the center console. It helped me find the VR problem very quickly.

[Joe Bob]

Gee thanks...

BTW, I had my VM/Head Temp gauge made by Westach. I had an over charge stoopid light added for 15v. Comes on at power on, goes dim at idle. Worth the extra 20 bucks at the time.

[James Brown]

He ment James Brown not Joe Bob!!!! Anyway, same info is always good, and "I feel good"!