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So my alternator has failed and I will be taking it to the shop for that and a few other things. The shop is about 30 miles away and I was wondering if anyone had any thoughts on how far I could go just on the battery. I have a new Optima red top in it and I have a jump box I could also take with me. I would just like to save a towing charge if I could.
 

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I drove over an hour recently on just the battery when my alternator failed. After Alternator was replaced, the battery voltage was down to 11.3 volts. After a nice hour or so drive after the fact the alternator charged the battery back up to 12+ volts again.
 

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Don't run the A/C, lights, fans, or other accessories and you can make it easy if the battery is charged. Don't waste money trying to fix the old alternator. Replace it with a Cadillac Catera alternator.
David Teitelbaum
 

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I drove over an hour recently on just the battery when my alternator failed. After Alternator was replaced, the battery voltage was down to 11.3 volts. After a nice hour or so drive after the fact the alternator charged the battery back up to 12+ volts again.
Thanks, good to know
 

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Don't run the A/C, lights, fans, or other accessories and you can make it easy if the battery is charged. Don't waste money trying to fix the old alternator. Replace it with a Cadillac Catera alternator.
David Teitelbaum
I definitely don't need to run any accessories on my way there so I should be ok. The Lotus shop has a rebuilt one on their parts shelf so I thought I would go that route but I have read about the Catera alternator working with only a slight mod.
 

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For me it was the 2001 Cadillac Catera Alternator, you just need to trim the air scoop on the alternator to make it fit. Wish I had taken pics. About 2 hours for the install start to finish.
 

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I had fantastic luck on my 98 getting the stock alternator rebuilt locally. It cost about $125 if I remember correctly. You know it fits and no mods are needed. Mine works perfectly.....just cant say that for my starter currently.
 

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Should I mention that I got the 2001 Cadillac Catera Alternator for $118?
 

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It was just a matter of trimming the cooling channel on the alternator with some snips. you take off around 2 - 2 1/2 inches of the channel and it fits.
 

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Or just leave the plastic cover off. When I did mine I had to jack the motor up a little to get enough room to put it in. I also had to "fettle" it a bit (file and smooth) the castings so I could do install it with my fingertips easily.
David Teitelbaum
 

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Ok, I have a question, has anyone else noticed that at least with the Cadillac Alternator that it doesn't start charging until you have reached 4000 RPM at least once?

I was monitoring the other day via my Bluetooth OBDII scanner and software dashboard and it showed 12v's until it reached 4000 rpms the first time of the drive, then after that it was 14ish volts.
 

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That is what I was afraid of. I know a one wire alternator needs a start up, but most I have seen are 2000 RPM or right close to it.
 

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Mine has done that forever. Did it with the original also. I changed the alternator... same thing. Had the alternator "upgraded" to higher amperage by sending it to one of the usual Lotus supply places... still does it. It's done it for 100,000 miles so I guess it's okay. Just don't let it idle forever because it's just running off the battery. What I do if the car is going to just idle for a while is watch the parking brake light and rev the engine until the light brightens. Once it switches over it's just fine, even at idle. I do notice that if the car has been driven and is warm then the next restart the switch-over RPM is a bit lower.

I just accept it a a thing know about and it's no problem. If somebody has a solution to make it switch over then I would love to hear the answer. I'm not going chasing speculation and claims of doom over a simple quirk of the car.
 

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My upgraded alternator from JAE measures 14.1 to 14.2V at idle. If I turn everything on (lights, AC, stereo) and temp is hot enough to run the upgraded fans, it will drop to 13.5V at idle.
 

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My upgraded alternator from JAE measures 14.1 to 14.2V at idle. If I turn everything on (lights, AC, stereo) and temp is hot enough to run the upgraded fans, it will drop to 13.5V at idle.
I also am running the same alternator with the upgrade from JAE. Works the same as the original on my car. After driving the car the voltages are fine at idle. I do ask if the 14.1 to 14.2V at idle are measured just after a cold startup or after the car has been driven.

As a favor I will ask you, when you start the car cold sometime, to simply start the car, let it idle for a minute or two with the parking brake on, rev the engine to about 3,700 - 4,000 RPM briefly while watching the parking brake light. The question is does the light get brighter after reving the engine?

I have looked at this several times and I have not found a way to get the full voltage at startup without getting the revs above some switch point. The only reason I ever noticed this is when I did the first California smog test on this car. The guy started the engine and had it idling for a long time, fans cutting on and off, and apparently running off the battery the whole time. Once done he shut it off and then it would not restart because the battery was too weak. That is when I noticed the voltage switchover on my particular car.

New belt, new battery, new alternator, upgraded alternator... they all functioned the same way on my car. I probably never would have known but for the smog check where the battery went flat when it clearly shouldn't have. Like many other things in life, just something I learned to live with. It is only a concern when I go to the re-learn process after having the battery disconnected for maintenance... then I just bump the revs until the brake light brightens before letting it idle for an extended period.
 

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A more convenient and objective way to monitor the voltage is this handy dual-USB power plug. There are several versions on eBay for around $4+/-. Provides system voltage with added bonus of ambient (interior) temp and the amperage draw for whatever you are powering (I use it to power Garmin GPS and charge the cell phone simultaneously).
1268748


1268749


1268750


As a data point for reference with my 2003 V8 I have never seen the delayed charging as described above. AFAIK she has the original alternator. Without touching the throttle it reads about 14.3v at idle after startup, turning on the AC/fan full blast and headlights drops it to around 13.7v +/-.
 
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