I wanted to see if you guys can advise me on the best way to test an FD alternator that is already removed from the vehicle? Also if I have to replace it what do you guys recommend to replace it with, AutoZone for the lifetime unlimited swap warranty?

Little bit of an intro, I just bought my FD a few weeks ago only drove her for about 10 mins so far decided to do some reliability mods first, when I drove her no issues with the charging system, no warning light on. The battery is new and does discharge very quickly when sitting, didn't start on me a couple times, luckily I have a battery tender. The previous owner did a lot of modifications with wiring, gauges, hids, hot wired rad fans( I'm working on getting it all back to normal) so there's something draining the battery, not sure if that affected the alternator but I know it could have.

I didn't have a known issue with the alternator, I'm doing some reliability mods and ended up removing the alternator to change the temp sending unit, since I removed the alternator I decided to take it to autozone to get tested. First test it passed, but I always like to do multiple tests. Second time didn't even test, was below 90amps. Third test tripped the testers breaker switch. I reconnected everything used a different ground point and re tested a few time, this time it wouldn't even test just the less than 90 amp warning, and triggered the circuit breaker switch again.

Anyone with experience can give me some advice here?
Should I test it at another auto parts or is there another way to test it?

Thanks in advance

 

Bump... Any advice appreciated.

Also has anyone here tried out AutoZone alternators?

 

 

I got mine from here, rated 200 amps, pricey though: Excessive Amperage

 

Also worth noting that with an 80% effective alternator, an increase in 100 amps, equals to a 2hp loss as the crank

 

I wouldn't hang my hat on the Autozone tester. Generally alternators are either fine and charging or not.

If you have a lot of aftermarket stuff in the car, most likely that's whats draining the battery. Search on Youtube, there are a number of good videos on finding parasitic drain.

Also, you probably don't need a high amp alternator if your car is relatively stock. The FD comes with a pretty gutsy alternator out of the box.

Dale

 

Thanks, once I finish with the Cooling system, I'm going to start on the wiring and find what's draining the battery.

Yea I haven't had an issue with the alternator...yet. The battery only drains when the car has been sitting. I just removed the alternator to access the Temp Sending unit, and thought I minus would test it since I had it out. I'm gonna head to another Store to test it on a different machine, it passed the first time, so there's something funky going on.

I looked it up and that IR performance one is not that bad, less than 100$ more than the AutoZone one my concern is like you said the turn around time. I'll send them a message and see what I'd be looking at.

Thanks.

 

I don't have any crazy electrical demands, once I get rid of the Hot Wired rad fan it just gauges and Hids, I don't think I need a 200amp...at least yet. Thank you though, I will save their info incase I do need that power in the future!



Good to know and yea I don't think I need a 200amp Alt, at least yet, thanks for the heads up!
Sorry for the noob question, but what do you mean an 80% effective Alternator? As in my case with excessive energy being drawn?

 

Right, I had no issues the little I drove her and while it was idling no charging indicator, plus it passed the first test. I know they aren't always accurate which is why I wanted to see if there was another way to test it out of the car, I'll try another tester at another store, if not I'll reinstall it and use a old school analog tester once it's running.

Yea has a few gauges, boost controller,and regular stereo no fancy double din but besides that only the Hot Wired rad fans. I will do that,find that what's draining and I have to get rid of the Hot Wired Rad Fans a.s.a.p.

Yea I don't think I need a High Amp one, at least yet. I was thinking the AutoZone one because I know how easy their warranty replacements are, no questions asked unlimited lifetime warranty swaps.

 

I've had issues with reman's. I replaced the OE one (preventive maintenance, I thought...) that had 190K+ miles on my '74 Chevy Van tow vehicle. The reman lasted only 10K miles, its bearings dying halfway to a race. I put the old one (which I was carrying as a spare) back in until I got one from another source.

So just make sure you get one from a reputable source. Even if they have an unlimited replacement warranty, it's no fun getting stuck somewhere because the one you bought crapped out.

 

Look for a local alternator shop. They can rebuild the alternator for you custom, and can even upgrade components. They can bench test the alternator by putting it on a test stand that measures power vs alternator rpm. It's sort of like a dyno for an alternator.

 

Yep, a local alternator shop is a great way to go. Alternators are pretty basic components and very rebuildable - there's nothing different or fancy about the FD's alternator.

Also, many of the high output alternators out there won't put out good voltage at idle. IR's alternator is in a sweet spot, it works great, but others may not do the trick. Again, if you don't need the high output (the FD's alternator is already 120 amps) don't worry about it.

Dale

 

It means that only 80% of the energy consumed ends up as electricity. In order to generate 1200W electricity, it needs 1500W kinetic energy from the crank. So on your case thats (12V*100A)*100/80=1500W and that is roughly 2hp.

 

IRP 140 Amp Alternator | IR Performance LLC

 

Yea I know remans arent the best option, which is why I would go with a lifetime easy swappable warranty. I get you, I definitely don't want to keep replacing the alternator or have it leave me stranded. I'm going to keep looking into it, I might take mine to get rebuilt If I can find a find a local alternator shop. Thanks brotha!


That's a good Idea, **** I don't know why I didn't think of that. I'm going to see if I can find one here locally. Thanks man I really appreciate it!

Yea it is, I can't believe I didn't think about it. I'm going to look for one now. I have only seen good things about IR's alternator and the price isn't bad so If i have to replace mine I am strongly going to consider it, but yea like you said I don't think I need the high output yet. Thank you again Rotary guardian angel! hahaha

 

Ah I get you, definitely not going to go for a 200amp unless I absolutely need to. Man thanks for explaining that to me. Now I have a new excuse if I lose a race... Hahaha

 

What is the turn around time for the Alternator rebuild once you receive it?

 

Generally, alternators are not producing the amperage without a draw. So if your system is drawing 100 amps (which can add up fast with HIDs, EWP, Rad Fans, etc., then the resistance/load on the alternator will reflect as such. So the 2HP ... is not really a factor unless you are actually drawing the amperage. SO, no, it is not costing you 2 HP all of the time. Only when you're using it... which means you don't care about the 2HP, because you're obviously busy with a bunch of electronics. Also, I have heard that the higher the amperage the alternator, the higher the efficiency loss across the board, but this will be pretty slight. But I have not researched that specific point, so don't quote me on it.

tl/dr: Alternator only uses as much horsepower (converted to electricity) as you are using at the time.

 

I had issues with 2 different uprated remans, unstable voltage, flickering lights, etc. The excessive amperage unit has been solid.

 

2-3 days

 

Awesome man, this really explains it in depth. Im going to be paying close attention to what power draws I have or upgrade to in the future. At the moment I don't think I need the extra power especially once I get rid of the hot-wired rad fans, but this is really good to know for future reference in case I do add more electronics.

Yea I've worked at AutoZone for 5 years and I definitely know how garbage the reman Alternators can be... Only benefit from them is the lifetime unlimited swap warranty, but I don't want to keep replacing them and risk getting stranded so I'm leaning to either rebuilding my same unit at a Alt rebuild shop or going with IRP's upgraded Alt that has good reviews in the community.

Nice, that's pretty quick! I'm still pinpointing if the alternator is defective. If I decide to go with a upgraded Alt I will get in contact with you guys!

 

Just a quick update in case someone is following this.

I found a local Alternator rebuild shop that will test and diagnose it for free! Bad thing is they are on a M-F 8-5 schedule so I have to try to figure a way to get there, hoping I can get it there sometime next week.

3/7: I took it back to the same AutoZone (Its the closest auto parts that I can make it to) and tested it again. Passed first 2 times with good Voltage, then didn't even test and triggered breaker switch next 2 times. I inspected the test lead myself and noticed it was pretty beat up and wiring wasn't too secure so I'm thinking that may be why I'm getting different readings. Decided that I will test at another auto parts.

3/8: I took it to O'Reillys and their tester and test lead were in a lot better condition. Tested 3 times and passed solid all 3 times no failing. Voltage was actually on the higher side at just over 15V safe high end is at 15.40 according to their specs. I'm now strongly considering the test lead was at fault with the different readings at AutoZone.

I'm still waiting on my water pump so I dont have to worry about putting my Alternator back in, I'm going to test it at a different Auto Part over the weekend just to see what I get and hope to get it in the Alt Rebuilder sometime next week to get a better test and accurate diagnosis on its condition.

Thanks to everyone for their help,advice, recommendations and Knowledge. I'll keep this post updated.

 

Final Update...

3/11: Took it into another AutoZone and they actually had a brand new test lead. Tested it 4 times and passed solid every time.

3/16: Of course it had to be the faulty test lead at the first AutoZone, but still haven't received my water pump (Don't buy from TascaAutoParts.com by the way, Over 2 weeks of processing time so far and not shipped yet... absolutely horrible but that's another story) and I finally had the chance to take it to the Alt rebuilder so I took it in. Passed with no issues.

 

Thanks for the update! A good alternator shop is a great resource.

Dale

 

They definitely are, glad you guys brought that up! Thanks again!