Higher Amp Alternator How Much Higher?

[screamin gt]

Hi all, been a while on here as I did a lot of mods a few years ago and now been just enjoying the car. And letting it rest in the winter.

Anyway I have relocated the battery to the trunk a while back, and all is good with it, but I think my alternator is on its way out. I think its working too hard to keep up with the long distance (relocation kit) and heavier electronic pull (Amps, extra gages, etc) so I think it should be replaced with a higher amp alternator. Suggestions?

Also the reasoning is I know the battery is good as it holds a charge no problem, and the batttery light is on. Battery gage shows a little low and everytime out it gets lower, headlights very dim, doesn't get any extra (electrical) power when rpms increase, etc.

Also I'd like to get one that looks half way decent too (powdercoated not chrome) as my engine bay looks pretty good and I want to keep it that way. I'll post up some pics in a minute.

 

[wmburns]

In the past I would buy re-man'ed or salvage yard units. I recently for the first time ever rebuilt my own alternator myself. I learned a TON about alternators that I didn't know before. Seeing the different failure modes and the effect it has on the parts was a real eye opener for me.

One of the things that I learned is that it's not always a good idea to run the alternator until it TOTALLY gives up the ghost. As a result I proactively rebuilt a working F150 alternator with 230K miles. It seemed like at 230K miles it was past time and rebuilding on my schedule might save a dangerous break down.

Lessons learned:

• It's quite possible to save some real $$ doing the work yourself.
• It's more work than I would have guessed at first but really does get easier with practice.
• It helps to have a rebuildable core because the rebuilding does take time and if working on your DD the time it takes is a real consideration.
• Running the alternator unit the slip rings totally burns up does make the rebuilding harder.
• There are TONS of different combinations of alternators out there. Different frame designs, frame sizes, stators, regulators and other subtle difference that make it important to learn the differences between a Ford 3G, 4G, and 6G alternator.
• Cleaning and greasing the electrical connectors including the MOUNTING locations can make a big difference. Corrosion is the enemy.
• It helps to follow all of the instructions for the best result. I didn't and had a fail on the first attempt.
• My soldering skills were rusty and needed improvement. It's true. If you don't use, you lose it.

For a "how to" reference I used the information from Rebuilder in a box.

How to rebuild Ford 6G alternator

View: http://www.youtube.com/watch?v=iGIdnOwHZUM

http://alternatorstarterrebuildkits.com/

Mustang GT: http://alternatorstarterrebuildkits.com/ford-mustang-4-6/ Note the 1999-2002 GT can come with a 4G or 6G alternator. I can only give direct experience on rebuilding the 6G version.

I found that the youtube videos to be very well done. Note that the rebuilding process is done using only common hand tools (sometimes in very inventive ways). Bottom line. No special tools required.

On to your question. rebuilderinabox offers a "higher amp" upgraded stators for certain alternators. Which could allow you to get a high amp alternator and save some big $$'s in the process. The other positive is this upgraded alternator does not require any vehicle modifications.

One down side is the end product will still look the same unless you send it out for powder coating or paint it yourself. In my case I tried to clean it with only marginal results.

6G High Amp Rebuild Kit For a Ford Alternator

View: https://www.youtube.com/watch?v=N7pFuDb5eBA


In my case I had an old salvage yard alternator that I didn't take back for the core. This turned out to be the perfect test case to practice on.

An option is to get a core from your local salvage yard. Try car-part.com for a searchable list of salvage yards in your area. Note, if you are planning to rebuild yourself it's not necessary to buy a working core. This is a way to save a few $$'s.

Anyway just food for thought. This isn't for everybody.

Edit: if this were my car and the alternator worked at one point in time and now does not, I would think about a worn out alternator or bad connection and not jump first to actually needing a high amp alternator. Also, if not having enough amps were the only problem THEN the situation would get better with higher motor RPM's. Is this the case?

 

[screamin gt]

Wow thank you for the very detailed response. I think rebuilding my own would be a cool project, but I have a ton of projects that have been on the wait list for way too long so adding another just isn't possible right now. Probably not cost effective for me either as I'm sure it would take me at least the equivalent time of an overtime shift which would more than cover the costs of just buying one. I'll definitely keep the core around and keep it on the shelf for IF I ever get time to experiment but it would be a long time from now. Maybe for when my kids a little older and they can learn to.

I actually did some research and found a replacement 200 amp for $196 shipped so I ordered that for now, and I can keep the old core.

As for need more amps, I really don't know but it makes a ton of sense to me. I mean how can the stock alternator be expected to keep up now that there is about 20 extra feet of line to the battery, not to mention the ground for the battery is now in the trunk instead of only 2 feet away like when it was stock. As stated there are also extra power consumptions going on like the 2 amps that power the sub and bigger higher wattage speakers, plus 4 extra gages and sensors that draw more power, and even most likely higher powered headlights as well than what was originally on it. They must make higher amp options for a reason and I'd suspect this is the reason.

I had my friend who I usually hire for anything over my head check it out with a voltmeter and he said the alternator is definitely not putting out any power at all. Car is running solely off the battery and you can even see the battery drop voltage slowly as the car is running.

Thanks again for the links, I will definitely keep those handy!

 

[Mustang5L5]

I'd go over your connections and verify everything is nice and tight, and the wire size is adequate. With the added distance, you're likely to see voltage drop issues arising from the distance, and this can lead to added strain on the charging system. A bigger size amperage alternator may not be the solution, but can alleviate the symptoms, especially if there are extra power drains like stereo equipment. However, verify your wire sizing is correct.

What size wire came in the kit?

 

[wmburns]

Allow me to expand on WHY I believe that the wire size NOT the problem in this case. And further WHY a larger amp alternator will not over come the problem IF the wire size is too small.

IF the only thing wrong was the size of the wire, THEN how do you explain how this did work at some point in time? But why guess. Let's test.

Using an accurate Volt-Ohm Meter (VOM), measure the voltage at the battery negative and the alternator case with the motor running and accessories off. Repeat the measurement with all accessories on. This will give a direct reading of the voltage drop caused by current flow. Compare the readings between accessories off and accessories on. The voltage reading should be small.

For completeness sake repeat the measurement between battery positive and the B+ post of the alternator.

Here's even more detail on how to perform a voltage drop test.
https://www.stangnet.com/mustang-fo...perform-charging-system-voltage-drop-test.56/

Note, this test assumes that the alternator is working. It will not produce accurate results if the alternator has flat failed.

If the wire size is so small as to cause a "no charge" condition then the voltage drop would have to be at least as great as the difference between battery voltage and alternator charging voltage. 14-12=2 volts.

Here's why a lager alternator won't fix a problem of under sized wire. The alternator's voltage regulator is located inside the alternator. So the regulator will attempt to maintain 14 volts at the alternator. The wire size is still the same. Therefore the voltage drop to the battery would still be the same even though the capacity of the alternator is higher.

The only way a larger amp alternator is ever going to fix a problem is if there's a difference between alternator voltage (case and B+ terminal) with accessories off and accessories on.

One point that's important to remember is in stock form the stock alternator is large enough. We know this because there are TONS of cars on the road with working alternators and batteries. So in all cases with all accessories OFF, the stock alternator has to be large enough. If the alternator isn't putting out enough amps there has to be a reason why it isn't.