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steffen707 · 04-09-2012, 10:47 PM

Well I've spent hours testing today and i've confirmed and refuted some theories with the Honda alternator.

My test setup:
96 civic hatch, with 96 civic alternator on a 92 d15z1 engine. I think the obd1 civic alternators operate the same way as the obd2a civics, but I can't be certain as I didn't test it.

I had a basically dead car battery (so dead that it wouldn't run the fan or light up any lights) and hooked that up to the battery cables. I then used a known good working battery to jump start the car for the beginning of each test. As soon as the car started I disconnected the jumper cables to isolate the good battery from the bad one.

The car was brought up to operating temp.

Note: When its up to temp when you start the car, the engine doesn't rev over 2000rpm. This is an important thing to remember, because when you test the voltage at the field winding with the car off there is .01volts, when you start the car its .05-.3 volts. When you rev it past 2000rpm it now reads 3-5volts and even if you let the car idle, it will stay at 3-5 volts.

There are 5 wires at the alternator. 1 white "B" charging wire, 1 yellow/black "IG" field winding exciter wire, 1 white/green "C" charging control signal wire from the ecu, 1 white/blue "L" charging warning lamp wire, 1 white/red "FR" charging rate wire from the alternator to the ecu.

I disconnected these wires directly from the 4pin plug at the alternator for guaranteed results.

Don't try pulling the alternator fuse because the manual, says it controls the alternator, vss, eld unit, evap purge control oxygen sensors and tcm. That's for a 96 civic anyhow. Its much better to disconnect the "IG" wire at the alternator.

TESTS:

1. First test was unplugging all 4 wires together. The car immediately died after disconnecting the jumper cables, but wait..... If you rev the engine past 2000rpm before disconnecting the jumper cables, the car would run very poorly. headlights would flash, the fan would pulse, it is a not drivable but actually charging at a super small amount.

2. Disconnect all 4 wires, but ground the "C" wire, The car immediately died like in 1, but if you revved it past 2000rpm before removal of the jumper cables the car idled, but was more rough than in 1. This is because grounding the "C" wire tells the alternator to charge at the lower rate.

3. It has been thought you can simply disconnect the "IG" wire and disable the alternator. This resulted in charging the battery and providing enough power for lights, fan stereo, ect. The car idled just like normal and you could drive the car just fine. This didn't work.

4. Another ecomodder ecomodder California98Civic http://ecomodder.com/forum/showthrea...8-a-20513.html told me that he found out that if you disconnect the "IG" and the "L" wire this disables the alternator. He thought that the "L" circuit was providing enough power to energize the field windings. Well he was right. I tested this by starting the car with both "IG" and "L" disconnected and it operated just like test 1. I also tried starting the car with just "IG" disconnected, removed jumper cables, the car ran fine, then disconnected "L" on the fly, the car imediately starting running super rough like test 1.

5. I read that if you soft ground the "IG" wire via a light bulb this will disable the alternator. With just soft grounding "IG" the results were the same as test 3.

6. With disconnecting "L" and soft grounding "IG" i got better running characteristics and presumably better charging than in test 1. (I can't remember if it was like normal running, or just smoother test 1 running, sorry. This isn't a good option anyway.

People should either do 1, 2 or 4. 1 and 4 are almost the same, except with 4, the "C" wire is still connected to ecu. I feel however that 2 is the best.

So what did I end up doing? Well you can disconnect the "L" wire anywhere between the alternator and the ELD. So for ease of turning back to stock i simply took the charging bulb out of the dash and got the same results as if you disconnected it at the alternator.

I also used a dpdt switch in the UP SETTING to switch "C" to ground, and simultaneously switch off the "IG" wire. This is the same as test 2.

In the DOWN SETTING the dpdt switch will reconnect the "C" and "IG" wire to their normal connections, allowing full use of the alternator in normal configuration. The only thing is that you will never see a charging problem because you took the bulb out; however, if you use a voltmeter to monitor the battery as most would be doing, you will notice when something isn't right. We don't need no dumby lights.

This DPDT switch also has an OFF setting in the middle. In OFF mode, you get the same results as test 1 except that the "FR" wire is still connected. I didn't notice any differences in any of the tests with or without "FR" connected.

So how did the MPG compare?? I picked out a flat 35mph road and picked out 2 mailboxes 1 mile apart. Car was up to temp, car was already cruising at 40mph before I got to the first marker to eliminate variation with acceleration up to 40mph. Once I passed the marker I reset mpguino to calculate just the mile long MPG. I read what mpguino said at the mile marker and then slowed down after.

I calculated from A-B and B-A, I tested with high beams on, fan on full blast, A/C off, and rear defroster on. I did the alternator on tests with a fully charged battery first to eliminate any extra load from trying to charge up a low battery from the other 2 test types. This was a high load test, i didn't have time to also test no load, but plan to do that sometime this week.

Results A-B Full load:
Alternator On normal: 70.7, 68.8, 68.1 = 69.2 average
Alternator Test 2 setup: 73.4, 76.7, 73.6 = 74.5 average
Alternator all 5 wires disconnected: 74.9, 74.2, 74.5 = 74.5 average

Results B-A Full load:
Alternator On normal: 62.8, 61.5, 62.2 = 62.16 average
Alternator Test 2 setup: 68.7, 69.7, 69.8 = 69.4 average
Alternator all 5 wires disconnected: 69.2, 68.8, 69.0 = 69.0 average

Alternator test 2 setup and completely disconnected (except belt) resulted in almost identical results. I truly think that test 2 setup hardly provides much charge, and thus puts very little mechanical load on the engine.

In the A-B test i saw a 7.65% gain in mpg, and B-A was a 11.6% gain.

I'm going to post these results on the first post of the thread as well.

04-09-2012, 10:47 PM	#48 (permalink)
steffen707 Master EcoModder Join Date: Oct 2009 Location: Midwest Posts: 337 Thanks: 4 Thanked 37 Times in 21 Posts	Well I've spent hours testing today and i've confirmed and refuted some theories with the Honda alternator. My test setup: 96 civic hatch, with 96 civic alternator on a 92 d15z1 engine. I think the obd1 civic alternators operate the same way as the obd2a civics, but I can't be certain as I didn't test it. I had a basically dead car battery (so dead that it wouldn't run the fan or light up any lights) and hooked that up to the battery cables. I then used a known good working battery to jump start the car for the beginning of each test. As soon as the car started I disconnected the jumper cables to isolate the good battery from the bad one. The car was brought up to operating temp. Note: When its up to temp when you start the car, the engine doesn't rev over 2000rpm. This is an important thing to remember, because when you test the voltage at the field winding with the car off there is .01volts, when you start the car its .05-.3 volts. When you rev it past 2000rpm it now reads 3-5volts and even if you let the car idle, it will stay at 3-5 volts. There are 5 wires at the alternator. 1 white "B" charging wire, 1 yellow/black "IG" field winding exciter wire, 1 white/green "C" charging control signal wire from the ecu, 1 white/blue "L" charging warning lamp wire, 1 white/red "FR" charging rate wire from the alternator to the ecu. I disconnected these wires directly from the 4pin plug at the alternator for guaranteed results. Don't try pulling the alternator fuse because the manual, says it controls the alternator, vss, eld unit, evap purge control oxygen sensors and tcm. That's for a 96 civic anyhow. Its much better to disconnect the "IG" wire at the alternator. TESTS: 1. First test was unplugging all 4 wires together. The car immediately died after disconnecting the jumper cables, but wait..... If you rev the engine past 2000rpm before disconnecting the jumper cables, the car would run very poorly. headlights would flash, the fan would pulse, it is a not drivable but actually charging at a super small amount. 2. Disconnect all 4 wires, but ground the "C" wire, The car immediately died like in 1, but if you revved it past 2000rpm before removal of the jumper cables the car idled, but was more rough than in 1. This is because grounding the "C" wire tells the alternator to charge at the lower rate. 3. It has been thought you can simply disconnect the "IG" wire and disable the alternator. This resulted in charging the battery and providing enough power for lights, fan stereo, ect. The car idled just like normal and you could drive the car just fine. This didn't work. 4. Another ecomodder ecomodder California98Civic http://ecomodder.com/forum/showthrea...8-a-20513.html told me that he found out that if you disconnect the "IG" and the "L" wire this disables the alternator. He thought that the "L" circuit was providing enough power to energize the field windings. Well he was right. I tested this by starting the car with both "IG" and "L" disconnected and it operated just like test 1. I also tried starting the car with just "IG" disconnected, removed jumper cables, the car ran fine, then disconnected "L" on the fly, the car imediately starting running super rough like test 1. 5. I read that if you soft ground the "IG" wire via a light bulb this will disable the alternator. With just soft grounding "IG" the results were the same as test 3. 6. With disconnecting "L" and soft grounding "IG" i got better running characteristics and presumably better charging than in test 1. (I can't remember if it was like normal running, or just smoother test 1 running, sorry. This isn't a good option anyway. People should either do 1, 2 or 4. 1 and 4 are almost the same, except with 4, the "C" wire is still connected to ecu. I feel however that 2 is the best. So what did I end up doing? Well you can disconnect the "L" wire anywhere between the alternator and the ELD. So for ease of turning back to stock i simply took the charging bulb out of the dash and got the same results as if you disconnected it at the alternator. I also used a dpdt switch in the UP SETTING to switch "C" to ground, and simultaneously switch off the "IG" wire. This is the same as test 2. In the DOWN SETTING the dpdt switch will reconnect the "C" and "IG" wire to their normal connections, allowing full use of the alternator in normal configuration. The only thing is that you will never see a charging problem because you took the bulb out; however, if you use a voltmeter to monitor the battery as most would be doing, you will notice when something isn't right. We don't need no dumby lights. This DPDT switch also has an OFF setting in the middle. In OFF mode, you get the same results as test 1 except that the "FR" wire is still connected. I didn't notice any differences in any of the tests with or without "FR" connected. So how did the MPG compare?? I picked out a flat 35mph road and picked out 2 mailboxes 1 mile apart. Car was up to temp, car was already cruising at 40mph before I got to the first marker to eliminate variation with acceleration up to 40mph. Once I passed the marker I reset mpguino to calculate just the mile long MPG. I read what mpguino said at the mile marker and then slowed down after. I calculated from A-B and B-A, I tested with high beams on, fan on full blast, A/C off, and rear defroster on. I did the alternator on tests with a fully charged battery first to eliminate any extra load from trying to charge up a low battery from the other 2 test types. This was a high load test, i didn't have time to also test no load, but plan to do that sometime this week. Results A-B Full load: Alternator On normal: 70.7, 68.8, 68.1 = 69.2 average Alternator Test 2 setup: 73.4, 76.7, 73.6 = 74.5 average Alternator all 5 wires disconnected: 74.9, 74.2, 74.5 = 74.5 average Results B-A Full load: Alternator On normal: 62.8, 61.5, 62.2 = 62.16 average Alternator Test 2 setup: 68.7, 69.7, 69.8 = 69.4 average Alternator all 5 wires disconnected: 69.2, 68.8, 69.0 = 69.0 average Alternator test 2 setup and completely disconnected (except belt) resulted in almost identical results. I truly think that test 2 setup hardly provides much charge, and thus puts very little mechanical load on the engine. In the A-B test i saw a 7.65% gain in mpg, and B-A was a 11.6% gain. I'm going to post these results on the first post of the thread as well. Last edited by steffen707; 04-10-2012 at 12:48 AM..