How do you properly test an alternators health on a B18C engine?

 

The information below is not engine specific. Though auto parts stores have equipment that gives more detailed information about your charging system, a simple multimeter will generally suffice.

1) Without the engine running, voltage should be about 12.5V across the battery posts. (battery test)

2) With the engine idling and no electrical load, voltage should rise to about 14.5V across the battery posts. (alternator test)

3) With the engine running under high electrical load (high beams, max A/C, and rear defogger on), the voltage should not drop much below 14V across the battery posts. (alternator test)

 

I'm sure I've ran this test once or something really similar. The reason I ask is because my car seems to sound really weak upon startup. I drive the car about 2-3 times a month so I can understand why it would sound weak upon first startup. But after it's driven for a few minutes, shouldn't it sound stronger when starting after the initial startup from hibernation? I just changed my batteries and inspected all wires and cables are in good health. Is there anything you recommend I check?

 

What year Civic/Del Sol?

Post results for the three simple voltage tests I described.

 

not to try and steal the thread but i did the test on my car because it seems my gauges are kinda dim at night. My car is an 00 civic ex d16y8. my results for each test are as follows

1. 12.21
2. 14.25
3. 12.22

Should i have any concern? I live in a cold climate and would like to address a possible issue before it gets cold here so if i have to change the alternator i will do it now.

Thanks

 

auto zone offers a free test

 

Test 1 and 2 look fine but test 3 is total fail. The alternator is unable to handle a large electrical load.

 

thanks for the reply Ron. I am going to replace the alternator either today or tomorrow and am looking into prices on them right now. I am getting one with a lifetime warranty that is a rebuilt due to cost. I can get a really good deal on one with a 70 amp rating compared to getting one with a 75 amp rating. Is it worth it to spend the extra money to get the 75 amp one. I have the following stuff in my car: aftermarket deck, hid headlights, a/c. Maybe adding a 4 channel amp for just the speakers later. What do u think?

 

Thanks for all of the replies. Here are my results...

1. 12.06
2. 13.42
3. 13.37

I guess it's time for a new alternator. I'm kind of a strange person when it comes to replacing parts. I'd rather pay a higher premium for a performance part rather than replace with a stock unit. I have an audio amplifier in the car, 4 upgraded speakers, and an aftermarket head unit. The audio system is not of anything high but I'm sure it draws and demands more power. Which alternator should I replace with? My car is a 1997 Honda Civic DX, with upgraded OEM power windows.

 

Maybe there are alternators from other engines that use the same type of alternator you could use... I say this because on W-bodies we can upgrade to a 125amp, or if we replace the bracket and tensioner, a 140amp. These came stock on certain other vehicles.

 

I'm not really sure if there are other doner engines I can source a usable alternator from. I'm finding a few reputable companies online selling high output alternators that might work for me. I'm not looking into getting anything too spectacular but I do want something to handle what I currently have and possibily other future electrical modifications.

 

Go to the phone book and look under "auto parts and supplies rebuilt" and find the guy who rebuilds starters and alternators. They usually can do it for $50 or less and have it back to you the next day.

 

Could using a dry cell battery throw the test off?

I've heard this regarding the Autozone testers, but it's uncommon for dry cell batteries to come in. But I have a dry cell Buddy Club battery and even though the car is running great the Autozone charging system test shows it's testing low.

 

Ok I just did tests 1 and 2 only but here were my results.

1. 12.5
2. 14.38 ish

My battery light came on so I did these tests. I drove 20+ miles with the light on I would assume the battery would have died within that 20 miles with lights and heater on. I had no dimming of lights or anything on the way home.

I think the shitty wiring someone did to put new gauge face lights in is the culprit of the light being on. Time to rip more **** out. If someone thinks different please let me know. I'm going to drive the car into work tomorrow so I guess I'll find out anyways

I also put the multi meter on the alternator and got a solid 14.5

 

Do the important 3rd test.