[Astroboy26]

Hi everyone, I am currently having electrical problems with my car and I am currently stumped on what to do next. This will be a lot of text, as detailed as I can, as I need all the help in finding out the problem on my car,
TLDR: (Civic 1.8 2008)

• car didnt start no click on starter, healthy batt, , replaced starter with brand new,
• recharged AC with R134a, voltage drops to 10.8V when AC turns on
• brand new starter still does not click and crank at times
• battery has low voltage 12-12.2 V (6 month old bat)
• alternator voltage is dropping to 10 volts or so when compressor kicks on

My car is a Honda Civic 1.8 L 2008, which I got 2 months ago. Has 100k km on the dash, runs well, no suspension issues. I brought it in for tuning and the internals all look good, tranny is good, basically all is well. I would like to mention too that I do almost all the maintenance and repair works on my cars, and this is my 4th Honda to date.

Anywho, off to the problem at hand. 2 weeks ago, as I was to leave for work in the morning, it suddenly didn't want to start. No crank, no click on the starter solenoid, nothing. I only hear the ignition relay under the dash clicking, but that's it. Battery was at 12.6 volts that time, and the battery was new this Feb, with receipts from the previous owner.

I took off the starter, and had it checked at a nearby electric motor repair shop. They replaced the carbon brush, and resoldered the armature on to the (spindle??). It worked again when I installed it, and I was okay for a few days.

3 days after, I was going around the city doing errands the whole day (the engine was at running temp the whole day), it didn't want to start again, same thing, no click, no crank. I had the engine cooldown a bit, then it started quickly, just a very short crank then the engine is alive. It behaved like this for the next few days, just have to try a few times before it clicks then cranks, then everything is normal again.

Not sure if this is related, but ever since I got the car I noticed that the AC was not very cold on hot days, it struggles to cool the cabin under the heat of the sun and traffic. So I had a shop check the system, the pressure was low, we added R134a, and we'll monitor if it drops again. That was last Wednesday. I noticed after that the voltage drops when the compressor turns on. So low that sometimes the stereo turns off then on again. I checked the voltage with an OBD scanner, and running voltage is at 13.6-14, but drops to about 10.8 for about half a second when the AC kicks on the back up again to 14.

Not wanting to depend on a refurbed starter, I ordered a brand new replacement, then had it installed last Saturday with the help of one of my friends who is a retired Honda mechanic. I had him check my installation before, just to be sure I didn't do anything wrong. Everything was fine he said, then we installed the new starter. It started quickly and normally again, until today, Tuesday, when it's back to the original problem, where I have to try a few times before the solenoid clicks and starts.


Now I am starting to doubt my alternator, so here are my voltage readings with engine running:
Battery +/- = 12.0 - 12. 2 V
Alternator + to alternator body = 13.8-14.2 V, 10.5 V as the compressor turns on
Alternator + to Battery (-) = 13.6 V, 10.5 V as the compressor turns on
Alternator (-) to Battery (-) = (- 1.6 V) ** A voltage drop between alt ground and battery ground

Now I know that Honda alternators have this dual voltage magic that only sends a high voltage to the battery when it needs it, so I'm not sure if my readings were normal.
If the alt was not charging the battery, then why is it that after a couple of tries, the starter cranks quickly and normally? In my experience low voltage batteries try to crank the starter a bit then fails.


My next possible options are:

1. Check the wirings for the alt and starter, maybe do a big 3 upgrade?
2. Buy a new alternator???

Please, help me out here I hate to drop money on new parts that I don't need, so I wanted to be as sure as possible before purchasing anything.

Thanks and stay safe!

 

[ncyankee101]

Buy a DC amp clamp and check the current flow from the battery and from the alternator under different loads. I got a decent one on Amazon for around $45 and it has been fun to play around with.


Are you checking these voltages at idle or revving to at least 1500 RPM?

You could be getting serpentine belt slippage on the alternator pulley when the AC is turning on. How is the belt tension?

 

[Astroboy26]

Hi,alright I have a DC amp clamp, will check it tomorrow.

All these voltages are at idle, when revving at 1500 and up, all voltages are consistent at 13.4-13.8.

I checked the belts conditions, and there's no slippage and slack, everything looks good.

I am starting to think that it may be a bad battery and have it checked under warranty. Reason being is that the battery serves as the voltage regulator right? If the alternator dips momentarily below 12v, the system voltage should stay at 12v right?

When I get up tomorrow I'll check all the main wires from bat to alt and fuse box, just to see if there's any loose connections. I'll also check the current coming out of the alt.

Thanks for the tip and I'll update soom!

 

[ncyankee101]

Somehow I missed the part about failed first crank then firing up OK. In my experience that has been caused by a worn out starter motor but you have used a new one so it is not likely. Was it OEM or aftermarket? Did you bench test it before installing? Prob not necessary with OEM but some aftermarket ones can fail out of the box.

The system can only maintain voltage if the alternator is supplying enough current to all the accessories being used. Any alternator is going to struggle at idle under heavy load. I was concerned about mine at one point because I was getting voltage dropping when ALL accessories were on (including the rear defrogger which pulls a lot of current), but voltage was OK when I revved it. I found there was a 10 amp drain at idle, 74 amps at battery but 64 at the alt output. When I revved it the alt output went over 90, so I guess it's healthy since it is only rated at 80. For the record most procedures I have seen for checking the charging system don't say to turn on the rear defrogger.

 

[Astroboy26]

So I was checking all the wires earlier, and I found a loose connection on the wire going from the battery to the fuse box. It's an aftermarket battery terminal, and the wires from the alt and fuse box were terminated using round terminal lugs. The one from the alternator had a washer, while the one going to the fuse box didn't have a washer. The terminal lug going to the fuse box was noticeably more loose than the other, it had almost a 1 mm gap!

So I fixed the connections and made sure everything was snug, then tested everything again. The engine started quickly, then I had an idle relearn for 15 mins just to be sure. At no load and idle, all voltages were consistent at 13.9-14.2. I know it's not advisable, but I removed the battery connector while in idle, and the engine didn't stop. Voltage didn't drop below 13.8 at idle. Then I connected again the bat, turned up all loads, lights, AC, stereo, and voltage readings were all consistent at 13.4-14! There was no dip below 12 at all. I drove around town and did some errands for a few hours, and it started on the first try each time I parked.

Assuming that I have found the culprit to this issue, here's my theory: The high current for the starter motor may be vibrating or kicking the terminal lug, which temporarily disconnects the power as the terminal "floats" on the connector? The vibration of the compressor kicking on may also trigger the same issue, which is why the voltage drops because the battery is disconnected. The only question here is that I didn't notice the gauges flickering when it was failing to start the engine.

I will continue to monitor this condition in the next few days, and will just borrow another car if I have to drive far.

 

[jamin1]

sorry for your charging problem. Sounds about like one I had. Alternator charging dropped a
bit more than 1 volt when aircon load was added while eng was running down to about 12 v instead of normal +/- 13.5 vts. Paid dealer $135 to diagnose bad alt at only 60k miles. Advance auto would do for free.

 

[Astroboy26]

sorry for your charging problem. Sounds about like one I had. Alternator charging dropped a
bit more than 1 volt when aircon load was added while eng was running down to about 12 v instead of normal +/- 13.5 vts. Paid dealer $135 to diagnose bad alt at only 60k miles. Advance auto would do for free.

So did replacing the alternator fix the issue with the dropping voltage?

 

[jamin1]

So did replacing the alternator fix the issue with the dropping voltage?

Yes, was the fix. my routine , measure batt voltage, car off-12.6 volts. start check, voltage is 14v to batt from new alt. turnon aircon access. voltage still going into batt of 14v. yea. old alt was only inputting 12-12.5 running width aircon on.