CRV Charging System

supton

supton

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Figured I'd start a new thread, as I got help in the other, but it was aimed at an ABS issue.

2003 CRV, battery is a bit under 5 years old and shows 60% life. Battery light keeps coming on, after sitting a bit. But then goes out and seems fine, once you start driving?

Today I hooked up the meter and cranked, and while in the past, if I rev'd it up, eventually it'd start charging and be fine. But today... no go, sat at 11.6V headlights off, 11.4 headlights on. Thought the alternator was bad... then the cooling fans kicked on (HVAC left in defrost mode, engine nowhere near operating temp, so no idea why it was cycling, 45F or so ambient, after a frost). And now it's sitting at 14.6V, lights on or off.

Any idea why having the cooling fans cycle on enables the alternator to operate properly? I could buy a bad ground, somewhere, but the alternator continued to sit at 14.6V after the cooling fan turned off. There's something intermittent here, but I'm not sure where to look. I watched an Eric O vid on monitoring the field line from the alternator, but I don't have a wiring diagram (let alone Eric's expertise at debug).

Am watching a vid on how to replace the alternator, boy that looks fun... and ours has some minor damage in that area, condenser is shoved into the radiator, so a bunch of stuff is tweaked, so if the alt has to come out, it'll be a yet more fun job.
 
supton said:
Figured I'd start a new thread, as I got help in the other, but it was aimed at an ABS issue.

2003 CRV, battery is a bit under 5 years old and shows 60% life. Battery light keeps coming on, after sitting a bit. But then goes out and seems fine, once you start driving?

Today I hooked up the meter and cranked, and while in the past, if I rev'd it up, eventually it'd start charging and be fine. But today... no go, sat at 11.6V headlights off, 11.4 headlights on. Thought the alternator was bad... then the cooling fans kicked on (HVAC left in defrost mode, engine nowhere near operating temp, so no idea why it was cycling, 45F or so ambient, after a frost). And now it's sitting at 14.6V, lights on or off.

Any idea why having the cooling fans cycle on enables the alternator to operate properly? I could buy a bad ground, somewhere, but the alternator continued to sit at 14.6V after the cooling fan turned off. There's something intermittent here, but I'm not sure where to look. I watched an Eric O vid on monitoring the field line from the alternator, but I don't have a wiring diagram (let alone Eric's expertise at debug).

Am watching a vid on how to replace the alternator, boy that looks fun... and ours has some minor damage in that area, condenser is shoved into the radiator, so a bunch of stuff is tweaked, so if the alt has to come out, it'll be a yet more fun job.
Click to expand...
Most cars are wired such that the A/C turns on when in defrost mode to help dehumidify the windshield. I'm pretty sure the cooling fan(s) will cycle on when the compressor is engaged on a Honda. As such, I suspect the increased electrical load induced by the fan(s) was detected by the ELD and allowed the alternator to output full voltage at 14.6 volts.

If you decide to replace the alternator, I suggest using the method that does not require removing the tensioner pulley and power steering pump or removing the radiator. I was able to complete the job in 90 minutes by following this video.



The only precaution I have is to only loosen, but not fully remove, the 10mm bolt that holds the bottom of the "T-bracket" crossmember in place (poorly shown at 5:30 into the video). The opening in the bottom of the bracket is slotted and will slide up and off without removing the screw. It was very difficult to reinstall the 10mm screw when I unwittingly removed it.
 
supton said:
Figured I'd start a new thread, as I got help in the other, but it was aimed at an ABS issue.

2003 CRV, battery is a bit under 5 years old and shows 60% life. Battery light keeps coming on, after sitting a bit. But then goes out and seems fine, once you start driving?

Today I hooked up the meter and cranked, and while in the past, if I rev'd it up, eventually it'd start charging and be fine. But today... no go, sat at 11.6V headlights off, 11.4 headlights on. Thought the alternator was bad... then the cooling fans kicked on (HVAC left in defrost mode, engine nowhere near operating temp, so no idea why it was cycling, 45F or so ambient, after a frost). And now it's sitting at 14.6V, lights on or off.

Any idea why having the cooling fans cycle on enables the alternator to operate properly? I could buy a bad ground, somewhere, but the alternator continued to sit at 14.6V after the cooling fan turned off. There's something intermittent here, but I'm not sure where to look. I watched an Eric O vid on monitoring the field line from the alternator, but I don't have a wiring diagram (let alone Eric's expertise at debug).

Am watching a vid on how to replace the alternator, boy that looks fun... and ours has some minor damage in that area, condenser is shoved into the radiator, so a bunch of stuff is tweaked, so if the alt has to come out, it'll be a yet more fun job.
Click to expand...
The battery is bad.
Honda alternators are battery excited, and when the battery goes bad the alternator won't put out. If anybody thinks that I'm full of crap, just start your Honda and remove the battery cable while it is running and you will see for yourself. Your battery is right on the line.
You are lucky that you got 5 years out of the chicken-crap 51R motorcycle battery, I don't get more than 3 years out of them, regardless of the battery manufacturer.
 
wag123 said:
The battery is bad.
Honda alternators are battery excited, and when the battery goes bad the alternator won't put out. Your battery is right on the line.
You are lucky that you got 5 years out of the chicken-crap 51R motorcycle battery, I don't get more than 3 years out of them, regardless of the battery manufacturer.
Click to expand...
I’ve been reluctant to replace, as that is the shortest lived battery I’ve had. I don’t mind replacing, well its $150, but I’m willing to, especially if that fixes the problem. I don’t mind shotgunning cheap parts, but a battery didn’t seem cheap.
 
supton said:
I’ve been reluctant to replace, as that is the shortest lived battery I’ve had. I don’t mind replacing, well its $150, but I’m willing to, especially if that fixes the problem. I don’t mind shotgunning cheap parts, but a battery didn’t seem cheap.
Click to expand...
Replace the battery and you will be good to go. Trust me. Report back.
 
supton said:
On a separate wire I thought, as controlled by the regulator, no? don’t think it needs full 12V to get current out.


Have a cheapo digital tester, it shows 60% (capacity?). Usually above 70% SOC.
Click to expand...
12v will still work, but 11.4v-11.6v is going to cause charging system output problems.
 
supton said:
I’ve been reluctant to replace, as that is the shortest lived battery I’ve had. I don’t mind replacing, well its $150, but I’m willing to, especially if that fixes the problem. I don’t mind shotgunning cheap parts, but a battery didn’t seem cheap.
Click to expand...
Supton, if you replace the battery on this CR-V, I suggest doing the common upgrade from the tiny 51R battery to a stout Group 24F battery. It only requires a minor modification of the battery tray and hold down bracket. 24F batteries are the most commonly available size and available for as little as $65. The 24F battery offers substantially more cranking amperage and reserve capacity than any 51R unit.



CR-V Battery Upgrade to 24F
 
supton said:
On a separate wire I thought, as controlled by the regulator, no? don’t think it needs full 12V to get current out.
Click to expand...

There's usually a sense wire connected at or near the battery which measures the voltage there, which is used to control the output of the regulator. Another wire supplies power to the regulator. Two separate wires, one to measure voltage, one to supply power. The reason why they are separate is to get an accurate voltage reading for the regulator--the power supply wire will have voltage drop which means it can't provide an accurate reading, so a separate wire is used just for measuring voltage.

supton said:
Have a cheapo digital tester, it shows 60% (capacity?). Usually above 70% SOC.
Click to expand...

Doesn't sound like the battery is the problem to me.
 
supton said:
But today... no go, sat at 11.6V headlights off, 11.4 headlights on. Thought the alternator was bad... then the cooling fans kicked on (HVAC left in defrost mode, engine nowhere near operating temp, so no idea why it was cycling, 45F or so ambient, after a frost). And now it's sitting at 14.6V, lights on or off.
Click to expand...
Does it have a decoupling pulley? The condition of the battery is irrelevant to the function of the alternator. As long as there is some load, the alternator should be charging. Even if the battery is down to 8 volts, the alternator should put out.
 
If CCA is less than 70% of listed on the battery or life left is less than 70% replace the battery.


Many upgrade to a 24F for CR-V's.


There are threads on "Honda CRV owners club" forum of how to do this upgrade.


You need the battery tray from a 2013 Odyssey and if you want to do it right you also get the battery cover for same.


Your existing hold down clamp and J bolts will work with the upgrade.
 
atikovi said:
Does it have a decoupling pulley? The condition of the battery is irrelevant to the function of the alternator. As long as there is some load, the alternator should be charging. Even if the battery is down to 8 volts, the alternator should put out.
Click to expand...
Honda alternators have a fixed pulley and the alternator is constantly spinning when the crankshaft turns unless the serpentine belt breaks. However, this vehicle has an Electronic Load Detector (ELD) which regulates the alternator's output by monitoring the current electrical load demand. Its purpose is to reduce alternator drag when additional load is not needed to conserve a minute amount of fuel. When the ELD or the alternator's built-in voltage regulator malfunctions, you will experience all kinds of voltage transients ranging from low to high (~8 to ~17 volts). By his description, the ELD seems to be doing its job.

I suspect a bad alternator or dying battery. Perhaps temporarily swap out the battery with one from another vehicle if compatible.
 
Last edited:
atikovi said:
Does it have a decoupling pulley? The condition of the battery is irrelevant to the function of the alternator. As long as there is some load, the alternator should be charging. Even if the battery is down to 8 volts, the alternator should put out.
Click to expand...
Negative. Not on a Honda.
I can't tell you how many times I have run into this exact problem in the better part of 45 years that I was working in the car business.
 
One of the things I don't like about Hondas is that they mount the ground to the chassis on a painted surface. Paint is insulator. They are relying on the bolt to conduct electricity from the part of it that touches the lug and then the threads of the bolt to the chassis. It's better to Simply scrape off the area with a 1/8 inch straight blade screwdriver and then coat it with some electrical contact cleaner and also scrape the lug and spray that and then put them back together. Probably not your problem but it is a much better ground once you clean it up like that.
 
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