LST2

I have been running into dead battery issues the last month and it has gotten progressively worse to where the battery went completely dead (no start) twice in a week after full recharges. I replaced my battery with a new one and had the charging system tested in the car at the auto parts shop, the battery tested well but it was only getting 11v charge, sometimes lower. I pulled out the alternator and took it in to the parts store and it passed the test as well. That seems to narrow the problem down to wiring. The wiring looks good superficially but I have not taken a DVM to it yet. Here are some things I think I could check but I was hoping a few of the experts would chime in to add some more insight (1995 Integra LS):

-Power cable to battery
-Check voltage output at alternator power post
-Check wires to the 4 post harness to alternator (no idea what to look for)
-Check for blown fuse (is there a particular one I should look for)
-Ground wires (any particular ones that affect the charging system)

Let me know what you think.

Thanks

turbodcxbro

iTrader: (1)

Ok, start with voltage at the battery terminals, must be a min. of 12.4, then check for voltage at the back of your alternator, should be the same with a min of .2 drop. This is with nothing on and engine off.

Now start car and check voltage at battery again, should be 13.5vdc min, check voltage at back of alternator, again should be within .2vdc.

If you have still have nothing coming out of your alternator, disconnect the green regulator connector (make sure the car is off!) and you are going to want to remove the "C" wire from the plug, it should look like this:

_ _
| |

The top left horizontal pin is the "C" pin when looking into the alt, so you will want to remove the top right pin on the harness plug (sorry if thats hard to understand, its difficult to explain)

Now plug it back it and start your car up and check voltage with a DVM, if it is now charging then your ELD (electronic load detector) is bad.

LST2

Thanks. I'll try that.

slowcivic2k

ELD's do not go bad, I have yet to see one go bad.

Was your battery load tested?

What was the output in Amps and Volts for the alternator?

If your battery was fully charged and it tested 11V, you probably have a bad cell. Get another battery.

ALT/SP SENSOR Fuse 15 in most Honda's, is what controls the alternator field current.

At full load you should be able to get 14.5V and around 60A. Voltage does not indicate charging, it indicates the difference in electrical charge, IE the direction the power is moving. You can have 14V and 0A, and your battery light would never turn on.

A battery can produce 12.6 Volts because that is what each of the 6 cells is rated for, that does not mean that it is capable of pushing its amperage. A 600A battery at 12.6 volts should be able to dump 600A on its will. That battery at 12 volts can barely push 300. At the same time, that same battery can have 12.6V and push 200 or less, because the majority of the plates are sulfated, indicating internal failure.

So, if the storage ability is impaired, the alternator will attempt to force it in, usually by putting out way too much amperage (100-150A) in an attempt to charge a battery that will not accept a charge, killing itself in short order.

turbodcxbro

iTrader: (1)

slowcivic2k- you make some valid points but you are also somewhat wrong in others. ELD's do in fact go bad and the only way to get an alternator to charge is to remove that "C" pin when it does. I've been in the rotating electrical field as an engineer for Remy for over 10 years now so pardon my 'stepping on toes" but I've done my share of charging system diagnostics.

There first off, there is no fuse to directly control field current in a honda, they are all internally regulated in which an IC and MOSFET power transistor housed inside the regulator controls the field current to the rotor. This can be switched to ground or battery positve depending on whether the system is A circuit regulated or B circuit regulated.

An alternator will not produce much over its rated output either, even in a shorted plate/cell condition. A 60-70amp alternator of nippondenso IF IR variety (90% of hondas use) will never produce much more than 80amps at full field and max load. I've never seen a 60amp alternator produce 100-150amps, its impossible!

Also at full load you will not see 14.5vdc and max amperage, as amperage goes up voltage goes down and as voltage goes up, amperage goes down. This is just the way a DC charging system works. Think of voltage as water pressure and amperage or current as the water volume. Voltage pushes the current through the wires.

A typically automotive battery is fully charged at 12.6volts. Anything below 12.6 and it begins rapidly decreasing strength. At 12.0volts a battery is really only 30% charged!

dtapia

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbodcxbro &raquo;</TD></TR><TR><TD CLASS="quote">Ok, start with voltage at the battery terminals, must be a min. of 12.4, then check for voltage at the back of your alternator, should be the same with a min of .2 drop. This is with nothing on and engine off.

Now start car and check voltage at battery again, should be 13.5vdc min, check voltage at back of alternator, again should be within .2vdc.

If you have still have nothing coming out of your alternator, disconnect the green regulator connector (make sure the car is off!) and you are going to want to remove the "C" wire from the plug, it should look like this:

_ _
| |

The top left horizontal pin is the "C" pin when looking into the alt, so you will want to remove the top right pin on the harness plug (sorry if thats hard to understand, its difficult to explain)

Now plug it back it and start your car up and check voltage with a DVM, if it is now charging then your ELD (electronic load detector) is bad.</TD></TR></TABLE>

agreed with turbo i have seen 2 in the last year for the eld and after testing confirmed bad.
so yes they do fail.
is this a common thing to fail no but as these cars get older things start to fail and we see new things every day.

LST2

Thanks for the posts guys. This is very informative. I am going to be testing things out this weekend.

I do have a turbo on my car, about 500whp, for about 3 years now. I recently added an MSD digital ignition and blaster coil so that could be working the charging system hard. I also keep a laptop continously on with a power inverter, but I don't think that draws much power.

Another thing I will try is disabling the ELD through the ECU. There is an option in most rom programers to do so.

Will post back results.

LST2

Here are the results on the in car test from a few days ago:
No load: 12.16v
With load; 11.86v

I am going to disconnect the alt control "C" wire tommorow and see if it fixes it.

LST2

Well, I put the alternator back in and it seemed be putting out the correct voltage for a few minutes so I shut her down. This morning I started the car to go to work and the voltage was low again. Pulled over, made sure the connections were on good and the voltage was good again... only for a few minutes. During lunch I took a better look at the positive white cable connection on the alternator and it was not looking good. Stripped back some wire and put a new connector on it an now all is well. Seems as if it was just a bad connection after all this. I should have started there first!