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Alternator not charging

13K views 15 replies 2 participants last post by  Aleks 
#1 · (Edited)
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#5 ·
This from the SM - for gasoline units. Sounds the same.

The PCM receives a voltage input from the alternator and also a battery voltage input from the TIPM, it then compares the voltages and if there is a difference it send a signal to the alternator EVR circuit to increase or decrease output. It uses a pulse width modulation (PWM) to send signals to the alternator circuitry to control the amount of output from the alternator. The amount of DC current produced by the generator is controlled by the EVR (electronic voltage regulator) circuitry contained within the alternator.
All vehicles are equipped with On-Board Diagnostics (OBD). All OBD-sensed systems, including EVR (electronic voltage regulator) circuitry, are monitored by the PCM.
 
#3 ·
According to the part cross-referencing it is the one in the pics.
 
#6 · (Edited)
I'll need to investigate that a little further, the manual is ambiguous on this.

The wiring diagram (8W-20-2) shows the PCM directly driving the alternator field coil.
The fact that a PWM (pulse width modulated) driving signal is used tells me that the field (at least on my car) is directly driven by this signal - no need for a regulator in the alternator..

PWM is a method of rapidly switching a DC voltage on and off with varying on and off time ratios. This switched voltage is fed to the field coil. longer off time vs. on time lower field current longer on time vs. off time higher field current.
The field current is automatically adjusted to maintain a constant alternator output under varying engine speed and load conditions. Also, a slight amount of output voltage adjustment is made to keep the battery fully charged under varying ambient temperature conditions.

http://en.wikipedia.org/wiki/Pulse-width_modulation

Probably TMI, but the basics are in this article.
 
#7 ·
Too much info?

I have ordered the regulator. $29

Chrysler are charging $800 for a new alternator.

I understand the PCM controls the charging but there is a failure.
Since the PCM 'uses' the regulator that's the bit I'm gunning for.
 
#8 ·
Back purring and on the charger. It WAS the Bosch Regulator
a $29 part instead of dealer quote of $800 for a new alternator.

The markings on the original Mopar fitment are

Bosch BR14-HO
F 00M 145 296
Made in Mexico
68315 095139 3RO
F 00M 145 431 - housing?
123873.48 - brushes ?

I only had 38k mi so no wear on the alternator shaft, if it went after another 40k mi I would replace the alternator discounted at £150/$245.

Access is not available in situ so the alternator has to be removed anyway.
Dodge labor book is hour off hour on plus the time to changeover the regulator (half-hour). Labor and tax came to another $460.

Definitely change the regulator if doing it yourself.
 
#9 ·
Battery has been on charge for two weeks now, no sign of it approaching a full load.

I think contributing factors to overloading the regulator were low battery, high drain - lights, wipers, heated window & seats, a/c demist

I had not recharged it for more than a year, Something to bear in mind when turning on additional items.
 
#10 ·
Aleks,
How are you determining the state of charge of your battery?
Most chargers (except trickle chargers) can get a dead battery up to full charge in 24 hours or less.
The regulator controls field current, usually 5 amps or so. Load on the alternator will not directly affect the regulator.
 
#11 ·
It's one of those computer controlled units, uses lower boost to protect the cells and get more juice in. There are LED indicators that pulse at different rates for state of charge.

My bike would recharge in 6 hours.
Different traditional car batteries would fill in 20 to 40 hours.

The Mopar / Optima Spiral would recharge in 8 days during first year.
On a previous discharge in took 2 weeks so that was my expectation.

This was a total discharge to the extent of killing the motor on idle, so I was hoping maybe 3 to 4 weeks would revive it.
Either 3 years is too much to hope for or I have damaged the cells with the discharge.
Still runs though so may get through to the fall before investing in the new AGM style.
 
#12 · (Edited)
OK on the charge indicator, how many amps does the charger put out at high charge?
The charge times you post seem to be way longer than I've ever seen. In the "good old days" of open cells, I used a hydrometer to check the electrolyte to determine the state of charge. Can't do that with a lead-acid dry cell battery like you have. Can't do that on my new battery either - it's completely sealed (not sure if it's a wet cell or an AGM type).

An older battery that has been overdischarged may never be able to be revived fully.
 
#13 ·
Put my injunear hat on so here's the science bit

The Mopar / Optima spiral was replaced by Dodge under warranty in Jan 09

It's 48AH 800 CCA

The charger was putting out 14.1 v

When I took it off charge the battery voltage started at 13.8 v and was falling settling to 13v after a few mins when I stopped measuring.

The indicator today was showing approaching a charge status.

After my fiddling and the interior courtesy light for 5 mins it went back to charging but hey that's good enough for me so I've taken it off.

The meter only goes to 10A so obviously I've not measured that.
 
#15 ·
Update - after 6k miles and just under 12 months the repaired alternator has packed up. Intermittent charging light then after a 3 day recharge turned continuous.
Christmas tree lights in last 1/4 mile to the dealer forecourt.

VW dealer no longer services Dodge UK. All computers and parts were transferred to FIAT UK last month. They jumpstarted me but had no throttle response with flattened battery. Could not move the mile to the FIAT dealer besides the mechanics with 16 years Jeep experience and VW engines are here.

Agreed I would source the alternator for them and they would replace without tech support.

Like others said alternator repairs are not economic especially if paying a mechanic to do them.
 
#16 ·
Interesting fact find. Another flat battery mid-winter. Had the charger on it for a week with no change in the indicator.
Background is that I had repaired and replaced the alternator with a prior battery swap.
Dug out the old Mopar spiral from 3 years storage and checked the charge, fully recharged in 1 hour.
Brought the Optima into the kitchen and it fully recharged in 12 hours.

From previous experience it looks like these spirals will not reach a full charge condition in low temperatures.
 
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