flak monkey
|
| posted on 24/4/09 at 07:04 AM |
|
|
More alternator woes?
Noticed on my datalogs that my batt voltage will occasionally drops to about 11.9 volts whilst driving then pops back up to 13.5 volts. Happens fairly
often.
What's it likely to be? My guess would be voltage regulator (I can get a new one if thats the case) or could it be something else?
David
Sera
http://www.motosera.com
|
|
|
|
|
02GF74
|
| posted on 24/4/09 at 07:15 AM |
|
|
or it could be the brushes?
or worn/corroded slip rings?
or even a loose or corroded connection? (NB wiring to your data logger must be considered suspect until proven otherwise.)
or slipping fan belt?
check the simple (cheap) thing first! i.e. all the wires to the alternator, if it is eartthed via body, ensure that is good all the way to the -ve of
battery.
having too much info. is sometimes a bad thing - do you see your charge lamp coming on? That would confirm alternator is not charging, especially if
the battyer is getting flat.
if it is found to be the alternator, then there are test to identify the cause - most common is rectifier/regulator that can be bought for ususally
about a tenner.
you sorted out your miss firing? is it possible that the alternator voltage dropping is affecting the ignition?
anyways, whaddy doing playing with cars when you have a wedding to plan/pay for!  !!
|
|
|
flak monkey
|
| posted on 24/4/09 at 07:46 AM |
|
|
Misfiring is temp fixed until after stoneleigh, once thats passed I'll do a proper job of it.
Both MS and dash are shwong the voltage drops I doubt both have the same bad connection at the same time.
Alternator was rebuilt a while back after I siezed it up. Not sure if the problem existed before or not. All contacts were cleaned when I put it back
together.
Charge light doesnt come on when the voltage drops.
Will have a look tonight and see if swapping the regulator makes any difference and will carry the other as a spare.
Slip rings are good
Sera
http://www.motosera.com
|
|
|
02GF74
|
| posted on 24/4/09 at 08:04 AM |
|
|
quote:
Originally posted by flak monkey
Misfiring is temp fixed until after stoneleigh, once thats passed I'll do a proper job of it.
What was it in the end?
Both MS and dash are shwong the voltage drops I doubt both have the same bad connection at the same time.
Are they connected to the same point?
Charge light doesn't come on when the voltage drops.
For how long does the drop out occur? Just had a look, and if the recrtifier/regulator is bad, it does not mean the charge lamp will dim
- sorry for misnfo. Can you connet one logger to the charge lamp, alternator side?
|
|
|
stevec
|
| posted on 24/4/09 at 08:57 AM |
|
|
Could also be a dodgy cell in the battery.
And as said is this the cause of you other problem?
Steve.
|
|
|
flak monkey
|
| posted on 24/4/09 at 09:17 AM |
|
|
I dont think its the cause, as I am seeing voltage drops which dont correspond to spikes in any way.
Not sure what the cause of the misfires was in the end. Changed the coil to a different type and the input circuit on the MS board. Still seeing lots
of noise on the dash, but the ms signal is clean.
The dash and MS pick up their voltage input from different places.
The drop outs usually last for 20-30secs and at any RPM. Probably once every few minutes.
I will check the battery with a hydrometer later. Charged voltage reads 12.4 so seems ok.
Sera
http://www.motosera.com
|
|
|
neilj37
|
| posted on 24/4/09 at 11:32 AM |
|
|
I had the same problem and found out it that the connector into the back of the alternator was a little loose. The voltage would always drop under
hard acceleration which was causing the connector to pull out of the back of the alternator as the engine moved because the cables were tied to the
chassis.
|
|
|
flak monkey
|
| posted on 24/4/09 at 07:07 PM |
|
|
Just been playing around and went for a drive.
Ok for about 8 miles, then intermittent for a couple of miles, now no charge at all, batt light is on now....  Will see what its like when its
cooled down.
Belt is tight, brushes look ok on rectifier.
Will try another rectifier tomorrow with new brushes to see if that fixes it.
If that doesnt then looks like another weekend of buggering around
Sometimes I think the car knows its getting an engine change and is making these next few months as difficult as possible!
David
Sera
http://www.motosera.com
|
|
|
flak monkey
|
| posted on 25/4/09 at 09:54 AM |
|
|
Still dead this morning. Had the alternator off again and apart. All looks ok. Plenty of length on brushes. Put it together again and now seems to be
working again. 
I have a feeling its a dodgy connection between the alternator body and the rectifier block. Seems odd the problem started after I had the alternator
apart the first time. Must be a loose connection somewhere, finding it is as always the fun part!
David
Sera
http://www.motosera.com
|
|
|
