Altenator charge under load

[nesty]

Read the WIKI bit and I am gussing something wrong with my Alternator. I done investigation today.

I got a Holdsworth 1984. I inspected my Alternator today. There are no markings on it or a label, all worn off. It looks fairly used, so guessing it’s a 45 AMP version.

Anyway started up here is my voltage readings

Battery
12.6v - engine off
13.7v - Engine running; no load
13.1v – Lights on
12.7v – Lights, Fan Blower & wipers

Shouldn’t the voltage be higher then that under load?

[toomanytoys]

Yes.. IIRC it ought to be 13.6-14.4 really... does it improve if you raise the revs a bit..?? sounds like the brushes could be a bit worn.. thats the cheapest way to keep it going a while longer if it isnt "bearing noisey"...

[nesty]

ok thanks. With high revs doesn't really get any better. The Altenator looks quite old. I was thinking of taking the plunge and uprating to a 90amp. I have a lot of added electrics on board now.

[kevtherev]

as toomanytoys says the brush pack needs renewing.. at a tenner it's worth a shot. as the pack fits the 90 amp one as well.
Incidentally I fitted a 90 amp alternator with no discernible benefit, I have now refitted the original

[nesty]

as toomanytoys says the brush pack needs renewing.. at a tenner it's worth a shot. as the pack fits the 90 amp one as well.
Incidentally I fitted a 90 amp alternator with no discernible benefit, I have now refitted the original

Really? Ok I thought a 90amp alternator would replenish the power quicker?

I have a power hungry stereo system and a few fog/driving lights, so unsure the 45amp alternator would cope?

What I’ll do I’ll get a new brush pack and give it go and see if it copes. Who sells the packs. I thought I saw a thread on here a place in Birmingham sells them? I couldn’t see the pack listed on GSF website.

[kevtherev]

yes birmingham.. search the tech forum for alternator brush pack red westie found them.

I too have a telly, toys, fogs, Lamps and a 50watt head unit with an amp + sub.

all taken in it's stride. I have fitted a voltmeter and ammeter to see what's going on, it's nice to see that it copes very well.

[Simon Baxter]

Volts tell you knob all.
You need an ammater to check alternator output.

An alternator is 3 phase, if a phase goes down then the alternator is still capable of putting out the correct voltage, but it won't have the amps behind it (all mouth, no trousers if you prefer)

A clip on ammeter is whats required for checking the output of an alternator.

[nesty]

OK Cheers I have the Facility to install a Ammeter, as my digital Voltmeter is dual function (volts/amps. However didn't like the set up of the shunt being so close to the battery terminals. You got a gauge KevtheRev?

[Red Westie]

Rectifier (diode pack) which is built in to an alternator, controls the conversion of 3 phase AC to DC output. Diode packs can fail but rarely in comparrison to the regulator/brush packs.
Contact details for the regulator/bush pack supplier:
Vehicle Electrics (Birmingham Ltd) The aftermarket number for MY alternator (yours may be different) was VERG 1009 but they have a list to cross reference your particular aternator number against so you can order the correct item. Mine was £9.70 incl post.
CONTACT VEHICLE ELECTRICS, 166 STOCKFIELD ROAD, ACOCKS GREEN, BIRMINGHAM, B27 6AU. TEL : 0121 706 0688 EMAIL: VEHICLEELECTRICS@AOL.COM
Martin

[nesty]

Cheers thanks for this. The only prob I think I will encounter all my marking have worn off on the Altenator. Hopefully there is a S/N on the regualtor?

[ermie571]

Volts tell you knob all.
You need an ammater to check alternator output.

An alternator is 3 phase, if a phase goes down then the alternator is still capable of putting out the correct voltage, but it won't have the amps behind it (all mouth, no trousers if you prefer)

A clip on ammeter is whats required for checking the output of an alternator.

Simon, thanks for this information. Can i ask for a little more as I didn't know this . Can we have a guage somewhere in the cab? Is this clip on tester something you put on just to test, rather than continually monitor? Finally, what amps mean its ok, and what amps mean its on its way out?

Thanks

Em
x

ok - done a little googling...found this http://www.type2.com/library/electrip/altertip.htm" onclick="window.open(this.href);return false;
some interesting info (know its bay, sorry, but the basics are similar!). Do those in the know agree with the content?


Em
x

[Red Westie]

I'm not sure what types of ameters are available but to read the sort of current flowing in a charge circuit the meter would need to be fairly substantial (if connected in series). I have seen a few clip on sensor type ameters that don't actually carry the current but just sense the current by induction. These are more useful and much safer to use. However, I'm really not sure if these are available to mount in dash?

Martin

[ermie571]

Thanks Martin,
have seen the clip on ones for testing - will look at getting one of those.

Em
x

[kevtherev]

click to enlarge




I find the voltmeter very good when all the toys are on.. it can drop to 12.5v when blowers stereo headlamps and front fogs and the telly are on.

the ammeter shows the charge to all the batteries, After a weekend camping trip to the Duke of York, using the propex (all night), lights and stereo, the readings are thus....

when I get in and switch the ignition on for the two hour trip home...
the needle swings to minus 12 amps, cranking then sends it to minus 16 amps.
Once started the ammeter shows a + ve charge of 18 amps, reducing quickly (5 - 8 mins) to around 8 amps, after an hour it's down to 2 and by the time were home it's zero.

I'm not charging leisures, I'm charging three starters (two as aux in parallel @ 150 A/h)

[nesty]

OK cheers for this. A lot of kit you got there!