Alternator brush pack / regulator types & part numbers

[bigherb]

Yep all at 2000rpm for constancy.

[T3luestar]

Been reading this thread with interest, so I thought I'd throw the testers on my alternator to see what output I was getting. At the alternator the meter readings were, 13.6 volts and 30amps! The alternator it's self has a pink label which I believe is a 90amp unit, as fitted to a Bluestar. What is the likely problem, the alternator? Or would it be worth replacing the brush pack?
Thanks for any helps guys.

[1664]

Just because it's a 90A alternator does not mean it will supply that constantly. If the van electrics only require 25A at any given moment then that's all it will supply. Heaviest demand (ignoring flat leisure battery scenarios) would be after a difficult winter engine start (e.g a few cranks) immediately followed by headlights and fog lights on, blower fan full on and heated rear window on I'd imagine....probably chuck a fair whack out trying to recharge a partially drained starter battery and run all that equipment simultaneously.

[T3luestar]

Thanks for the information, started panicking for a minute. No need to cancel the turkey!

[California Dreamin]

Been reading this thread with interest, so I thought I'd throw the testers on my alternator to see what output I was getting. At the alternator the meter readings were, 13.6 volts and 30amps! The alternator it's self has a pink label which I believe is a 90amp unit, as fitted to a Bluestar. What is the likely problem, the alternator? Or would it be worth replacing the brush pack?
Thanks for any helps guys.

What voltage do you have at the alternator 'without load'? really needs to be high 13's .

Martin

[T3luestar]

What voltage do you have at the alternator 'without load'? really needs to be high 13's .

Martin

Getting 13.8 volts at the alternator and around 13.6 volts at the battery.

[ghost123uk]

Getting 13.8 volts at the alternator and around 13.6 volts at the battery.

That's OK, some might prefer / recommend higher, but that is within normal spec.
I bought (a couple) of new regs to get 14 and a bit volts but 1 of them only gives 13.6 at the alternator (it is rated at 14.5 on the case !) and the 14.2 volt one gives 14 at the alternator and 13.8 at the battery (with minimum load)

The higher the voltage the faster it will replenish the battery(s) if they are run down. Other than that it is not an important issue.

@ "T3luestar" = How did you measure the (30 amps) current

[T3luestar]

@ "T3luestar" = How did you measure the (30 amps) current

Sorry mate getting confused with meter readings and bad advice from a friend.
Having investigated what is actually involved in measuring the current draw, I can understand why you asked the question. Watched a youtube video of a company making and testing a 400amp alternator and I don't own that kind of test equipment!!!

[ghost123uk]

.

[California Dreamin]

@ "T3luestar" = How did you measure the (30 amps) current

Sorry mate getting confused with meter readings and bad advice from a friend.
Having investigated what is actually involved in measuring the current draw, I can understand why you asked the question. Watched a youtube video of a company making and testing a 400amp alternator and I don't own that kind of test equipment!!!

Indeed...most hand held digital multimeters only go upto 10amps.

Martin

[1664]

Just thought I'd mention that cheap/DIY meters are not the most accurate machines, and you should take any readings as a 'ball park' rather than 'gospel' figures.

[ghost123uk]

Just thought I'd mention that cheap/DIY meters are not the most accurate machines, and you should take any readings as a 'ball park' rather than 'gospel' figures.

Yes this is very true.

I have 6 meters in total (note = I am / was an electronics engineer )

2 of the common or garden "yellow" ones of the type you get for £12 on ebay / Maplins etc are at least 1/2 a volt out @ ~13 Volts

The dash mounted LED readout thingy I got off ebay from the van is rubbish with the accuracy wandering about all over the place, even though it does have "trim pots" inside. Useless really for accurate charging voltage monitoring. (and I know some on here are using them for just that )

My "proper" bench meter and 2 of my "proper" hand held ones ARE accurate. I check them every so often with a voltage reference source (MAX6250 I.C.)

Even with a meter that has a calibration adjustment (and many don't), finding an accurate source voltage to compare against is not as easy as might be thought.

I would recommend anyone who is not sure of their meter (and needs it to be accurate) to go along to someone who has a calibrated meter and get theirs checked against that. As I am writing that I realise that doing that may not actually be practical for many. Off now to find an easy way to get an accurate voltage reference. p.s. 7812 regulator chips (etc) are not accurate enough