Checked the batteries when the van was running; 12.5v on the starter Battery: 11.6 on the leisure battery.
I did have my lights on and music running, but as that is common I guess it should hinder it too much. I guess I should be getting 13.6v across both batteries?
I have a split charge relay.
So my question, how do I check that my alternator is putting out the correct charge?
thanks folks!
Josh
1984 Voltswagen 25 Pop-Top (No idea what type!?) 1.9 W/C Petrol based in Guernsey, C.I.
Whs^^^
Low volts at batt can be bad alternator but also because your batts are low on charge and the high current draw over long cables lowers the volts.
Good alt and bad cables is another possability.
Try charging your batts with a smart charger for 12 hours min and repeat the test , wait 5 or 10 miniutes before testing to allow for recharge from starting and any heaters to switch off.
Morning...I would agree with charging both batteries separately (12 hours each) before drawing any conclusions. However, in order to get an accurate reading 'without' any interference from the second battery, I would pull off (and insulate) the leisure battery terminals, then start the engine and take readings. At this point I would measure the voltage at the disconnected positive clamp and compare it with what you are getting across the starter battery.
This way you can determine whether a 'failing' leisure battery is to blame in bringing down the voltage or a faulty relay isn't allowing power across to the leisure battery..... a happily cranking engine suggests that there is nothing wrong with the starter side.
Martin
Last edited by California Dreamin on 16 Dec 2014, 10:50, edited 2 times in total.
Smosh wrote:cheers guys, I just wasn’t sure where you take the reading off?
To check the reading on the alternator, put the red probe onto the metal stud and associated nut that holds the red wire(s) on the rear of it. It should read between 13.6 Volts min to 14.5 Volts max, the higher the better.
Might also be worth checking the split charge relay - while in France earlier this year, I noticed that my leisure battery wasn't charging on a run, and discovered that when the engine was running, the leisure battery voltage dropped to 8 volts . If you switched the engine off the voltage went back up again. I can't explain it, but verified it with two different multimeters, and Sarran1955 as an independent witness! Voltage at the starter battery, and wire leading to the relay was 13.5 with engine running.
Needless to say I disconnected it - i've bought a new voltage sensing relay to fit when I get some van time
Former owner of 1983 DG panel van and 1983 Devon moonraker pop-top, 1.9 tdi (1z) conversion
John, there isn't so much as a bolt with the red wires on but a plastic connector with three wires ( I should have taken a picture! )? So I took a reading off all of them, earthing against the body of the Alternator.
The top (Blue Wire) = 13.78
Middle (Red Wire) = 13.50
Bottom (red wire) = 0.00
Does that sounds like the alternator is performing fine? I didn't have stereo or headlights running at the time; not sure if that'll make any difference!
1984 Voltswagen 25 Pop-Top (No idea what type!?) 1.9 W/C Petrol based in Guernsey, C.I.
Smosh...sounds like you have one of the older 45 or 65ah Bosch alternators with the push on block.
13.5 volts from one of the two 'large' spade connections is a little low, spec is 13.9 - 14.2 volts.
What are you getting at the starter battery? take the revs off idle to 2,000rpm.
Obviously...if you are seeing only 13.5 volts at the alternator I would expect an even lower reading at the battery once resistance has taken its toll...maybe 13.2 volts...either way, this is far too low.
I would try a new voltage regulator/brush pack ... cost about £13 posted.
If its an 84 1.9, there will be two thickish red wires that act as one. They will more than likely terminate in the black box at the back, towards the left of the engine compartment?
If both red wires are the same size, they should in fact be acting as one (ie doubled-up). If one is reading zero volts, it might be cut/disconnected en route. That may explain reduced alternator output at battery end as the ouput is running through one, thinner cable. Definately replace voltage regulator but see if my WIKI on this helps as its about reduced voltage and is probably same layout as yours:
Pay attention to pic 2 (and pic3), as thats the black box and state of those wires on mine. I cut those two red wires and ran a new thicker cable direct to starter - as explained. You'll struggle a bit as your alternator will only accept spade or a plug terminal. Just check connections across the board. If its all old and showing signs of acid corrosion, rewire as I did. I gained a volt or two afterwards.
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Have any of you guys tried one of these adjustable voltage regulator? I just ordered one from an ebay vendor here in the US and cost was $21 shipped. I have read that the campers with a house battery will have good results when one of these are attached.
I was chosen to be part of a Beta test for one of the vendors on the Samba. I was given a new alternator harness and basically saw great results form the get go. The new harnes has thicker wires and supply the injectors the 12 volts they need. What I saw first was how it smoothed out my idel and it seemed to start right up as soon as I turned the key to the On position. Here's a short video of the harness.
Can see that being a good thing, perhaps more so on an injection engine but theres a slightly higher rated voltage regulator out there too. What also reduces voltage is old or inadquate cables and as many of these vehicles are 30 years old, its not uncommon to find bad connections, frayed or decaying copper and all sorts. I suppose you'd have to be careful you weren't trying to compensate for that by simply turning the voltage up.
However, with cables in A1 condition, setting the alternator output accurately seems a great idea.
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. If you switched the engine off the voltage went back up again. I can't explain it, but verified it with two different multimeters, and Sarran1955 as an independent witness! Voltage at the starter battery, and wire leading to the relay was 13.5 with engine running.
)? So I took a reading off all of them, earthing against the body of the Alternator. 
