Not enought Volts

Post by **westyguesty** » 04 Feb 2008, 20:50

I'm confused on how to track down my problem with charging.
I've got a 86 Westy and most things are working now, but i can't work out how to get to the bottom of my charging / batteries problem.
A new lesiure battery was installed a few months ago, but if I don't use the van for a week or so, the battery was going flat, driving the van for a while will put some charge back into it, also just got the 240v working, including the charger.
The problem I have is the voltage at the alternator is about 12V (with the engine running), and just under 11V at both batteries (without the engine running). I thought faulty alternator/regulator, however after connecting to 240v for 48hours, both batteries are showing just under 12v. I can't work out if I have a fault with both batteries, or with both chargers. When I check the voltage on the batteries, it starts at about 11.5v, but counts very quickly to just under 12v, where it stops.
I've not had any problems starting the van, but the leisure battery does go flat (250mah drain for the stereo and 50mah for the heater control explains that). I'm guessing this would be Ok if I was getting enought charge in the batteries.
Any idea what I need to do next.
Thanks

Post by **jamesc76** » 04 Feb 2008, 20:52

check resitance on the cables esp. the earth straps could be that not allowing enough current flow????

Post by **Dan Wood** » 04 Feb 2008, 20:53

Is it worth trying another voltmeter, just in case yours reads a little low?

Post by **westyguesty** » 04 Feb 2008, 21:31

Not thought of the earth cables, could that effect the alternator reading aswell ?

Got a new voltmeter at the weekend, as i thought that was the problem, but both reading the same.

Post by **VWCamperfan** » 04 Feb 2008, 22:23

If your batteries are going flat and your voltage is showing low across terminals when connected to van, it could indicate a partial short in the voltage regulator on the alternator. This would also cause charging problems.
Check voltage of batteries when connected to van and when not connected. If voltage is higher when not connected then that would indicate a short or power usage somewhere.
To trace fault, disconnect positive terminal on battery and wire in meter between battery terminal and disconnected battery connection. Set voltmeter and connections to read up to 10 amps (the usual on most metres) and check reading on display. If you have an ampeage reading then there is a load draining power somewhere. If it is small then it could just be a clock or the stereo and is nothing to be concerned about. If it is higher then start by removing one fuse at a time and checking reading again. If the reading drops then that is the circuit where power is being drained and needs to be investigated further.
To check the alternator for power drain, simply disconnect the connector on the rear of the alternator and check meter reading again. Same applies as for fuses here... If the reading drops, then the fault is there.

Hope this helps.

Post by **lhd** » 04 Feb 2008, 22:29

shouldn't the alternator be producing 14v ?

Post by **irish.david** » 05 Feb 2008, 01:20

If your alternator is producing 12v then you've got a problem. As lhd says it should be producing 14v.

Just to make sure, to take the alternator voltage you're measuring between the large bolt with the big wire attached on the alternator and the metal body of the alternator itself. If that is 12v then you need to replace or repair (new regulator and/or bushes) your alternator. If it's 14v then check the voltage between the large bolt with the big wire attached on the alternator and a good solid chassis ground (i like the catch for the boot lid). If it's 12v or lower you need to renew the earth straps on your engine and gearbox. If it's 14v then you need to check the wiring between the alternator and battery.

The standard westy charger can output 8 amps so if you have left both batteries charging for 24 hours then that more than enough time for both to get fully charged. This means that there's a problem with both batteries (could be if they've been fully discharged for too long), a problem with the charging circuit (unlikely as the alternator and the westy mains charger have separate wiring), or a problem with the mains charger (i'm biased cause mine was dead but they are over 20 year old....).

Try disconnecting the battery feeds from the mains charger and check the output of said charger to see if it's ok (you can find info on the wiring on a previous post called "westy battery charging").

My personal feeling from what i've read is that your alternator and your mains charger are kaput but i could be wrong. Keep us informed.

Dave

Post by **westyguesty** » 05 Feb 2008, 20:39

Thanks for the help, sorted now. Part me not reading instructions

and one faulty voltmeter. I tried the voltage at the alternator, on the case and terminal and still only 11-12v, same at the output of the bbb charger under the seat

Tested the voltage on my car, and the same.

The one voltment was faulty and gave a similar reading all the time, my new one has two volt settings, one for batteries and one ac (or that's what it looked like). After reading the manual the battery one is designed to read max 9v (not sure how it was getting to 11v) and the other is either ac or press the range button and then dc. Showed just over 14v at both batteries with engine running. 14.2v with just the charger plugged in. Few hours wasted, but learnt alot.

Next question that's probably easy is how can I tell the amps running when the eber is on. Tried disconnecting the earth from leisure battery and putting the meter between the earth and negative terminal (that's how I found 250mah drain from the stereo - might be looking for a new one), but when I try to start the eber after a few seconds the voltmeter beeps and turns off, along with the eber. I was thinking of getting the eber running, leaving for 5 mins then pull the earth cable of the battery while trying to keep the voltmeter connected. I want to make sure it's not pulling 20A all the time. Got at 65mah battery, so I should get 50 ish hours running from it if all's well.

Post by **lhd** » 05 Feb 2008, 21:14

when you fire up the eber keep the battery indicator LED's(kitchen unit) on, you should then see if the glowplug gets turned off.
the indicators should be green before the eber kicks in then change to either orange or red depending on the condition of battery/power source.
If all is ok once the heater has got hot enough the LED's should go back to green.
This wont tell you how much its drawing but is a good indicator if the glow plug is staying on.

Post by **VWCamperfan** » 05 Feb 2008, 22:18

The meter beeps because you are pulling about 20 amps when the ebber starts. As I stated earlier, most metres will only go up to 10 amps and complain a bit when you go over this!

Post by **westyguesty** » 06 Feb 2008, 17:31

Thanks everyone, all sorted.

Heater off 12.32v (orange light on the LEd though - only get green when charging)

Heater on 11.83v

Heater on after a few minutes 12.20v

Post by **Red Westie** » 08 Feb 2008, 00:29

Lead Acid Battery has 6 Cells each producing approx 2.1 volts.
6 X 2.1 = 12.6 volts, this is an approx voltage for a static/charged battery in good condition.
Bosch alternators around this era had voltage regulators set tollerance of 13.8-14.2 volts
Voltage under cranking (no lower than 10 volts)
Fully charged hydrometer specific gravity of 1.280
Bushes and regulators were the common failure.
An amp clamp is the best way to check battery drain.

Martin

Post by **lhd** » 09 Feb 2008, 11:45

It sounds like the battery is the problem.

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