Need new 24v alternator - URGENT

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jlager
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Need new 24v alternator - URGENT

Post by jlager » Fri Feb 03, 2017 2:09 pm

I just bought a 24v tgb 11 and I'm driving it home. I have quite a drive and the alternator died. The truck came with a spare alternator from a tgb11 radio truck but the mechanic I'm at isn't sure he can make it work. It is physically a lot larger so doesn't look like it will fit (haven't taken old alternator out yet) plus it has lots more connections and a wiring harness hanging off it. Anyone know what's needed to make it work?

If that fails, what could I buy as an alternative that is available locally? I'm currently in Pennsylvania.

Thanks!

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rmel
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Re: Need new 24v alternator - URGENT

Post by rmel » Fri Feb 03, 2017 2:55 pm

Dono much about Volvo alternators, you may want to see if it's not
the voltage regulator -- needless to say make sure ALL connections to
and from the regulator, battery and Alternator are solid and not corroded.

If the regulator is not driving the field winding (bad regulator) there will be no output.
The first test to see if the alternator is dead is to measure the battery voltage before
you start the truck, then start and you should see the battery voltage rise -- charging.
If not then you could try bypass the regulator "full field" the field winding -- connect
the Battery directly to the field bypassing the regulator. If then you see increased
battery voltage when running then it's your regulator. If that does not pan out then
your bridge rectifiers in the alternator could be blown.

Again I am not verse on Volvo's, but I'd bet it's a brand name alternator like Bosch.
Just about any Alternator/Starter shop in your area likely will be able to rebuild this
quickly. Shops around here, San Jose and San Fran can turn an alternator around
same day, or next day if they don't have the bearings or diodes -- funny, I just called
one of these shops just yesterday for informational purposes. It's more routine than
one might think.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
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dokatd
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Re: Need new 24v alternator - URGENT

Post by dokatd » Fri Feb 03, 2017 3:21 pm

If the problem is the alternator then you can take it into most alt/starter shops and have it repaired. Or you can have a 24V one wire built in a day or so like I did so I wouldn't have to deal with it anymore.

jlager
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Re: Need new 24v alternator - URGENT

Post by jlager » Fri Feb 03, 2017 3:49 pm

Swapping the alternator didn't fix it. Guessing bad regulator? Can someone tell me where the regulator is and provide dummy steps for testing if that's the problem?
Thanjs

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rmel
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Re: Need new 24v alternator - URGENT

Post by rmel » Fri Feb 03, 2017 4:32 pm

Some alternators have the regulator built into the unit.
More so for newer generations, dono about yours, but
likely it's an external regulator. How many connections
do you have on your alternator -- trace then back. Or
see if you can find the make and model stamped on the
unit and you should be able to "Google it up".
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712M

Driver: Ron // KO0Q

jlager
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Re: Need new 24v alternator - URGENT

Post by jlager » Fri Feb 03, 2017 4:48 pm

Here's the current situation. Grateful for any help.

Alternator ws swapped for a spare one from a TGB11 radio truck that came with this truck. It is not working either. Multimeter reads 24v at the batteries. Should be higher from what I understand if it was working.

Note that the "laddning" (charging) light on the dash was lighting up even with the old alternator. With the new one it was lighting up but then I just drove a while (to a hotel for the night) and it turned off. Should it always be on if the alternator is working?


It definitely has a separate voltage regulator. Previous owner just confirmed that and where it is located.

Any simple way to test it? Give me dummy steps if possible.

If it's dead, what can I use as a replacement? I'm in the middle of small town Pennsylvania so not a lot of options here.

I have a long drive home but if im just trying to make it home, what can I do as a bandaid solution? Was considering buying a small generator and running that in the back of the truck to keep the batteries charged. Is that a crazy idea?

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rmel
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Re: Need new 24v alternator - URGENT

Post by rmel » Fri Feb 03, 2017 5:09 pm

When the "charge" light went out did you see if the voltage was going up?
Again, I don't know much about these Volvo's but if it's your regulator and
if it's solid state your kinda hosed. If it were me, I'd buy a high capacity
24V charger and a good long extension cord. Travel in daylight using as little
power as possible. Recharge where you can. Maybe buy a pair of spare
batteries too. It's just hard to debug with little information -- sorry.

Someone here who is a TGB guy might chime in with some expert advise
on the Vovlo charging system.

Good luck.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712M

Driver: Ron // KO0Q

jlager
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Re: Need new 24v alternator - URGENT

Post by jlager » Fri Feb 03, 2017 5:23 pm

rmel wrote:When the "charge" light went out did you see if the voltage was going up?
Again, I don't know much about these Volvo's but if it's your regulator and
if it's solid state your kinda hosed. If it were me, I'd buy a high capacity
24V charger and a good long extension cord. Travel in daylight using as little
power as possible. Recharge where you can. Maybe buy a pair of spare
batteries too. It's just hard to debug with little information -- sorry.

Someone here who is a TGB guy might chime in with some expert advise
on the Vovlo charging system.

Good luck.
Supposedly someone used one of these: http://www.lima-shop.de/en/product_info ... tpl=mobile

Can't find where I read that now. If I can find one of those do you think it would work? I don't even know if it's the regulator that is bad though.

As for when the charge light went out, no I didn't notice. The voltage meter installed on the dash can apparently only display 24V max or less so I dont know if it went above that. But it was saying 24v with the charging light on too. That is with all electronics off. With all of them on it says 22V. But the mechanic measured 24V at the batteries with a multimeter whIle I was revving the engine too, suggesting it's not working..

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Jimm391730
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Re: Need new 24v alternator - URGENT

Post by Jimm391730 » Fri Feb 03, 2017 5:29 pm

Here is a link to basic alternator operation (fits most vehicles): http://www.tb-training.co.uk/marinee08.html
Scroll down a bit and there is a schematic with the alternator light at the very top. You can see that it connects between the battery positive terminal, and the other end goes to the positive terminal of the rotor brushes. If everything is working correctly, both ends of the bulb are at 12 (or in your case, 24V) volts so the bulb is not lit. But if the alternator is NOT getting power to the brush to the rotor then it will be the ground (through the brushes, slip rings, and rotor) which illuminates the bulb. From that perspective, if the voltage regulator is bad and won't supply the few amps that the rotor needs then the bulb is lit. Plus, having tried the other alternator you still have the same result. I would suspect the regulator and/or the wiring from it to the alternator seems the most likely problem.
Jim M.
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jlager
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Re: Need new 24v alternator - URGENT

Post by jlager » Fri Feb 03, 2017 5:34 pm

Jimm391730 wrote:Here is a link to basic alternator operation (fits most vehicles): http://www.tb-training.co.uk/marinee08.html
Scroll down a bit and there is a schematic with the alternator light at the very top. You can see that it connects between the battery positive terminal, and the other end goes to the positive terminal of the rotor brushes. If everything is working correctly, both ends of the bulb are at 12 (or in your case, 24V) volts so the bulb is not lit. But if the alternator is NOT getting power to the brush to the rotor then it will be the ground (through the brushes, slip rings, and rotor) which illuminates the bulb. From that perspective, if the voltage regulator is bad and won't supply the few amps that the rotor needs then the bulb is lit. Plus, having tried the other alternator you still have the same result. I would suspect the regulator and/or the wiring from it to the alternator seems the most likely problem.
Hmm I just read that the bulb being lit indicates a problem with the charging system or its charging excessively (is what the manual says). Does the fact that the light went out after a bit driving mean I could actually be fine now? Just nervous to start driving again but I guess I will be able to tell if the voltage drops low enough and then I can head for the nearest town

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Re: Need new 24v alternator - URGENT

Post by VinceAtReal4x4s » Fri Feb 03, 2017 7:20 pm

Wire a cheap $10 meter on it and keep it in the cab while you drive.
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Jimm391730
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Re: Need new 24v alternator - URGENT

Post by Jimm391730 » Fri Feb 03, 2017 8:09 pm

Wire a cheap $10 meter on it and keep it in the cab while you drive.
Right. Or put a permanent meter on the dash so you never need worry again. A "24" volt system will generally be 27-28 volts while driving; this is the normal running voltage. It is enough to recharge the batteries from the starting drain but not over charge them, and should extinguish the alternator light. But depending on where the meter is wired into the harness, you may see somewhat lower voltages. I tapped into the harness in the dash of my Pinzgauer and the voltage can drop by as much as a volt when the lights are on. That change in voltage is not a problem. The best place would be to run independent wires directly to the batteries but this is not often practical, so dash power will be "good enough" even if it changes depending on what is turned on.

And in the case of my Pinz, voltages above 20V while cranking show strong batteries. If the voltage drops below 20V I know to check the batteries as something is not right (one battery needing additional charge or one or both batteries are failing). Your voltage in a Volvo might be a few volts different; you will have to see what is normal.
Jim M.
712W and 710M

jlager
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Re: Need new 24v alternator - URGENT

Post by jlager » Fri Feb 03, 2017 8:33 pm

There is a permanent voltage meter on the dash but it's part of and LCD display with cabin temperatures and other stuff. Previous owner says it never goes over 24V though as its capped to display that.

With the headlights and electronics on, that display drops to 22V. I don't have a voltmeter with me now so can't check what it is at the batteries but the mechanic measured 24V there too. And it didn't change as I revved the engine either. That suggests to me it's not working but then again, the alternator warning light that had always been on turned off 10 mins after driving away from the mechanic.

I don't know what to make of the situation now. I guess with the voltmeter I have on the dash I can still drive it and if it drops too low, pull over and charge the batteries separately.

Unfortunately I'm so behind in my driving schedule nown it looks like I will need to leave the truck and fly home instead and either ship it home or come back and drive it at a later time.

Thanks for all the replies. If anyone had any other ideas, I'm happy to hear them.

jlager
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Re: Need new 24v alternator - URGENT

Post by jlager » Sat Feb 04, 2017 7:05 am

Update:

Drove the truck a bit this morning and now it seems fine. When the truck first starts and idles and I drive in 1st gear, the charging light is on but as soon as I speed up a bit, the light goes out. The voltmeter is also maxed at 24V and doesn't drop when I turn on electronics.

Is this normal behavior?

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Re: Need new 24v alternator - URGENT

Post by one2many » Sat Feb 04, 2017 9:34 am

Sounds to me as if your voltage reg is still playing up...your voltmeter should be reading 27-28 volts when the engine is running .I've had a similar problem in one of my volvos with an intermittent fault at the voltage reg making the charge light come on occasionally, then after a short time it just stayed on.

Your charge light should go off when you lift your revs up to about 1000rpm but it is normal for it to be on at low revs say when the truck is cold, it should not take 10 minutes of driving before it goes out. You probably know by now that the voltage reg is inside the cab behind passenger seat mounted to the engine hump. Check the wiring/and plugs there are making good contact and follow it underneath and do the same at the relay, but I would suspect the old SEV Marshal? Voltage reg is cactus. It's an easy and cheap fix check the thread below, there are links there to suitable replacements as well as part numbers. Don't bother trying to find that same voltage reg as they haven't been available for years but Bosch make a suitable replacement as do many other makes so you should be able to find a replacement without to much trouble. P.S. fill in your location so we know where you are.

viewtopic.php?f=29&t=10073
1985 pinzgauer 712K factory 2.7lt civilian (RHD, 4 door K)
1979 Volvo tgb 1314a (under construction to om606 diesel/722.6 trans. Dual cab/tray)

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