Alternator problem ?

[Sweety]

Noticed when I start the truck up & let it tick over it's only charging at around 12.5v for the first 3-5mins of the engine running & then will suddenly jump upto 13.8v. If you rev the engine you can see the charge rate going upto 13.8v at 1.5-2K rpm (volt gauge fitted) now can't remember if my last T2 was like this or not but what's worrying me is if I switch the heated rear window on the volts drop to 11.8 only seems to mainly happen on the first start up of the day as you can drive to somewhere & when you restart the engine it starts charging fully. The earth strap from the alternator mounting to inner wing isn't great as there is some rust on the inner wing where the earth bolt is fitted so going to clean that up & prob fit a second much more heavy duty earth cable:thumb2 but not sure if this is pointing to a fault on the alternator or not:nenau

 

[jims-terrano]

Whats the condition of the battery? Such a drop makes me think about that.

 

[Sweety]

Whats the condition of the battery? Such a drop makes me think about that.

Fitted a new battery on about this time last year, Put my multi meter across the battery as well in case my volt gauge was giving out a false reading but the both matched but the truck is starting up fine even when not started for 3 days so think the battery is still ok

 

[AlexD333]

I'm sure when I was having battery issues someone mentioned the initial drain of cranking and lower voltage reading for the initial first few mins? :nenau

 

[supergnome]

The more dials and readouts the more you have to worry about. Don't think there's much wrong with the readings. David.

 

[solarman216]

Think I would be sorting out the possible poor connections first then check it again, it is not normal for the battery voltage when charging to suddenly jump, it should be a steady rise, Rick

 

[Lazy-Ferret]

funny you should post this, mine has been doing something similar over the last month, not every morning, I think it seems to be on the cold dark days, first thing in the morning, when you have lots turned on. The volt stay low for quite a long time, and in the end, I switch a couple of things off and find that mine then rises rapidly, and is then fine once I turn everything back on.

Like Rick says, I checked all the connections, except the actual alternator one, but have not found the cause yet, and the last little wile, it has been fine, so maybe it was one of the connectors on the battery.

 

[Sweety]

Cheers guy's:thumb2 as I said if you hold the revs up a bit it's charging no probs but there does seem a delay in tick over charging at max out put from the alternator. I cleaned the battery terminals not that long ago & checked them for any damage etc before reconnecting them to the battery & greasing the terminals. Think I might order some 110a welding wire to make up some new earth leads & in the mean time clean the earth points I can see

 

[rustic]

If you are only letting it tick over after a start, the alternator can only give out so much current, which isn't enough to put back enough into the battery, once enough is put back, the voltage will slowly rise to the normal alternator output.

If you start it and rev it to say 1500 revs, for say a minute or so, the voltage should start to increase quickly and then hold a higher voltage, but again, if the revs drop, the voltage could still drop to below 13 volts, until a replacement charge is put back.

Also a similar effect can be caused by a slipping fan belt, they don't all squeel, I would be concerned if the voltage dropped to 12.5 volts after a few miles drive at normal road speed.:thumb2

Certainly worth checking all connections as well.

Rustic

 

[Sweety]

Cheers Rustic I forgot about the belts:doh just been out & checked them & the power steering belt could do with adjusting up as there is almost an inch of movement one way on the longest point & about 1/2" on the alternator belt but can't remember how much is recommended now

 

[Sweety]

Scrap my last post just been out to check them & they are fine a few mm tighter than recommended & I checked them in the wrong place