Alternator problem ?

[Ricksurf]

Can anyone help me diagnose a problem with my truck?
Recently, it doesnt start as good as usual (bit sluggish), so I put a voltmeter across the battery with the engine at 2500 rpm.
It showed 13.2 volts initially rising to 13.4 after a few minutes.
I also have a basic 3 x LED ammeter wired up to the truck which shows red (bad) at idle and green (good) when engine revved.
The strange thing is that it will show constant green at idle but only when the truck has run for about 5 minutes.
Could this be the alternaor brushes or regulator, as both seem easy to change or would a replacement alternator be my best choice?

Rick

[MattF]

Your batteries are in what condition?

[Ricksurf]

Sorry forgot .. battery (only one) new in April.
Belt tension checked.
Cleaned battery posts just in case.

[wishbone]

I'm assuming that when you said 'ammeter' you meant 'voltmeter' ?

Anyhow, for a start check all your battery connections are clean and secure, both on the batteries and the other ends. (positives and earths)

Rob.


A rough guess would be that your batteries are on their way out as you are showing an ok voltage at the batteries when running. My surf used to show around 13.4 volts running and with some cleaning / new earths I now see 13.8 - 14 v.

[MattF]

Personally, I'd try a different battery first, (just incase), and then if that isn't the cause, see if one of the breakers on here have a complete alternator. Repair/rebuild is feasible if you can get the parts at the right price too.

[wishbone]

Wow - I took so long typing that you'd answered my suggestions before I'd suggested them to you

[wishbone]

When you say it starts sluggish does it turn over ok and not start or does it turn over slowly ?

1st bit suggests glow plug replacement..

Rob

[Ricksurf]

I always presumed it was an ammeter that I had.
If it helps it is built into one of these

[MattF]

Nope, that'll be a charging indicator, (voltage).

[Ricksurf]

When you say it starts sluggish does it turn over ok and not start or does it turn over slowly ?

1st bit suggests glow plug replacement..

Rob

It turns over a bit sluggish after being stood for a day, and starts but turns over real fast and starts after a 10 minute or so run

[Ricksurf]

Nope, that'll be a charging indicator, (voltage).

OK but if it stays red until revved or engine idling for 5 mins then could this be alternator or is battery more likely
Once the engine is warmed up this unit remains green

[wishbone]

Haha I bought the exact same one for my truck and they are useless - I plugged my laptop charger into it with my satnav and the laptop charger couldn't even charge my laptop through it. To say I was pee'd off would be an understatement as I had all my music on my laptop and 3000 miles to cover..... ended up listening to europop radio etc. Thank god that it was so hot all the windows were open and you couldn't really hear the radio anyway..

Anyway I digress... The wiring to the surf cig socket is too thin to give an accurate assesment of what is going on at the battery., and the ring thingy ain't no use anyway....Trust your multimeter..

Check your glow plugs.

Rob.

[wishbone]

What is the A/H rating of your battery ? and what is the CCA rating ?

Rob.

[Ricksurf]

Haha I bought the exact same one for my truck and they are useless - I plugged my laptop charger into it with my satnav and the laptop charger couldn't even charge my laptop through it. To say I was pee'd off would be an understatement as I had all my music on my laptop and 3000 miles to cover..... ended up listening to europop radio etc. Thank god that it was so hot all the windows were open and you couldn't really hear the radio anyway..

Anyway I digress... The wiring to the surf cig socket is too thin to give an accurate assesment of what is going on at the battery., and the ring thingy ain't no use anyway....Trust your multimeter..

Check your glow plugs.

Rob.

OK will do at weekend and thanks for both your time

[BUSHWHACKER]

OK but if it stays red until revved or engine idling for 5 mins then could this be alternator or is battery more likely
Once the engine is warmed up this unit remains green

The battery is knackered!
The alternator is doing it's job because your truck starts faster and the red light changes to green after 10 minutes of running, but the battery loses charge during the day.

As Matt sad, the little lights are a battery condition indicator.