Charging system question

[Gonzo12c]

Hi folks I had a bit of an odd moment this morning having just driven for about an hour then stopped for 5 minutes and as I tried to re start the truck acted as if the battery was dying but started. So I've put a fluke over the batteries and both reading just under 12v with one of them being new a few months ago.

With the engine running I'm reading just under 12v again but it is steadily climbing so I'm just wondering if it is just trickle charging as there is no abnormal loads on the engine and the belt is fine.

Marty

[wishbone]

http://www.hiluxsurf.co.uk/showthread.php?t=78299

[Gonzo12c]

Thanks for the link I have seen that and it doesn't answer my question really

[wishbone]

With the engine running I'm reading just under 12v again but it is steadily climbing so I'm just wondering if it is just trickle charging as there is no abnormal loads on the engine and the belt is fine.

Marty

From the link I posted:

To check, start the engine and switch in 'idle up'. Check the voltage at the batteries. It should be approximately 14.4V. little bit over or under is OK. Stick your lights on. Once again, the voltage shouldn't change much. If this is so, your alternator is fine. You can also try switching on everything you can find step by step, and check your voltage holds up under maximum load.

[Gonzo12c]

Yes I read that I'm also asking about a trickle charge as my batteries are still charging otherwise the truck would be dead by now.

It does seem a little strange as it appears that the alternator has regulated the voltage down or I'm getting intermittent charging.

[Bonk]

I had this (difficulty starting sometimes even just after a journey) and it turned out my batteries were charging but not holding the charge. I replaced them and it's perfect again.

[Gonzo12c]

I've got another uprated battery to go on as I know the older one is pretty poor from a drop test done before

[wishbone]

Straight after starting my alt drops a little bit, but within 10 seconds or so the voltage should be ~ 14V .My old 2.4 used to idle at 13.8v on its original alternator. My 3.0 sits on idle at 14.5 v with a new alternator fitted.

12v is not enough to charge the batteries.

[Gonzo12c]

Yes it does seem strange as the batteries haven't died as I would of thought they would by now. Hopefully should be able to get an output voltage on the alternator as I would if thought if there was an issue with the charging syst the light would of come on by now

[Gonzo12c]

Omg I just realised what it is. It's a dual belt alternator and I only have 1 in there that certainly won't help things now to see if I can pick up a belt quick.

[shokenore]

Having one belt or three won't make it charge any better.
Disconnect a battery and see what voltage you get at each battery.

And then compare voltages.
If you have twin batteries and one is duff it will bring the other good battery down .

[Gonzo12c]

Both batteries are good and now both belts are new. Gauge in the truck is now reading as it should although I know someone will say don't trust these but the truck is now charging fine thanks for the help folks.

[shokenore]

As has been mentioned before 12volts will not be enough.

[Evelix]

Just a thought - but this can be one of the symptoms of the famous starter motor solenoid contact problem. When the contacts burn away the motor gives a click but doesn't turn over. But sometimes the contacts almost meet - enough to make the motor operate but with a high enough resistance to imitate a low battery charge. Might be worth checking.

[Gonzo12c]

Starter motor is fine there was no moment when it didn't start it just seemed to struggle indicating a drop in battery starting voltage.

I should of pointed out as well that I am a vehicle technician so was looking at a more technical point of view without trying to offend anyone.

Marty