Charging voltage

[Wandering Aengus]

This is a slightly long tale so please bear with me!

About a week ago I noticed that my fridge, whose battery is charged through a charge controller that comes on at 13.1v input wasn't working due to the battery being flat.

I immediately checked the charging voltage of my alternator (A1) at the batteries in the engine bay and noticed it was only 13.4 - 13.5v. The fridge started charging again but only at 13.5v, it usually charges at up to 14.4v (endangering my supply of cold beer - mission critical). Otherwise the car was running fine.

Luckily when I bought my car it came with a spare second hand alternator of unknown history ("A2') This had a different plug on the rear but I found one to match it fairly easily and swapped it in, charging voltage was between 14.2v and 14.4v, all good.

The next day my 10A dash fuse blew, the first fuse i've had go in the 2 years i've owned the car, swapped it out, no problem.

The day after that the bolt that tensions the alternator and the belts sheared so, guessing the problem was the voltage regulator on A1 I removed the regulator on A2, put it on the body of A1 - it was charging at 14.2v, all good.

The following day my dash fuse blew twice in about 30 minutes and as I was running out of 10A fuses I swapped in A2 body now with A1 regulator just to get me back to town. To my surprise for the first hour of driving this combo ALSO charged at 14.2v, suggesting to me that the A1 regulator wasn't the problem after all. After an hour the charge dropped down to about 12v.

When I got to town I fitted a new non toyota regulator AND a supposedly working toyota regulator of the same shape but different part number, both gave charges of about 13.5v.

1. Various bush mechanics here in Congo & Gabon have tested both alternator bodies and rectifiers using a lamp and have declared them fine
2. I have checked and cleaned the main ground on the engine block
3. Batteries are less than a year old and I have no reason to suspect they're bad, when the car is switched off they're sitting at about 12.5v charge, a bit low presumably due to not being charged fully?
4. Both my regulators have slightly different part numbers, both have a big 'M1S' and then '12600-' but that is followed by different numbers on both
5. It may be conincidence but I think that all the times the dash fuse blew i'd just switch on the CDL, this could just have been either that I only looked at my dash after pressing the button to check it had engaged and just noticed the dash wasn't working then. I presume that the dash fuse has something to do with my problem?

Any help would be greatly appreciated. I'm going to try and find a regulator that matches at least the first bit of the parts number on the ones I have but to be honest it's pretty unlikely i'll find one here in the bush in Gabon.

 

[Dave2000]

First when checking the battery voltages they should be disconnected, left overnight (unless you have decent battery tester)and then take a reading. Fully charged they should be reading around 12.6v Do that first to see if you have a faulty battery. Forget how old they are, a cell can fail overnight on a new battery. Assuming all good then I would check the fusible links near the battery for corrosion (=high resistance), I would then disconnect the charge controller to your fridge just to take it out of the picture for a moment. I don't quite get the paragraph:

The day after that the bolt that tensions the alternator and the belts sheared so, guessing the problem was the voltage regulator on A1 I removed the regulator on A2, put it on the body of A1 - it was charging at 14.2v, all good.

Why would you suspect a regulator if the tensioner bolt broke? Next thing to look at is where your system was charging at 14.2v and then suddenly dropped to 12v, you do not state which model/year your vehicle is, the later 24 valve engine had numerous problems with the manifold heater relay staying on and knocking out he batteries. Check all earths, inc battery to body AND engine.

Need some more info about your vehicle please.

regards

Dave

 

[WanderingAengus]

Dave200, thank you for the reply.

My car is a 1995 24v GX

I found a regulator yesterday after posting which had a similar but not exactly the same part number as my original two, it seems to be working for now with the slight difference that it only gives the full 14.2v when the engine is revved beyond about 1000-1500rpm, below that it gives 13.5v or so.

1. I will check the batteries properly as you suggest tonight
2. I've checked the connections at the battery already but will do so again
3. I will disconnect the charge controller also but will be surprised if that's the issue
4. That paragraph you highlighted can be clarified - While driving I saw that the voltage dropped right down to around 12v. I stopped to investigate and saw that the bolt that tensions the alternator and belts had sheared so that the belts were completely slack and the alternator obviously wasn't being turned. I figured that the guy who had fitted the alternator the day before had over tightened the bolt or something, causing if to break the next day. I couldn't remove the sheared bolt from the alternator body on the road side so I swapped in the A1 alternator and A2 regulator, I figured that the A1 regulator was the problem so this combination should work fine.
5. Yes, i'm aware of the problems the 24v had with that relay. Mine has been removed completely along with the heating element so that can't be the problem,

Thanks for your help

NB: I had some trouble logging in to my account just now so set up a new one with a slightly different username just to post this reply

 

[WanderingAengus]

I think I may have traced the issue that was blowing the dash fuse to the reversing light. It's now disconnected so we'll see if it happens again. Could have just been conincidence that this problem started at the same time as the alternator change?

 

[grantw]

Hi there,
Yes more than likely that it was a coincidence. Just to clarify are you sure your'e just not getting confused with the way the alternator works? It is perfectly normal for the voltage to drop after driving for a bit, this is the job of the regulator. I.e to raise the voltage to charging voltage (~14.7volts) for the battery to recover from the previous start and then drop back to a lower voltage.

Cheers

 

[Dave2000]

Once the battery is fully charged and the engine is running the voltage indicated will stay at around 13.8+ however, the amps being drawn will fall. Those of us who used to run around in Cortina '1600E's' and 'GT's'.........(yeh I know) will remember the extra gauges will recall the volt meter climbing and the ammeter falling as the battery charged up, completely normal.

Assuming your alternator is working correctly then I would be suspicious of at least one of the batteries, being new....ish should not lead you to discount them, the 24v system is notorious for hiding a faulty battery until the second one fails and the car does not start, this is just one of the reasons I swapped to a 12v starter, see

http://forum.ih8mud.com/threads/my-lc-80-thread.365673/page-5

Post 93 onwards

regards

Dave