One for the sparkies?

Many follow http://forum.ih8mud.com/threads/my-lc-80-thread.365673/page-14 and my last post was to say I was moving the charge wire presently running from the alternator across the engine bay to the battery on the left. I had made mods a few years back and was basically tidying the engine bay and while at it shortening wires and grabbing back some voltage drop, this was showing up running the charge cable from alternator to the left battery and back across the engine bay to the right battery, it varied from around 0.3 - 0.5 volts.

Presently up in the mountains 'house sitting' so I never do anything too adventurous not wanting myself stuck with no transport around 15 miles from the nearest shop so only do the simplest of repairs/maintenance, so this is going to be 'easy peasy' right......wrong!

In simple terms I disconnected the alternator charge lead from the alternator and from the left battery, cut out around 1.5 metres and fitted a new terminal end to the remaining piece, connect direct to the right battery and job done....NOT.

I started the engine and looked at the NL battery monitor, normally it would show the left battery charging slightly ahead of the right as would be expected, now with my new short runs they should both be charging at the same rate. The left battery was not charging at all, the dashboard volt meter was way higher than normal, within a few seconds the dashboard lit up like a Xmas tree, everything from the red charge warning thru to the 'water in the diesel' indicator. Those who have had problems with the small plug in the alternator being loose will know what I am seeing.

Switched off straight away and checked all the connections and wiring all good, disconnected the charge cable from the right battery and jump leaded it to the left side, i.e. exactly how it was prior to me getting the tools out. Restarted and all was perfect, and everything worked as it has for the last few years since removing the 24 volt starter and moving over to a full 12 volt system.

If I connect the charge wire to the right battery and restart the fault comes back but, if I engage the splitter the fault disappears immediately. Voltage checks during normal running left battery 14.4/14.6, right battery 14.1/14.3. When connecting just the one battery i.e. when the dashboard shows a fault the voltage rises to 16.8.

So here goes the list, I have:

Checked and rechecked plug in the rear of the alternator.
Checked OE fusible links on right battery all good.
Disconnected the main parallel leads and fitted the charge wire back to right battery, fault came back.
Getting desperate I even swapped batteries, fault still there.
Checked and rechecked the Blue Seas split charger all wires and connections OK.
Connected solar panel to right battery Blue Seas splitter responded as per normal and connected batteries in parallel in the usual manner, start engine and relays disconnect the solar panel i.e. perfect.
Taking the Blue Seas out of the equation the fault still was there.

It was getting windy and the dogs wanted feeding, my patience wearing thin I done a quick temporary link, taped it up and called it a day, in effect I have done nothing!

As I am typing this, it occurred to me the only thing I have not tried is connecting the starter motor to the right battery along with the charge cable, on the left battery they are connected together so, is it possible the alternator (being of the machine sensed type) needs to 'see' the feedback via the starter cable/windings to regulate it's charge output?

I do declare myself as being quite leccy savvy but have to say this is the first time I have seen this fault (or should I say weird behaviour) on any vehicle........thoughts?

regards

Dave

Dave is it a poor earth on one of the batteries ?

Or a poor earth on a component? My rear wiper packed up and all the lights came on on the instrument panel. I found a poor earth inside the tailgate. I was lucky though as the faulty wiper gave it away. You might check everything works OK though.

I'm thinking your split charge controller will be the wrong way round and you also need to check that the alternator voltage sensing wire that goes via a fuse or fusible link straight to the alternator is connected to the battery you are charging otherwise I guess it will keep pumping the volts higher, without knowing how high it is going.

Thanks for the replies thus far guys, everything works perfect when the wiring is put back to how I have had it for about four years?

Nothing is out of the ordinary Frank when it comes to what works and what does not, jump leaded in temporary earths, no change. I hear where you are on this Star Cruiser but, the fusible links are perfect, I did look there thinking I had disturbed one when moving the wires about, back probing shows them all good. If the voltage sense wire was broken then why would the voltage drop to the correct level when the second battery is engaged? Thinking what you are I left the engine running at idle for around half an hour and the voltage pegged at both batteries at 14.2 -14.3, if the regulator or voltage sensing was 'iffy' that would have climbed even with two batteries in parallel, the NL battery monitor also shows all is good when in parallel, the Blue Seas split relay detects over voltage and disconnects the batteries if one goes over voltage so that too is happy. Re the split charge controller being the wrong way around, it is a 'dual sense' unit, it detects battery voltage from each battery, and connects them in parallel when one is being charged, it makes no odds which one is being charged as long as it is from one direction or the other. Although I have left it as it has been for years without issue I did check their wiring diagrams and they state it makes no odds which battery is 'engine' and which is 'house' but I may have missed something, I will read through them again just in case.

I am convinced at the moment that the answer lies with the starter live cable not being in circuit but, that does not really make much sense as in theory the starter is no longer in use.

I would also add I disconnected the cooling fan supply wondering if there was any connection via the switch relays, again no difference, so as it stands, engine running alternator feed to right battery shows over voltage, connect left battery via the split relay or a jump lead and all returns to normal, I am adding in a second battery and a starter cable AFAICT. I fancy connecting a jump lead from the right battery over to the starter and see if that helps, it does not make sense but if nothing else it dispels the theory the alternator needs to 'see' the starter windings, I really am grasping at straws on this theory though. Of course I could put it back exactly how it was and run around for another four years with no issues whatsoever but, where would the fun be in that besides, I just NEED to know why it does what it is doing....if you know what I mean?

Tomorrow I am swapping back to the van as getting behind with workload, also MOT coming up and most of the brake parts are here or on the way so that will have to take priority at the moment, it will give you guys some time to kick this around and come up with some ideas.


Keep throwing out ideas guys,

thanks again

regards

Dave

Ok, the Blue seas sees both ways. But I'm certain your battery sense wire from the alternator needs to move with the charge cable and what you have just described only reinforces that.

Breaking this down, where the charge cable was connected, the No2 (house) battery could be connected or not connected at the whim of the Blue seas. Charging voltage we know behaves correctly.

Moving JUST the charge wire, means the alternator is sensing voltage from the No1 battery rather than the No2 battery where you have now connected it. UNTIL the batteries are connected together, then the voltage is sensed correctly as the volt sense wire is connected to the same battery the charge wire is THROUGH the relay in the Blue Seas.

As a test, If you were to jump the + of one battery to the + of the other, they will charge correctly within the voltage difference across the jump cable. I.e, if the jump cable drops 0.1 volt, one battery will be at, say 14.2v and the other 14.3v. (This bit is just observation really)

I see where your coming from SC but, the battery sense wire has never been moved ever, I did think this was a 'machine sensed' alternator and not battery sensed as everything has worked great for years, this was simply a 'tidying up exercise' and if you like, 'honing' the install for the 12v starter and charging that was done around four years back?

If one of the cables is for voltage sensing then putting it on the battery furthest from the alternator as you suggest would make bang on perfect sense but Toyota AFAICT didn't. There are only three cables on the left battery i.e. + to right battery, + to one side of charge splitter (which continues down to starter), and a - to body earth, this at present rises to four as the alternator is connected back on to left battery+ as well which make all work ok.

24v starting aside, if you think of the stock wiring, engine idling and both batteries are in parallel i.e. one big battery, then removing just the left battery + should make no difference to the alternator, it would just see a smaller battery and continue charging right?

I really need to sit in front of a diagram but do not have the time at the moment, further thoughts welcome.

Many thanks

regards

Dave

Update, I may have found the answer to this, fingers crossed. If I am reading the wiring diagram correctly then my wiring is perfect for an all 12 volt system but, when you look at the starter circuit there is a 24v warning relay. I am betting that terminal 'L' from the alternator which is connected to that relay is seeing it as open circuit and upping the voltage. I reckon pulling the relay may cure this? I will try later in the week when I get a moment.

regards

Dave