VSR question

Do all VSR units kick in the relay at 13.7 volts as I have read for a few ?

Have done a complete post-cowboy re-install of mine. Now while I am able to trigger the relay by earthing the switch wire, it never connects the second battery while driving.

I have a dual voltmeter to monitor both batteries (wired directly). This appears to be telling me that while driving, the charging voltage on the main battery never seems to rise above 13.3-13.5 volts, the leisure battery sits at a constant 12.2 volts and the indicator LED on the control unit remains unlit indicating that the second battery is not receiving any charge.

Might I have an under performing alternator ?

As an aside, I have an intelligent CETEK charger and this seems to cycle through the relevant stages easy enough before dropping into floating charge. This includes charging at 14.5 volts which makes me rule out the battery condition.

I'd say that your alternator is not too happy, time for a service. About 14.4 volts should be seen when the engine is running at anything much above idle unless you have heaps of other load on at the time. 13.7 seems possibly a little high to cut over, but not unreasonable. Is yours a bi-directional one?

Bi-directional ?

Actually I jumped in there without fully thinking as some vehicles now have smart control of the alternator so may only put out 13.x volts if the controller thinks the battery is fully charged, but I think that came quite a bit later than 1991 which your profile shows your vehicle to be (note to me: I need to correct my profile info!) so my original comment probably still applies. In the case of the smart alternator control there are switchmode charger units made which will give the correct charging output even when the smart alternator turns down its charge voltage. Alternatively if fitting is physically possible a second alternator dedicated to charging the house battery is another option but in a Hiace there isn't much room for that.
In our new camper we have a bi-directional VSR. It senses the voltage on BOTH sides and if either is sufficiently high it connects the two together so if the engine is running the alternator charges both batteries but if the engine is off and there's sufficient output from the solar regulator it will also connect both batteries together and the solar will keep both charged. I never knew such a thing existed until I saw this one. It also has a connection which you connect to the start contact of the key switch so that it doesn't allow any starting current to flow from the house battery although we are having a problem which I suspect is due to that not responding quickly enough so I'm considering adding a delay circuit to stop the starter relay from activating until a short, perhaps 1 or 2 seconds, time afterwards so it will definitely be de-activated when the starter current hits the vehicle battery. Just thinking about it as I type, that may not even work as the glow-plugs will still pull the main battery down so maybe even more thought is needed!
Our one is: Blue Sea Systems M-ACR-7601 and its cut in voltage spec is 13.6 v and cut out is 12.75v.

I appear to have vanished down some auto-electrical rabbit hole in my efforts to identify the VSR I have installed.

.... any way this is it and also the thread I found it on.

Even more convinced now that the issue might lie with the alternator...... especially when I recall the fan belt squealing at weekend.



thread link here

Interesting; I haven't seen a two-piece one before but that does mean you can use whatever size relay you want and place the control box elsewhere.
I guess you're about to pull out that alternator unless it's just a loose belt.

AgathaAlice wrote:

Interesting;I guess you're about to pull out that alternator unless it's just a loose belt.

Am I correct in my belief that the central wheel on this image is the alternator ?

If so then I think I have identified the problem. I can spin it freely with my fingers as contact with the belt seems minimal.

That central wheel looks just to be a tensioner but even so it shouldn't be that loose. I'm not familiar with the layout of that engine but I thought the alternator was on the other side of the engine. Your image shows the fan and its coupling and I think I can see the aircon compressor and its clutch at the very top of the image. I think the alt. will be driven by the double belts that can just be seen beneath the radiator hose. Take out the driver's seat and remove the access panel which is beneath the seat and look down, you should see it there if it is anything like the 3L layout (it's quite large). Note that there may be a pump attached to the rear of the alternator, this supplies vacuum for the brake booster. If it exists it will mean that there are oil and vacuum pipes which you will have to remove as well as the wiring if you do need to take it out, it's not so straight forward as in petrol vehicles. Oh and please disconnect the engine battery and VSR before doing anything to avoid letting any smoke out or blowing expansive high current fuses.

Other folks who know this engine please chip in to either confirm or refute what I've said and give any suggestions for removal if it does need to come out.

Just checked our engine today and that tensioner rotates freely on ours so maybe it is correct that way. Also on ours the alternator is definitely driven by the twin belts and is where I described, your layout is probably not much different despite the different engine.