VSR and solar panel - issue?

[cbeeson]

I've just removed a Heath Robinson split charge relay arrangement, and had planned to install a proper 140A voltage-sensing relay setup (Durite). I've already got an 80W solar panel connected via a controller to the feed from the leisure battery. But I'm beginning to have my doubts.

Here's the problem. The solar controller is producing 13v or more at the leisure battery. Once the VSR is installed, this will be enough to hold in the VSR, and keep the LB and the starter battery connected. Some of my precious solar current will be diverted to an unnecessary trickle charge for the starter battery. Also, what then happens when I come to start Bongo, if the VSR is holding the connection to the LB? I don't want to be drawing current from the LB to the starter, even for a few moments before the voltage drops; and the VSR only drops out after a fixed delay of a few seconds.

It's beginning to look as if I'd be better going for a straight relay and connection to the alternator signal terminal. What does the team think, please?

Chris

[g8dhe]

Two aspects to this;
1. It depends if the Duritc relay senses both battery voltages and operates if either is above the trigger level. http://www.g8dhe.net/bongo_images/elect ... spec_1.pdf It is implied that it is unidirectional (i.e. only SB) but does NOT specifically state that it is ....
2. DO NOT use the the alternator sense signal, it isn't intended for this operation, and any additional load on its connection will cause the Charge lamp to glow to a varying extent at all times.

If you decide to use Ignition control of the relay then you need to make use of the IG2 circuit from the ignition switch, this goes High (+12v) whilst the ignition switch is in position 2 only, i.e not during Off, Ancillary position or during Starting itself. This means you have control of relay operation when needed, if you should end up with a flat SB for any reason, then going to the ON position will allow you to transfer charge from LB to SB, but isolates the LB during actually Starting.
The IG2 circuit is best picked up from after one of the fuses it feeds below;

[cbeeson]

Hi Geoff. Thanks for your reply.

I'm still not sure if the Durite is dual sensing or not. It doesn't say on the technical document, so I'd originally assumed not; but one of the Facebook crew says he's got one and it is dual sensing.

One factor I don't get about single sensing VSRs though, which seems relevant: once the VSR has sensed a high enough voltage to pull in, then the batteries will be connected in parallel and both will be seeing the same voltage, and the VSR will only drop out when that common voltage goes low enough. In the Durite, that's 12.65v. But the solar controller is holding the voltage up at 13.1v in moderate sunlight, so the VSR will presumably not drop out until the sun goes away. So what happens if the sun is shining when you turn the starter key?

I understand your point about not connecting to the alternator signal line, and using Ign2 instead. My problem there is that, having a diesel Bongo, Ign2 is when the glow plugs are powered up, so current would be drawn from the LB to the glow plugs.

[cuchillo]

Hello

I'm still not sure if the Durite is dual sensing or not. It doesn't say on the technical document, so I'd originally assumed not; but one of the Facebook crew says he's got one and it is dual sensing.

I have a Durite VSR:


and I believe that it does flow both ways. I say this because yesterday morning I noticed that the red light was on but only the LB was being trickled charged from the EHU; I had previously disconnected the Solar feed to the LB as well as the trickle charger to the SB. Checked with the volt meter and both read the same value. (13.x Volts)

So I turned the EHU off, switched on all the lights and turned on the fans and demister. Checked the Durite and saw that the light was off. Checked the voltage and saw that the SB was now lower (11.x) than the LB (13.x).

I switched everything off. Turned the EHU back on and left the LB on its trickle charger. The light was still off at this point.

This morning I went back to it and saw that the Durite light was back on and that both batteries were reading the same voltage again (13.x volts)

From this I concluded that the VSR (annoyingly) does flow both ways.

HTH

Cuch

[g8dhe]

Yup these are exactly the problems that make VSSCR systems a bit of a pain at times
OK on your concerns on the Glowplugs, yes these will draw from both batteries, but you would also expect the engine to be running and charging within a minute or two, unless your in a habit of turning on and walking off, to do other things - not an impossibility! In which case your back to using the Charge light circuit, in which case you either put up with having a Charge lamp always glowing, especially noticeable when driving at night, or add some additional electronics to reduce the load on the Charge lamp circuit and drive the relay from that - I've not seen any commercial products for that, so would mean designing your own, nothing overly complex NPN transistor rated for automotive work with a resistor from base to Charge lamp circuit would be enough.

[cbeeson]

Cuch wrote:

From this I concluded that the VSR (annoyingly) does flow both ways.

That's what I was afraid of. Won't work for me then; I'll have to see if I can swap the kit for a simple relay kit.
Thanks for clarifying that - it saves me a lot of bother.

[cbeeson]

Geoff, I do leave the ignition on for a while when I'm attaching the external screens on the windscreen and doors, as I have to open and close the windows. From the Glow Plug Fact Sheet, it seems that the plugs stay on until the engine warms up.

I think I will have to go back to the alternator connection. I don't know how the signal is implemented in practice, but it seems to be a hard earth when the alternator is stationary, but more or less floating when the alternator gets moving, so I can see how the problem with the warning lights arises. I can do the elctronics, so that might turn out to be my solution.

Thanks for your advice, and your circuit diagrams!

[corrour]

Is it not the case that the Durute vsr correctly fitted measures it's trigger voltage between the +ve terminal and Earth. This being the case if the other side voltage is increased it will not trigger.
Will do tests tomorrow and report.

[redrocket]

I had this exact same issue just last week when i installed my solar system. I have the exact same VSR and spoke to the seller who i bought it off who told me they are dual sensing, so i this weekend replaced it with a standard automative relay, but i connected my ignition on to the Radio & Cigar lighter fuse with a bypass fuse holder as i noticed when cranking the engine, power cuts to the radio so the relay would be off not drawing any power from the LB at that time but will be in parallel after.

Is there a reason why no one else seems to use this place for a +12 ignition on and using the charge lamp instead???

[redrocket]

Anybody??

[g8dhe]

Well the normal circuit to use is the IG2 circuit, this goes live when the engine is "ON" but not during starting. This means you don't run the risk of leaving it turned to ACC (first position) and flattening both batteries. Neither the IG2 or the ACC is powered during starter motor running to prevent damage from spikes.
You can access the IG2 circuit using a Piggyback fuse on the 10Amp RED fuse far right middle row of the fuse panel by the drivers knee;

[redrocket]

Ahhh got ya....it's all about leaving the keys in the first ignition position......so how does this charge lamp on all the time come about?? As i read that commonly

[g8dhe]

The "Charge" lamp (ON) is an error condition from the alternator, the lamp is connected to the +12 and when the alternator isn't generating then the output from the connection goes to earth (otherwise its effectively disconnected) - turning the light on. The relay connects between the signal wire and ground, all the time the alternator is generating then the relay is held operated via the current thru the lamp itself, hence the slight illumination how much depends on the resistance of the relay some are more sensitive and draw less current than others. If the alternator isn't generating then it shorts the relay out whilst turning the lamp fully on.

[redrocket]

Ahh got ya! Thanks for clearing that up

[Katka]

I'd been playing with the idea of putting a solar panel on the 'van to keep the LB topped up for future longer trips but it hadn't occurred to be that it might be able to keep the main battery topped up charged too, especially useful when laid up in the winter..........
I'm afraid the techie talk was way over my head and apart from the basic idea, I'm not really any clearer how this double battery charging might be done.
Any chance a 'How-to' guide could be written for those of us who can follow instructions / pics, and kept for members future use ???