Solar and VSR relays

Introduce Yourself…

Hi this is my first post I’m interested in vehicle solar installation,
My solar set up is as follows was wondering if all sounds ok???
During sunlight

  1. voltage at leisure battery showing 13.3v
  2. 140A Durite VSR closed (LED illuminated)
  3. voltage at starter battery showing 13.3v
    Now obviously the 2 batteries will show same voltage as when relay closed they are connected in parallel. So this now makes sense.
    I mistakenly thought that the VSR would only sense voltage from one direction but it appears that it senses from either the in or out (SB or LB)
    There fore if the solar is above 13.3 v (which it is in direct sunlight) then the VSR will remain closed. My only question would then be is there any issues that when I start van that current will be drawn, if only momentarily from both batteries? Also do anybody know of a VSR relay which only senses voltage from one direction??
    I’ve also attached a pic of my set up. Cheers for the reply :+1:t3:

Greetings & Welcome!

The picture didn’t come through, but your description sounds good.

You didn’t mention the exact model of VSR, and when I googled it, I got many…

I’m not a huge fan of VSR’s, reports seem to indicate they are finicky and have short lifespans. Typical isolators, relays, or solenoids that are triggered by the ignition seem to be much more in favor.

My best advice would be to use it for a while, and if it works satisfactorily, keep it, but if it doesn’t, or it dies, replace it with the more popular choice.


"If you prepare for the worst, every thing else is easier." ~ Off Grid


Hi thanks for the reply, pic now attached. Only a small set up for now but plans to scale things up a bit.
I do prefer the idea of an ignition controlled relay rather than a voltage sensitive relay one reason being that the relay is kept in th closed position even when ignition off due to the solar panel providing a voltage to trigger the VSR, I appreciate that this will also maintain the starter battery but with the solar charge controller set for AGM batteries (which my leisure battery is) and my starter battery being lead acid I’m worried the charging may not be suitable for it? I maybe wrong though. Would I just need a relay similar to the one also attached to achieve this??

Like this


Yes, that should work if it is wired normally open, so that it only closes when power is supplied to it via the ignition.


"If you prepare for the worst, every thing else is easier." ~ Off Grid

Thanks so much for taking the time to reply, as you say I’ll use what I have for now but in time if this fails I will swap for standard high current relay, possibly with some kind of override switch just for those days when the starter battery inevitable plays up thanks again. :+1:t3::+1:t3:

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