VSR and solar inter-working question

[scrambledegg]

All this talk of VSR chatter and instruments turning off when engine goes on got me thinking about how to make a VSR work with a solar panel.

The installation instructions for the BEP-made one that I googled stress that the size of the house bank should be matched to the size of the engine alternator (assumes separate starter and house batteries), otherwise the VSR "chatters". The chatter, or, cyclical connection/disconnection of the two battery banks, is caused by the alternator raising the charging voltage above a threshold, causing the VSR to connect the banks together, then rapidly disconnecting them because the (too large) house bank drags the voltage below the threshold.
How then would one connect a solar panel (plus regulator) in such a way that it avoids the chatter effect but also successfully charges both battery banks? Presuming of course that the solar panel is relatively small compared to the alternator, in terms of charging current.
Has anyone done this?
Thanks

 

[VicS]

All this talk of VSR chatter and instruments turning off when engine goes on got me thinking about how to make a VSR work with a solar panel.

The installation instructions for the BEP-made one that I googled stress that the size of the house bank should be matched to the size of the engine alternator (assumes separate starter and house batteries), otherwise the VSR "chatters". The chatter, or, cyclical connection/disconnection of the two battery banks, is caused by the alternator raising the charging voltage above a threshold, causing the VSR to connect the banks together, then rapidly disconnecting them because the (too large) house bank drags the voltage below the threshold.
How then would one connect a solar panel (plus regulator) in such a way that it avoids the chatter effect but also successfully charges both battery banks? Presuming of course that the solar panel is relatively small compared to the alternator, in terms of charging current.
Has anyone done this?
Thanks

You could, infact surely would normally, make the house battery the priority battery for charging from the solar

 

[lw395]

I'm not sure a VSR is a good answer to this problem.
However small the house battery, it can always be flat enough to drag the volts down if the panel doesn't have a huge amount of sun on it.
TBH I don't like VSRs at all, they remind me of dynamo regulators on old motorbikes.

 

[scrambledegg]

You could, infact surely would normally, make the house battery the priority battery for charging from the solar

Thanks VicS. I think I would like you to expand a bit. Specifically how would I prioritise the house battery? And when the solar completes charging the house battery would it then charge the engine battery via the VSR?

 

[VicS]

Thanks VicS. I think I would like you to expand a bit. Specifically how would I prioritise the house battery? And when the solar completes charging the house battery would it then charge the engine battery via the VSR?

Yes

You can fit a dual sensing VSR then the solar, wind gen and/or battery charger can be connected to prioritise the house battery while the alternator can be connected to prioritize the starter battery if desired.

As soon as the volts reach the VSR setting it energises and connects the other battery as well.

This means that the first call on the alternator can be the engine start battery while the fist call on the wind / solar / battery charger can be the house battery.


basically the alternator is connected to the start battery in the usual way while solar, wind or charger are connected to the house battery and a dual sensing VSR links the two. When either reaches the VSR trigger voltage it closes and connects the other.

 

[scrambledegg]

Yes

You can fit a dual sensing VSR then the solar, wind gen and/or battery charger can be connected to prioritise the house battery while the alternator can be connected to prioritize the starter battery if desired.

As soon as the volts reach the VSR setting it energises and connects the other battery as well.

This means that the first call on the alternator can be the engine start battery while the fist call on the wind / solar / battery charger can be the house battery.


basically the alternator is connected to the start battery in the usual way while solar, wind or charger are connected to the house battery and a dual sensing VSR links the two. When either reaches the VSR trigger voltage it closes and connects the other.

-
Great! That sounds almost too good to be true. The perfect energy management system that directs the power where you most need it without any human intervention. Glad I asked the question and thanks for that reply.

 

[neil_s]

I have a solar panel with a dual battery PWM charge controller. This charges the house and start batteries in a 70%/30% regime without connecting them together. Found it on e-bay!

 

[scrambledegg]

I have a solar panel with a dual battery PWM charge controller. This charges the house and start batteries in a 70%/30% regime without connecting them together. Found it on e-bay!

Hi Neil_s, Thanks. yes indeed that would work very well. Before this set of posts I thought a dual bank controller was the only way to do it. If I go to the trouble of fitting a VSR then, as I've just discovered, I can revert to a single bank solar controller. That has some minor advantages: 1. can use an MPPT controller (never found a dual-bank MPPT controller) for slightly greater conversion efficiency. 2. avoid one cable run.
But, as I'm still new to all this, am prepared for people to point out the flaws in my cunning plan.

 

[JumbleDuck]

I use a dual-output solar regulator and a VSR which is only active when the engine is on; its earth is connected via a relay which closes when the ignition goes on.

 

[PaulRainbow]

Yes

You can fit a dual sensing VSR then the solar, wind gen and/or battery charger can be connected to prioritise the house battery while the alternator can be connected to prioritize the starter battery if desired.

As soon as the volts reach the VSR setting it energises and connects the other battery as well.

This means that the first call on the alternator can be the engine start battery while the fist call on the wind / solar / battery charger can be the house battery.


basically the alternator is connected to the start battery in the usual way while solar, wind or charger are connected to the house battery and a dual sensing VSR links the two. When either reaches the VSR trigger voltage it closes and connects the other.

This is how mine is connected and it works very well.

I have a Victron Cyrix VSR which doesn't suffer from "chatter" as it has some microprocessor control.

 

[Iminei]

I'm also trying to get my head around this. I am thinking of a durite (or copy) VSR & single output MPPT controller. If the solar is connected to the house battery and the alternator to the start battery, what happens on a sunny day with the engine running - the VSR will see a charging voltage on both sides. Does that matter?

 

[PaulRainbow]

I'm also trying to get my head around this. I am thinking of a durite (or copy) VSR & single output MPPT controller. If the solar is connected to the house battery and the alternator to the start battery, what happens on a sunny day with the engine running - the VSR will see a charging voltage on both sides. Does that matter?

It does not matter. Fit a decent dual sensing VSR though, for instance the Victron Cyrix.

 

[TRUNDLETRUC]

I fitted a Sterling Prolatch R VSR when we changing engine because the new alternator provided more amps. This saved having to run a very thick cable to both sets of batteries.
It is a bi-directional one and being a "latch" relay it only uses current when it is latching over from "joined" to "connected" etc. Some VSRs use current to hold the contacts together and I tried one which go hotter than you could touch! Because it is bi-directional and the solar panels are connected to the house batteries, as soon as they reach 13.3volts it will connect these batteries to the starter battery. If the house batteries are low, when the engine is started and the voltage from the alternator is above 13.3 volts (instantaneously) the VSR will connect again.
It has been working well since 2012 including the winter when the solar panels top up the whole system.

 

[William_H]

I don't think that a VSR is a very good way to go with a small solar panel. VSR is usually set to sense a high voltage on the first charged battery like over 13 volts maybe higher when being charged by a high current alternator. Your small solar panel may not get the charged battery that high so would never get charge into the second battery. To make things worse the VSR will waste some current in its sensing circuits 24/7 so negating some of your solar charge.
It may also suffer from "VSR chatter" even if on a long time frame ie many seconds. Depending on voltage on and off settings.
Best bet for small solaar panels is get another one for the other battery or get a charge controller with duel output. Or the simplest is a small panel with 2 diodes feeding the 2 battery banks and no charge controller. Ok for small panels large batteries. (perhaps less than 20w in winter.) olewill

 

[billcole]

This is how mine is connected and it works very well.

I have a Victron Cyrix VSR which doesn't suffer from "chatter" as it has some microprocessor control.

Mine too, I have a dual sensing Merlin branded VSR, which I bought used on eBay, but it looks just like many other cheap ones on ebay.

My engine battery is 70Ah car battery and my house battery is a 115Ah leisure battery. I've never experienced any chattering. I cant remember the spec, but there is a decent difference between the quoted "connect" and "disconnect" voltages which must be what governs how stable the system is

 

[lw395]

Mine too, I have a dual sensing Merlin branded VSR, which I bought used on eBay, but it looks just like many other cheap ones on ebay.

My engine battery is 70Ah car battery and my house battery is a 115Ah leisure battery. I've never experienced any chattering. I cant remember the spec, but there is a decent difference between the quoted "connect" and "disconnect" voltages which must be what governs how stable the system is

But do you know what will happen when one or other battery is due for replacement?
Not an issue for everyone, but a lot of people seem to find problems when they are a long was from battery retailer.

 

[PaulRainbow]

But do you know what will happen when one or other battery is due for replacement?

What do you think will happen ?

 

[lw395]

What do you think will happen ?

Dunno! Nothing, chattering, small fire, failure to charge the other battery?
It's something I'd like to understand for the particular VSR I was fitting.
Hard info about the likely what-if cases seems hard to track down.