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kmac



Member Since: 07 Oct 2009
Location: Middlesex
Posts: 860

United Kingdom 2009 Defender 110 Puma 2.4 USW Santorini Black
Which Voltage Sensing Relay

Going to implement a simple dual battery system - second battery will run the fridge and perhaps phone charging when camping. May also run a rear Scenelite occasionally.

Not sure which brand/amp capacity VSR to get.

1) The Blue Sea ML-ACR looks tasty with its 500Amp load and 2000Amp peak load. But they cost the earth over here (Only USD 180 over the pond, circa GBP 260 here, if you can find one)

2) Victron Cyrix 230Amp one also looks fine. 500 Amp peak load.

3) Multiplicity of others at the 140Amp range e.g. Durite etc

Any advice on which one to go for?

I guess the peak load is only needed if jump starting the vehicle with the VSR connected?
Anyway what are you guys using?

Post #792527 12th Sep 2019 5:04pm
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LandRoverAnorak



Member Since: 17 Jul 2011
Location: Surrey
Posts: 7119

United Kingdom 2013 Defender 110 Puma 2.2 USW Orkney Grey

I bought a generic 140amp one and it performs perfectly:


Click image to enlarge
 Darren

2013 Defender 110 USW XS
2013 Discovery 4 XS

"You came in that thing? You're braver than I thought!" - Princess Leia

MY 110 USW BUILD THREAD - MY 200tdi 90 BUILD THREAD - Instagram: @landroveranorak

Post #792532 12th Sep 2019 5:07pm
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Bluest



Member Since: 23 Apr 2016
Location: Lancashire
Posts: 1940

United Kingdom 2007 Defender 110 Puma 2.4 XS CSW Java Black

You need to decide if you want the ability to combine batteries for a self jump start scenario. I think the Victron and T Maxx ones let you do that. If not, the generic Durite/M-Power 140 amp ones do the job ok. I think mine is an M Power one from Simply Split Charge. 2007 110 TDCi Station Wagon XS

Post #792540 12th Sep 2019 5:26pm
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kmac



Member Since: 07 Oct 2009
Location: Middlesex
Posts: 860

United Kingdom 2009 Defender 110 Puma 2.4 USW Santorini Black

Thanks both - will give it some more thought and decide based on price and availability

Touch wood I have not had to jump start the vehicle ever so maybe that's less of an issue. One can always manually disconnect the VSR when doing so I guess.

Post #792732 13th Sep 2019 10:24am
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LandRoverAnorak



Member Since: 17 Jul 2011
Location: Surrey
Posts: 7119

United Kingdom 2013 Defender 110 Puma 2.2 USW Orkney Grey

Yes, you can. The thin black wire in my photo above is the trigger wire, which just needs to be earthed. In its' simplest form, it can be connected to the battery neg terminal but by routing it through a switch you can create a manual override to disable the VSR. Darren

2013 Defender 110 USW XS
2013 Discovery 4 XS

"You came in that thing? You're braver than I thought!" - Princess Leia

MY 110 USW BUILD THREAD - MY 200tdi 90 BUILD THREAD - Instagram: @landroveranorak

Post #792735 13th Sep 2019 10:32am
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custom90steve



Member Since: 21 Jan 2010
Location: South West England
Posts: 17218

United Kingdom 2007 Defender 90 Puma 2.4 SW Stornoway Grey

I would go with Durite.
Whilst a VSR is good for split charge battery set ups.
I’d be cautious on use for other more sensitive electronic equipment purposes, as there is a cut in voltage and cut off voltage.
On start up the Defender by nature always has a significant voltage drop often circa 8 - 9v during cranking.
So ignition would trigger it, cranking drop it off and then when motor is running it’ll be back on again.
Often in a pretty sudden and extreme manner.

For purposes other than split charging etc I’d rather use a traditional relay as the coil voltage drop out of the switch disconnection is typically lower.
They are also significantly cheaper, easy to change and pretty reliable. (Fining a RMT 12v ignition switched source to trigger is usually not a problem at all either.)

Either way, BlueSea and Durite you won’t go wrong with. Thumbs Up Made In GB. 🇬🇧

Watts ÷ Volts = Amps.
Amps X Volts = Watts

Post #792755 13th Sep 2019 11:43am
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kmac



Member Since: 07 Oct 2009
Location: Middlesex
Posts: 860

United Kingdom 2009 Defender 110 Puma 2.4 USW Santorini Black

Thanks Steve - this is for split charge only.

You mention Blue Sea and Durite - latter is a simple VSR rated to 140amps and costs about 40 quid. Former costs a lot more, main one sold via kits form the likes of Mobile centre is rated at 500Amps continuous and costs almost 300 quid

Post #792776 13th Sep 2019 12:50pm
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TJH1985



Member Since: 22 Aug 2016
Location: Midlands
Posts: 177

United Kingdom 

I have the 180 amp CARGO (Bosch) and have no complaints Smile

Comes in at 13.4volts and switch off at 12.6volts so doesn't cut in until a few (ish) seconds after the engine is running.

I have have a secondary fused link that I can connect to bypass it, for if I ever need to jumpstart.

I use it to run a fridge, charge phones, CB etc Thumbs Up

Post #792779 13th Sep 2019 12:58pm
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LandRoverAnorak



Member Since: 17 Jul 2011
Location: Surrey
Posts: 7119

United Kingdom 2013 Defender 110 Puma 2.2 USW Orkney Grey

custom90steve wrote:
I’d be cautious on use for other more sensitive electronic equipment purposes, as there is a cut in voltage and cut off voltage.
On start up the Defender by nature always has a significant voltage drop often circa 8 - 9v during cranking.
So ignition would trigger it, cranking drop it off and then when motor is running it’ll be back on again.
Often in a pretty sudden and extreme manner.

That's not the way these VSR's work. The cut in voltage is such that they don't connect until the engine is started and stable, so they don't cut in and out during starting. They're also solid state, so no coil and associated EMI. There's no problem using these in circuit with electronics. Darren

2013 Defender 110 USW XS
2013 Discovery 4 XS

"You came in that thing? You're braver than I thought!" - Princess Leia

MY 110 USW BUILD THREAD - MY 200tdi 90 BUILD THREAD - Instagram: @landroveranorak

Post #792789 13th Sep 2019 1:52pm
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sako243



Member Since: 08 Jul 2014
Location: Wales
Posts: 641

United Kingdom 1994 Defender 110 300 Tdi CSW Alpine White

LandRoverAnorak wrote:
so no coil and associated EMI

Not true - just likely to be less intrusive and more easily dealt with by the filters in the electronic power supplies. Ed
95 Defender 110 300Tdi
96 P38 4.6 HSE

Post #792805 13th Sep 2019 3:30pm
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LandRoverAnorak



Member Since: 17 Jul 2011
Location: Surrey
Posts: 7119

United Kingdom 2013 Defender 110 Puma 2.2 USW Orkney Grey

Not true about the coil or the EMI, or both? Confused Darren

2013 Defender 110 USW XS
2013 Discovery 4 XS

"You came in that thing? You're braver than I thought!" - Princess Leia

MY 110 USW BUILD THREAD - MY 200tdi 90 BUILD THREAD - Instagram: @landroveranorak

Post #792811 13th Sep 2019 3:58pm
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sako243



Member Since: 08 Jul 2014
Location: Wales
Posts: 641

United Kingdom 1994 Defender 110 300 Tdi CSW Alpine White

Both and/or one or the other...

Clue is in the name. Voltage sensitive/sensing relay. Normally they'd make a song and dance about it being a solid state relay VSSSR Laughing.

For applications like this it makes more sense to use a good old fashioned relay because once closed realistically it's resistance is effectively 0 ohms. Even the best high current MOSFETs will have an Rds(on) (on state resistance) of a few milliohms which means they'll heat up and you need to get shot of that. At high currents it adds up quickly (in fact squares) so unless you need high speeds then there's no point.

You will also get EMI issues with solid state stuff, in fact in most scenarios (this not being one) its worst. The problem is in the switching, all wiring has inductance which is an opposition to changing current. You in effect build up charge in the cable which then causes an overshoot of the voltage. It's a right sod to deal with and the low frequency stuff unfortunately just means bigger components which means more money which is where cost is usually cut on cheaper electronics.

You can create a much cheaper VSR by simply wiring a relay up to the W (or is it Y) terminal on the alternator. Once the alternator is turning (and in most scenarios the engine is running) then that voltage is no longer shorted to ground and rises to battery which can be used to only turn on the relay when the engine is running. I had this but with an extra switch in parallel to a permanent live so I could connect both batteries if I wanted when the engine was off.

However, most VSRs are a bit more intelligent in that they monitor the voltage and can guess at when the primary battery is charged before switching in the second.

There is a good discussion on a thread involving Si Rafferty on LR4x4 where the idea behind the X-Charge came to fruition which details the pros and cons of each method. Ed
95 Defender 110 300Tdi
96 P38 4.6 HSE

Post #792821 13th Sep 2019 4:18pm
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sako243



Member Since: 08 Jul 2014
Location: Wales
Posts: 641

United Kingdom 1994 Defender 110 300 Tdi CSW Alpine White

The best of both worlds would be a microcontroller driving a relay. You could also use something called an ideal diode (built using MOSFETs) which allows you to actually control charge direction should you so desire. Ed
95 Defender 110 300Tdi
96 P38 4.6 HSE

Post #792822 13th Sep 2019 4:21pm
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LandRoverAnorak



Member Since: 17 Jul 2011
Location: Surrey
Posts: 7119

United Kingdom 2013 Defender 110 Puma 2.2 USW Orkney Grey

Ah, ok. Interesting. I'd always assumed they were solid state given the way that the operate and that the term 'relay' was being used figuratively. I'm happy to stand corrected though. I guess the relevant point is that they don't suffer from the issues that Steve suggested above, of the voltage dropping in and out on starting and being aggressive to electronics.

sako243 wrote:
You can create a much cheaper VSR by simply wiring a relay up to the W (or is it Y) terminal on the alternator. Once the alternator is turning (and in most scenarios the engine is running) then that voltage is no longer shorted to ground and rises to battery which can be used to only turn on the relay when the engine is running. I had this but with an extra switch in parallel to a permanent live so I could connect both batteries if I wanted when the engine was off.

I've done exactly this in the past, fitted to a 300tdi Discovery. It used, from memory, a 180amp relay as the base and included a manual override switch (and some LED's to indicate what it was doing). I used it to charge two 100amp batteries in a trailer and it was very effective. The modern VSR's are just easier to install and, as you mention, include some nice monitoring features. Darren

2013 Defender 110 USW XS
2013 Discovery 4 XS

"You came in that thing? You're braver than I thought!" - Princess Leia

MY 110 USW BUILD THREAD - MY 200tdi 90 BUILD THREAD - Instagram: @landroveranorak

Post #792826 13th Sep 2019 4:38pm
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Mo Murphy



Member Since: 01 Jun 2008
Location: Letchworth Garden City, Herts
Posts: 1133

United Kingdom 1984 Defender 90 200 Tdi HT Orkney Grey

I just use a 100 amp relay switched by the alternator. If I need to jump start myself, which I've only ever needed to do once, I plug the jump leads into the Anderson connector and onto the leisure battery and then leave for 30 minutes.
I run the fridge, scenelites and charging points off the leisure battery and has served me well on many trips abroad.
It's not fancy or elegant or trick but it is inexpensive and simple Very Happy
Mo The Land Rover 90 - Many are called, few are chosen.

Post #792837 13th Sep 2019 5:15pm
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