Lynx Shunt Wiring

[Rumbledethumps]

Having recently watched Wills excellent youtube video called Victron systems made easy, I loved the neatness of the system and have taken the plunge and slowly been purchasing the components that he demos for this 12v setup.

With the help of this forum I’ve wrapped my head around the solar input side of things and am now looking at the batteries.

I bought the lynx distributor and lynx shunt but would like to know is whether it is acceptable for me to wire 3 batteries in parallel and connect these directly to the (fused) lynx shunt as Will does in the video or would any additional measures be desirable for added safety?

I ask this as Will mentions a couple of times that this is just a demo system to show beginners the basic wiring/connections so I’m wondering if there is more that I need to know/add with regard to this setup. I’ve seen a few other systems online that use a lynx distributor for the parallel battery bank that then connects to the lynx shunt and then the other lynx distributor for the charge controller and inverter ins/outs...

I’m currently undecided on which batteries to buy, but also wonder if the batteries having an internal BMS will have any affect on how they need to be wired or is this irrelavant?

Thanks.

 

[John Frum]

Devil is in the details.
The fuse in the Lynx shunt is ANL style.
The ANL fuses have good arc quenching capacity at 12 volts but not so good at 24 or 48 volts.
The lynx shunt is pretty expensive compared to other options like the smart shunt.
Also its meant to go between other lynx devices.
Its really great when you have something like this lynx_power_in<->smart_shunt<->lynx_distributor

What is the capacity of your batteries in amp hours?
What chemistry are they?
What is the system voltage?

 

[Rumbledethumps]

Devil is in the details.
The fuse in the Lynx shunt is ANL style.
The ANL fuses have good arc quenching capacity at 12 volts but not so good at 24 or 48 volts.
The lynx shunt is pretty expensive compared to other options like the smart shunt.
Also its meant to go between other lynx devices.
Its really great when you have something like this lynx_power_in<->smart_shunt<->lynx_distributor

What is the capacity of your batteries in amp hours?
What chemistry are they?
What is the system voltage?

Hi Joey,

It's a 12v system as per the one Will demos.

I'm still deciding at the moment but was going to go with 3x100ah lifepo4; possibly TN Power or if my budget can stretch, the Victron superpacks.

Just so I'm clear, are you saying that connecting the batteries to a lynx power in, then to the shunt, then the distributor would be preferable to connecting the battery cables to the lynx shunt as Will does? If so is this for neatness or are there other benefits/safety implications to this?

 

[John Frum]

Hi Joey,

It's a 12v system as per the one Will demos.

I'm still deciding at the moment but was going to go with 3x100ah lifepo4; possibly TN Power or if my budget can stretch, the Victron superpacks.

So are you saying that connecting the batteries to a lynx power in, then to the shunt, then the distributor would be preferable?

Its what I would do.
I would connect each battery individually to one of the branch positions on the power_in.
I would use 4 awg wire
a 150 amp mrbf fuse.

150A: MRBF-Series: Blade Fuses | Waytek

Bolt-down fuses provide protection from 30A to 600A and are ideal for battery and alternator circuit protection. Order from Waytek today!

www.waytekwire.com

mounted on the battery positive terminal using one of these if its an m8(5/16") terminal stud

Littelfuse 0FHZ0201Z SMZ Series, M8 Stud Mount ZCASE Fuse Holder | Waytek

Littelfuse 0FHZ0201Z SMZ Series, M8 Stud Mount ZCASE Fuse Holder w/ Fuse &Stud Cover, 400A, 80V is in stock and ready to ship. Order today!

www.waytekwire.com

or one of these if its a m10(3/8th) terminal stud

Eaton's Bussmann Series CFBAR1-250BP Mounting Bar, 3/8 Mount | Waytek

Eaton's Bussmann Series CFBAR1-250BP (CBBF-MBC) MRBF Mounting Bars with 1/4"-20 stud and 3/8" mounting hole work with CBBF Series Fuses and available at Waytek.

www.waytekwire.com

That way the chance of an upstream short approaches 0
The other advantage is all the batteries get charged/discharged equitably
And this way a battery can be taken offline within minimal impact on the rest of the system

 

[Rumbledethumps]

Its what I would do.
I would connect each battery individually to one of the branch positions on the power_in.
I would use 4 awg wire
a 150 amp mrbf fuse.

150A: MRBF-Series: Blade Fuses | Waytek

Bolt-down fuses provide protection from 30A to 600A and are ideal for battery and alternator circuit protection. Order from Waytek today!

www.waytekwire.com

mounted on the battery positive terminal using one of these if its an m8(5/16") terminal stud

Littelfuse 0FHZ0201Z SMZ Series, M8 Stud Mount ZCASE Fuse Holder | Waytek

Littelfuse 0FHZ0201Z SMZ Series, M8 Stud Mount ZCASE Fuse Holder w/ Fuse &Stud Cover, 400A, 80V is in stock and ready to ship. Order today!

www.waytekwire.com

or one of these if its a m10(3/8th) terminal stud

Eaton's Bussmann Series CFBAR1-250BP Mounting Bar, 3/8 Mount | Waytek

Eaton's Bussmann Series CFBAR1-250BP (CBBF-MBC) MRBF Mounting Bars with 1/4"-20 stud and 3/8" mounting hole work with CBBF Series Fuses and available at Waytek.

www.waytekwire.com

That way the chance of an upstream short approaches 0
The other advantage is all the batteries get charged/discharged equitably
And this way a battery can be taken offline within minimal impact on the rest of the system

OK, that's great.

Just so I'm clear; rather than connecting the batteries in the conventional parallel way, each of the 3 batteries will feed into the lynx power in as 3 pairs of cables. I then put a fuse with one of the holders you've specified directly on the positive terminal of each battery, rather than putting these in the lynx power in? (i'm not familiar with the power in or whether fuses can be placed on the positives inside?). This being the case, what size fuse would you recommend in the lynx?

 

[John Frum]

OK, that's great.

Just so I'm clear; rather than connecting the batteries in the conventional parallel way, each of the 3 batteries will feed into the lynx power in as 3 pairs of cables. I then put a fuse with one of the holders you've specified directly on the positive terminal of each battery, rather than putting these in the lynx power in? (i'm not familiar with the power in or whether fuses can be placed on the positives inside?).

The power-in is like the distributor but the branch circuits are not fused.
Its also cheaper.
See this video for details on how to hack a power_in to be nearly functionally equivalent to the lynx disributor.

You can even have fused and un-fused branches on the same power_in.

This being the case, what size fuse would you recommend in the lynx?

You mean the lynx shunt?
If yes then 500 amps.
We don't want it blowing unless things have really gone pear shaped.
Each battery has a fuse and each branch circuit on the lynx distributor has a fuse so the shunt fuse should not blow.

I did have a really good conversation recently with @TerryTtibbs https://diysolarforum.com/threads/battery-and-system-fusing-size-question.27032/post-471232

His idea is belt and braces but he does have a point.

battery and system fusing size question

I have a 300 watt S 12v solar array , 3000 watt inverter charger and want to hook up to a 6000 watt Honda generator and cottage panel off grid . Outback 80 voltage reg . When I hook up generator hot wire I get E3 code short circuit . Any ideas.

diysolarforum.com

 

[Rumbledethumps]

The power-in is like the distributor but the branch circuits are not fused.
Its also cheaper.
See this video for details on how to hack a power_in to be nearly functionally equivalent to the lynx disributor.

You can even have fused and un-fused branches on the same power_in.


You mean the lynx shunt?
If yes then 500 amps.
We don't want it blowing unless things have really gone pear shaped.
Each battery has a fuse and each branch circuit on the lynx distributor has a fuse so the shunt fuse should not blow.

I did have a really good conversation recently with @TerryTtibbs https://diysolarforum.com/threads/battery-and-system-fusing-size-question.27032/post-471232

His idea is belt and braces but he does have a point.

battery and system fusing size question

I have a 300 watt S 12v solar array , 3000 watt inverter charger and want to hook up to a 6000 watt Honda generator and cottage panel off grid . Outback 80 voltage reg . When I hook up generator hot wire I get E3 code short circuit . Any ideas.

diysolarforum.com

OK, great I'd thought it would be around 500a for the lynx shunt (ie. 150a x3 plus a bit extra).

If I went with a modified lynx power in for the battery connections, would it still be best to place the fuses on the battery positive terminals or would putting the fuses in the modified lynx power in suffice? I've heard that the closer to the battery the fuses are the better so i'm guessing no?

 

[John Frum]

OK, great I'd thought it would be around 500a for the lynx shunt (ie. 150a x3).

If I went with a modified lynx power in for the battery connections, would it still be best to place the fuses on the battery positive terminals or would fuses in the modified lynx suffice? I've heard that the closer to the battery the fuses are the better so i'm guessing no?

Put them on the battery terminals to minimize the chance of an upstream short.

 

[John Frum]

Besides, mega fuses don't have a pretty low AIC rating so they are used for branch circuits but not for batteries.

Breaking capacity - Wikipedia

en.wikipedia.org

 

[Rumbledethumps]

Besides, mega fuses don't have a pretty low AIC rating so they are used for branch circuits but not for batteries.

Breaking capacity - Wikipedia

en.wikipedia.org

Got it.

Cheers again for the info; this has really helped my understanding of things.

 

[John Frum]

Got it.

Cheers again for the info; this has really helped my understanding of things.

I said that wrong.
Mega fuses have a low AIC.

 

[Rumbledethumps]

I said that wrong.
Mega fuses have a low AIC.

OK, cheers for clarifying.

 

[rfbuehler]

Hi Joey,

It's a 12v system as per the one Will demos.

I'm still deciding at the moment but was going to go with 3x100ah lifepo4; possibly TN Power or if my budget can stretch, the Victron superpacks.

Just so I'm clear, are you saying that connecting the batteries to a lynx power in, then to the shunt, then the distributor would be preferable to connecting the battery cables to the lynx shunt as Will does? If so is this for neatness or are there other benefits/safety implications to this?