What size Victron shunt please ..

[SteveandSueJ]

Hi, got a 100ah Eco worthy lithium battery just installed in my 2009 Rapido. Cbe316 charger set to Gel, 120w solar into a Victron 75/15 mppt Bluetooth controller. All works great but no way of knowing real SOC of battery. Don't think I will need to expand battery capacity tbh as all good at present. Pls explain difference between the 300 or 500 Victron shunt and which one I need? Thx guys ..

 

[Jev88]

I think it boils down to maximum amps it can handle/measure.

 

[SteveandSueJ]

Right so a 300 is likely enough, even if I added another 100ah battery in parallel, later?? Wasn't sure if there was any other difference other than the amp it would handle .. thx .

 

[TrudeandDall]

Hi, got a 100ah Eco worthy lithium battery just installed in my 2009 Rapido. Cbe316 charger set to Gel, 120w solar into a Victron 75/15 mppt Bluetooth controller. All works great but no way of knowing real SOC of battery. Don't think I will need to expand battery capacity tbh as all good at present. Pls explain difference between the 300 or 500 Victron shunt and which one I need? Thx guys ..

300 has 8mm studs for the cable connectors and the 500 has 10mm studs. 8mm is the standard battery bolt size..
If you have 8mm cable eyelets already then the 300 needs no changes to your existing negative cable. You will just need a new 8mm short lead gor between the battery and the shunt.

 

[autorouter]

Pls explain difference between the 300 or 500 Victron shunt and which one I need?

Make sure you don't confuse amps and amp-hours. The amp-hours is the charge capacity of the battery. A battery with a charge capacity of 200 amp-hours can supply 1 amp for 200 hours, or 20A for 10 hours, and so on. A battery will have a maximum amps limit, so it couldn't supply 2000A for 1/10 of an hour in practice even though the calculation suggests it might.

The maximum amps limit of lithium batteries varies, but is generally much higher than a lead-acid leisure battery with the same nominal charge capacity. A 100Ah lithium will have an amps limit of at least 50A, and some are good for 100A.

The shunt limit is for the amps, not the amp-hours. A 100A shunt would be fine on a 1000Ah battery bank if the maximum amps demand was only say 70A or 80A. So you need to find out the maximum amps.

Usually any habitation loads are less than 20A to 30A, except if you have an inverter. To find out how many amps an inverter will draw, divide the watts output by the voltage (12V) and add about 10%. So for a 1200W inverter the amps demand will be around 1200 / 12 = 100A, plus 10% makes it around 110A.

So to answer the question, a 300A shunt would be OK for an inverter up to say 2000W. But for 3000W you are probably best getting a 500A shunt.

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[SteveandSueJ]

Great replies... Thank you ..

 

[SteveandSueJ]

300 has 8mm studs for the cable connectors and the 500 has 10mm studs. 8mm is the standard battery bolt size..
If you have 8mm cable eyelets already then the 300 needs no changes to your existing negative cable. You will just need a new 8mm short lead gor between the battery and the shunt.

For that short lead connection, what size cable should it be please? I do have a 1000w inverter in use....thx.

 

[TrudeandDall]

For that short lead connection, what size cable should it be please? I do have a 1000w inverter in use....thx.

I am not an expert like Autorouter and Lenny HB etc.
My advice is to work out the amps that your system can pull from the battery (inverter + hab loads) simultaneously and then make sure that the short cable between the negative pole on the battery and the battery side of the shunt is able to handle all of your inverter and hab loads simultaneously and with a safety margin!
In my case, I have gone oversize on the cables for the 1200 watt inverter at 25mm2 and the hab load/charging cables are 16mm2.
The absolute maximum that my system could draw s 110 amps, I added a 20% safety margin, so 132 amps load.
My short lead from the battery neg pole to the shunt is 25mm2, which can handle 170 amps = belt and braces..