Installing shunt

[learjohn]

Hi, can anyone please tell me the correct location to instal a shunt. A or B, or elsewhere?


John

[dapope]

At position B
Straight off the battery

[learjohn]

Thanks very much

[BruceS]

Maybe you should explain what the shunt is for?
Technically I think you could place a shunt anywhere you wanted to but the shunt will only show the current flowing through it.
For instance if you were silly enough to put one on the neg or pos of your headlights it'll only record what flows through that wire.
Victron Battery Monitors need it in the neg cable, as close to the battery as possible. (or before any branches)

[learjohn]

Thanks for that Bruce. I just want to be able to accurately read the amps I am using with different things. e.g. fridge , tv etc.
John

[BruceS]

John if you really want an exact report on usage of one item you really should get one of those fantastic "WattMeters".
Not only can they give instant readout of watts & Amps but you can leave it connected in-circuit for 24 hours to see how many AHr's (say) a fridge uses for that period... divided by 24 to get hourly rate. It's the only way to accurately measure a fridge's consumption. (in my opinion)
As the units arrive they have ridiculously short leads either side & a lot of people are fitting them with quick-connect Anderson plugs/sockets.
http://www.ebay.com.au/itm/Boat-RC-Heli ... 3f2c426557

[T1 Terry]

Be aware that the shunt will only measure current entering or leaving the battery. If a charging source such as solar or mains charger etc is supplying current into the circuit after the shunt, any loads will be powered by that charging source. If the current from the charging source is more than the load you will see it recorded as amps in, if it's less than the load the difference is supplied from the battery and that will appear as amps out. As an example, if the fridge required 10 amps to run but the solar was only supplying 7 amps, then the other 3 amps would be drawn out of the battery. The shunt will only record 3 amps out because that was all that was needed from the battery, the real load was still 10 amps, it's just that 7 amps were supplied direct from the solar to the fridge. If you want to know what the actual load is, make sure all charging sources and other loads are disconnected first, otherwise you will get some crazy reading

T1 Terry

[learjohn]

Thanks Terry, will isolate the solar before I take the readings.
My main concern is I run all 12v equipment off a 240v - 12v transformer (All runs off the inverter), rather than 24v -12v step down. I want to see what this is drawing with different appliances, or if it is uneconomical.
John

[T1 Terry]

Unless the inverter has another load as well that must be run 24/7 then it would be uneconomical as far as power useage, whether it is sustainable is another question though. If you have that much power generation that the waste doesn't cause a significant problem then the efficiency is far less important. With the 24v Li set ups we generally use a smaller capacity 12v Li battery and a lower output 24/12 converter to charge it. The idea is the battery can power the spike loads and sustain a high output for hrs without voltage drop so the 24/12 converter can be much smaller as it doesn't need to power the peak load, just the load averaged over 24hrs.

T1 Terry

[learjohn]

I should have mentioned, I run a domestic 240v fridge 24/7 off the inverter. I have 700w of 24v panels and 210 ah AGM batteries. When they die, it will be Lithium. (That will be a bit down the track)
John