Hello I need to measure between 35 upto 50 amps of DC current on 12v. Everything i found so far is upto 10 to 30 amps. I'm measuing 12v batteries. Is there a current sensor out there that can take that much between 35 to 50 amps? I'm just trying to make sure I'm not over charging or under charging my batteries.
Joseph
Its called a resistor (or a shunt).
Hello johnerrington, I looked into Shunts but the problem I'm facing is limit on spacing within the box. I looked into ina219 but it can only do upto 32amps Which is at the low end of what i need. But not high enough for what i really need it to do.
Joseph
So you get a bigger box.
Simple, wasn't it!
Or mount the shunt externally and use a heatsink
Agreed, bigger box. At this kind of currents space is the last you should skimp on. 75 mV at 100A is 37.5 mV at 50A so almost 2W of heat to get rid of - any current sensor will have this issue.
Besides, you can't read 37.5 mV with an Arduino directly, you need an OpAmp to increase the value, 20-25x sounds about right, that's 750-937.5 mV which is comfortable for the 1.1V range of the internal reference. That's more space needed inside your box.
Check out the Allegro ACS758LCB-050U-PFF-T, available at Digikey.
josephchrzempiec:
I looked into ina219 but it can only do upto 32amps
Did you read that somewhere ? The INA219 measures the voltage over a shunt. There is no current limit, it all depends on the shunt, you can use the INA219 to measure up to a few JigoAmps 
Hello all thank you for the input. I will think about maybe putting the shunt externally. Just hope no one will touch it when I'm away lol. But that is a good idea. Also for the ACS758 currnet sensor I will look into it. Thank you I love the option to make sure i have the current shunt and not have to not be enough.
Joseph
May I ask where you use such a current with 12V? 50A needs quite heavy wiring.
Cheers,
Kari
Hello to measure battery packs That i have made. Using 18650 batteries.
Joseph
josephchrzempiec:
Hello to measure battery packs That i have made. Using 18650 batteries.Joseph
So many questions:
How many cells in series and how many strings in parallel to achieve the final battery?
How are you charging it?
What is the application?
What are the load requirements? how many amps for how long?
Looking at the data sheet it looks like 4 x 3.7 18650 in series gives 14.8 volts Nominal voltage with a cut off voltage of 3vpc or 12 volts per string.
To get 50amps at the standard discharge current of 0.52a requires approx 96 cells so 96 strings of 4 in series so 384 cells?
This would give approximately 5 hours at full current.
Sounds an interesting project.
Sounds more like an explosion waiting to happen.
Hope the Op is aware of protection circuits, maximum/minimum voltages and maximum charging current these cells require.
Those currents and numbers of cells are quite common in solar power applications.
Hi,
Can you explain your battery box please.
Number of batteries and how you have configured them?
What size conductors are you using in the construction.
A diagram would be great! 
I gather you are using series/parallel configuration, do you have a BMS to ensure even cell charging?
30A to 50A at 12V is a very high charger current, more like an electric forklift battery bank.
Can you please tell us your electronics, programming, arduino, hardware experience?
Thanks.. Tom...
Hello Yes this is a solar setup i have. I put together almost 2 years ago. I setup and build. But I'm building a smaller version for something else. I do have BMS setup and they are all balance good. I do not have a way to monitor the new system. I spend 6 months charging and discharging each cell. Also Each pack has the same or close in capacity.
The monitoring i have on my main setup does have monitoring. I build one for my smaller setup. total the packs will put out about 30amps continuously but be able to monitor up to 50 amps just incase.
Joseph
Modify one of this, add a spacer under hall IC
google - ACS712 module ACS712 5A 20A 30A Hall Current Sensor Module For Arduino
[ACS712 module ACS712 5A 20A 30A Hall Current Sensor Module For Arduino - Search](ACS712 - Search module ACS712 5A 20A 30A Hall Current Sensor Module For" arduino&pc="cosp&ptag=G6C19N824D111219AEE67B61E61&form=CONBDF&conlogo=CT3210127)
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