Amp Clamp?

So I was thinking it would be handy to have an amp clamp like device via an arduino so I can do what I want with it.

Here's what I'm thinking..

I work in the Industrial Battery Industry and we repair and maintain them. For testing we use a load bank that puts the equivalent of a forklift usage on said battery for 6 hours to determine how well the cells manage.

Each hour we take readings of all the cells and then have to readjust the load bank because the draw dissipates a little over time. So I want to put a dedicated sensor on the load bank with a nice little LCD that displays the amps so we don't need to get an amp clamp (Not like its much work, but hey)

So I was thinking a hall sensor (Never used before) but most I've seen only go up to 100A. We go just a bit higher sometimes depending on the battery in question... so don't know if this is viable.

My other thoughts were of a sort of shunt internally between the Pos/Neg output cables (Never made anything like this, but through my work I've seen them used)

Any thoughts fellas?

for AC it would be easy....

open energy monitor

buy clamp-on CT's
plug them in to the board
get a display and Bobs your uncle !

the board : emonTx Arduino Shield SMT - Shop | OpenEnergyMonitor

CT's : Current Transformers

for DC, we do not have a common CT that does DC at a low cost and easy availability.

however....
robotshop
does have an array of sensors.

you have to bolt your cable onto the board, so you would need to add the boards and more cables.

lastly, at more expense, a DC,non-invasive transmitter with ModBus output
DC amp meter

and here is a link to their data sheet for this DC capable donut:
datasheet

As a design note, you would want to get one whose span is close to your max. the output into the Arduino will be 1,024 steps, so your resolution will be dependant on how close the current is to the span of your sensor.