Current sensors for AC

I have on order a couple of the ACS711EX current sensor boards. These will be used to automate / monitor the charging regime for a pair of 6V flooded lead acid golf-cart style batteries. This is a low-voltage DC project. After spending some time reading the datasheet for the ACS711, and also taking a quick scan of the ACS709 datasheet, something that became more obvious is that either of the sensors could be used to monitor current on AC as well as the obvious DC circuits.

The ACS709 has a rather high isolation voltage, but there are numerous warnings on the product page, and one or two attempts to discourage people from going there in forum posts. Going there referring to using the ACS709 to directly monitor AC line voltage current usage. While technically possible, it opens up all kinds of issues having to do with insulation and safety.

After thinking about this a bit, it occurred to me that one solution that might still allow this capability, but maintain full safety protocols, is to use a toroid (which would have a primary (carrying the line voltage/current) and an isolated secondary (to connect to the sensor card).

Is this a fair approach, and if so, are there any technical notes that might point me in the right (and safe) direction ? This is not my primary project, but something down the road after I get the battery charging working as desired.


The use of a toroidal transformer is standard to measure currents in 50/60 Hz AC circuits. Here is an example … -interface

I use CTs from Coilcraft – they give out free samples for experimentation

Thank you, that looks like a much better method than trying to put actual AC voltages against the sensor card.