Shunt vs Hall based battery monitors.

[mrdavvv]

Hello Forum!.

So im going to buy a couple of battery monitors for my banks. Im interested in the ones recommended by Will:

Shunt Based

Hall Sensor

Seems like they can serve the same function, check battery state and measure capacity.

However, what are the considerations for deciding between each one?.

Shunt:
- More accurate probably.
- Can measure charge / discharge (Bidirectional).
- It requires a prob, wich needs more connections (Adding some resistance to the circuit).

Hall
- Gives more data, cheaper.
- Can only measure charge or discharge
- Its cleaner as it doesn't need a "physicall" connection.

Right now im tipping over the Hall side, i dont need very acurate numbes, and im only interested in the SOC and capacity of my batteries. Also would preffer to have less connections in my system.

So, what are your toughs on this?

 

[John Frum]

Hall sensor is ok for a stationary setup but not a mobile.
The ones you linked seems to be rated for 100amps.

Looking for a DC Ammeter that can connect serial/usb/bluetooth to a computer

I think the cut and paste jumbled the code a bit.

diysolarforum.com

 

[Fred S]

You can get Hall's that are bidirectional. The two below (and the one you linked) at least "say" they are:

Amazon.com

Amazon.com

 

[RCinFLA]

If you are not looking for too much accuracy (10-20%) and like Hall effect sensors go with it.

Most of what you buy are open loop Hall sensors. They are not super linear over all current range because of magnetic 'S' curve on their core. They will typically read greater current then actual at low current and less then actual at high current.

There are more expensive 'closed loop' hall effect sensors that are very accurate. They have a feedback winding on core that is fed by an op amp (which requires separate DC power) that amplify the actual hall effect sensor output and feed it to feedback winding on core. The feedback winding drives the net field in the core to near zero flux thereby always keeping in the most linear region of core and small flux range. The actual measurment output is from the output of op amp. They are also very accurate for phase measures.

They have various AC bandwidths available range from DC up to above 500 KHz. I have one of these I use to measure instantaneous current along with instantaneous voltage on air conditioner compressor during initial compressor startup along with its power factor on a two channel portable scope.

Amazing results when I measured my 3.5 ton Scroll type A/C compressor that runs at about 13.5 amps at 240 vac at 92% power factor. The startup surge was a wopping 120 amps at 240 vac for 400 milliseconds with 40% power factor. My normal service handheld clamp on ampmeter with 'peak startup' capabillty showed 40 amp peak current.

The whole exercise was to find out what inverter power capability was required to provide the necessary startup current to run the central A/C for the house.

One thing that I learned was the locked rotor amperage (LRA) on the compressor name plate was 105 amps and seemed strange that my reading was greater then this. It turns out LRA rating is based on the lowest voltage spec (205 vac) on the compressor for the purpose of sizing the maximum amperage breaker on a shared branch circuit. You want to be sure the breaker pops if compressor locks up for some reason.

 

[mrdavvv]

Hall sensor is ok for a stationary setup but not a mobile.
The ones you linked seems to be rated for 100amps.

Looking for a DC Ammeter that can connect serial/usb/bluetooth to a computer

I think the cut and paste jumbled the code a bit.

diysolarforum.com

Its quite interesting that you cannot use them for mobile because of earth magnetic field, i guess you could use them as a rudimentary speedometer if you have nothing to do

You can get Hall's that are bidirectional. The two below (and the one you linked) at least "say" they are:

Amazon.com

Amazon.com

Thanks for the links, the bidirectional 200A looks great, i think im purchasing it.

If you are not looking for too much accuracy (10-20%) and like Hall effect sensors go with it.

Most of what you buy are open loop Hall sensors. They are not super linear over all current range because of magnetic 'S' curve on their core. They will typically read greater current then actual at low current and less then actual at high current.

There are more expensive 'closed loop' hall effect sensors that are very accurate. They have a feedback winding on core that is fed by an op amp (which requires separate DC power) that amplify the actual hall effect sensor output and feed it to feedback winding on core. The feedback winding drives the net field in the core to near zero flux thereby always keeping in the most linear region of core and small flux range. The actual measurment output is from the output of op amp. They are also very accurate for phase measures.

They have various AC bandwidths available range from DC up to above 500 KHz. I have one of these I use to measure instantaneous current along with instantaneous voltage on air conditioner compressor during initial compressor startup along with its power factor on a two channel portable scope.

Amazing results when I measured my 3.5 ton Scroll type A/C compressor that runs at about 13.5 amps at 240 vac at 92% power factor. The startup surge was a wopping 120 amps at 240 vac for 400 milliseconds with 40% power factor. My normal service handheld clamp on ampmeter with 'peak startup' capabillty showed 40 amp peak current.

The whole exercise was to find out what inverter power capability was required to provide the necessary startup current to run the central A/C for the house.

One thing that I learned was the locked rotor amperage (LRA) on the compressor name plate was 105 amps and seemed strange that my reading was greater then this. It turns out LRA rating is based on the lowest voltage spec (205 vac) on the compressor for the purpose of sizing the maximum amperage breaker on a shared branch circuit. You want to be sure the breaker pops if compressor locks up for some reason.

Plenty of interesting info, i just want to get an idea of where my batteries are so i think im good with a simple open loop one. 120amps @ 240V its a great deal of power, wich type of inverter you ended up using?

 

[tictag]

Imho, shunts are easier, simpler devices that are not impacted by magnets (or the Earth!). They can be far more accurate than a magnetic sensor (10's of mA accuracy at hundreds of Amps) with far more linear measurement because they work on the basic principle of Ohm's Law. I'm an advocate of the KISS principle (in most things).

 

[mrdavvv]

Yeah i ended up buying a couple of shunt based meters at the end .

My only worries is adding more complexity to the system.... now i have a new device and connection in the system (Point of failure)... in my mind the real KISS would be the hall sensor, as its just a probe with a screen, and even if it fails the system would be OK.

But i guess shunt failures being only a resistance are extremely rare, so it should be ok

 

[Liam M]

The Ali monitor is back ordered through aug/sept,
would this be a good substitute?

https://www.amazon.com/dp/B07T8GN61Z/ref=cm_sw_r_cp_awdb_t1_KG1cFb79ZYFVN

 

[Dougyfish]

The Ali monitor is back ordered through aug/sept,
would this be a good substitute?

https://www.amazon.com/dp/B07T8GN61Z/ref=cm_sw_r_cp_awdb_t1_KG1cFb79ZYFVN

I have a Baylite that I'm pretty happy with:

Amazon.com: bayite DC 6.5-100V 0-100A LCD Display Digital Current Voltage Power Energy Meter Multimeter Ammeter Voltmeter with 100A Current Shunt : Automotive

Buy bayite DC 6.5-100V 0-100A LCD Display Digital Current Voltage Power Energy Meter Multimeter Ammeter Voltmeter with 100A Current Shunt: Voltmeter - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[mrdavvv]

The Ali monitor is back ordered through aug/sept,
would this be a good substitute?

https://www.amazon.com/dp/B07T8GN61Z/ref=cm_sw_r_cp_awdb_t1_KG1cFb79ZYFVN

I think that was the one that had some bad reviews in Amazon... but not sure.

I ended up buying this one:

juntek battery monitor - Buy juntek battery monitor with free shipping on AliExpress

Quality juntek battery monitor with free worldwide shipping on AliExpress

www.aliexpress.com

Its a recomendations from Gazoo in here: https://diysolarforum.com/threads/recomendations-on-hall-battery-monitors.9276/#post-100521