Battery Monitor measuring current

I'm playing around in creating a battery monitor for a portable power pack (to run a small invertor) and I may want to charge it with a charger or solar panel, The idea is to monitor charge going in and current out of the battery so I can roughly display runtime and AH left or how many AH has been put back into the battery. I know there are high side current monitors out there but recently I've done a similar thing to measure current draw using one sensor, This can measure the current flowing in and out the battery but the trouble I'm facing is that if I have a solar panel connected at the same time and running the small invertor I can't measure both at the same time. Because I've got a couple of these built already my idea was because I've got two of them built use one for the charging side and one for the current draw side, But not sure means everything is in the low side with common ground if there would be any effects or issues. I did not just want to try it incase I destroyed the micro or ADC converter or anything like that,
I've attached a drawing to show how I think it could be connected any feed would back or suggestions would be great

My $0.02, you're really monitoring charger output current and load current, subtract in F/W to get net battery current. But it falls apart when you add extra power/loads.
You only care about the battery health, so if the solar array or a battery charger is supplying input power, you don't need to know- unless then you want to measure current on every device?
You can add/subtract the currents in firmware then, it's just more shunts and op-amps A/D channels.

I would consider measuring battery current with a single shunt. Zero center is at say 2.5V and read +ve, -ve current from that.

Hi,

I agree.
Assume 10A of charging current and 10A of load current..then the battery current is zero. So what's the gain of measuring two different currents.
And consider: you measure 10A charger current...but the battery doesn't become charged at all.

I also tend to a one single "battery current" measurement.
Let's say positive current is discharge current...and negative current is charge current, true charge current. It's easy for a microcontroller to accumulate charge current and accumulate discharge currents.
Then there is charging efficiency...you may take care about this factor..
Then there is self discharge .... you may take care about this.
If you measure battery voltage...then you may know 100% charged state ... and you may know the discharged state...so you may calibrate for battery Ah drift with time..
You are free and flexible to add more health monitoring functions (age, charging cycles, maintenance informations...)

Klaus

I only want to measure the input current from the charger so I can calculate the amp hours that get put back into the battery, I understand if the current from the charger is 10amps and the draw from the battery is 10amps then in theory there's nothing been put into or out of the battery so remaining amps hours should remain the same.
I have a working prototype on the bench but just for testing I'm just using pot's to set current draw in and out and the calculations are very accurate, I've tried setting the both currents the same value and amp hours/predicted runtime remains the same also in firmware I've allowed for charge efficiency of the battery and also using the peukurts factor again calculations for predicted run time is accurate with higher current than your allowed within the 20hr period.
More than likely it will either be Charging the battery or running the Invertor but may be at times both this is the reason I wanted to know if the above circuit would be ok as set up without any implications