Battery level indicator for 48v 30ah li-ion battery

I am working on a project (Electric motorcycle), and I wanted to use Arduino as battery level indicator. All I know is you can reduce the voltage by voltage divider circuit but what about the current?

I know there are devices that can measure current and interface with an Arduino but I don’t know any specific names.

You will probably get better advice if you change your Title (edit the Original Post) to something like “How to measure battery current and voltage with Arduino”

…R

Don't cross post. http://forum.arduino.cc/index.php?topic=493200.msg3364983#msg3364983

Depends, how much current?

Sharath007: I am working on a project (Electric motorcycle), and I wanted to use Arduino as battery level indicator. All I know is you can reduce the voltage by voltage divider circuit but what about the current?

This is a great project which I have great interest in. Yes you can use a resistor divider for the voltage quite easy.It depends how accurate you want it, I would use an MCP3426(16bit a/d converter) or ADS115 from E-bay there cheap enough. AS for the current what is the max current draw and max charging current ? You could use a shunt for example 100amp 60mV then an op-amp to boost the voltage to convert to the current reading. I'm working on a portable 12V 22Ah power supply for my laptop 12V to 16V converter and displaying remaining percentage plus amp hours out and in, Because the current is less than 10amps on both I use the ACS712 hall effect X 2 one for charging and measuring the load out on the high side which is easier. This is only due to a solar panel charges the battery which could be at the same time while running the laptop. All this is computed in software so far the results seem to be accurate, but still carrying out a lot more testing with a constant current load to make sure run time of the battery is correct. I got the idea from here which could easily be modified to suit your application.http://www.4x4community.co.za/forum/showthread.php/190968-Cheap-DIY-Semi-Intelligent-battery-monitor

I have modified it to use and ADS1115 to obtain more accurate readings and made loads of changes to the code, but all credit goes to the author of the project. You could you a single shunt and a op-map as in differential mode with a voltage reference of 2.5V to measure current in and out of the battery, This was the way I first started but then thought if I need to use it while charging the battery. Hence the reason for using 2 current sensors.

I just want to measure the voltage and nothing else. So is it okay if I just use the voltage divider circuit?

Sharath007: I just want to measure the voltage and nothing else. So is it okay if I just use the voltage divider circuit?

Yes.

...R

Hello everyone, I have a similar situation, I am trying to display on Serial the voltage level, just using 4 different messages depending on charge, the matter here is that since the batteries have different curves (depending if they are charging or discharging), how could arduino know if the battery is charging or discharging?, thank a lot.