Read Battery Charger status from a device.

[Sperkowsky]

Originally Posted by dirtbikerxz

If I do that, won't i just get the voltage that the charger is outputting not the current voltage of the battery?

It will probably be something you have to make yourself.

I would check out the documentation on the Battery Beak
http://www.andymark.com/product-p/am-0995.htm

[dirtbikerxz]

If I spliced in a voltmeter between the charger and the battery, would I get the reading of the output of the charger, or the Voltage on the battery?

[Daniel_LaFleur]

Originally Posted by dirtbikerxz

If I spliced in a voltmeter between the charger and the battery, would I get the reading of the output of the charger, or the Voltage on the battery?

If the charger is on, and charging the battery, you will get the voltage of the charger.

If it's an intelligent charger, then it will depend on the 'state' of the charger.

[dirtbikerxz]

Originally Posted by Daniel_LaFleur

If the charger is on, and charging the battery, you will get the voltage of the charger.

If it's an intelligent charger, then it will depend on the 'state' of the charger.

If I'm using the frc charger (which is "smart" i believe : http://www.andymark.com/Battery-Char...-p/am-2026.htm)

would I just be reading the volts of the battery after the charger stops charging it?

[GeeTwo]

In order to know the "battery voltage" while actively charging, you will need to measure the charging current I_c as well as the terminal voltage V_t, and have a good idea of the "internal resistance" of the battery, R_i. Then, V_batt ≈ V_t - I_cR_i. Ideally, you'd measure R_i
yourself, but if you just want a nominal value, a study by team 1640 a few years ago indicated that a good FRC battery has an internal resistance of about 0.02Ω. Alternately, if you use a 2A trickle charger, the difference would only be about 0.04V, even when still charging at full current.

[Ari423]

Originally Posted by Daniel_LaFleur

If the charger is on, and charging the battery, you will get the voltage of the charger.

If it's an intelligent charger, then it will depend on the 'state' of the charger.

Oh, I forgot about that. Maybe you could send an output from the tablet through the microprocessor to a switch to turn off the power to the charger for a second every minute or so and take readings then?

Obviously full disclaimer: I have never done this before.

[dirtbikerxz]

Originally Posted by Ari423

Oh, I forgot about that. Maybe you could send an output from the tablet through the microprocessor to a switch to turn off the power to the charger for a second every minute or so and take readings then?

Obviously full disclaimer: I have never done this before.

Ya, maybe I can use a arduino and a relay, to turn it on and off. But I guess I also don't want to do that, because it would be interrupting the charge of all the other batteries on that charger. So that might get annoying. Don't know. Too bad the frc chargers don't have a serial output on them, lolz.

[dirtbikerxz]

Or is there maybe a way that you could measure if its full or not based on and amperage reading? Or would a amp reader also just show the amp output from the charger. It probably would. (in case you guys haven't realized yet, electricity isn't really my thing )

I could just use a volt reader like this : https://www.adafruit.com/products/460 but so no need for a tablet interface, but it wont be effective, since it would just show the volt output of the charger right?

[Daniel_LaFleur]

Originally Posted by dirtbikerxz

Or is there maybe a way that you could measure if its full or not based on and amperage reading? Or would a amp reader also just show the amp output from the charger. It probably would. (in case you guys haven't realized yet, electricity isn't really my thing )

I could just use a volt reader like this : https://www.adafruit.com/products/460 but so no need for a tablet interface, but it wont be effective, since it would just show the volt output of the charger right?

Reading the amperage between the charger and the battery will only give you the charging current, which is usually limited (purposely) by the charger (to either 2 or 6 amps).

To measure the battery appropriately you'd want to measure the internal resistance of the battery. This can only be done when not charging the battery (you actually need to draw current from the battery)

[Ari423]

Originally Posted by dirtbikerxz

Or is there maybe a way that you could measure if its full or not based on and amperage reading? Or would a amp reader also just show the amp output from the charger. It probably would. (in case you guys haven't realized yet, electricity isn't really my thing )

I could just use a volt reader like this : https://www.adafruit.com/products/460 but so no need for a tablet interface, but it wont be effective, since it would just show the volt output of the charger right?

I can't say about the amps, but you could do some testing with a clip-on ammeter to see if there's a correlation.

I was thinking of using something like what you linked. Make sure whatever you use is rated high enough for the current these batteries can produce. Maybe mount a button next to the output displays that says "PUSH TO TAKE READING". The button would be wired to a relay to control the charger. Then the charging is only interrupted when you want a reading. The button would also need to switch on some kind of load. It wouldn't allow for continuous reading, but if that wasn't a feature you needed, it should be a fine way to go.