Parallel Lipo Setup & Current Sensor

[lonewolf7717]

Just curious if this would work? I am a little concerned about any extra resistance the current sensor will create on the lipo its connected to. Also concerned with the current sensor on just one leg of parallel will it allow the two lipos to discharge evenly while allowing them to balance each other out? Anyone else flying a similar setup with success? In case you are wondering I modified the ESC with the parallel connector in attempt to save on long battery leads in a already rather confined space, I can always convert ESC back to 1 lead and use a conventional y-cable with connectors at each end but boy thats a lot of extra wire. I also understand that for the purpose of OSD read out of mah I will only see one lipo, although I typically gauge flight time based on voltage rather than mah used anyways. Any help would be greatly appreciated.

 

[colorex]

If you want to read how many amps you are pulling through your system you would have to put the sensor across the two batteries, not just one. Otherwise it would just show you about half the amperage.

When you have two packs in paralell, you have the same voltage, you pull the same current, but you have double the mAh in your tank. So if you want it to show the voltage, you can put it either way. If you want to see the right amount of mAh's that have been used or the right amount of A's that you are currently using, then you need to put it across both batteries.

 

[tramsgar]

A good current sensor has very low internal resistance. You should be able to measure this resistance with a good volt meter.

 

[lonewolf7717]

If you want to read how many amps you are pulling through your system you would have to put the sensor across the two batteries, not just one. Otherwise it would just show you about half the amperage.

When you have two packs in paralell, you have the same voltage, you pull the same current, but you have double the mAh in your tank. So if you want it to show the voltage, you can put it either way. If you want to see the right amount of mAh's that have been used or the right amount of A's that you are currently using, then you need to put it across both batteries.

Thanks for the reply Colorex but that aspect of this setup I understand. I have found most current sensors regardless of brand to have pretty bad mah counters, typically way off one way or another very gimmicky. I would be flying based on the mah used from one lipo knowing once 60-70% has been pulled its time to start looking for a place to land even if I am looking at half my available capacity. But as I stated I trust the voltage readout under load far more than those dang mah counters. Still would like to know though if anyone flys with a similar setup without issue

 

[lonewolf7717]

Guess I could simply give up on the parallel setup even though I have tons of 2200mah lipos and spend the big bucks on some 4400-5000mah big boys.

 

[colorex]

Guess I could simply give up on the parallel setup even though I have tons of 2200mah lipos and spend the big bucks on some 4400-5000mah big boys.

I think you should put the voltage sensor after joining the two batteries together, anyway. That is, the sensor right on the ESC, and the batteries branch out from the sensor.

 

[lonewolf7717]

I think you should put the voltage sensor after joining the two batteries together, anyway. That is, the sensor right on the ESC, and the batteries branch out from the sensor.

Now that sir is a fine idea! Not sure why I didn't think of that, can solder sensor direct to esc with a few cm of battery wire, then have split soldered on other side going to lipos! This will be a purpose built fpv plane so not a problem to have sensor permanently attached.

 

[colorex]

Now that sir is a fine idea! Not sure why I didn't think of that, can solder sensor direct to esc with a few cm of battery wire, then have split soldered on other side going to lipos! This will be a purpose built fpv plane so not a problem to have sensor permanently attached.