# Is the VESC 4.12 energy measurements reliable?

Hi guys! I have some issues regarding energy measurements.

I have a 15Ah battery connected to two VESCs 4.12 (different brands). According to them they each consume ~1,2Ah on a 7,8km ride (~5miles). That is a total of 2,4Ah. If I use 12Ah of my battery, that should then give me a range of 50km (~30 miles). This is far from the truth unfortunately. It’s like a factor 2 wrong.

When I charge the battery after a 7,8km (5miles) ride with initially fully charged battery, I get ~4,3Ah!! into the battery according to the IMAX b6 clone. Not the 2,4Ah stated by the VESCs. Using 4,3Ah in my calculations makes much more sense since I have around 25km range (15miles). ( 12Ah / 4,3) * 7,8km = 22km.

To add confusion… I don’t actually know the status of the cells. It is possible that they were aged before I got them and it would explain that I don’t get the 50km range. However, my two IMAX b6 clones I use for charging tells me another story. Not sure what to believe now. Either both IMAX chargers measures wrong, or both VESCs measures wrong… or my thinking is wrong

So two questions: 1. Are the VESC energy measurment accurate and if so, what am I doing wrong? 2. I can only see two current shunts and they are for the phase current measurement. Does it mean the I_DC is calculated and not measured?

Here is a screen shot of energy calculations for a typical 7,8km ride. 3,5 *2,24 = 7,8km. Don’t mind the 0,4V battery voltage offset on VESC 2.

Interesting, sure sounds like your VESC measurement isn’t accurate. I might have to go back to my Lipo setup so I can charge them on my RC charger and test mine…

My VESC battery current measurement is not accurate!

Tested with an very old but good HP power supply.

Thierry