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Armattan Japalura 4" Build Log
#16
Yes, I'm sure you'll love it, I use 650mah & 850mah R-Lines on my 3" Jap and it's very quick indeed
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#17
The little 500mA/h Graphenes certainly are not up to the job. On a punch out that drew a reported 37A, the voltage dropped all the way down to 11.9V!

No flying today. Even though it has stopped raining, it's still so wet on the ground that I'd probably destroy the Split's electronics on the first landing in the grass. I don't want to start covering everything in conformal coating until I'm sure I've got everything working perfectly.
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#18
(23-Sep-2017, 12:14 PM)unseen Wrote: The little 500mA/h Graphenes certainly are not up to the job. On a punch out that drew a reported 37A, the voltage dropped all the way down to 11.9V!

No flying today. Even though it has stopped raining, it's still so wet on the ground that I'd probably destroy the Split's electronics on the first landing in the grass. I don't want to start covering everything in conformal coating until I'm sure I've got everything working perfectly.

I do use this stuff 

https://www.electrolube.com/products/how...ating.html

and i do fly in rain helps alot with wet grass and rain!!!

Saves money even if you dont fly in rain.protects electronics well.

Before then like u sayd i have smoked loads of stuff in grass but not anymore.Never had problem since love this stuff !!!

Regards
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#19
I use an acrylic based coating spray. It can be soldered through after application if required. If I need to do that then after soldering, I just decant some of the liquid from the can and re-apply over the soldered areas with a small brush.
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#20
So, I finally got the time to put a good few batteries through the Japalura this weekend.

The first thing I noticed was that the default current meter scale of 400 was way off. I fully charged my 850mA/h battery and flew until it was down to 3.7V per cell. Betaflight reported that I'd used 629mA/h, but my charger (in non-balance mode) put back 697mA/h.

If you look at the Cleanflight documentation, specifically the file "Battery.md", it shows the following formula:

Code:
amperage_meter_scale = old_amperage_meter_scale * (charging_data_mAh / reported_draw_mAh)

This is incorrect! If I use the formula as given, I get:

new scale = 400 * (697 / 629)

That gives a new scale of 443 which is the wrong direction - it should be smaller, not larger! I tried it, just to prove the point and Betaflight reported 594mA/h used while the charger put back 734mA/h.

The correct calculation is:
Code:
amperage_meter_scale = old_amperage_meter_scale * (reported_draw_mAh / charging_data_mAh)

Using the first figures, I get:

new scale = 400 * (629 / 697)

Which gives a new scale of 360. After changing to 360, I did another run and got 546mA/h reported by Betaflight and 551mA/h put back by my charger.

Much better!

With the correct scale for the current sensor, I also saw that the maximum current draw in a punch out was 61A, which is what I would expect from the 1407 motors spinning 4045 props. In a static thrust test, that configuration pulls 21A on a single motor and given that actual current draw is normally about 30% less than the static measurement, an actual draw of 15.25A per motor is correct.
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#21
(23-Sep-2017, 11:11 AM)RENOV8R Wrote: Yes, I'm sure you'll love it, I use 650mah & 850mah R-Lines on my 3" Jap and it's very quick indeed

Yeah, no kidding with the 'very quick indeed'.

I was actually quite shocked that such a tiny little craft with 4" props could be so fast. Those 1407 motors are truly amazing!
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