Data Logger info.

[G Doggett]

I had my Eagle Tree data logger on board my Toysport Triton during a couple of heats on the weekend and thought I would share this info with anyone interested.

Feigao 8XL , 4S 5000mah, Hydra 120, Octura X442.

Total run time 2.85 minutes.
Battery capacity used 2586 mah.
Peak amps 84.32
Average amps 72
Maximum watts 1149
Minimum voltage 13.18

Battery voltage at rest was 16.8 which dropped to 13.2 under load for first laps but increased to 13.6 about half way through the race. I presume this was as the cells warmed up.

From this data it is clear that the lipos could handle a lot more load ( bigger prop)as they only used just over half their capacity, but I'm not sure if the 8XL could manage much more as although it only measured108F at the end it is pretty close to its rated max ampage.

Interesting stuff !

Graham.

[ReddyWatts]

That is great info. It is exactly what we should be doing if we want reliable setups, but I would try a bigger prop. lol!

[SJFE]

I am comfortable with 125 on the motor. Kick it up a bit

[G Doggett]

OK - I've got an X642 and X445 I could try, I just don't want to fry my cheepo chinese motor !!!
Graham.

[ReddyWatts]

Thats the right attitude, we need to be careful. Its just to easy to burn something up.

[robby76]

is your 8Xl water cooled?

[Steven Vaccaro]

Good info. If your not racing, I would say thats a great setup and wouldn't change a thing.

[G Doggett]

is your 8Xl water cooled?

Yes, with an OSE water jacket.

It is primarily a race boat Steven,but I have learnt from years of racing nitro and gas boats to be reasonably conservative and go for reliability over blistering speed.
Many of the young wipper snappers in our club haven't figured that out yet.
Graham.

[Steven Vaccaro]

In that case I would setup to a m445. Bit more pitch but less blade.

[Ctonez]

m445 got the motor too hot for me with the same hull, but I was running too wet at the time and no cooling on the motor...just be careful.

[D. Newland]

Graham-nice info.

Did you happen to confirm if the MAH used in that run matched (relatively close) the MAH's put back into the cells when re-charged?

Also, when does the logger clock start? When plugged in or when you first hit the throttle??

[D. Newland]

Oh-one last thing. What cells are you running?? The voltage drop seems a tad on the high side. No biggy, but I would think that at that load the voltage should have stayed above 14.0.

[Steven Vaccaro]

David how low do you figure is two low? I have seen similar readings on my polyrc cells.

[D. Newland]

Well, good question since I don't use a logger!

But, I do test my cells from time to time with 20 bulbs and an E-Flite meter and can simiulate 50-55 amp drain with a 4S pack. The voltage routinely hovers around 14.4 volts, then drops to another "shelf" at about 14.07 volts. I try to start the packs off at 80 to 90 degrees before testing them to limit any further voltage drop.

The extra amps Graham is seeing could cause the voltage to drop further than what I see. It just seemed that the 13.3 volts he was seeing in the beginning was a little "too" low. That's how I think I damaged my first lipo pack...I ran it too cold.

[Darin Jordan]

That's how I think I damaged my first lipo pack...I ran it too cold.

That's exactly right... If the packs are too cold, they'll drop down in voltage a LOT compared to when they are warmer... 90-degrees or so is a good place to start for local racing... Some guys report putting the cells in at 100 or 110 degrees... and having them come out at 95 or so... Those same cells put in at 60 or 70 degrees come out at over 120 for the same run...

Take care not to run them hard when they are cold... You'll hurt them...