450 Starting Problem..

[Tony]

The Scorpion motors are known to run pretty hot. So as long as it is not smoking hot, it 'should' be fine. As for the batteries, I'm going to bet the C rating of the battery is not near enough to handle the motor which is why you are puffing them. Gens Ace is a great brand if you can find them, if not look into Tattu batteries. They are EXACTLY the same battery, just a different label. I run a few of them and they are pretty good. Glacier is great as well and IMO Pulse is at the top of the game. Get a high C rated battery when you order. Better safe than sorry.

 

[Rob Lancaster]

No, no, no smoke. Just hotter than I was used to. This setup is supper nice and I'm have'n fun tuning her back in! The ESC runs very cool so I figure we all got it right. But man,, I still can't get over the killer head speed and more that is now available; nice, nice indeed! All you're guys suggestions were as I hoped.

I ordered 4 Glacier 2200 3s 11.1v 30-35C packs with my XT-60 connectors.
As soon as the weather clears I'll runout the last 2 packs I have, discharge them and jettison them, ha!
Are we having fun yet...……………….

 

[murankar]

Yeah scorpions to run a bit hotter than a normal motor. Xnova runs the coolest of the top end motors. Don't panic if it gets toasty. There are times where you can't touch it for more than a second or two.

 

[Rob Lancaster]

Well,, as I expected, the last two batteries puffed up like puffer kits. Their on my discharger panel and get'n ready for the trash tomorrow.

Ok, about the heat, that's about right, about two seconds seems to be the norm. And there's another WHEW...………
Hey I did my first auto rotation today after my battery fail right on time. Ok, It wasn't a full on auto rotation but it was interesting to be sure...

My new packs should be here on Monday. So in the mean time I want to work on the tracking and another little problem that just popped up. My red nav LED on the left skid is not working. Oh Man, if it's not one thing it's another LOL! This time it should be an easy fix without a 7 page thread "A" guys...
Ok that's the latest.

 

[murankar]

What resistors did you end up going with? I am still trying to figure out what I need to have.

 

[Rob Lancaster]

I used five 100 watt 50 ohms ... In parallel that will get you a safe 10 ohm load. I used some metal stock I had and bolted the resistors down to the panel for a great heat sink. The fan is from an old computer and is pretty redundant. The resistors barely get warm.
Have fun...……

 

[murankar]

What discharge times are you getting? I am trying to get mine put together for 25v 6s packs. I am finding it difficult to figure out a good current draw.

 

[murankar]

What is your amp draw voltage and time to discharge

 

[Rob Lancaster]

Don't know, I just plug in the battery for 24 hours. then I cut off the leads and dump them. There will be a miniscule voltage left over. I think because of the batteries IR. But when you short the battery with a paper clip the left over voltage disappears and the clip don't even get warm. she's done....

 

[murankar]

I am looking at dropping voltage a lot quicker than that. I want to go from 25.2 volts to around 22v in about 10 minutes. I am thinking i am going to need something close to 1 ohm with 5 resistors.

I am running a .8 ohm 5 resistor set up and drain my packs in about 3 to 4 minutes. I am trying to get to storage charge not totally dead.

 

[Rob Lancaster]

You got me thinking now...
I wonder how long it would take my discharger to go from 4.20v to 3.7v ……. Probably not long.
I just built mine to drain the battery completely. I figured if I made it to run cool it'll last forever and without the chance of a fire too. It works as advertised. I love making little projects that make my life fun'r…

Ok about your resistors..... let's see, your approach seems sound. I'd go ahead and try the 1 Ohm 5 pack in parallel. If its still to fast try 5 1.5 or even 2 Ohms.
I'll run this situation by my brother tomorrow. He's the electrical math guy; boy is he the electrical math guy. The book I used to illustrate the sign wave patterns of AC/DC and pulsating DC that's in the Power Supply Thread, were his...
I know what you want and we'll get you there..

Hey guys!
I'm bust'n in 4 Glaciers tomorrow. Weather permitting...………

 

[murankar]

this project has been scratching my head. Thanks that would help out a lot. in the mean time I am going to check out ohs law calculator on the net.

 

[bigone5500]

The Scorpion motors are known to run pretty hot. So as long as it is not smoking hot, it 'should' be fine. As for the batteries, I'm going to bet the C rating of the battery is not near enough to handle the motor which is why you are puffing them. Gens Ace is a great brand if you can find them, if not look into Tattu batteries. They are EXACTLY the same battery, just a different label. I run a few of them and they are pretty good. Glacier is great as well and IMO Pulse is at the top of the game. Get a high C rated battery when you order. Better safe than sorry.

Those Ovonic batteries are just like the Tattu ones too. Cheaper also.

 

[Rob Lancaster]

Talked with my brother today and he said we're on the right track. However it's the variables that get the head scratch'n going.. Let's start with a particular capacity and time that's known).. I would go in the 1 Ohm direction and see were you end up. from there you can either go up or down in resistance to zero in on the time you want.

Now here comes the variables in the equation,, if you change capacity, like using a different capacity pack for a different model you change the over all out come. Also you want to make sure your resistors can dissipate enough power, (WATTS) so they don't get hot. Mine can dissipate 100 watts of power at 50 Ohms X 5 in parallel = 10 Ohm load...
I guess I wasn't to much help but like bro Tom says,, "every time you change something here, you change something there"... Start with the known and record it and make the necessary adjustments to that one part of the equation. Ohm's law is in play here. So your idea of checking out the charts will be beneficial.

If you have any questions, just ask, I know there's always some confusion when it come to this stuff. That's why I keep my brother around, LOL!>>> OH and you guys too...……….

 

[murankar]

Right now I working with 2 3300 mah packs and 4 3000 mah packs. One thing I do know is that at approximately 40 to 50 amps my packs are at 30%. My basis is on that info alone. My telemetry has keyed me in.

As for resistors in just ordered 5 5ohm resistors. Ohms law calculators tell me I have 625 watts of heat to dissipate. So in will need some.kind of mechanical advantage to removing the heat.

Once I get my deliveries in i will update the article with the new info.

 

[Rob Lancaster]

Here's a little Greek my math bro gave me today.
See if this helps...

 

[murankar]

I was just running that through my head while going to the bathroom. At 3 amp hours, I can then reduce to 6 amps over 30 minutes, 12 amps at 15 minutes, 24 amps over 7.5 minutes.

Reducing down the amo hour to about 10 minutes. Here is the problem we have to substitute the 11.1v with 25.1v and my packes are as follows 4@3000 mah and 2@3300 mah.

I am going to leave a note here to move the load bank stuff to its own thread. Ill do it tonight unless Tony gets to it. This topic really needs to be its own thread. Lots of valuable information for those trying to DIYing there own load banks.

 

[Tony]

This thread is going down a rabbit hole lmao. Glad URI found someone smarter than me to bounce ideas off of though.

 

[murankar]

Hey look at the bright side. I learned how to solder.

 

[Rob Lancaster]

I've have a few epiphany's while on the john. I'll bet that's where they got the idea for the Thinking Man Statue... LOL!

Yeah just use your battery packs specs in the formula. Then see what you get and then zero in on the target resistors. Don't feel bad about get'n it wrong. This is harder than it sounds but not impossible. Heck we all have the math guy scratching his head too, ha!

Smarter than you Tony? Awe shucks...………

All my new batteries are broken in now but its a rainy day so I'm rebuilding the tail rotor hub assembly. I had a bad idler pully bearing. The belt was pretty waisted to so it too is out a here...