Two digital servos and a CC BEC have gone into thin air.....

[redshift]

I have a Spektrum, so that's good news, thanks jhautz.

I'll definetely take a potential pack to pack imbalance over a potential 2 hundred dollar bill for toasted radio bits.

As I said I'll be running about 10 leds and either 2 or 3 fans off the other pack, shouldn't be far off as I only have one 128 oz steering servo and one 80 oz shifter servo, and that's intermittent enough to where it doesn't really count much.

Are you sure about 9.6 on the receiver tho? That sounds way high......

[jhautz]

Originally Posted by redshift

Are you sure about 9.6 on the receiver tho? That sounds way high......

http://www.spektrumrc.com/Products/T...ProdID=SPM1200

[BrianG]

Originally Posted by redshift

I have a Spektrum, so that's good news, thanks jhautz.

I'll definetely take a potential pack to pack imbalance over a potential 2 hundred dollar bill for toasted radio bits.

As I said I'll be running about 10 leds and either 2 or 3 fans off the other pack, shouldn't be far off as I only have one 128 oz steering servo and one 80 oz shifter servo, and that's intermittent enough to where it doesn't really count much.

Are you sure about 9.6 on the receiver tho? That sounds way high......

Figure about 15mA per LED (up to 25mA for high brightness ones), and around 100mA per fan. That's 0.45A total being conservative (15mA X 10 LEDs and 100mA X 3 fans). Figure average of around 1A for both servos together (bursts will be higher). So, that's 1.45A.

If I were you, I'd put some of those LEDs in series. Each "string" will only take 15-25mA, so that's better right off. Depending on the battery voltage and brightness/color of the LED, you may only need two or three strings instead of 10 individual strings. Then, get the appropriate resistor for each string and tie them direct to your full battery pack.

Then, use 12v fans instead direct to the battery, maybe use a linear regulator configured for 13v if you're using higher than 4s. 12v fans use much less current than their 5v counterparts for a given airflow.

Both of these suggestions will remove the ~1/2A load from the BEC.

[redshift]

That's great info, 2S is cheap insurance there!

Brian I should have mentioned I'm using automotive style leds each with their own resistor, so I'll just be merging them all close to the resistors and use a single JST plug.

And yeah 9.6 on the RX, thanks for verifying jhautz. Good stuff to know.

[redshift]

Well, turns out my fear was not unfounded. CC BEC is history. I guess seeing how much smoke it could produce was worth the $25.......

Radio gear did survive, but somehow it managed to half-melt the insulation on the receiver lead of , my brand new MM, looks like my esc may have JUST survived. I am way more irked about that. I tested it multiple times with a meter, had it set at 6.2, the second it had an actual load on it, poof.

I don't know if it's even worth trying to get a refund. I'll eat the $25 knowing it'll never happen again cuz my experience with bec's ends here. So I'll be paying my LHS (2 hour round trip) a visit to buy a $3.49 4AA receiver 'pack'.

Joy.

When my CC BEC failed sometime ago, it took out my servos with it. But later, I found out why it fail. Its heat. The first one I fry was mounted next to my MM ESC...good source of heat there. One of my friend mount his in the same matter, and he fry his too. The second CC BEC I got, I mounted it where is not next to any source of heat and a location where air and pass over it...and no problem since...knock on wood.

[BrianG]

Has anyone with a failed CC BEC did any digging to find out which component blew? During my testing, the inductor was the hottest part at full load. I wonder if the lamination are simply melting? If so, a larger inductor (physically, not inductance value) may be the way to go. I still don't like how the CC BEC goes though - I think a UBEC should simply output 0v instead of full battery voltage...