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 Scorpion and bbots BEC circuits suck

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rjw
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PostSubject: Scorpion and bbots BEC circuits suck   Thu May 28, 2009 10:00 pm

Since we went to 5 and 6 cel lipos, the bec circuits of scorpion and banebots esc's are having heart failure.

It seems that when using a br6000, that the receiver alone draws more than the bec circuits can supply at higher voltages, duh!!

So, the voltage to the receiver falls out randomly and you're toast.

This was happening with our latest drumbot, until we switched to the bec from the drum esc.

On our wedgebot, we WERE using a BB esc and its bec, but it is de-rated to 25ma at 21 volts, or enough to power a small led MAYBE....

we need new technology , not stuff meant to run with fm recievers from 100 years ago.

any thoughts?
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Jeff L
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PostSubject: Re: Scorpion and bbots BEC circuits suck   Thu May 28, 2009 10:06 pm

rjw wrote:
Since we went to 5 and 6 cel lipos, the bec circuits of scorpion and banebots esc's are having heart failure.

It seems that when using a br6000, that the receiver alone draws more than the bec circuits can supply at higher voltages, duh!!

So, the voltage to the receiver falls out randomly and you're toast.

This was happening with our latest drumbot, until we switched to the bec from the drum esc.

On our wedgebot, we WERE using a BB esc and its bec, but it is de-rated to 25ma at 21 volts, or enough to power a small led MAYBE....

we need new technology , not stuff meant to run with fm recievers from 100 years ago.

any thoughts?
You could give a dedicated receiver battery a try. There are plenty of small (and light) batteries that would run ALL day at competition with no need to recharge them except maybe overnight out of a wall socket.
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Jeff L
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PostSubject: Re: Scorpion and bbots BEC circuits suck   Thu May 28, 2009 10:08 pm

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rjw
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PostSubject: Re: Scorpion and bbots BEC circuits suck   Thu May 28, 2009 10:19 pm

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Dan Curhan
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PostSubject: Re: Scorpion and bbots BEC circuits suck   Wed Jun 10, 2009 12:58 am

you can also try a dedicated BEC that taps into your main battery; certainly lighter than adding a whole battery. This ParkBEC fom robotmarketplace is what we used on Copperhead. We didn't have any problems with it, running at 24V.
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rjw
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PostSubject: Re: Scorpion and bbots BEC circuits suck   Wed Jun 10, 2009 2:02 am

Actually a little digital camera 6v lithium does the job, weighs nothing and has lasted over 45 minutes so far...???

with 2 bec's onboard already, adding another along with the deans cons, etc is a pain and weighs as much or more, plus more stuff to go wrong.

No problem with the drumbot, in that the weapon esc has a good bec...just the wedgebot which uses a bb 12 amp esc with only 25ma bec power when used with a 5 or 6 cel lipo pack....duh????

we're dealing with OLD obsolete technology when talking banebots and scorpions

no problems with 5 cel a123's just the lipos
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rdubard
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PostSubject: Re: Scorpion and bbots BEC circuits suck   Wed Jun 10, 2009 12:27 pm

The BB-12-45 is really not that good. Will Bales had lots of problems running them above 18V, and even rewired a 'tap' out of his battery to avoid them overheating and shutting down (in Fluffy). I am convinced that the BEC in them is responsible for the death of several Spektrum R3100 DSM2 receivers, makng it really difficult to use the Spektrum pistol grip transmitter. The signal wires are notorious for shorting or breaking. In Cuddlebunny, one of them would not respond until it had been on for about 2 minutes or so (what is THAT all about?) They cannot be programmed (although there is a calibration rountine). I am also forced to admit that their power handling capability is pretty decent--the test bot for the vacuums was running two of the 36mm gearboxes with 540 size motors, and pushed 100lbs without burning up. (the motors smoked a bit tho). The best things about them are that they are small and comparatively inexpensive.
and don't get me started on BB wheels!!
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rjw
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PostSubject: Re: Scorpion and bbots BEC circuits suck   Thu Jun 11, 2009 1:37 pm

The bb esc's are fine up to 5 cel li-ion...when you go to 18 v lipo, it's really 21 volts fully charged, while the 5 cel li-ions start at 18 and drop to 16 almost immediately.

If you look at the specs, they de-rate the bec to 25ma at 24 volts, so it won't reliably power anything.

A BR6000 draws 250ma (I'm told) so while the bb esc may power the receiver for a little bit, it will eventually drop out.

Also, I'm told that spektrum receivers don't like more than a .1 voltage fluctuation....

Our experience is that scorpions and bb esc's is that 5 cell li-ion or 3 or 4 cel lipo is the limit (haven't tried 4).

These manufacturer's need to get with the technology....castle's esc's are meant to power a servo as well, so they provide much more amperage, but also may have problems with higher voltages other than the monster.

hope this helps

Richard

btw: Mr. D ..nice to see another adult on the forum....
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