Internal BEC's

[raceeng18]

Not being electronics minded at all, I have a question about ESC internal BEC's. Why don't the ESC manufactures just install say a 7amp internal BEC in their ESC's and eliminate the need for an external BEC in most cases. Seems it would be an easy fix for a lot of issues I read about here and eliminate the extra electronics of the external BEC. Thanks

[Charlie-III]

Cost is the likely biggest reason.
Size, of the ESC, is the 2nd thing. A better internal BEC can add a lot to the size of the ESC.
Outside of crawlers, most rigs use lower torque steering servos, thus the internal BEC is fine (up to ~200inoz).

The Holmes Hobbies BR-XL has the best internal BEC, but even that has it's limits.

For me, I like having the external BEC, if I fry it I replace a ~$20 external BEC, not a much more expensive ESC.
The external BEC (Castle 10A) is also adjustable, so I can pick what I want for a voltage.

Edit... The internal BEC's in ESC's are set to allow working through the RX without damage to the RX. If you overvolt or overamp the RX traces, you can burn them off which kills the RX. There have been some cases, on this forum, where people have killed RX's by running too much load through the RX. I don't remember what RX's or the volts/amps used that killed the RX's.

[raceeng18]

Originally Posted by Charlie-III

Cost is the likely biggest reason.
Size, of the ESC, is the 2nd thing. A better internal BEC can add a lot to the size of the ESC.
Outside of crawlers, most rigs use lower torque steering servos, thus the internal BEC is fine (up to ~200inoz).

The Holmes Hobbies BR-XL has the best internal BEC, but even that has it's limits.

For me, I like having the external BEC, if I fry it I replace a ~$20 external BEC, not a much more expensive ESC.
The external BEC (Castle 10A) is also adjustable, so I can pick what I want for a voltage.

I figured size would play into it somewhere. I run HH BRXL's in all of my rigs but only have one Castle 10A bec on the rig where I run a 400inoz servo. thanks for the reply Charlie-III.

[shakemandril]

I ran my Tekin RS gen2 bec which is adjustable for 6.0V or 7.4V and 5.5A on a 400inoz Savox servo in my wraith. I was running a Tekin ROC 412 3100kv on it. If I was going to do all day runs with it I would buy the RX8 Gen2 which has a 7A BEC built in.

**Note**
Its much cheaper to buy a MMP and Castle BEC than an RX8, but the option is there if you really want a built in BEC.

[Charlie-III]

Added to my earlier post.

[Johnnysplits]

Another reason not to use the internal bec is the fact that it adds additional heat to it, which you really don't want. For a $20 CC bec, you will save your esc from having to work harder than necessary and you can dial in the exact output voltage that you want, instead of being stuck with what the esc puts out. For example, take the HH brxl. Awesome esc, however it's internal bec only puts out 6v. My servo and winch both run on 7.2v, so I have the CC bec set at 7.5v out to the Rx so everyone's happy.

[raceeng18]

Originally Posted by Johnnysplits

Another reason not to use the internal bec is the fact that it adds additional heat to it, which you really don't want. For a $20 CC bec, you will save your esc from having to work harder than necessary and you can dial in the exact output voltage that you want, instead of being stuck with what the esc puts out. For example, take the HH brxl. Awesome esc, however it's internal bec only puts out 6v. My servo and winch both run on 7.2v, so I have the CC bec set at 7.5v out to the Rx so everyone's happy.

Aren't there limits to how much voltage you can pump into a receiver?

[shakemandril]

Originally Posted by raceeng18

Aren't there limits to how much voltage you can pump into a receiver?

Yes there is a limit, consult your manual. I know a couple of my futaba's will take 4.8 or 7.4 and the spektrum sr300 is up to 9.6 so best bet is to double check.

[raceeng18]

Originally Posted by shakemandril

Yes there is a limit, consult your manual. I know a couple of my futaba's will take 4.8 or 7.4 and the spektrum sr300 is up to 9.6 so best bet is to double check.

Yes I checked mine after asking the question, 7.4.