HiTec 7954 w/ BEC or 7950 off a lipo?

[Arctic Fire]

For my wraith, just a quick question should be easy to answer. I am lookin at servos, and can't figure out what is best:

Hitec 7954 with a 10amp castle BEC (403oz torque @ 7.4v)

or

Hitec 7950TH run straight off the lipo (486oz @ 7.4)

What are the advantages/disadvantages to running the servo straight off the lipo? I am only running 2s, so it seems like the logical choice to go without a BEC (one less component to worry about).

Anyone have any suggestions?

..there's also the 7955 titanium gear, less power, but Ti gears- would need a BEC

[AX10wannabe]

what esc are you running??? if its the 2.4ghz AE-2 esc and have a high torque servo you'll need an external BEC. i ran the AE-2 esc and put a hitec 7955TG and the internal BEC of the esc could not handle the power it would shut itself off every few seconds.

[Arctic Fire]

It's a mamba max pro set up for brushed. I understand the need for a BEC with a hi torque, but I have read that the 7950 can run right off the battery. So My question is whether to go with the BEC and a hi torque or power the 7950 directly off the lipo with no BEC

the 7954 + BEC works out to the same price as a 7950

[AX10wannabe]

im running a novak rooster crawler ESC with a hitec 7955TG servo and no BEC and i've had no problems. im sure you could run the 7954 with no BEC and it would work fine, if it starts acting up add a bec.

[Robotboy]

Many people run the 7950 right off the battery.
The 7950 is an amazing servo. If you can swing it, get it

If not, then def get a BEC, forget all the bad advice of not having one.
It's a small price to pay to not stress your ESC.

[Man of 5lay]

I run my 7954 off my fxr internal bec, and it works great for me with no problems so far *knock on wood*

[Arctic Fire]

Originally Posted by Robotboy

Many people run the 7950 right off the battery.
The 7950 is an amazing servo. If you can swing it, get it

If not, then def get a BEC, forget all the bad advice of not having one.
It's a small price to pay to not stress your ESC.

..Thats exactly what i was asking. I think you understood my question perfectly Thanks!

I'm thinking 7950 with the power wires jumped right into the battery directly, and the signal wire (white) still going to the reciever. Hopefully I can get someone who has been running it off the battery to chime in

[hoghead5150]

i would spend the extra $20 and get a bec AND the 7950. if your gonna stay in this hobby, you will eventually need a bec. and think of the 7950 as an investment since you will be able to keep it and put it in any rig you would want (when and if you upgrade)

[Grimreeper]

I dont think there is any advantage to running a bec if your only running 2s. However if you ever decide to go up to 3s or 4s even you would have to get the bec then. Basically if you want to limit yourself to 2s you can save the $25 or go ahead and get the bec and leave you options open to more powwwwwer.

[SMR 510RR]

Yea go 3s and get a servo and a BEC...You wont regret it!

[meatmonkey]

The 7954 is also rated to run straight off of 2s lipo. I have a couple setup like that.

The 7954 is plenty strong, but the better gearset of the 7950 makes for a longer lasting servo IMO.

[SINister]

Originally Posted by meatmonkey

The 7954 is also rated to run straight off of 2s lipo. I have a couple setup like that.

The 7954 is plenty strong, but the better gearset of the 7950 makes for a longer lasting servo IMO.

Beat me to it. Both servos are rated for 2cell use.

[Charlie-III]

As stated, who cares what ESC, the original question was....."CC BEC or direct off the 2S LiPO??".

You can do either, but I would likely suggest the CC 10A BEC for nothing else other than is should supply a consistent voltage output to the servo, thus a consistent power output.
If you run direct off the 2S LiPO, the voltage to the servo will vary as the pack drains down.

[meatmonkey]

I've heard that argument multiple times, but even if you set the BEC at 7.4 volts, your using less than the packs voltage. Then once the pack voltage dips below 7.4 the BEC can't bring it back up. So you don't really loose anything with wiring the servo straight to the battery, you instead gain power during the majority of your run.

Running the servo straight to the battery makes for the most possible servo power. Period. It also saves weight and cost. The only real downside is you can't run more than 2s lipos.

[Charlie-III]

Originally Posted by meatmonkey

I've heard that argument multiple times, but even if you set the BEC at 7.4 volts, your using less than the packs voltage. Then once the pack voltage dips below 7.4 the BEC can't bring it back up. So you don't really loose anything with wiring the servo straight to the battery, you instead gain power during the majority of your run.

Running the servo straight to the battery makes for the most possible servo power. Period. It also saves weight and cost. The only real downside is you can't run more than 2s lipos.

I won't argue in general, except for one case.

If you overload the servo, you are more likely to take out a $20 BEC, not a $100+ servo.

As I stated, you could do either one with a 2S LiPO rig and a servo capable of handling the voltage.

[Arctic Fire]

Originally Posted by meatmonkey

The 7954 is also rated to run straight off of 2s lipo. I have a couple setup like that.

The 7954 is plenty strong, but the better gearset of the 7950 makes for a longer lasting servo IMO.

I guess I must have missed that. They all have crushing torque, more than I may need, so I might shell out for the extra money and have a servo I won't outgrow.

I think I will go with the 7950 direct wired to the Lipo, with my 2s setup. Once I get my powertrain (currently mamba esc and tekin motor) upgraded, I'll switch to 3s and install the BEC.

Thanks for all the advice, I'll let you guys know how it works out.

If you overload the servo, you are more likely to take out a $20 BEC, not a $100+ servo.

Thats a really good point too, how would an overload happen? voltage spike or something strange?

[Scattman]

Originally Posted by Grimreeper

I dont think there is any advantage to running a bec if your only running 2s.

Actaully there is......

1. With a CC BEC you can up the voltage over the 5-6V that the ESC provides for more power........

2. 5 amps is the max amperage that any ESC provides on the BEC circuit (BR-XL for example) although most are in the 3 amp range, whereas the CC BEC will provide 7-10 amps............

3. Removing the need for the ESC to provide the power for the BEC circuit to run the servo results in a cooler running ESC...........

[AX10wannabe]

you dont NEED a BEC. if you want to run one thats up to you. if your jobless like me and cant afford one than run what you can. i dont need one and my friends and i all dont run one. its a personal preference. to me buying a BEC if you dont need it is a waste of money.

[Scattman]

Originally Posted by Arctic Fire

I guess I must have missed that. They all have crushing torque, more than I may need, so I might shell out for the extra money and have a servo I won't outgrow.

I think I will go with the 7950 direct wired to the Lipo, with my 2s setup. Once I get my powertrain (currently mamba esc and tekin motor) upgraded, I'll switch to 3s and install the BEC.

Thanks for all the advice, I'll let you guys know how it works out.



Thats a really good point too, how would an overload happen? voltage spike or something strange?

Just remember, when you wire the servo straight to the battery you will actually be supplying 8.4 volts(the voltage of a fully charged 2S lipo) to the servo. That is a little more than I wanted to run to mine so I opted for a Castle BEC set to 7.6 volts.

[SMR 510RR]

Originally Posted by AX10wannabe

you dont NEED a BEC. if you want to run one thats up to you. if your jobless like me and cant afford one than run what you can. i dont need one and my friends and i all dont run one. its a personal preference. to me buying a BEC if you dont need it is a waste of money.

Thats great with a low torque servo but at some point you will not be able to drive you rig, there are tons and tons of thread on here where the resolution was adding an external BEC...

That said, I do have rigs that dont have a BEC. With lower powered servos you can get away with not running them and that is $20 I can spend elsewhere.

Now a servo like the 7950 will not run anywhere near full power on any internal BEC with the exception of a BR-XL.


OP, your electronics are perfectly capable of running on 3s or even 4s and I still think that is the way to go.