Need a couple of pointers

[Hizz85]

Hello, Im new here and to Crawlers. I bought an Axial Wraith about 2 months ago and put a few upgrades in it, so far the shocks, steering linkage and servo horn. My servo finally stopped working so i want to buy a hitec 7954 and i read that you need a bec for that. Can i run the stock esc with a bec and the hitec servo? Do i need a lipo battery to use a bec or can i use my current battery which is a 7.2v NiMH 5000mah? Im lost when it comes to crawlers.

 

[meatmonkey]

While a 7954 is a very strong servo, the steel gears aren't up to prolonged high-speed, jumping style abuse. If your just doing slow crawling then it will be a good pick.

I broke a couple 7954 gearsets, a few other lesser servos, and then finally settled on a Hitec 7980 (which is slightly oversized, meaning a home-made mount is required to fit a Wraith).

Many go for the Titanium geared 7950 and it lasts for them. I just wanted the strongest servo that could physically fit in the truck after breaking multiple expensive servos.

An external BEC is essentially a power supply for your power-hungry new high torque servo. It drops battery voltage down to a programmable voltage to feed your servo so that it doesn't over-load the receiver and cause glitching, or "brown-outs".

If you run a "high voltage" rated servo, which most of the Hitec 7900 series are, and don't plan on running more than a 2s lipo, or 7 cell Nimh pack, then you can simply solder the power and ground wires of the servo to the ESC's battery leads. This is what I do since I had such terrible luck with external BEC's. Since a BEC can only reduce the output voltage from the input voltage, not raise it, there is no advantage to running a BEC over direct wiring to the battery plugs.

If you run higher voltage than the "high voltage" (meaning direct 7.4 volt, which is actually 8.4 volts fully charged) rated servos than you MUST run a BEC to drop the input voltage down the the 8.4V that most "high voltage" servos are rated for.

A BEC is compatible with all other hobby grade electronics.

I'm amazed you got two months out of the stock servo!

 

[lostonthetrails]

I have 2 7954s on my Wraith(4ws) and they are awesome. I waterproofed mine. They are easy to water proof, just add silicone to the outer case except on the top and heatsink and marine grease on the horn. Good to go. meatmonkey is right though about the bashing and high speed. I don't bash. I hill climb and crawl but its great. Loads of torque. You definitely need a bec. I recommend getting one of these. You need to solder the bec to the esc wires but you don't have to cut the throttle wire on the esc or solder the bec to the servo. It makes life a little easier. Good Luck"thumbsup"