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View Full Version : Buying cells and motors secondhand..


V6Jim
03-09-2012, 10:04 PM
Is it fair to say that buying secondhand cells and motors isn't really a very good idea. Every time I read an advert for somebody's used cells/motor I just imagine that the real reason the item is for sale is because it is either;

a) a dud,
or
b) knackered.

True?

Jimmy

SamRCRacing
03-09-2012, 10:12 PM
Most of the time that is not the case, people like a change including me. I have bought and sold a few motors off here and have been perfectly fine. I can understand what you are saying though and I prefer to buy new it is just if I am short on money.

Sam

BeachBuggyPhil
03-09-2012, 10:33 PM
All the motors and servos I've bought on here have been great.

You'd soon get bad feedback if the stuff you sold was dud.

benl
03-09-2012, 10:37 PM
I've bought a fair few items off the site whilst I've been starting out and all have been fine to be honest. You can always check a members trader feedback if you are dubious or unsure.
I think one of the reasons there are lots of motors and batts etc for sale is that some people prefer to have the newest and best or flavour of the month components (I don't blame them wish I could afford it).

V6Jim
03-09-2012, 10:49 PM
To expand on this then. Do the cells and motors 'go off'? I'm sure the cells do, even LiPo's, but the motors? What wears out? Can bearings be replaced? What is the general working life of a brushless motor...

Jimmy.

Hpi_guy
03-09-2012, 10:57 PM
in theory a brushless motor should never wear out as there is no contacting parts such as a brush but that is only in theory, the bearings can become tiered, sensor boards can wear out and the stator can come unglued from the rotor.

the reason why people sell motors and lipos is that they have replaced them with a better version eg from a 50c lipo to a 80c lipo or just need a faster motor

neallewis
04-09-2012, 12:13 AM
in theory a brushless motor should never wear out as there is no contacting parts such as a brush but that is only in theory, the bearings can become tiered, sensor boards can wear out and the stator can come unglued from the rotor.


As you say in theory... Not quite true the neodymium magnets do go off with a lot of heat and use, but a replacement rotor can solve that, cheaper than a whole new motor. Bearings to take some abuse over time and depending on where its run. Sensor boards to fail, as do sensor lead sockets. Normally you can spot an abused motor from a sellers picture.

I've bought a new-in-box second hand motor for significantly cheaper than retail price, and been very pleased with it. I last week sold two relatively new (bought in April'12) and low usage stick pack lipos that I no longer could use as I've moved to a chassis that takes saddle packs. They were hardly used and will serve the new owner well for some time. He got them significantly cheaper than I paid for them, and I wouldn't have sold them if I didn't need saddles.

Not everything is being sold on because its junk. I'd say there is more chance of getting a good deal buying second hand from here, rather than say ebay, which is a bit more anonymous. Here, it's a bit more of a community where people have connections in real life, and reputations to keep.

Just be careful what you buy and inspect the pictures and descriptions beforehand, and ask yourself is the price realistic.

neallewis
04-09-2012, 12:31 AM
To expand on this then. Do the cells and motors 'go off'? I'm sure the cells do, even LiPo's, but the motors? What wears out? Can bearings be replaced? What is the general working life of a brushless motor...

Jimmy.

To expand on my last reply, some top end motors offer a full range of spares, bearings, sensorboards, rotors, etc. So buying a second hand that needed new bearings would still be significantly cheaper than a new one at full retail price.

The lifetime also depends on the environment that the motor has been run, the previous owners gearing and to some extent driving and maintenance style. Dirt and dust will be the biggest threat to the bearings, rear motor cars have a more exposed motor than mid mount, etc etc. Gearing and how hot its been run in the past will also dictate the life it's had, as will the chassis type, 2wd/4wd, etc.
In terms of how long it will last.. I've personally only been back to the hobby since April this year, so have not yet seen a how long one my my brushless motors has lasted me. But buying a low usage quality brand motor should serve you well, possibly more than a brand new super cheap range motor? Work out what you have to spend and see what's available on oople forsale. some bargains do pop up if you are quick.

Personally I'd always look for a motor with solder posts on, rather than gold bullet style connectors on the can. The motors i've seen in use at my clubs with bullet connectors have all suffered with connectors that have gone bad, built up a high resistance, and heat up so the connector on the wire becomes unsoldered. Obviously this happens mid race, causing the racer to retire.

racingben
04-09-2012, 04:36 AM
Nothing wrong with my 2nd hand 6.5 motor and hobbywing esc 100, savox servo 25 and shorty lipo's 2 for 20 - they were a real bargain, a bit swollen but otherwise fine.

Car is as fast as any team car I've come across and was running 4th in the a final at the one regional I managed to get to this year. Motor and esc are 2 years old and only time they've been out was when I changed car to a Durango 210 at the beginning of the year.

mx836
17-09-2012, 10:39 PM
I've bought quite a few used motors from ebay, rctech, etc. Never had a problem with any of them. Some I have sold right back on ebay and now someone else can enjoy them for a third the price of new. I like to buy my batteries new so I know what they have been through. Batteries are much more likely to take a crap than a brushless motor although I feel a lot of sellers are dishonest with how much use is on any of their electronics.