robot

**typhoon_driver** · 26th August 2010, 00:23

Lol blew two of the 25A ones. Ran them on 20 nicad cells (24v). The stats say don't run it on more than 25V (fine for 20 cells in theory), in practice you are told to run them on 18 cells because they can't handle the extra little bit of voltage you get with a fully charged battery pack, ie don't run them near their limits.

**Laser** · 26th August 2010, 09:45

I'm only going to be using the sabertooth on 12v at 3.3a so hopefuly it wont blow up.
The reason I cant get the batteries from hong kong is because it's shipping is expensive and they normmally give you rubbish things.

**typhoon_driver** · 26th August 2010, 10:00

I assume you mean you are using 3.3Ah batteries? That doesn't mean that they will only give 3.3Amps. What it means is that they are in theory able to give 3.3Amps continuously for 1 hour before they will be drained. They will therefor give 6.6Amps for a half hour (again in theory) and so on. You need to look at the rough power output of your motor.

For example a 120Watt motor running on 12Volts. Current = Power / Voltage therefore the current that this motor will draw in continuous operation will be roughly 10Amps.

Now that is again in an ideal world. In reality a motor draws a large current at startup as it is temporarily stalled (stopped) and once it is up to speed the current draw drops off considerably. Basically a motor will try and suck as much current from a battery pack as it can get its hands on.

shipping is expensive and they normmally give you rubbish things

Hong Kong doesn't give you rubbish things, your budget does. I can almost guarantee that most things in the room you are currently in came from the far east in some way. You get what you pay for. I can understand being hesitant about buying from abroad but having ordered parts from the USA, China, Japan, Australia and many others I can say that you get what you pay for. If you know what you are looking for you will be fine.

**Laser** · 26th August 2010, 19:44

I do trust Hong Kong and I will get things shipped from America but ir's my dad that does'nt like hong kong but some things that are dirt cheap from hong kong you can sometimes not trust them.
Now to the good news, I'm selling things on ebay tonight so hopefully in the next few days i'll have enough to buy some 12mm thick HDPE so i can start building the frame for my new robot, I also got a drill motor for using on the electric lifter and I'll be going to the local car scrap yard to get the threaded rod from a sissor jack.

**elobire** · 26th August 2010, 22:55

Originally Posted by Hard Time

I do trust Hong Kong and I will get things shipped from America but ir's my dad that does'nt like hong kong but some things that are dirt cheap from hong kong you can sometimes not trust them.
Now to the good news, I'm selling things on ebay tonight so hopefully in the next few days i'll have enough to buy some 12mm thick HDPE so i can start building the frame for my new robot, I also got a drill motor for using on the electric lifter and I'll be going to the local car scrap yard to get the threaded rod from a sissor jack.

buying things from hong kong is usually a bad idea. they sell alot of fakes and items made with poor materials.
if your dont have much money though its really great.

**rallikas** · 27th August 2010, 17:46

Originally Posted by elobire

buying things from hong kong is usually a bad idea. they sell alot of fakes and items made with poor materials.
if your dont have much money though its really great.

I have ordered stuff from hongkong for several years. (only from http://www.hobbycity.com)
I never had any failures during flights (rc planes). Read user reviews about the products!
QC is just lower on hongkong/chinese stuff, if youre unlucky you may get a bad product.