Speed controller

[billy breach]

Re: Speed controller

Perfect ill get a few 25amps then. What size of fuse do you think to place just aftery lipo battery for the full system. I was thinking 100amp?

[RogueTwoRobots]

Re: Speed controller

What is the 'C' rating of your pack(s) again? Just multiply that by your Ah rating and that will give you the maximum current the pack can output (if I picked that part up correctly). Then put in a fuse slightly lower than this.

[billy breach]

Re: Speed controller

I havent got the lipo pack yet but itll be 18.5v and either 3500 or 4000 mah

[PJ-27]

Re: Speed controller

The 15a Electronizes have a 40a peak rating so I use 30a fuses.

[billy breach]

Re: Speed controller

is that a 30amp throughout the full system or 30amp before the speed controller (or after the battery?)

[PJ-27]

Re: Speed controller

The fuse after the battery has to be rated at or below the the constant current rate of the Li-Po.

You can calculate that by doing C rating x Amp Hours.

I'd then fuse the ESC's at their own rating. That way you get the most from your battery (for say a weapon) and your individual components are protected.

[billy breach]

Re: Speed controller

if I were to get a 30c 18.5v 5000mah lipo then that would work out at

150?

so if I were to use a 100amp fuse then?

I have got one of those maxi fuse holders but the wire is 8awg i'm using 14awg throughout my bot. Will i need to upgrade my wire within my robot or can you get a 100amp fuse holder that will have 14awg?

thanks
billy

[PJ-27]

Re: Speed controller

I doubt you'll draw 150amps unless you have some monster brushless setup turning a 6kg weapon, or a short!

[billy breach]

Re: Speed controller

i was just doing the calculations there
c 30 x 5000

150?

What do most use a 80 amp fuse?

[PJ-27]

Re: Speed controller

Your calculations are right, that battery could supply 150amps but I'm saying it unlikely you'll ever draw that so just fit a fuse that has a high enough rating to allow your battery to work to it's full potential given the components (so say 60a) and is low enough to be within the rules (in your case 150a and under).

If you think you'll draw over 100a then you'll need to up your wire gauge to accommodate this. Not only to fit a fuse holder, but having adequate wire thickness is also a rule.

Hope that helps.

ps. if you can't find fuse holders, just solder the fuses straight onto the wire, that's what I do. Trick I picked up from the Big Nipper guys.

[billy breach]

Re: Speed controller

thanks for the help

[MikeNCR]

Re: Speed controller

Not sure how known these are, but I've been using the Holmes Hobbies BR-XL controllers with no issues running 18v dewalts in a hobbyweight with a 6s A123 pack and a featherweight with a 5s A123 pack.

Here's the Holmes Hobbies page for the BR-XL- http://holmeshobbies.com/product.php?pr ... t=2&page=1
They're listed as out of stock until the end of the month, but it appears that robotmarketplace has a few of the waterproofed versions still in stock- http://www.robotmarketplace.com/product ... MBRXL.html

I've only killed two of them in combat and that was due to a direct impact from my opponents weapon-
http://www.youtube.com/watch?v=IpUIkBLS ... re=related
In the video you'll be able to see two small black boxes dangling outside of the chassis after my robot (the green and black one) flips. I only lost power after the direct hit that completely destroyed the speed controllers. They seem to handle abuse fairly well, as even when the robot throws itself around violently they're still working without issue- http://www.youtube.com/watch?v=HoHERDQgZwo

[billy breach]

Re: Speed controller

how do they compare to the electronize ?

[harry hills]

Re: Speed controller

think about it, these are like £70 each while electronize are about £35. there is a reason for that

[billy breach]

Re: Speed controller

yeah I suppose with robotics you're right, but a higher price doesn't always mean its better. I suppose with teh higher price thats why many people don't use them.