Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: Dom on September 20, 2009, 04:42:59 PM

Title: problem blowing fuses
Post by: Dom on September 20, 2009, 04:42:59 PM
Good Morning all,
have a problem with a robot biggie, I'm two 24 volt wheelchair motors via a sabertooth DC motor controller, the saber tooth is a 25 amp duel motor controller with r/c signal input
Ive connected it up to the exact specs and its works for a short while and then blows fuses Ive steadily increased fuse to 30 amp, with doubts of going any higher,
i have connected the motore to an amp meter and had a total of 16 amps at full stall, per motor, when i connected the motors to a volt meter there is a voltage produced(of coarse is is a brushed motor, a generator)

can any one help please??
Title: Re: problem blowing fuses
Post by: Admin on September 21, 2009, 06:46:24 AM
http://www.societyofrobots.com/electronics_fuse_tutorial.shtml (http://www.societyofrobots.com/electronics_fuse_tutorial.shtml)

I suspect you are using a fast blow fuse, and current spikes (much higher than at stall current) are causing the blow.

How much current can your battery supply? Choose a fuse more like:

(max_current_drawn + max_battery_current)/2 = fuse rating
Title: Re: problem blowing fuses
Post by: Dom on September 21, 2009, 03:06:19 PM
Many thanks, Will give it a go  :)
Title: Re: problem blowing fuses
Post by: RoboGeek on September 22, 2009, 12:16:41 PM
If you put large capacitors on the power leads right at the controllers, these will supply the controller current peaks instead of the current peaks coming from the battery through the fuses.

Most controllers have SOME internal capacitors but they rarely have enough as caps are big and can be expensive.