Electrolize and relays

[gizz]

Hi i was wondering what sort of relays that is good using with the 30A Electrolize with external relay option speedos and how big relays you could use,for example if i use a relay that can handle lets say 50A continiously, could the speedo be able to work with that or shall the external relays be rated at 30A continiously?

[storm]

Electrolize and relays

Technobots sell some that are sutiable

http://www.technobots.co.uk/en-gb/dept_31.htmlhttp://www.technobots.co.uk/en-gb/dept_31.html

Ed
http://www.teamstorm.comhttp://www.teamstorm.com

[gizz]

Electrolize and relays

Thanks but if i take a 40A relay, can the rest of the speedo handle the current?
2.Or shall the relays be maximum 30A?
3.Is it the sort of relays that are in cars?

[blazerbotics]

Electrolize and relays

what motors you running?

[tim_jones]

Electrolize and relays

Danny

Our 30A controllers using the relays provided with them were quite capable of handling peak currents of over 100 amps when trying to push the workbench through the workshop wall.

Sadly the 7.2v motors at 13V+ on a fully charged SLA tended to get a little warm ;(

regards

Tim

[gizz]

Electrolize and relays

Ok but for how long did u try to push it? I havn´t built a robot yet but I will use some cheap 18V drillmotors for the drive, 900rpm, 3:1 reduction @ a 25cm/diam wheel and I want the speedos to survive the motors being stalled when pushing robots and such things. Because I´ve heard that some drillmotors get stall currents of about 40A and that would be quite dangerous for the 30A electrolize or?

[team_ireland]

Electrolize and relays

No.

Electrolises can handle more than 30A once the relays are capable of handeling the current. I am using 15amp electrolises with 40amp relays without a problem.

Regards
Ian

[gizz]

Electrolize and relays

OK so it is the relays that handles the current? Does that mean that i could use 100A relays on a small 15A electrolize without frying the speedo?

[blazerbotics]

Electrolize and relays

the FETs supply the current, the relay is used to change the direction. I think the FETs are capable of about 90Amps peak, the controller is mainly limited by the relays (hence why people change them).

[gizz]

Electrolize and relays

Ah ok but what about the continious current the FETs can handle?

[Guest]

Electrolize and relays

I may be a cynical here, but vould it be so simple that its 15A for the 15A version and 30A for the 30A version?

Seriously, you didnt really have to ask that.

[gizz]

Electrolize and relays

What I mean is if my robot should be standing pushing against another robot for 10 seconds, that would generate more then 30A and not just 1 peak over 40A? That makes me wondering if an electrolize could handle more then 30A for a couple of seconds?

[blazerbotics]

Electrolize and relays

why would you stall your motors for 10 seconds? as soon as you stall you should pull off the power, you speedos may take it, but your motors wont.

[gizz]

Electrolize and relays

I dont intend to stall them in 10 seconds but when 2 robots are trying to push eachother one must win and during the time they push the motors draw extra current, you shouldnt back away all the time to avoid getting into pushing or? Then you dont get good at agressivnes if it goes to the judges...what i mean is that it must be able too stand up to a bit of pushing robots around and such

[blazerbotics]

Electrolize and relays

but the point is they shouldnt stall for that long, youre motors wont be turning when stalled so you cant move so you have to back off the power.

Ive always had pusher feathers (about 3 1/2years now) so i know what to do during fights. If youre that worried about stalling then get a controller with current limiting (although be prepared to pay at least £140).

If your motors are powerfull enough to push a robot, the chances are your wheels will spin before stalling.