Newbie from NZ

[rjsutton]

Doody
hi
the controller just stopped after about 15 seconds
no puff of smoke -no load on motor lead from battery was 300mm and had correct polarity
had worked 10 times but i was only running for a few seconds each time to test motor setup. Just stopped
Didnt buy from china but the nz supplier did as they are identical to ones on ebay etc.
ill try and digest your ather comments. i just didnt want to destroy the new controller as well

[Doddy]

Have a read here... https://medium.com/jungletronics/dc-...f-589d8ed174cc, you might consider this a pragmatic approach.

[rjsutton]

Morning.!
Doody i want-(NEED) to protect these motors and electronics so thought i could use relays to protect each high amp motor circuit
would https://www.ebay.com.au/itm/MICTUNIN...frcectupt=true
something like this work ?
or this?https://www.trademe.co.nz/electronic...45063f2ae1-003

im not sure HOW large the amps-watts etc need to be but i just want to protect the electronics.
OR do i simply hardwire a 10-15-20 amp car fuse in the power supply feeds? this may be messier
trying to get smallest-neatest setup so i could fit them all in a protective case somewhere.
thanks if you can help
Richard

[Doddy]

Richard,

I need to understand your thinking. How do you perceive a relay will protect the motor and/or electronics? A relay is effectively a switch, so my question is really what quality is actuating the switch? Are you talking thermal overload? (a thermistor somewhere in the speed controller?) Some form of limit control? (already accommodated with the motor speed controller)? Sorry, I don't understand where you're coming from for "protection".

Similarly the timer module that you have there. From the outset I'd argue a couple of points - that module is likely (from a glance at the image of the board) to fry with the current draw from your motor (and I'm only talking of the principal motor in this thread). And in terms of "protection" you're only looking to introduce a timed on-state with that, and the only protection this effectively offers is against prolonged use (the quality here being the probability of over-temperature of the power devices in the speed controller). That presupposes that particular failure mechanism.

For the new controller and motor... tread with caution. If you use a long supply wire from the battery to the controller (increasing the resistance) you should introduce a level of protection that you can use to test, and then start to reduce in length as you gain confidence that the controller isn't overheating etc, with the motor under load. Ultimately you do want that cable length to introduce as low an electrical resistance as possible to allow you to attain the power through the motor that you expect

This is what I recommended to avoid overheating. It's a heath-robinson solution but it's robust.

There is another potential failure mechanism of back-EMF from the PWM output to the motor frying the electronics (if poorly designed - pure speculation on my part) - which

Have a read here... https://medium.com/jungletronics/dc-...f-589d8ed174cc, you might consider this a pragmatic approach

was intended to address. Here, add one or three capacitors across the motor terminals, or (I prefer, but seems to have limited traction in a number of articles) a TVS to suppress the back EMF.

[rjsutton]

Hi
i guess im just trying to stop any of the electronics from frying. MY THOUGHT is that if i put relays in the switches( realize a relay is a low voltage switch) then it MAY stop the electronics getting zapped by to much V or Amps when switched on. Maybe im not heading in the right direction.
On my unit i have a 200W geared motor with a 60 Amp fwd-rev-speed controller
, a 120w geared motor with the 2 proximity switches with the 30A speed-reversing controller
and 10A linear actuator.
Non of these will be run simultaneously they will go in sequence so the current draw is lower.
the whole units in the boot of the vehicle so i imagined running a fairly decent sized awg feed direct from battery to the boot and feed of a contact there . ( lessening power drop)
Nothing runs for more than 40 secs at a time either...
being overly cautious perhaps but this is a prototype and i cant-dont want weak points that could cause returns -claims etc.
at the moment the battery is on the floor 1m away from the electronics but obviously when installed it would be feed off the car battery ( with motor running) which gives slightly higher V. and could possibly cause problems?? ( or not)
Thats really where i am. it will probably fine with a few inline fuses but i dont know .During trials ive never over stressed any motor or controller as when i fried the last one it costs $ to replace ( $ which are running out)
I do need to put pressure on all parts as who knows what the purchaser may stupidly do. It needs to be pretty foolproof.( or protected)
Cheers