Re: [PSUBS-MAILIST] trolling motors?

[Subscuba@aol.com]

Herve,

You really ought to consider an active current limit. I suggest you call 
someone knowledgeable at MK or MG and ask about using their motors without 
controllers. If you have a locked prop you will have excessive currents with 
a fast rise time such that these currents could cause brush damage or stator 
demagnetization in a very short time. I can go into more detail but you ought 
to contact the actual motor vendor.

Any decent controller with current limit will prevent these problems even 
with a locked propeller. You might be degrading the stator magnets with a 
drop in thrust that you don't notice.

Call someone at the vendor remains my suggestion. As well as looking at the 
PSUBS archives. I started my sub motor design cycle not intending to use a 
controller and after much trouble contacted Lake motors in Chicago and 
discussed the problem with them and ended up with a controller.

I'll be glad to send you a copy of my controller but I would need your number.

If you make it to Florida, welcome. I live in Florida.

Best wishes,

Ken Martindale

I will be glad to send you a copy of my schematic

In a message dated 11/26/00 7:25:21 PM Eastern Standard Time, 
caribsub@coqui.net writes:


> Ken,
> On MK and MG the controllers are certainly Pulse Width Modulators for speed 
> control, but I am not sure of their efficiency for current surge 
> protection, your controller seems to be the one and I d be glad to look at 
> your design if you fax it to me to include it in my subs, since only the 
> current limit interests me.
> As of controller, I switch 36 V and 24 V on the motors leads through high 
> rating switches and relays for speed control.