Smallest, Simplest, Cheapest

[Andywest]

I'm new to the forum and to the world of electronics. I have a small 795 motor. It runs at different speeds from 12volts to 24volts. It's written that the motor is 100 watts. It has anbac adapter but I would like to run this motor from a portable DC power source (something like a small lithium power bank used for phones) What is the smallest and lightest way I could do this. Any helpful advice would be appreciated.

 

[rjenkinsgb]

Can you add the details of the output ratings of the power adapter, or another photo showing the label clearly?

 

[Andywest]

This is a photo of the adapter

 

[Andywest]

As you see it has a switch to change between different different voltages. However, I don't really need this and would be happy with one or two options like 12v and 24v.

 

[rjenkinsgb]

OK, how long does it need to run from on the battery pack, and under what load - what is it driving?

eg. Something that only needs to run for a few seconds occasionally has very different requirements to a pump, grinder or whatever than may need to run at high load for long periods.

That gives some idea of how big the battery pack would have to be.

eg. Something like this would give roughly around 60 - 90 minutes at full load, much longer at light loading:
**broken link removed**

Those need a special charger that costs probably another £30 or so.

 

[Andywest]

Thank you for the response! It will be used for grinding but only for short periods (1-10 minutes) I know this likely sounds like a stupid question, but how would this actually be attached properly to the motor.

 

[Nigel Goodwin]

Thank you for the response! It will be used for grinding but only for short periods (1-10 minutes) I know this likely sounds like a stupid question, but how would this actually be attached properly to the motor.

Buy a cordless grinder - that's already designed for the job, and it's battery should be optimised.

 

[gophert]

You need a tiny portable grinder? For what? Are you...
- doing body work along a highway?
- giving roadside manicures?
- cutting locks?
....

 

[Andywest]

Nothing glorious like roadside manicures. I'm just student doing research. The grinder I already have works perfect, my only problem is that I don't always have access to an electrical outlet. I was hoping for a simple solution. There is a market that sells things similar to the picture below but I wasn't sure what would be enough for the job. I apologize for my ignorance. I hope to solve this problem and also learn something as I'm doing it. I am very grateful for your knowledge.

 

[rjenkinsgb]

how would this actually be attached properly to the motor.

I'd actually get a battery that has a better connector, such as this:
**broken link removed**

Then a matching XT60 connector such as these:

Pardon our interruption...

Then some cable rated over 20A, eg. 2.5mm^2 flexible and a suitable power switch.
Just battery connector negative to motor negative, battery connector positive to a fuse then to the switch, and switch to motor positive.

You also need a "Balance charger" such as one of these; both the battery power connector and the small multipin connector must be connected whilst the battery is being charged - chargers such as these control the voltage on each cell in the battery, to avoid the possibility of overcharging - which can cause a battery to burst or catch fire.

iMax B6 80W Battery Balance Charger Discharger Lipo LiFe LiIon optional 12V PSU | eBay

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[gophert]

He has a 100W motor running at 24v = 4A so a less beastly connector and thinner wire could safely be used. I would pick 18 to 20 gauge wire (1.0mm to 0.8mm).

 

[rjenkinsgb]

The connector is part of the battery pack; that determines the matching type.

The startup or stall current will be many times higher than the basic running current.

The connecting wire or cable needs to be rated higher than the circuit fuse, which must in turn be rated to stand startup currents, eg. probably 20A as first estimate.