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Jump that bike ( boost box )

a little OFF TOPIC - But.... This got me thinking. Can I power a 12V Motor, say a 3500# winch for a hoist, with a 20v Dewalt battery ?

A Quick search says NO.



" Dont overlook the basics of Ohm’s Law for motors with equivalent load resistance and power for no load + load. I doubt you measured the DCR (DC Resistance) of the coil to see if that did not exceed the OCP limit of the supply.

Consider ; Is motor DCR < V²/Pd=20²/90=4.4 ohms? Then the supply will fault out and shutdown.

The rule of thumb is the voltage source should be capable of supplying Vbat/DCR without blowing a fuse and >10% of Vbat/DCR at rated load and max current about 1% V drop desired and 10% V drop tolerated.

These simple equations and winch milliohm DCR test measurement will tell you must have at least a motorcycle battery and probably a car battery at 12V+- 20% and never 20V @4.5A.


Nope --- not even close "


To run a motor/winch, you will need a traditional jump pack or at least a MC battery
 
a little OFF TOPIC - But.... This got me thinking. Can I power a 12V Motor, say a 3500# winch for a hoist, with a 20v Dewalt battery ?

A Quick search says NO.



" Dont overlook the basics of Ohm’s Law for motors with equivalent load resistance and power for no load + load. I doubt you measured the DCR (DC Resistance) of the coil to see if that did not exceed the OCP limit of the supply.

Consider ; Is motor DCR < V²/Pd=20²/90=4.4 ohms? Then the supply will fault out and shutdown.

The rule of thumb is the voltage source should be capable of supplying Vbat/DCR without blowing a fuse and >10% of Vbat/DCR at rated load and max current about 1% V drop desired and 10% V drop tolerated.

These simple equations and winch milliohm DCR test measurement will tell you must have at least a motorcycle battery and probably a car battery at 12V+- 20% and never 20V @4.5A.


Nope --- not even close "


To run a motor/winch, you will need a traditional jump pack or at least a MC battery
I put an 18V Ryobi battery in what was probably a 9.6v RC truck once. It ran like a scalded cat right up until the motors let the smoke out.
 


Pretty compelling video 🤷

The reason this works without bursting into flames is that discharged Lead Acid batteries have pretty high internal resistance (or low internal impedance, if you want to be anal, and have nothing else to argue about). Also, under load the voltage of the DeWalt battery drops, while the Lead Acid voltage rises as it charges. So the a second or two after being connected the DeWalt battery output might be down to 14-15 volts, and the 12 volt battery usually charges at 14 volts. Small voltage difference, and high resistance in the near empty Lead Acid means this is not as dangerous as it looks. Just make sure the wires don't get too hot and you don't empty the DeWalt battery completely.
 
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