Amp Rating

[jodeb720]

Ok - I thought I understood electricity ratings (watts, volts, amps).

I know volts and undestand watts is a measure of work - but amps are a capacity.

So when a motor has a rating of 12volts and 12 amps are the amps consumped of amps over an hour (60 minutes)? or is that a constant draw of amps per minute?

If it were watts (it would be volts x amps = watts or in this case 144 watts) - but again, watts are a measure of work - not a capacity or a rating of wires.

This all goes back to me using a 12 volt winch with a 12 amp rating - so if i'm sizing a battery and I expect the motor to run for no more than 10 minutes then i'd use 2 amps if amps are measured per hour.

What am I missing?

Forgive my ignorance, but it's better to ask and understand it than spend money foolishly.

Thanks in advance

Josh

[MEXICOWANDERER]

A 25' run of 6 AWG allowed 17 amps with a Delta T of 2-volts. Your Delta T drop would be much greater. Try it with 8-gauge.

[jodeb720]

I could run a wire from the batteries in the front of the 5er to the rear of the Trailer and put one of the those "new fangled" Anderson Powerpole connectors, but that distance is about 25' - plus the ups and downs Figure 30 feet of wire.

What gauge of wire would I need to run that distance for this 12 amp motor?

As to what it's for... It's for my back! 🙂

I have a rack on the back of my 5er (that's 38 x 80) that will support both of my motorcycles. Since my son is in college, my "able bodied assistant" might be around to help me load it at home, but when I'm out on my own wrestling a 250lb motorcycle up a 38" height off the ground on a ramp that's 45 degrees to the ground would be a challenge on my own.

The winch would be used to pull the motorcycls(s) up on the rack and I can man handle them into final resting position once they are up.

I figure it's easier to wrestle with electrons and leverage the knowledge base that's so vast here than my back!

I'm thinking of getting one of those 18ah Lithium Ion jump starter battery packs which should give me enough of a buffer for the 12amp motor rating and there internal resistance should be much lower than a lead acid based battery.

Oh, that 10 minutes of run time, it's more like 2 minutes starting and stopping while I pull up each motorcycle into position.

Probably more information that you wanted to know... 🙂

Again thanks!

josh

[time2roll]

jodeb720 wrote:
This all goes back to me using a 12 volt winch with a 12 amp rating - so if i'm sizing a battery and I expect the motor to run for no more than 10 minutes then i'd use 2 amps if amps are measured per hour.

What am I missing?

The only issue I have is you are draining the battery at 1C+ and is very fast discharge. Voltage may sag and at this rate the battery rated at 12 amp/hrs may only give half the power before it gets to 10.5 volts. The faster you discharge the less energy you get. Most ratings of capacity is over a 20 hour rate.

1C = 1 x capacity. or 2 amp/hrs in 10 minutes = 12 amp/hrs in 60 minutes.
And that is the full rated capacity discharged in one hour.

Some batteries are OK like lithium, some tolerate a bit better like AGM but most flooded may not serve long. But then if you are only doing this six times a year it may not matter.

I would be looking for a battery with 30 to 50+ amp hours capacity. Or tie into some other system with more capacity.

[westend]

Another wrinkle is that any motor rating from the rating plate, box, or instructions/manual will not be what the motor uses when in operation. Typically, it will be less than the rating.

If you intend to use a winch to load a motorcycle in a truck, it may be cheaper and more elegant to pull wire from the vehicle's battery and, if the winch is a temporary convenience and will be moved, install a quality connector system. I like Anderson Powerpole connectors for devices like this.

[3_tons]

mrkoje wrote:
I think you are confusing Amp Hour with Amp.

BINGO!!

[MrWizard]

I don't think so
That would be the same thing as using (1) 100 amphr battery to power the the MW at 100 amps to the inverter
And that has never worked very well, if ever

That 12 amphrs is probably at 1/2 amp rate
It might do it the first time even the second, but never again
Or might not work at all
What is the work load rating of the winch,
What is the dead rolling weigh of the motorcycle, what is the inclined of the ramp
But then again a little jump box will start a car, but that spike is only for about 2 seconds

jodeb720 wrote:
So my expectation is I could get a 12 amp hour battery (12 Volts) and I could use the winch to pull a motorcycle up a ramp onto the back o my 5er and using the winch (not at maximum load) I'd use about 2 amps of the battery capacity.

Once the bike is in place, i'd recharge the batter to full capacity.

So - 12 Ah battery would suffice for this?

As we get older, things seem to get heavier and we look to use leverage to make things easier.

In this case, I'm looking for those wild electrons to help me out.

And by the way, thank all of you for the help in getting this sorted out. I really appreciate the clarity.

Josh

[red31]

duplicate!

[red31]

is it a secret what this winch is for? or how often it is used?

if there is a vehicle near, the winch would be minimal load for its spinning alternator.

[mike-s]

You can get a U1-7 battery (common for lawnmowers) for about $20 at Wallyworld. They're about 19 Ah, and I think they'd be able to handle 12 A for 10 minutes easily.

[2oldman]

jodeb720 wrote:
So - 12 Ah battery would suffice for this?

I doubt it. This is where things get a little complicated.

Acid batteries must maintain a certain voltage when doing the work, and, although theoretically a 12ah battery would work, you may find the voltage drop would be too great at a 12a draw. That 12ah rating may be at say, 1 amp draw, not 12. The greater the load (amp draw) the more capacity you need to maintain a working voltage.

Lithium batteries change all that, as they can maintain voltage no matter what the load. They are light weight, expensive, used in drones and yard equipment, and generally higher voltage.

[wa8yxm]

You are confusing Amps and Amp Hours

Amps is a rate of flow.. Gallons per minute

Amp hours are Amps times Hours Gallons delivered

I will use "Gallon minutes" for this

If you are flowing 5 GPM you can fill a 5 gallon bucket in 1 minue

The rate is 5 and the use is too.

But let's say you had a variable faucet

IT runs 3-15 Gallon, and you start at oh, say 15 (Quickly filling the bucket) then as it fills you "Throttle" back to 3 GPM till full

Your rate (Amps) is all over the range of 3-15 BUt your AMP HOURS is still 5

[jodeb720]

So my expectation is I could get a 12 amp hour battery (12 Volts) and I could use the winch to pull a motorcycle up a ramp onto the back o my 5er and using the winch (not at maximum load) I'd use about 2 amps of the battery capacity.

Once the bike is in place, i'd recharge the batter to full capacity.

So - 12 Ah battery would suffice for this?

As we get older, things seem to get heavier and we look to use leverage to make things easier.

In this case, I'm looking for those wild electrons to help me out.

And by the way, thank all of you for the help in getting this sorted out. I really appreciate the clarity.

Josh

[MrWizard]

Yes as stated you would use 2 amp hours of the battery capacity

Only one battery?
Then because of perkut effect you would use a little more than that

That's the chemical reaction verus time thing
Where a battery rated at 100 amp hrs , only if you use less than a 5 amp load
Use more the capacity goes down

Means you could use 5 amps for approximately 20 hours to reach total discharge , which is bad

But if you use 12 amps you can not do that for 8.5 hours, instead it might last 7 hours or maybe less

But in your case of only ten minutes, the effect on total capacity in minimal

Just like driving your vehicle
Pick a flat road do 50 mph get better mileage, than going up hill at 60 MPH

[2oldman]

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