Charging Extreme DC

[dougmcp]

I can't address using a welder for recharging but I can address charging in general.
I have a 130 amp inverter/smart charger on my boat and it charges at 130 amps then tapers to almost nothing as the charge completes. 130amps charging at 12v is 1560 watts which draws 13 amps and within the capacity of the breaker. Your car or truck has a 130 amp alternator, giving the batteries a 100 amp charge is not the issue, it's the power available to do that.
If you had a 100 amp charger to charge a 48v pack, it will use 100x48=4800 watts. 4800w divided by 120v= 40 amp draw and no 120v circuit will take that. Even at 220v it will still draw 21.8 amps which means you would have to plug it into something equivalent to an electric dyer plug/breaker.
Golf cart/battery charger manufacturers need something that will plug into a standard 120v/15amp circuit so they are limited in the charging rate to keep the breaker from tripping, thus the longer charge time frame.

[roady89]

Just to keep it simple because this isn't a code forum ....Using the above math, he's wanting to charge 132 volts @ 100 amps. 100X132=13200. 13200/120= 110 AMPS. Thats 110 amps from a 110 Volt AC circuit....aint gonna happen at home EVER. Even at 220 AC input it will draw at least 55 amps. I'm sure theres a more exact way to figure but like I said (this isn't a code forum)...this will give you an idea what kind of amps is going to be required....not gonna happen at home.

There is not ANY welder commercially available that will put out that much voltage. OSHA rules limit the maximum open circuit volts for arc welders to 100 volts. That alone throws the welder/charger scheme out the window. (for a 132 volt pack) Like I said, if there is one that will do it ask them to point you in that direction.






GOOD LUCK!

[dereckbc]

This is NUTZ. A 130 volt battery stack requires a charge voltage of 162 volts at some given current. Assuming the OP is talking about a standard NEMA 5-20 receptacle can only deliver 1920 watts continuously (16 amps @ 120 VAC). When converted to 162 volts DC, (ignoring efficiency) that translates to about 12 amps @ 162 volts.

I don’t know of a DC welder on the face of this earth that can deliver 162 volts @ even 10 amps continuously. There are battery chargers that can do this, but not any welder.

Smell that smoke? Its you house wiring on fire inside your walls.

[dereckbc]

OK this post got my interest peaked so I did some checking with some of my peers (electrical engineers), and this will never work as I suspected.

A welder no matter what current limit rating on the output (DC or AC), or voltage input will ever develop more than 40 volts open circuit voltage as required by OSHA and UL. If it did you would electrocute yourself with the open welding leads.

When you short the leads out, start welding and draw current, the voltage folds back to a few volts, and the saturation of the transformer core limits the current to what ever is selected. In addition welders are limited to 10 or 20% duty cycle, battery chargers need 100%.

So the short story is quit wasting valuable time, money, and energy on this, it will never work, and if you try to force it all you will do is burn something up like your home, cart, or something no one cares about; YOU!

[GarageBuilt]

roady89

Please bear with me. This is what I found today.

80 Amp Inverter Arc Welder. 120v, DC output current,
0-80 amps. Duty cycle:35%@ 80 amps, 60%@ 65 amps, 100% @ 50 amps.

At 50 amps & charging a 50% BATTERY PACK to 132volvts, 10 minutes

[roady89]

Originally Posted by GarageBuilt

roady89

Please bear with me. This is what I found today.

80 Amp Inverter Arc Welder. 120v, DC output current,
0-80 amps. Duty cycle:35%@ 80 amps, 60%@ 65 amps, 100% @ 50 amps.

At 50 amps & charging a 50% BATTERY PACK to 132volvts, 10 minutes

Thats 50 amps @ 100% duty cycle at what voltage? I can promise you its not 132 volts. More like 20 volts maybe. Thats 20 volts @ 50 amps. You have to have 132+ volts to charge your pack. Less amps = more time to charge but the voltage has to be 132+. You are not going to find a small welding machine to do this. ( or a "cheap" charger.) It NOT going to work. If your trying to charge 1 battery then thats a different story.

[GarageBuilt]

roady, yes you are correct.

But here is how I understand it to work. The size of the batteries states how many amps it can be charged in. In my case it is 125.amps max.

OK, now lets say that we use the 80 amp inverter. We would plug stright to the pack as if it was a charger. Now we clip on our dig volt meter, turn on the welder & with amps set @ 80.

Now keep an eye on the volts, they will start to rise. And they continue to rise in voltage, even with the amps still set at 80. Now when they reach 132. volts,The pack is only 80% charged at this time. So now you have to slowley bring down the amps while maintaining the voltage at 132.volts. The lower you can get the amps down to while keeping the volts at 132. The more volts you get into pack.

[roady89]

I don't see How you are going to get 132 volts? When a battery is being charged you need amperage AND the proper voltage. Simplified, trying to charge a 12 volt battery with a 6 volt 100 amp charger will not work. Unless I have had it wrong all these years. lol. That is how I am understanding the theory of your post.

[dirtysouth]

WOW, This is DEEEEP.... I,m not sure what is goin' on, but ya'll sure got my attention...
Keep it alive... (or at least on life support).

Between the two of ya', It seems like ya'll can make something happen'.

[dougmcp]

Regardless of what you do or hook up to a circuit you can only get so much.
Using a simplified version of ohm's law: E=IxR I-Power(voltage) X R-Current(amperage) = E-Energy(watts)

A 20 amp circuit on 120v will give you 120vx20a=2400w
If you are charging a 50v battery bank you only have a max of 2400w/50v=48amp

A 20 amp circuit on 220v will give you 220vx20a=4400w
If you are charging a 50v battery bank you only have a max of 4400w/50v=88amp

With a 20 amp circuit assumed there is no way on this green earth you can get any more charging amperage than 48a at 120v or 88a at 220v.

These numbers are an absolute max which never happens in real life, reduce these by about 10% and that's closer to reality.
Anyone who says they can get more than that is on drugs.