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› Help in determining amp output of generator
10-10-2013 05:51 PM  4 years agoPost 1
HeliNutAndy

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worcester, MA USA

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I have never understood this fully....

I have an 800 watt generator and the specs state that it produces 6.5 amps. I have been using it to charge 10S packs at 20 amps without issue. When I bump up the charger to 24 amps the charger shuts down even though my ps is rated to deliver 60 amps maximum. How am I achieving a 20 amp charge rate when the generator is supposed to only output 6.5 amps? My power supply is adjustable from 15 to 24 volts and my charger is rated at 1000 watts. Is the formula watts/volts = amps or in this case 800/24 = 33.333 potential output?

TIA,
Andy

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10-10-2013 10:23 PM  4 years agoPost 2
poerQwa

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Rotterdam, The Netherlands

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Well, add to that some 10% loss in conversion as well as the 800Watts are probably only the max. "Watts" and not the "continues" or "Rated" Watts

As an example I have a 1000Watt generator that only delivers 900 continues. another 10% lost in conversion gives me 800 watts usable for charging.

Regards,

Marc
P.S.
The 6.5 amps is what your genny can deliver at 110V.

Edit:
Your 20 amps charge calculates back to:
10 cells * 4 V(nominal) * 20 amps = 800 Watts
I guess you have hit the limit

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10-10-2013 10:50 PM  4 years agoPost 3
Ace Dude

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USA

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I'd highly recommend using a Kill-A-Watt to see what's going on.

  

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10-11-2013 12:21 AM  4 years agoPost 4
qraptor

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Illinois

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And don't forget some small losses occur in the power supply as well. It too could be costing you 5% or so of the input watts, even if you are using a highly efficient one.

So, all in all, you are doing the theoretical max.

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10-11-2013 12:54 AM  4 years agoPost 5
Ace Dude

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USA

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Power supplies are approximately 80-85% efficient. The efficiency will vary depending on input and output voltages.

  

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10-11-2013 02:32 AM  4 years agoPost 6
HeliNutAndy

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worcester, MA USA

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Thx for the help but...

I'm still a little lost. I just need some clarification. Is this the correct formula to use?
10 cells * 4 V(nominal) * 20 amps = 800 Watts
So if I was to charge a single 6S packs I should be able to bump up the charger to ~32 amps before tripping the generator?

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10-11-2013 09:34 AM  4 years agoPost 7
poerQwa

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Rotterdam, The Netherlands

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Yes, but you would need a decent charger to generate 32 amps

What charger are you using?

Regards,

Marc

p.s.
The kill-a-watt is a very good suggestion.
My genny actually has a digital display showing the watts pulled from it.

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10-11-2013 11:56 AM  4 years agoPost 8
HeliNutAndy

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worcester, MA USA

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I am using a Voltz 101K iCharger - 1000W Synchronous Balancing Charger which I read is a copy of the iCharger 3010B. The generator is a Harbor Freight cheapo as some call it but it has worked excellent for me. I need to look into a kill-a-watt and check out the specifications. Thx again for the help.

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10-11-2013 11:18 PM  4 years agoPost 9
qraptor

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Illinois

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So if I was to charge a single 6S packs I should be able to bump up the charger to ~32 amps before tripping the generator?
Theoretically, yes. But I have to think that your genny is supplying more than 800 W.

Please be sure that your batteries are capable of taking the current!

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10-12-2013 01:21 AM  4 years agoPost 10
HeliNutAndy

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worcester, MA USA

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It was only $90. It was the best $90 I have spent in a while. The little thing is a work horse. It's no Honda or Yamaha but for the cost of a cheap pack it runs non stop all weekend.

http://www.harborfreight.com/catalo...7/category/429/

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10-12-2013 09:22 PM  4 years agoPost 11
qraptor

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Illinois

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They under promised and over delivered. Isn't it great when that happens.

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10-13-2013 05:25 PM  4 years agoPost 12
Justin Stuart (RIP)

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Plano, Texas

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You have to figure in "power factor".

http://en.wikipedia.org/wiki/Power_factor

Not all AC-to-DC converting power supplies are "power factor corrected". This is why you are not realizing the full specs of your generator.

If you were using a Meanwell or other brand of power factor corrected power supplies, you would not have a problem.

Avant RC
Scorpion Power Systems
Thunder Power RC
Kontronik Drives

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10-14-2013 04:44 AM  4 years agoPost 13
Tyler

rrElite Veteran

Chicagoland area

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A generator's AC output of 6.5 amps equates to about 800 watts of DC power.

Enjoy things that money can buy IF you don't lose the things money can't buy.

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10-15-2013 01:08 AM  4 years agoPost 14
edwelds

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hartford,ky-usa

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I think everyone has forgot about Ohms law. V=I X R and P=V X I. That is power = Voltage X Current. So 800watts AC at 120 volts =6.66amps on the high voltage side. Low voltage side 800 watts= 12 volts at 66amps. depends also on what the output breaker is on the 12 volts too.

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10-15-2013 03:12 PM  4 years agoPost 15
Tyler

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Chicagoland area

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Edwelds,

Good post.

That 66 amps of dc power must include losses in resistance, heat, charger consumption, etc. therefore the charger output cannot be 66 amps.

Enjoy things that money can buy IF you don't lose the things money can't buy.

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10-16-2013 12:25 AM  4 years agoPost 16
edwelds

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hartford,ky-usa

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I did not include losses. I doubt his generator will output that much anyway. Probably has a breaker set at 20 or 30 amps, on the DC output.

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10-16-2013 12:38 AM  4 years agoPost 17
Ace Dude

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USA

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I don't believe that unit has a DC output, it's an AC generator.

  

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10-16-2013 01:55 AM  4 years agoPost 18
Tyler

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Chicagoland area

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I don't believe that unit has a DC output, it's an AC generator.
Ace Dude, the above is understood, and thanks for clarifying. Most generators do offer AC and DC output, but the DC is minimal and often unregulated. There is not enough DC power to run a charger directly from the generator.

I will try to clarify my comments above with greater detail...

120v AC = 6.66 amps output @ 800 watts.

12v DC = 66 amps output @ 800 watts.

This does not mean that a 6.66 amp AC output from a generator will result in 66 amps of charging capability from a charger because the AC must first feed an AC/DC power supply, which then feeds the charger, and finally the lipo battery pack.

Enjoy things that money can buy IF you don't lose the things money can't buy.

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10-16-2013 02:15 AM  4 years agoPost 19
Ace Dude

rrProfessor

USA

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I was replying to edwelds comment:
Probably has a breaker set at 20 or 30 amps, on the DC output.
The generator the OP is referring to does not have a DC output.

I have a Honda EU2000i and I'm well aware of the capabilities unregulated 8A DC output.

  

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