Confused about watt numbers for a 240v genarator


Sash

Member
Location
Switzerland
Hi all,
Im on the search for a good generator for charging on track. I now that the numbers for the alta rapid charger when charging on 240v is around 4000w.
Im not long in the game so please dont get angry about my not enought knowledge:
Whats the charge amp on the rapidcharger that you guys calculate those 4000w wich are needed?

My charger charges with 20amps for 72v, i calculate 1440w then. Means a 2000w generator would be more then enought for my charger!?
Is that correct or do i miss something?

Im very intrested in a ITC Power generator. There is the 6500w one wich would be more than enought i guess, and the smaller 3500w one. The thing is that the big one is almoste double the weight and much bigger, so i would prefer the 3,5kw. Gasoline Inverter Generator GG2600i(E) / GG3500i(E) - ITCPOWER

Regards from switzerland, Sash
 

Philip

Administrator
Staff member
Location
Ann Arbor, MI
Whats the charge amp on the rapidcharger that you guys calculate those 4000w wich are needed?
240V * 16A = 3,840 W

My charger charges with 20amps for 72v, i calculate 1440w then. Means a 2000w generator would be more then enought for my charger!?
Is that correct or do i miss something?
That's true. A bigger than needed generator won't charge your bike any faster.

But that is a small and slow charger. How big is your battery? How many hours would it take you to charge it? Your charger is similar to what you'd get if you plug in the Alta's charger into 110V at 14A (1,540 W). In my experience that is not worth bringing to the track because it takes way too long to charge.
 

Sash

Member
Location
Switzerland
240V * 16A = 3,840 W


That's true. A bigger than needed generator won't charge your bike any faster.

But that is a small and slow charger. How big is your battery? How many hours would it take you to charge it? Your charger is similar to what you'd get if you plug in the Alta's charger into 110V at 14A (1,540 W). In my experience that is not worth bringing to the track because it takes way too long to charge.
Yeah now i get it where i made my mistake in thinking. The cahrger i use needs 240v and charge with 20amp`s 72v battery. Now its clear.

So that would be 4800W i need to run the charger.

The generator i am looking for has 6000W running wattage and 6500w peak.
 

Dirt-E

Active member
Location
King George, VA
Essentially, you want your generator to provide 10-20% more running watts than the peak draw. Long story short, you basically just want a little bit of overhead in the capability for the good of the generator, not because you empirically need it.

For example, if you are drawing 4000W constant, you want anywhere from a 4500W to 5000W running watt generator (note, this is not the peak capability). Peak generation is good for lock rotor amps of an AC load where it is very temporary. You just want to limit the number of overclocking events you are doing with the genny.
 

Sash

Member
Location
Switzerland
Yeah, so add 20% to the 4800W i need is 5760W so shoud be safe on the 6000W generator.?.!

What happens in worste case? Do the charger do not charge with the full 20amp`s?
 

Redwolf

My dog thinks I'm cool
Location
Brinnon, Wa.
Worst case, the generator will probably stall out and shut down.
If you have a 4800w base load, a 6000w unit ought to be capable. Assuming you are trying to use it at or below 2500m elevation.
 

Dirt-E

Active member
Location
King George, VA
Good point about the elevation. I'm pretty sure you wouldn't be able to re-jet the carb on a generator. But if you could, then theoretically you might have a little less wattage drop. You might burn a bit more fuel as a tradeoff.
 

Brad 594

Member
Location
Houston, TX
I use a Q6500 Quiet Power Briggs & Stratton generator at the track to charge my MXR. It is works very well and is relatively small and very portable with wheels. I use a Rapid Charger at the track. The Standard Charger was too slow for track use in my opinion.

 
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