what does max amps really mean?
 

i have a neu motor 1515/2.5d and on the enclosed documentation there is a value stated as such: Max. Amps (A) 20 sec. = 80* am i to believe this motor will only draw 80 amps? or is there something i am not seeing

does anyone know what this value is really supposed to mean? the reason i ask is because i hear that often times motors will draw well over 150+ amps upon a dead hook launch and braking so i am kinda confused

Yes, and no. The Neu motors are rated for a certain amount of power. They most likely determine the max current rating for whatever voltage the motor needs to reach the max rpm of 60k (using the kv value). For example, the 1512 2.5d is rated at 2000 for the kv and 3000 watts max. Well, to get the max speed of 60k rpm, you'd need 30v. 3000 watts devided by 30v is 100A. But since they say 3000w "max", they probably derate the current a bit.

With cars/trucks, you almost never pull that kind of current constantly. Usually, you pull 120A+ on takeoff and heavy acceleration, but the average current is MUCH lower. I wouldn't worry about it unless you plan to gear to the moon or haul something.

I also have the 1515 2.5d so I know the bit of paper you're talking about. The * after 80 is telling you to look at the bottom of the table, where there is another * . After the * it says "At max voltage. Otherwise,=Watts/your voltage"
"At max voltage" means 80amps is the 20sec max current draw on max voltage, which is 35v.
"Otherwise,=Watts/your voltage" means the max watts for 20 seconds (2700watts) divided by the voltage your using.
So say your using 5s (18.5v) like me it would be
2700 divided by 18.5 = 146 amps for 20 seconds is the maximum that motor is able to handle on that voltage. It doesn't mean it will always draw that much power though, since it can only use what your batteries can put out. And even if it did hit that current, in a car it would usually only be for the first second or 2 of take off.

you really think the motor will pull any amps needed to achieve the maximum power? That means I would fry eagletree micrologger I wanted to get :)
2500W/19.2V = 130A on acceleration if needed :)
Does anyone have any eagletree info about Neu and how much power they actually draw?

As long as your batteries can supply that sort of current and your car is able to put the power down somehow, then the motor will pull that much current. It won't fry the MicroPower, but the MicroPower won't display anything past 120amps.

If that is correct, then my punny HvMaxx does:
375/14.4 = 26.0416amps. Or with the new rotor in theory: 550/14.4 = 38.194amps. Its almost laughable compared to your figures guys, but as they say: Its not how big it is, its what you do with it that counts....

at least it wont suck out batteries in few mins :)

wtb portable nuclear power plant :028:

What about running a dynamo in conjunction with the motor on a stock emaxx motor mount, then use that to recharge the batteries as you drive! You would need a small bicycle dynamo, and a really torquey motor, but it might extend run times by a little.
I was actually doing some more late-night research into batteries, and I saw the specs on some D-cell NIMH.... up to 9000mah. Granted, they would weigh nearly twice as much as sub-c cells, but think of the runtimes....
Going the other route, I saw some good AA-size Nimh with about 2500mah capacity @ half the weight of sub-c. Now, you could build two 14.4-16.8 packs, that wouldnt be much larger than 2 7-cell packs, and then run them in parallel to get 5000mah+ at the same weight. The only factor to consider is discharge rates, but the sites I looked at werent terribly specific. With a lightweight setup and not too insane motor/gearing its a viable idea I reckons....

AA amperage support is like null. i have no specific numbers on them but i know they are far worse than the stone age nimh sub c

The dynamo/generator idea sounds good at first glance, but you have to remember that there are losses in the motor turning electrical energy into kinetic energy and then more losses from kinetic energy into electrical. So, whatever runtime you gain from having a dynamo/generator would be negated by the added load of that device plus the losses. Runtime would actually be less.

Last time I've read about the other batteries, the large D cell 9Ah cells have lots more mass vs surface area so they will heat up a lot more and retain the heat longer. And the 2500 AA cells cannot deliver the pulse amperage these cars require. Both of these cells are better suited for applications where long runtimes are wanted but on low current devices.

Your not the first to try and invent a perpetual motion machine.:dft012:

It was a nice idea, while it lasted. I'll start work on the 1:10 scale rc fusion reactor then.....

If you mean those like greenbattery brand D size cells, I asked them for discharge rates, and the PDF file I got only mentions 1C, no indication as for max rate.... And they weigh 135grams each...

Hmm, I looked at various sites (again) and the best discharge rate was about 10c I think, though I would have thought they could do more due to the extra capacity/size. I would have thought so anyway....
Weight is the main problem, so they would only really be anygood on a lightweight truck/truggy- by the time you have the packs fitted the weight wouldnt be all that light though.... bah.

Or, you could invent some motors and alternators with more than 100% efficiency :027: , then the alternator should be able to put out more power than the motor is using to turn it. That could help solve energy problems if you could get power for nothing.

I've thought about other size nimh cells in my cars as well, but there not very good at holding voltage. I put 6 2500mah AA's in my mini-t, and when I put the mamba 25 and 8000kv motor in it every time I accelerated more than about 50% the mamba would cut out for half a second, like it was hitting LVC, even though I set it as low as I could. Anyway when I put some good 1500mah 2/3 A (normal nimh size for mini's) batteries in it never cut out during acceleration and was a different car.
They could probably make D and AA batteries better, but for what they usually get used for they don't need to be as good as our car batteries, so manufactures probably don't see a market for high quality cells in those sizes.

I think sub-C are the perfect compromise between output power and proper size to shed heat. I've tried paralleling those AA's and it helped, but still not as good as a decent sub C. Not to mention the weight.

Boo. It would be nice to have 9000mah capacity in a Nimh cell, but the overheating issue is worrying. What with 1/8 and 1/5 scale becoming more common place, I would like to see larger cells with more capacity, but like has been said, the manufacturers dont see the need yet.

There must be some type of "wall" to capacity in the sub-C NiMH cell. Seems like if you go much beyond 4200's, something suffers. Plus, with new and better chemistries out now and in the works, it only makes sense to concentrate on those.

That is very true. Its a bit like Digital tv- at first there were only a few manufactures, and prices were silly. Now there are tons of different makes & models to choose from and prices have come down loads. I may well have to look at getting some of the A123 type cells at some point- they seem very much like Nimh in how you use them, just need a cc/cv charger to get a 100% charge, and they last for over 1000 cycles..... way better Lipos in most respects.