What happens if...
 

...your batteries are rated lower than your Motor draw?

I've been running TrakPower 4900's with a 1515/1y. The Motor calls for about 110 amps and the batteries are rated at 122 amps so everything seems just fine. The problem I'm having is that making 15 mins is still too dicey. I was thinking that a perfect solution was to use the new TrakPower 5400's but they are rated much LOWER than the 4900's. The 5400's are only 86 amps. What happens in this case? Does the truck just go slower? Does this make the ESC or Battery or Motor work harder? Does it spontaneously combust?

Any thoughts would be appreciated.

Thanks,

if anything it would make your batteries work harder, the ESC prefers WOT , if the batteries cant deliver what the motor is asking for it just wont be as fast as it can be

I can deal with some speed loss, it's already crazy fast. I hardly ever hit WOT and when I do it's for an instant before I have to get on the brakes.

But making the batteries work harder is counter productive to my goal, more runtime.

what is "WOT" mean just curious

cant tell if this is sarcastic (you have a lot of posts so leaning on sarcastic) but the answer is Wide Open Throttle "WOT"
some one that doesn't really know what it means can read this and find out with out asking it.

Have you tried gearing down to increase runtime? If you barely ever hit WOT it may be that gearing down will pull less amps and increase runtime. It won't increase it by much but it may get you to a reliable 15min.

from my understanding of lipo I believe you are asking for a large fire if you are discharging your lipos too quickly, which would be what you would be doing if you are trying to pull more current from them than they can safely supply.

I am certain one of the more lipo savy members will jump in here.

I'm about to try that. There seems to be some misinformation about the prospect of gearing down. If you gear down, it causes the motor to spin faster to achieve the same speed, doesn't the faster spinning motor draw more juice? Time will tell.

While I'll always err on the side of caution, it's my understanding that most LiPo fires occur during the charge phase. I'm not saying it can't happen when running but it's rare, like if there were a short or something. I don't think they can really catch fire from running a motor within the "burst" limit of the packs. But as you say, I'm hoping some of the Electro-wizards out there will chime in.

LiPo's can definitely overheat and fail if you're pulling more than the rated amp draw. You must keep in mind though, just because you're motor is rated for 110A, does not mean it's actually pulling that. It depends on gearing, voltage, weight, etc. To be 100% sure you'd really need to run some sort of data logger on your current setup and see what the amp draw looks like.


J.

A number of thing could happen:

- Lipo's get stressed and overheat - Could puff and trash your lipo
- Lipo's get stressed and go below LVC and car stops
- Lipo's get stressed and cause voltage ripple which your caps can't stop and your ESC goes up in smoke.
- You get away with it

I doubt the extra 500mah on a lower C battery will help you that much... I would look at the enerland 4s 6000's 25c if you need the extra capacity.

Spinning faster (with lower load ie) does not draw more amps - Analogy Is it easier to use stair master fast with no load that slow with higher setting.

That really does sum it up well...

Thanks,

NO i was actually serious. no joke, i have a lot of posts, but i have not seen this abbreviation since a few months ago. before that i never saw it being used a while ago. thanks again

But there is a caveat - spin too fast too often then the motor can be ineffecient and heat up - It is a balance of gearing and the right motor in the right application.