long lost newbie lipo questions

[andrewhendler]

Hey John,

If you get the motor back can you post your findings, i am interested in the motors escpecially with the sealed can. Also the price is definatly right for a motor that size, just wondering if I should just step up the next level

[Chris_The_Battery_Man]

A few things:

In regards to the outrunner and 860 combo...


-Sounds like your battery pack is too small and the gearing is a hair to tall. your battery doesn't have to get warm for it to not deliver enough current.

-Set the LVC to 9v

-Burst amp draws mean nothing in the hobby world. It's all about the constant amp draw. So don't focus on the bursts, they are irrelevant. you may have better lock that way.

Personally with the 6+ years of battery experience, 10+ years in RC, and 2+ years in crawling, I would not use a pack smaller than a TRUE RATED 1350(ish)mah with no less than 15C. 860 seems way too small and would not be able to deliver the voltage under load that the outruners need on startup. Outrunners suck out of the hole on start up. And in situations where they are bound up or dont have enough battery, they will cogg like crazy.

If you gear down a little more, bump up in battery and drop the LVC down to 9v you probably will have much better lock that way

[JAM MaxAmps.com]

You guys are not listening to what I'm typing. The motor on start up never had any issues at all. It only froze up after it got hot from being loaded up. When I held it back on the carpet and forced it to dig the motor never cogged or missed a beat and I was hard starting it everytime I did it. The motor only got goofy after it got hot the first time it was only 120 degrees the second time with the 1550 was 222 degrees. I put on a 2100 3S one of our best selling packs and guess what same thing happened. It's not the packs the sport motor doesn't like heat. Once it is allowed to cool off and driven under normal crawling conditions it works great and has a ton of power with what ever pack I use.

Jason

[JohnRobHolmes]

You are not listening to what I am saying either. The heat of a motor will not change the startup. A hot motor does not magically change electrical properties unless the wires have burned through the ceramic coating or the magnets have degraded. Either case cannot be solved with cooling down. If the motor is hot, it tells you a few things. One, the motor is doing work. Two, the battery is supplying the power so that the motor can do the work. Just by looking at the discharge graphs I can tell you that the lipo batteries you are using are not up to the task that you are presenting to them. At only five minutes into the run (only a third of the capacity) the battery is not recovering above 11 volts with the load you are presenting. The recovery of the battery tells the full tale- it can't keep up with your test. See this graph you posted http://www.nitrokillers.com/attachme...2&d=1201990082 With low recovery voltage comes voltage depression under load. Voltage depression under load will not allow proper startups, and will cause further motor and ESC heat. We can argue back and forth "chicken or egg" all day.

Here is a sample data log, as you can see the voltage pops back up to an average of 12.25 after every burst. This particular intermittant load is not taxing the battery enough to cause voltage depression. I had zero startup problems and the motor was indeed hot.

[Chris_The_Battery_Man]

Originally Posted by JohnRobHolmes

You are not listening to what I am saying either. The heat of a motor will not change the startup. A hot motor does not magically change electrical properties unless the wires have burned through the ceramic coating or the magnets have degraded. Either case cannot be solved with cooling down. If the motor is hot, it tells you a few things. One, the motor is doing work. Two, the battery is supplying the power so that the motor can do the work. Just by looking at the discharge graphs I can tell you that the lipo batteries you are using are not up to the task that you are presenting to them. At only five minutes into the run (only a third of the capacity) the battery is not recovering above 11 volts with the load you are presenting. The recovery of the battery tells the full tale- it can't keep up with your test. See this graph you posted http://www.nitrokillers.com/attachme...2&d=1201990082 With low recovery voltage comes voltage depression under load. Voltage depression under load will not allow proper startups, and will cause further motor and ESC heat. We can argue back and forth "chicken or egg" all day.

Here is a sample data log, as you can see the voltage pops back up to an average of 12.25 after every burst. This particular intermittant load is not taxing the battery enough to cause voltage depression. I had zero startup problems and the motor was indeed hot.

I agree totally. If the pack is not getting back up to 12v after a burst, then the battery is not the right one for the motor/ESC combo. Not to say your product sucks, just saying your not using the right battery for the job or the gearing is too tall. Playing the "Blame Game" while testing your own product... not good form.

[32inchTSLs]

after reading this entire thread carefully i completely agree with john. and i'm a little confused why jason would defend this 850mAh battery. there's nothing wrong with maxamps or jason just because a particular battery isn't suited to the task. no point in arguing and finger-pointing. the deep discharge (upside down spikes) cycles on your own graph are by definition damaging to the pack, and the loss of voltage recovery after each one of those episodes is the proof. if that arrangement of cells was suited to the task they wouldn't respond by dropping so hard.
speed controls are just logic gates that do what we ask them to. motors do a certain amount of work that can be measured in watts. i'm sure you all know that if you reduce the voltage that you must increase the amperage to achieve the same number of watts. i'm also sure none of you would debate that the heat in the motor came as a result of the gates in the speed control staying open longer and supplying greater current to get the motor to do what was easier and less heat at higher voltages.
as the voltage decayed in the cells jason had to ask for even more current to do the work, resulting in more heat and even deeper voltage losses during peak load.
i agree with chris that pretty juvenile to make accusations about who's at fault over this.
jason, if you signed up here to try to sell batteries then just stick to that. leave the science to your engineers, and instead look to us for how you can serve our needs rather than trying to prove a useless point. sure, the pack might have physically fit beautifully on that axle but that in NO way makes it suitable to the demands of rock crawling. let it go.