Higher pinions = safer MMM's? Or no? Someone's lying....

[Unsullied_Spy]

Originally Posted by What's_nitro?

Or, let them continue down their own path and figure it out the hard way. Maybe after the 12654615th time their ESC thermals (or worse) they'll understand.

The problem is that they will burn up ESCs left, right, and center and blame CC for it and go all around the internet trying to sully their reputation. It already happens, but with all the n00bs coming into the market because of these RTRs we're going to be seeing more and more of it because people simply don't understand how it works and they want to go 60 MPH through 3 feet of grass with 8" tall tires and have everything work perfectly.

I agree on the EagleTree, I'd like to see someone running 15T, 20T (stock, I believe), and 25T pinions on 6s and post up good graphs on all 3 to show exactly what gearing does to amp draw. Also post up temperatures and such to show what the increased/decreased load does to temperatures across the board.

[BrianG]

Originally Posted by Unsullied_Spy

The problem is that they will burn up ESCs left, right, and center and blame CC for it and go all around the internet trying to sully their reputation. It already happens, but with all the n00bs coming into the market because of these RTRs we're going to be seeing more and more of it because people simply don't understand how it works and they want to go 60 MPH through 3 feet of grass with 8" tall tires and have everything work perfectly...

Amen to that! All that power and no knowledge/appreciation of how it works is a recipe for disaster.

[What's_nitro?]

Yeah I hear what you guys are saying. I was referring to the people who have been told it's not the case but continue to do so.

[suicideneil]

That should be Castle's and HPI's (even traxxas's) 'line':-

1.noob cooks esc through over gearing/ massive tires/ tall grass etc, send it to castle for repair.
2.castle kindly repairs/ replaces cooked esc, but includes a note to say that excessive gearing in the wrong conditions (tires/ grass etc) will result in further meltdown, will not warrenty the esc if same thing happens again.
3. noob cooks esc again 'cos da manual says 6s + tall gearing am okay', sends it to castle.
4. castle say 'get knotted' because they didnt heed the warning **from the esc & motor manufacturer no less**, forces noob to pay for non-warrenty repair.
5. noob cries to all his mates about paying the repair fee, hopefully warns them about overgearing.

In an ideal world that is....

[shaunjohnson]

trouble is..we feel all cool because we know this!!
all traxxas and hpi need to do is say "60mph!!* *under correct conditions and using ONLY 30C 5000mah lipo's"

that'd fix quite a few issues!!
but nooooo..the companies in question, traxxas = speed runs and HPI = high load back flips AND speed runs (and not advertising a gearing change between monuvers)

[lutach]

As they all say, speed and power sells. Too bad they fail to realize how much current is actually needed to push a vehicle at the claimed speeds. It doesn't only come down to using the best lipos. Castle should put some rules out and also call them out to avoid many more failures.

[BrianG]

I thought it was sex that sells? They should start displaying scantily clad women on the boxes of their products.

Sex sells but stupidity is always free

[lutach]

Originally Posted by BrianG

I thought it was sex that sells? They should start displaying scantily clad women on the boxes of their products.

I was going to say that....But if you're buying a vehicle, most would go for speed and power. Example: The new Ford car with ECO boost. I don't know where the ECO come in, but the car seems to be fast.

[Bernie Wolfard]

How do you tell if your battery is a good one and how to do track your batteries ability to discharge as they age? Several Lipo chargers can also measure battery resistance. The ones I know of are several Hyperion and NeuEnergy chargers. I am sure there are more that have this feature, I am just not aware of them. Internal resistance is what controls a C-Rating, the lower the internal resistance the faster the battery can discharge before it overheats. A batteries internal resistance (C-Rating) also determines the amount of ripple current the controller will have to deal with. The lower the batteries internal resistance the better the battery. With one of these chargers you can simply plug the battery in and records its resistance. The lower the number, the better the battery. If you track a batteries internal resistance over time you will see its resistance going up as the battery reaches the end of its lifespan.

With a charger that measures internal resistance it is interesting to plug in different packs of the same size and type from the same battery seller and see how different they are. If you do this you will find that the better battery companies have much less variance in their batteries because they QC the cells they use. You can also go through several cheap batteries and separate the good from the bad. Another interesting thing to track by measuring internal resistance is how many good cycles you can get out of specific packs. Again, you will find that the better batteries (except for bleeding edge supper high discharge cells, which typically don't last very long) will last much longer than cheapos. If you then calculate cost per run you will find the more expensive better packs are actually much less expensive in the long run.

The equipment it takes to measure battery internal resistance makes doing it yourself expensive and impractical, but it can be an easy job for a charger. Look for this feature in your next charger.

Bernie

[zviper]

bernie i dont have a charger that reads internal resistance. can i use a volt meter to get the internal resistance ?

[Pdelcast]

Originally Posted by zviper

bernie i dont have a charger that reads internal resistance. can i use a volt meter to get the internal resistance ?

You could, but it's difficult. You need a large constant current load to put on the batteries to see what the voltage change is under load.

[zviper]

ok so its a little more complicated then i thought. i guess when i get new batts ill pickup a new charger. thanks patrick, awesome product btw

[BrianG]

I'm curious how chargers do this. Resistance can change even over the course of a charge/discharge cycle so that would mean the charger would have to monitor pack voltage while applying the charge current in on/off cycles over the course of the charge, apply the resistance formula (r=(V_unloaded-V_loaded)/A), and then plot the curve. Or do these chargers simply measure the ir at the start of the charge?

Also, doesn't the ir change dramatically at near the cells max discharge rating? So, the ir value you see when charging at 1C may not be even near the value at 20C.

[JThiessen]

Bernie - that's terrific information. I asked quite some time ago what the resistance info meant to me, but it apparently stumped all of us at that time - either that or I couldn't understand BrianG's EE language when he explained what he knew!!