Just came accross this

The load from the motor determines how much current is drawn from the batteries. Batteries don’t push current, hence you cannot have too large or too high a discharge battery. The ESC, between the motor and the batteries has two jobs. First, it run the motor by analyzing the motors back EMF then sending commutation pulses to the motor based on its analysis of the motor. This involves much more than knowing the position of the rotor, there are several complex algorithms that, by analyzing the back EMF, set the computation pulse advance to get the most power and efficiency of out any motor is it running.

Its second task is to control the speed of the motor to the users command. It does this with Pulse Width Modulation or PWM. PWM works by turning full throttle current on and off very fast. The portion of the pulse that is 'on' in relation to the part that is 'off' determines how much power the motor sees. I.E 50% on, 50% off the motor sees 50% power. The PWM switching rate is 13,000 times per second (13 khz). DC power sources, in this case batteries, do not like high current being switched on and off, they want to put out steady current. The ESC wants to see square waves, instant full on, instant full off. However, the battery takes time to go to full on and won't switch off immediately. This creates a sloped instead of a square wave. The caps on the ESC are there to get the PWM pulse back closer to a square wave. The reluctance of a battery to put out pulsed current also creates a side affect called 'ripple current.' The caps also control ripple current. The less capable a battery is of keeping up with the current demands of the motor the higher the ripple current. If the capacitor overheats or get completely drained from inadequate batteries the caps will burn or blow up and the ripple current cascades thought the power board burning up the ESC. The other primary cause of ripple current is resistance on the battery side of the circuit. A plug with too much resistance, long or too small battery wires, bad connections etc. will increase ripple current, possibly to catastrophic levels. I cannot prove it but my guess is that more of our ESCS are burned up from inadequate batteries than over current.

The minimum discharge rating for cells used with a Monster Max is 75 amps continuous, burst to 150 amps. This is a minimum to keep ripple current low enough to make sure the batteries don’t damage the ESC, more is better. Also, the more capable the batteries the more torque the motor will produce.

To answer the question of why don’t NiMh batteries damage the ESC is the fact that these cells voltage drop quickly under load then climb back. The drop in voltage protects the system from the motor pulling too much amperage and creating too much ripple current.

With high power electrical systems, the battery is the most important part of the system. Saving money on batteries not only gives lower performance, it puts the ESC at risk. Choose your batteries wisely.

Bernie Wolfard
Supervisor, Product Support
Castle Creations
235 S Kansas Ave.
Olathe, KS 66061

Is there a way of overdoing the discharge of the battery?
They recommend minimum 78A cont. and 150A burst, was just looking at the Thunder Power and their 125A cont. 250A burst

I just got my MMM from Mike today, got her all soldered up, hooked up, armed and away we go, i run a 7XL on 14 GP 3300 just bashing around, geared tall at 24/56 in my mostly stock 3905 maxx, it is awesome, nice job CC. Steve

Overdoing battery discharge? Never, until the weight of the pack negates your increased power. I just got some 30C/50C Polyquest to stack against some 18C and 25C packs. It will be interesting to play with.

Message from Joe Ford

Gents...we are seeing few of these come back versus the number that were sent out. If you're going to have an issue it'll probably be in the first minutes of operation. If ANYONE has this issue, please send the ESC to us and we will put you on RUSH repair service. Fill out the copy of the service request form at the link below and include it with the ESC. This is a very easy issue to fix on the controller. We are sorry for any inconvenience to those of you who experience this issue.

Shipping address is as follows:

Castle Creations
ATTN: Repair Dept/Monster MAx
235 S. Kansas Ave.
Olathe, KS 66061
USA

http://www.castlecreations.com/suppo...quest_Form.pdf

That is super tall gearing. I run a 9xl with 14 gp3300 and run 22/58-62. whats the temps on the motor with that setup.:gasp:

Have you contacted CC yet MTBikerTim? How was it sent?

Is this means this bec problem in MMM just with lipo?
I don't have lipo I will run 16 nimh cells until i buy A123 that recommended by cc.. so I will be in safe side with nimh?

I just sent mine back two day air so it will be there tues. Hopefully I can get it back rapidly. Joe sent a nice email back to me and they are obviously taking this all very seriously. Customer service is still top notch.


No, mine did it with nimh.

So are they still sending out new units to people how have had problems? Or is it all on hold now?

Also, for guys that buy it off ebay (not a store on ebay) are they still covered under warranty? Just looked at the Service Request form and they want a reciept as well as when and where bought?

Temps were fine 98 ESC, 105 batteries, 137 on the 8xl and i ran it without a heatsink clamp. Steve

Nope, doesnt appear they are holding off shipments. A friend, and myself ordered one each from Tower and they will both be here on Monday. I would think if Castle wanted to put a hold on anything they would have contacted the distributers and put a stop on further shipments. I guess the best thing to do is run the crap out of it over a few days period. Honestly from what I've read the first batch was 2500 units, and so far I've read maybe 6-8 failures on tech boards. It would seem most are having great success.

And if they are having success, it is more likely they are running there trucks with it, rather than posting on the forums. Usually if the ESC doesn't work, people would post the problem on the forums...

I sent them an e-mail a few days ago and have not received a reply yet. I'm sure I will in a few days but I just sent the thing back via air mail in the mean time, not express. Honestly couln't be **** spending another $40+ to have it shipped back express. I have to say that the one thing that is a little annoying about castles customer service is that it takes them forever to answer e-mails (probably cause they are just busy). I have called them before but that is a pain as I have to get up stupidly early in the morning and everytime I do the person I am calling for isn't there. Anyway when they get my parcel I'm sure they'll be able to figure out what to do with it.