Ways to protect MMM when used with subpar batts

Please don't chew me up too much for asking this...

I've tried to do my homework, doing searches and readiing posts, etc. I understand that Patrick recommends the biggest, baddest, batteries on the planet. However, I'm not after an extreme setup, or to do any racing just yet. It's just that I can't go out and drop more $$$$ for new batts right away. So, I'm trying to figure out how to run what I have for a little while, if at all possible.

The posts about Castle's new insert said to use mild gearing. Check.
The deal with hard braking causing voltage spikes which pop the FETs is not something that I think will be a problem for what I'm doing. (I hope.)
So, that leaves voltage stress taking out the power supplies...

One question there is which of the 3 blows most often. I'd suspect it's the BEC since that deals with the most current. As a result, I wonder if using a external one (or an Rx pack) will offer additional protection.

Anything else, I've left out?

For reference, I'm not running a huge MT. It's an RC8E/MMMv3 2200, on a medium-sized indoor "stock slash-friendly" track. I have run it out there a little bit already with a 15T pinion, motor timing set to 0, and 100% punch control, and it wasn't bad. My goal would simply be to have some fun with it without shortening the life of my controller.

Can I get away with it, or not? Thanks!

[nitrostarter]

Originally Posted by elcheapo

Anything else, I've left out?

What batteries are you running? Thats the main question in my head.

I would use BrianG's speed calc and figure out a gear ratio for about 35mph MAX!

if your talking about zippies, they are fine, i run 40-50$ packs in my buggy and truggy all day with no problems, i dont agree with castle on there battery recommendation

Originally Posted by big greg

if your talking about zippies, they are fine, i run 40-50$ packs in my buggy and truggy all day with no problems, i dont agree with castle on there battery recommendation

Other peeps prefer not taking expensive chances.

[shaunjohnson]

i would prefer the biggest baddest batteries i could find as well.
but since i cannot afford them, i do my reaserch and have settles with a few of the top end zippes and turnigy packs, they are showing good performance on the eagle tree at present and my setup isnt pushing them hard either.

[Bondonutz]

Agreed, Zippys in a 30C are fine. I have a dozen in 4s &5s and like them as much as any expensive pack I've had over the years.

Thanks for the replies...

I ran it with 12 x NiMH, since I don't have lipos for it yet. I've heard about the Zippys, but I'm also looking for some used 2s packs to pair up. The speed calc gave between 29.5 and 33 MPH, depending on the exact battery specs I put in. RC8E has 4.30:1 ratio diffs, and 46T spur.

[suicideneil]

That sounds fine really, and still perfectly useable, even if it doesnt have the same punch and top end as a lipo powered machine.

Castle doesnt recommend the biggest and baddeest batts to use with the MMM, they just say dont go buying crappy chinese batts or naff ebay items that cost $20 each, yet claim 40c like proper lipos in the ~$200 range can actually manage.

The 30C hobbycity lipos a re great budget lipo, or the Hyperion G3s for a good value top-end option; I run older 25-35c hobbycity lipos and no problems here, even with my old V1 MMM.

I see no advantage to running the external BEC or RX pack with the V3 MMM, very few internal BEC failures these days, seems to be more physical damage causing BEC failures (heavy landings and such)- given Castle's excellent customer service you wont be without a working esc for very long, maybe pickup a spare esc to run in the mean time if its important to have a working one for racing and such.

[lincpimp]

"Ways to protect MMM when used with subpar batts"

Sell thew subpar batts to the noobs on the trx forum and buy decent batts. Simple easy fix.

Originally Posted by lincpimp

"Ways to protect MMM when used with subpar batts"

Sell thew subpar batts to the noobs on the trx forum and buy decent batts. Simple easy fix.

/End thread.

[Bernie Wolfard]

Originally Posted by elcheapo

I'm not after an extreme setup, or to do any racing just yet.

El,

This statement is somewhat of an oxymoron. The MMM system is an extreme system, no getting around it. This is sorta like saying I just bought a Ferrari and want to run it on regular gas. Just like the Ferrari, if you run with cheap batteries you risk serious damage, just as you would get with a Ferrari on regular gas. This can get expensive quickly. The other issue with cheap batteries is that if they do work without damaging the ESC you will get short cycle life out of them, perhaps 50 - 75 cycles. With good batteries you can expect 300 - 500 cycles. Even if you pay twice as much for them they are much less expensive to run and give you peace of mind. Patrick doesn't just say to use good batteries to make our system look good. We have no interest in selling batteries. We just wish that the bad batteries would go away so we would get less calls about the ESC burning up from running inadequate batteries.

Bernie

[Unsullied_Spy]

How hot are your NiMHs when you get done with a run? If you are hitting 120 or higher by the end of the run you are still pushing them too hard. You're trying to run a Hummer off a Civic engine, it will technically work but really shouldn't be done. If you want to keep from causing a catastrophic failure, you'll save up a little and get some decent lipos. I am a big fan of the Turnigy/Zippy/Rhino packs from HobbyCity. They aren't the best in the world but for the money you could gear for 40MPH and not have an issue.

[bryan]

So, who does determine the quality of a battery other than the one setting a high msrp.. I do have 2 5s flight powers, and two 5s turnigy,and i really like my rhino 4s batteries. Yes they were cheap and they work great.were did the cell come from in your battery?

[Unsullied_Spy]

High MSRP is not always indicative of a high-quality battery. My pair of Maxamps packs ran me about $500 after buying the warranty, "hard case," shipping, etc. and both of my Monsters that have burned up blew out while running those lipos. On the other hand, I paid $30/ea. for my Turnigy lipos and have never burned up an ESC while running them and they stay balanced better.

[hoovdog]

Originally Posted by bryan

So, who does determine the quality of a battery other than the one setting a high msrp..

That certainly is the tricky question. I'm always searching for the next best bang for the buck combination so I did a little purchasing for a not so experiment, experiment. :) Bought a pair of Turnigy 20C 4S 3600mAh packs ($45 each) and a pair of Hyperion G3 35C 2S 6500mAh pack ($97 each). I believe these to be the opposite ends of the spectrum from my readings. One is continually called cheap and the other the cat's meow. Now, the included "Do the math" sheet would indicate that I take 80% of the rated continuous draw. OK, so my Turnigy packs will yield 115.2A continuous draw which is certainly above the cutoff on that insert. The problem is most people will say these packs are insufficient "cheap" so where exactly is this boundary line crossed? I'm just looking for some kind of conclusion that says any battery (within reason) can be good as long as it's used in the correct setup. Granted, I'm pretty sure I know which will perform better (love my G3's but looking forward to running these new 6500's :) )

I'm going to take a slightly lightened (via aluminum upgrades) ERBE geared for approximately 40mph on 4S which I believe to be fairly modest for the setup being used. Now, does this general setup make my Turnigy batteries insufficient or would it need me to try for a 50mph gearing to be insufficient? It is feasible to think a user couple pick up a pair of cheap batteries and only wish to run 30mph. I would then tend to believe low rated batteries are sufficient yet a lot of people will discredit them instantly without knowing the details. It's then possible to say that cheap batteries of a certain brand will be great at 30mph, ok at 40mph, and not such a good idea at 50mph. Is this a better way of yielding information to new users? I guess my point is doesn't it greatly depend on how far a user is pushing the setup that dictates the battery's usefulness?

I did take notice to what Bernie had mentioned which I believe was somewhat related to my point. "The other issue with cheap batteries is that if they do work without damaging the ESC you will get short cycle life out of them, perhaps 50 - 75 cycles." I completely agree with this statement but does this still mean the "cheap" batteries are not sufficient? They won't last as long but they do work so once again that boundary creeps up.

I also took note of what suicidneil wrote: "Castle doesnt recommend the biggest and baddeest batts to use with the MMM, they just say dont go buying crappy chinese batts or naff ebay items that cost $20 each, yet claim 40c like proper lipos in the ~$200 range can actually manage." Also a statement I agree with but where is the data for the masses to determine which chinese packs are the overrated packs? What's a crappy chinese battery mean or does this mean any chinese battery? Not really looking for a response on this but you can hopefully see what I'm trying to say.

I guess an underlying theme for my post is I fully understand where newcomers have difficulty piecing together a quality setup for their uses. I think it's awesome that some will share their data with everyone to help decision making and weed out the bad products but it's still extremely difficult because everyone's driving style etc. is so different. WOW....I rambled on enough! :)