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!

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

Other peeps prefer not taking expensive chances.

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.

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.

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.

"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.

Hiigh power and cheap gas
 

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. :whistle:

Bernie

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.

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?

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.

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! :)

Spy,

Not sure how long I was out there, and didn't have a transponder in it either. The pack was warm, but not overly so. I'm not concerned about the batts at all, just don't want to blow out the controller. Bernies seems to be saying that the soft batts can do that, so it appears to be a moot point.

I went looking at the Zippys, but the tray is only 138 x 47. I think their packs were a bit bigger than that. I need to look around for someone else who has this car and see what they're running. Of course, there is AE's new Reedy pack for this car, and it's a real steal at $300. :cry:

Determining what batteries have accurate ratings and which ones don't is indeed the real challenge. Better batteries will yield better results(more cycles, more power less problems, etc.), but how does one determine what batteries to use?
Other people's experience is one way - Turnigy/Zippy packs get mixed reviews, for instance. Hyperion G3 packs get glowingly good reviews. Maxamps packs get mixed reviews. ETC. The list goes on and will continue to grow. Over time, the better batteries will show themselves with less overall reported problems.
Reported success and reported failures need to be taken with a grain of salt, though. Some people just can't or don't drive hard enough to maximize the system potential or to realize their battery's downfalls. The Zippy or other low end packs that work great for a casual user that doesn't use brakes a lot, or putts around at low speed is not indicitive of a safe and recommended setup for a skilled and competitive racer, for example. While they may appear to be a good value on the surface, long term results are likely to tell a different story. Over time, the better batteries will show themselves with less overall reported problems. I have seen more reported failures with Zippy packs, yet some people swear by them. No setup is exempt from occasional failure, either. Experienced users with premium equipment can have troubles, though it is going to be far less common.

I agree with Bernie(and posted a similar analogy some time ago) - if you want Ferarri performance, you can't buy Yugo batteries and expect good results for any length of time. If you run cheap batteries, I suggest leaving yourself some head room in the setup - gear conservative, minimize hard braking, etc. Most importantly...take your licks like a man(or woman) if things go sideways - all the money you saved on batteries can go towards a replacement controller. :)

Like you said Mike, I think the usage plays a HUGE role in determining what works and what doesn't. Someone who is looking for long runtimes just playing around in the yard is probably geared low with settings to maximize runtime. Sure is different than a hardcore racer (where weight to power ratio matters) or the guy trying to break speed records with a MT.

My personal experience with Turnigy has been mixed as well. Eagletree tests show very good voltage under load and they are barely warm after a run. However, out of 5 packs I had/have, one had a defective cell (wouldn't hold charge but returned that to the LHS for an exchange), and one cell on another one needed some TLC (needed to charge it individually) but now stays balanced all the time. The other 3 have been flawless. Seems like if they run right and stay balanced for the first 4-5 cycles, then you are good to go. Far outperforms certain other overpriced packs, but then again, warranty for Turnigy is not exactly ideal. Basically, you're gambling with them. You could hit the jackpot with all good packs, break out even (or maybe a little better) with a few bad packs, or take a hit if QC was asleep that day. As far as cycle life, time will tell.

Mike and BrianG....In your own words I believe you are reiterating exactly what I was trying to say so thanks for your replies. I get so frustrated when I read these one liners around certain packs being cheap junk without qualifying the statement. As we all know, not all people can afford to buy the known powerhouse packs so I'm always looking to find fellow locals a less expensive alternative WITH setup limits. I believe that to be the real help.

I'm hoping an EagleTree logger is in my B-Day gifts (thanks dear! :) ) so I plan on doing as much testing and data sharing as possible.

pack quality
 

I think BrianG touched on a HUGE factor to consider with the lower priced packs - CONSISTENCY. I don't doubt that some folks have gotten Turnigy/Zippy packs that perform great, but others have issues. The Hyperion G3, conversely, are consistently great performers. BrianG has the knowledge and ability(and willingness) to test his batteries and determine their worthiness - most users don't share these qualities. The low end packs require the user to assume more risk, as there is a greater chance of lower quality. Not all brand x packs are bad, but without the equipment, knowledge and ability to test the individual packs, the chances of getting a problem pack is significantly higher with the "low-end" packs.:intello:

Thanks Mike. :smile:

It's just hard for people (me included) when they see that they can buy 3 Turnigy packs for the approximate price of 1 Hyperion or other good lipo. You know the Hyperion is better, no doubt there, but that pricetag sure is appealing. You take a chance and hope that at least two packs will last, and if one goes bad, oh well, you are still ahead. And if you don't use your vehicles all that ofen (I probably have only 75 cycles on my oldest lipo) cycle life isn't that important because by the time it becomes an issue, the current market offerings are better, smaller, lighter, cheaper.

You're definitely right though, the knowledge on how far to use any cell is vital - especially so with the lesser products. If I buy cheap, I expect cheap and use it in a setup that is not demanding. If it holds up extremely well, I may then step it up a notch. But I definitely do not slap any old battery in my heaviest vehicle, gear for world record speed runs, and then act surprised when my car is engulfed in flames.

I'm glad the discussion expanded on this topic. Personally, unless I'm playing around in the yard I'm running my Hyperions but I do want to find an operating space for the Turnigys. I have created a log for the new batteries I just purchased. Every charge and discharge is going to be recorded for the first 30 cycles to see what can be determined...if anything. I may expand that if it's deemed useful.

We'll be watching you Traxxas mod

This is all really interesting reading and certainly as a newb to the BL/Lipo world then by far the most difficult choice for me has been with batteries....it is a minefield....maybe literally in some cases!!!

I ended up just saying sod it, get a Hyperion 4S 6500mah....this has cost me a lot but everyone with far greater knowledge than me seems to rate them, good enough for me.

However, I am also going to look out for some good cheaper/secondhand packs or similar for just bashing and things where runtime is not so important. The Hyperion was mainly for the big mah to try to get a racing 20 minute final achieved on one battery.

But, when I buy cheap, I do it with the acceptance of risk and some personal responsibility. Not to say that if I get a cheaper pack from a store and it's crud that I won't expect a refund/exchange.....but that I do it knowing I might have some of that pain to go through....

OK, so the G3 VX 5000 is too big for the tray. Do I go with the CX 5000 or VX 4200?

That's awfully nice of you but it's not polite to stare. Guess it's better than your original reply though. :)

:rofl:

If ratings are true to spec then I'd take the VX 4200's as long as you feel you'll get the runtime you need. Prices seem to be really close to each other for that extra 22 amp buffer with the VX 4200. I only own VX packs but have been really interested to know if the CX packs will be sufficient for my uses. Anyone have any input as to how true to spec these packs are? It would be great to hear the CX packs are underrated! :yes:

here's a test of the g3's cx and vx. My German isn't that good, but I believe the conclusion of this particular test is that the vx(35c) performance is very close to the cx(25c) performance.

http://www.elektromodellflug.de/akku...rion-cx-g3.htm
google translation

I have a couple of pairs of Hyperion Litestorm CX 5350mAH packs which are the older 16C versions and have used them with my MMM V2 and MMM V3. I have run them in 2x 2S and 1x 5S configuration and they run beautifully and have not damaged my ESCs, obviously. Maybe I have got my set ups right because I have no temps issues and I am happy with the available power and run times. I think I will get a pair of 3S 5350s and run 6S as soon as I get my battery budget up again.

Yet you still run SMC Puffer Packs :lol:

so here's the other question....noting that there is no real standard for testing a C rating and eagletree data sometimes shows these "lower end" packs are a hit or miss, isn't there a determining factor to be considered in MAh too?

for example: X pack is a 10,000 mah 15C pack.... and then you have a 25C 5000mah pack, dosen't the mah have a determining factor for applied power almost the same as the C rating? this, to me is a confusing formula simply because my cheap 10,000mah 15C pack out performs my "high end" 5000mah pack with very similiar cycles.

this makes me hesitate to buy the "higher end" packs that are rated 25-35C but are sometimes below the 5000mah mark. at that point aren't you just splitting hairs between the "lower end" packs and the "higher end" packs?

if someone could explain that one to me it would help clear up alot of confusion.

Of course, a 5000 20 c pack is "capable" of doing 100amps, and a 10000 10c pack is "capable" of the same thing. Now they may not be correctly rated, but lets just say that they are for the sake or an example.

Generally the lower c rated packs are old technology, and are usually heavier or bulkier than the newer generation stuff. So that 10000 pack may be physically bigger and heavier than the 5000 pack. The 5000 pack may also be capable of charging faster and also have lower IR, so it may last longer. It may also have more "punch" than the 10c pack. It all depends on brand.

You may find that you have an inflated spec 5000 pack, that is why your 10000 pack outperforms it.

So in conclusion mah is very important, a 1000mah 30c 4s lipo will not run a revo, but a 10000 mah 15c 4s lipo will. But if all the packs have the same capacity (mah) the higher c rated pack should outperform the lower ones.

The mAh of a pack is simply when they are discharged a 1C. All the C ratings do as of now, is make a certain pack look good for marketing purpose. I know various places that makes cells and they get pushed to make all the powerful cells without much test. Some if not most of the brands out there will most likely always go for the cheaper manufacturer to make more profit (Nothing wrong with that). How do they test the packs afterwards, who knows. If the people I've contacted yesterday are up for the idea I have in mind, we will find out soon enough what's real and what's bogus. It should also teach a lesson to all the over rated items in our Hobby. The only problem is, if there's still uneducated people out there always talking about the numbers, there will always be over rated products.

Example: A guy that drag races RCs went to my LHS to buy a brushless top of the line LRP esc. I was there with my ESC and offered to let him use it. He asked what's it rated for and I told him 200A burst continuous. He said the LRP was 400A per phase and I told him the rating they use is just to make it look good and I told him that no RC battery will be able to deliver such AMPs. Well he spent $200+ on the LRP and I guess it didn't work as he came back a few days later trying to return the ESC. So I offered him my ESC again and this time he said he was making his own, but I never seen it. I should've told him the specs on my ESC using the pulse AMP rating was 250A X 3 = 750A. I guess some people just don't have common sense and lack of knowledge nowadays.

thanks for the explanation, much appreciated. :yes:

Ok, read the rest of this thread.

I have a unique perspective of the various lipo brands. I have taken apart and rebuilt almost all of the brands that are sold. I can say that the lower priced lipos from HC are not assembled very well, and this causes a fair amount of their issues.

Same thing with maxamps, and most of the losi hardcase lipos. The best that I have seen are the enerland cells that all of the high end packs used to use. The tabs were twice as wide and at least 3 times thicker. Much better made tabs than anything else save for the elite cells from cheapbatterypacks.

Also, did not was to seem down on the traxxas noobs, but alot of them seem to like maxamps marketing so they are not very well versed on the lipo stuff. But everyone has to learn somehow... And experience is the best teacher.

I will not buy turnigy/zippy packs myself. I can usually find lightly used high end packs from the plane guys for similar prices so I go with that. Maybe for a boat or something that could get destroyed?

The guy didn't realize that the 400A rating was effectively bogus, and now he is going to make his own ESC?!?! Talk about trying to fly when you don't even know how to crawl! :oh:

this is exactly what i mean. it's been supposed more than once that some of the "high end" manufacturers and some of the "low end" manufacturers are all getting their packs from some of the same places and it's getting very difficult to determine what's inflated and what's real.

some day, there is gonna need to be a standard of testing these numbers.
example:. my lhs has stopped carrying one of the top battery companies because he said they switched manufacturers to save money and they have been getting a ton of warranty claims. he went on to say they used to be a very trusted company and now he wouldn't put one in his heli if it was the last battery on earth. so who do you trust?

I know, but it's his money lol. I told him to even get the MM as it was in stock and proven in many record set ups. It's been a couple of years now so my best guess is that he didn't want to look like a moron.

I tend to look at what works and what doesn't work. To me the best lipos so far are from Kokam and Enerland. I haven't bought any of the new lipos jut because I have no clue who's making them and how well the technology is. I have gotten accurate answers from a few brands that have told me the 25C technology is mature and the other rating are not mature yet. One manufacturer wanted to send me a few samples, but I declined as I don't like to take chances.