Ways to protect MMM when used with subpar batts

[fastbaja5b]

Originally Posted by Freezebyte

Other peeps prefer not taking expensive chances.

Yet you still run SMC Puffer Packs

[DwightSchrute]

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.

[lincpimp]

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.

[lutach]

Originally Posted by DwightSchrute

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.

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.

[DwightSchrute]

Originally Posted by lincpimp

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.

thanks for the explanation, much appreciated.

[lincpimp]

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?

[BrianG]

Originally Posted by lutach

...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.

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!

[DwightSchrute]

Originally Posted by lutach

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.

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?

[lutach]

Originally Posted by BrianG

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!

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.

[lutach]

Originally Posted by DwightSchrute

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 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.

The original poster of this thread asked about ways to protect MMM when used with sub-par batteries.

Obviously, using good batteries is better, but it doesn't answer his question.

I was thinking something along the way of using extra capacitors and/or TVSes.
Would that help to protect a MMM?

Avner.

[BrianG]

The long and short of it:

Extra caps will help reduce the ripple current. However, more capacitance creates a bigger hookup spark, which eats away at the connectors each time it arcs.

Extra TVS devices are to clamp the braking voltages to a safe value.

So, both of these will help when using subpar batteries. But IMO, it's better to use those cells in a smaller/lighter/less demanding setup instead.

[himalaya]

Originally Posted by lincpimp

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?

As you said experience is the best teacher, maybe you can give yourself a chance to TRY one of the new turnigy packs and let what you find tell you what you are refusing to know for now.

Personally I am very grateful I came to this forum and got to know the zippy/turnigy stuff which saved my HUGE money and get much better result than my 3 enerland based packs. Enerland is known having big problem in cycle life and IR buildup under storage condition. They are great when fresh from factory but dont't survive long even not in use. I am clearly not a lucky man, bought 3 big enerland packs, one 25C 6S 4350mAh and two 6S 35C 4500mAh. They do have excellent build quality and is very pleasant to look but that just can't stop the internal chemistry from going bad. They are still in perfect balance, with 20 miliOhms IR for each cell. Now the only use of those packs is a field charger power supply for my Hyp0720. I returned the 25C to AirCraft Japan for a replacement of a new Hyperion G3 VX6S-4200. and wow, this china made blue block is a power monster! with 1/10 of the IR compared to enerland cells. Doing more dig you can find why all big name lipo vendors leave enerland for Chinese cells.

[BrianG]

With Turnigy, I don't think the cell quality is in question, it's more about build quality and cell matching. I've posted this earlier in this thread, but out of 5 Turnigy packs I've had, one went back to the LHS because one cell simply wouldn't hold a charge. And on another pack, a different cell needed to be individually charged in order to bring it up to the same level as the other cells (balancing would have taken forever). Since then, that pack has held up fine, so barring that one pack, I have a 20% failure rate. Personally, given the price, it's worth it. Some people may not want to deal with that kind of thing though. I think they would have a better rep if they weeded out the bad cells better.

I will say that so far, the build quality is ok; my only gripe would probably be the weak heatshrink they use.

[hoovdog]

Originally Posted by BrianG

I will say that so far, the build quality is ok; my only gripe would probably be the weak heatshrink they use.

110% agree here. All our Turnigy packs have been good minus the heatshrink coming apart too quickly. 6 packs with 0 functional issues thus far. If I needed a complaint I could comment on soldering the "jumper cable" wire. :)