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I'm not familiar with how CE recommends to hook up the balancer.

Where do you put the voltage sensing leads ?

You may want to look into a Common Sense RC balancer. You just plug it into the balance connector of your pack. You would need to put the voltage sensing leads on the power connector.
I've got it wired the way it is shown on the lipo users manual addendum. The way it is shown in the second picture here:

https://www.competitionelectronics.com/media/pdf/LiPoGFX_Addendum12_08.pdf
 

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Discussion Starter · #62 ·
There is 2 things you can do. One is to buy a Common Sense balancer and charge your pack without the balancer and at the end of the charge you put the balancer on the pack and balance it out. Once it's balanced it will stay balanced for many cycles. Just repeat this step once in awhile to keep in balance. This will require that your voltage sensing lead be attached to the balance connector to get the proper voltage sensing.

The other way is to attach the Common Sense balancer to the pack while it's charging through the balance connector. This method will require you put your voltage sensing leads on the power connector. You can put them on the side of the male Deans connector. Due to this you may want to pick the first solution as this will be the easiest way.
 

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I've got it wired the way it is shown on the lipo users manual addendum. The way it is shown in the second picture here:

https://www.competitionelectronics.com/media/pdf/LiPoGFX_Addendum12_08.pdf

In that second picture, it looks like you are taking the 12 ga. power wires and running them into the balancer, and then the balancer output is connected to the pack power leads with those little like 20 ga. ? wires ???

I'm not sure I'd want to put 10 amps through those ??
 

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I'm not familiar with how CE recommends to hook up the balancer.

Where do you put the voltage sensing leads ?

You may want to look into a Common Sense RC balancer. You just plug it into the balance connector of your pack. You would need to put the voltage sensing leads on the power connector.
Could you post a picture of the wiring if using a Common Sense balancer in-line with a GFX ?

Thx
 

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Discussion Starter · #65 ·
I don't have pictures as I don't use this balancer but I have seen guys who use it.

You don't plug it in-line with the GFX. Just plug it into the balance connector of the pack and plug the GFX like there was no balancer. You will need to have the GFX sense leads attached to the power wires or build some sort of adapter to tap into the balance connector once the pack is plugged into the balancer.

I think just using the balancer at the end of a charge once in awhile will keep the pack in balance as packs will not get out of balance that easily.
 

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In that second picture, it looks like you are taking the 12 ga. power wires and running them into the balancer, and then the balancer output is connected to the pack power leads with those little like 20 ga. ? wires ???

I'm not sure I'd want to put 10 amps through those ??
LOL! No, the balancer will only handle 7.5 amps. We charge them at 6 amps.
 

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There is 2 things you can do. One is to buy a Common Sense balancer and charge your pack without the balancer and at the end of the charge you put the balancer on the pack and balance it out. Once it's balanced it will stay balanced for many cycles. Just repeat this step once in awhile to keep in balance. This will require that your voltage sensing lead be attached to the balance connector to get the proper voltage sensing.

The other way is to attach the Common Sense balancer to the pack while it's charging through the balance connector. This method will require you put your voltage sensing leads on the power connector. You can put them on the side of the male Deans connector. Due to this you may want to pick the first solution as this will be the easiest way.
Thanks for the help!
 

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Discussion Starter · #69 ·
I finally released info on our new line of packs using our own C rate standard.

http://www.hobbytalk.com/bbs1/showthread.php?p=4146193#post4146193

I really hope this new line of packs will help show how C rates are just used for marketing. I have a 65C and 90C pack coming in tomorrow from our competitors and I will compare them to our new Premium Certified 25C pack.
 

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Discussion Starter · #70 · (Edited)
4mm connector test

I was finally able to test our low resistance 4mm connectors versus the typical split/swivel type connector that comes with most cheap inboard style packs. I knew the split/swivel type had more resistance as I had done a test in the past but using the ESR meter I can easily show the difference in resistance.

I took a 5400 pack with storage charge and used the good 4mm connectors we sell and tested the first cell. I took the same pack using the high resistance split/swivel type and tested the first cell.

SMC connector: 2.80mOhms

Split/Swivel connector: 3.80mOhms.


A 1.0mOhm difference is a significant difference as this means the voltage will drop 0.05 volts under a 35 amp discharge. The higher the amp rate the more drop there will be. On a 5400 pack 1mOhm is equal to 4C so basically a 24C pack using higher resistance connectors will run like a 20C using good connectors.
 

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Discussion Starter · #73 ·
I will have some cycle life data on some of our competitors 90C and 65C pack by the middle of this week. Cycle life testing takes a long time as I put 50 cycles the pack. I'm also testing cells/packs from other factories so my equipment is pretty much being used all day long.

I think the results I will show will be very interesting and prove once and for all that not all Lipos are the same.
 

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Discussion Starter · #76 ·
SMC Hardcase Race Pack Comparison

When talking with some customers/racers I realized that many don't understand that a higher mAh pack will have a better voltage curve due to the extended mAh. This will only be true if the cells are made to have the lowest possible IR. If the pack is made with lower C rate/higher IR cells then it will not have a better curve than a lower mAh pack with lower IR.

You can look at the graph and see how mAh impacts the voltage curve. All packs are tested on the same GFX at 35 amp discharge.

Hope this helps everyone better understand the difference between the different SMC models.
 

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Danny-SMC, I want to take a moment and thank you for all of the battery information you have put forth, you do a great job explaining C-ratings and such so as a person with "0" knowledge of LIPO batteries can make an informed decision, i have purchased numerous 2 and 1 cell LIPO's over the past 2 years from several different companies (including yours) and have found that some of the most expensive purchases have been the most disappointing. I treat every battery exactly the same as far as charging/discharging and storage methods and yet my most expensive 2 cell packs (4 each) have puffed to the point that I must dispose of them, prior to the puffing I could see that they were degrading much faster than the lower priced units, very disappointing because they cost me 120 dollars a piece, yet several of the midpriced and low end 2 cell LIPO's continue to perform flawlessly with no signs of degrading. You have opened my eyes and I look forward to dealing with SMC for my future battery needs. Rich
 

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Discussion Starter · #78 ·
Glad that you like the info I'm providing as I really want to help everyone better understand Lipos. The way I see it there is three important factors when trying to rate or chose a LiPo. One is performance. If you race or want your RC ride to go as fast as possible you want to buy a pack that has low IR so you will get more speed out of the pack. The second is cycle life. You want a pack that will not lose it's capacity or increase it's IR to fast. The third is pricing. Buy packs that have the best price with good performance and good cycle life.

One thing everyone should understand is high performance can come at the expense of cycle life. As with anything that pushes the limits to extract the most out of it this can create potential issues. A few factories are using a certain material that lowers the IR and costs less so there cells have an increase in performance but that increase comes at the expense of the mAh dropping off very fast. You can see the 6500/90C pack I tested as it uses this material. There is a fine line between performance and reliability.
 

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Discussion Starter · #79 ·
Interesting C rate info.

As most of you know I've been doing allot of tests on various Lipo packs and I recently got an email from a Lipo factory that I thought was very interesting in regards to C rate and the various claims.

Here is a copy of the email.

Hello Danny,

In the Lipo battery industry, there's no real 70C~90C .... you know well that those are marketing stuff.
The fact is that, the positive/negative tags of Lipo cell would be burnt off at high current.
The chemistry & cell packaging materials only support a real 40C~45C indeed.

With the above background, please find our internal guidelines on C-rating as follow :
1) for 30C or below, the cell models would be subject to continuous discharge at specified C-rate, where we expect MPV 3.40~3.45V.
2) for 40C and above, you know well that the cells would have gas formation upon 100~120Amp continuous discharge.
3) those Hi-Power cells would be tested for Pulse-discharge at specified C-rate -
40C models Pulse 40C x 30sec
50C models Pulse 50C x 10~15 sec
4) along with that, the Hi-Power cells would go for 20C/30C continuous-discharge, and compare their MPV.




This is some very interesting info. Not sure I agree on the method they use to claim 40C or 50C but the fact they tell me the truth about C rates and testing is very good. I truly believe that the best method to rate a Lipo would be to use IR but then again that can easily be manipulated and the factories and resellers would quickly start claiming lower IR. That being said it could easily be tested with the ESR meter unlike C rate which is very hard to test.


 

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So Danny, they are admitting that their C-rating claims are false and that it is in-fact not a constant C-rate (as most advertise), but a "burst" rating being shown on their packs?

I wonder if they'd be so willing to give this information to their consumers? :confused:
 
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