SMC 28C 4000/5000 Hardcase Lipo part 2
11-22-2008, 09:06 PM
#1366
Danny - I just got two top wire exit Traxxas Connector 5000 SMCs and noticed the number on the back are much lower than the side wire exit ones.
My side wire exit one has
7.47 ave. voltage
4.0 int. resistance
~5200 mah
My new TRA conn. top wire exit ones both have
7.37 ave. voltage
7.0 int. resistance
~5000 mah
The numbers were low like this when you guys didn't measure directly from the power leads, and then when you did, they were much higher. Did you guys go back to not measuring it directly from the power leads? Or is it just like that because they have Traxxas connectors?
My side wire exit one has
7.47 ave. voltage
4.0 int. resistance
~5200 mah
My new TRA conn. top wire exit ones both have
7.37 ave. voltage
7.0 int. resistance
~5000 mah
The numbers were low like this when you guys didn't measure directly from the power leads, and then when you did, they were much higher. Did you guys go back to not measuring it directly from the power leads? Or is it just like that because they have Traxxas connectors?
As with any batteries there can be fluctuations in batches. We did get one freak batch that had very low IR and higher average voltage but we were also seeing more cells with internal shorting. In our pack cycling method we discovered that going through the Deans connectors was creating erratic readings so we decided to change the way we measure the packs. Since the packs come with shrink on the 12 gauge wires where they are soldered to the connector we need to find a way to measure the voltage wihtout removing the shrink. So we decided to tap into the balance connector. We did this on 200 packs that came in and the IR and voltage looked really good which made me wonder why. So I took a packs and cycled it a few times then removed the shrink on the 12 gauge wire and cycled it a few more times. The results was 1 milliohm higher in IR and .03 lower in voltage. So since that batch of 200 packs we now adjust the numbers to compensate for the difference.
Your side exit pack was surely from that batch of 200 so you lucked in and got a low IR pack with high average voltage. We have asked our supplier why that batch was like that and he can't figure it out as he tells us he uses the same materials and same way of building the cells. I know they have to buy materials and maybe it can fluctuate from batch to batch. Hope all of this makes sense.
11-23-2008, 06:17 PM
#1371
Glad to hear you new pack ran well. I think that testing packs at a constant load only tells part of the story. I have seen to many cases where certain packs/cells should of been better based on the numbers but on the track they weren't.
11-23-2008, 06:26 PM
#1372
Im glad 2 c bumps on the bottom.....
And the only reason they are faster is because the higher capacity keeps the voltage up longer .
At the start , theres no difference, Id like to c what a platinum(yeah i know , no bumps )lol would compare to the lightning volts pack.. apples to apples sort of test . and as for the cells fitting its funny .. the guys here all tried to put them in their losi cars and guess what .. it wouldnt fit without modifiying the pack and the car. Im not wrong... and they also use the 3800. That doesnt mean its better .. ok, so what .. And I have beaten cars equiped with those smc packs as well.. i had 2 of dannys packs and they are fast. But what can i say when no one is listening.
And the only reason they are faster is because the higher capacity keeps the voltage up longer .
At the start , theres no difference, Id like to c what a platinum(yeah i know , no bumps )lol would compare to the lightning volts pack.. apples to apples sort of test . and as for the cells fitting its funny .. the guys here all tried to put them in their losi cars and guess what .. it wouldnt fit without modifiying the pack and the car. Im not wrong... and they also use the 3800. That doesnt mean its better .. ok, so what .. And I have beaten cars equiped with those smc packs as well.. i had 2 of dannys packs and they are fast. But what can i say when no one is listening.
11-23-2008, 06:42 PM
#1374
Furthermore you are testing cells beyond what industry recomends .
Over discharging Li-Po's beyond 80% of capacity is not good.
That chart really makes no sence .. where does the actual # of "c" get represented on that chart? Plus I need to reiterate the fact that the deans connector adds 2 solder joints to the car ... or have we forgotten why all the pros direct soldered their wires to the cells on Ni-Mh's? Test them at the deans (yes , very good connectors) but remember the car has conectivity issues as well.
Over discharging Li-Po's beyond 80% of capacity is not good.
That chart really makes no sence .. where does the actual # of "c" get represented on that chart? Plus I need to reiterate the fact that the deans connector adds 2 solder joints to the car ... or have we forgotten why all the pros direct soldered their wires to the cells on Ni-Mh's? Test them at the deans (yes , very good connectors) but remember the car has conectivity issues as well.
11-23-2008, 06:50 PM
#1375
Yup, I noticed that the wires will exit right where my speedo is too. Which means more wire to connect them to it. Gotta make a loop now. Also please consider its for a 1/12th can and we perfer to use smaller wires. Not much bigger than 14ga. more like 16 for stock. But who knows , we might have to use a hotter wind . Seems to me all the cars are still too fast and ppl are havine issues finishing races. And actually Danny .. These look nicer with the red c/f pattern on them! 
11-23-2008, 06:56 PM
#1376
I'm not sure what your trying to accomplish by coming on this thread but if you don't like our packs because there not nice enough for you or you don't believe they are better than whatever you run that is fine with me but there is no need to try and start s$$t on this thread.
On another note you only use 20% of your Lipos capacity when you race ? Your races must be short or you have 10 000 mAh pack. There is nothing wrong with discharging Lipos down to 6 volts.
The graph shows how the cells we use retain capacity at different C rate. I reccomend you contact a Lipo manufaturer and ask them how they determine C rate. You will see that the graph is showing what the C rate of our cells are.
On another note you only use 20% of your Lipos capacity when you race ? Your races must be short or you have 10 000 mAh pack. There is nothing wrong with discharging Lipos down to 6 volts.
The graph shows how the cells we use retain capacity at different C rate. I reccomend you contact a Lipo manufaturer and ask them how they determine C rate. You will see that the graph is showing what the C rate of our cells are.
11-23-2008, 06:59 PM
#1377
Yup, I noticed that the wires will exit right where my speedo is too. Which means more wire to connect them to it. Gotta make a loop now. Also please consider its for a 1/12th can and we perfer to use smaller wires. Not much bigger than 14ga. more like 16 for stock. But who knows , we might have to use a hotter wind . Seems to me all the cars are still too fast and ppl are havine issues finishing races. And actually Danny .. These look nicer with the red c/f pattern on them!
Your talking about the 12th scale pack on the 7.4 pack thread. The wire on the 12th scale pack is 14 gauge so I hope that works for you.
Our packs come wired with connectors as this allows the racer the option to use connectors or hard wire. With all the inboard packs that use soldered tubes on a circuit board and the board soldered to the cells you have no options to hard wire.
11-23-2008, 07:26 PM
#1378
These forums are here for expression of interests in whatever. If im not allowed to say what I wish to then pardon me if I'm not in line to s**k Danny off. If you look.. I have said time and time again that they are fast. No arguement there. But for some reason NO ONE SEEMS TO BE ABLE TO UNDERSTAND A F#@%*&G WORD IM SAYING! Sheesh ... Objective perspective ok.... <<<IDK---FTG>>>
After all I've said and done....
Blow up the outside,
Blow up the outside,,
Blow up the outside,,,
World
WTF?
Apparently you dont understand the 80% rule.. Ask an R/C pilot.
After all I've said and done....
Blow up the outside,
Blow up the outside,,
Blow up the outside,,,
World
WTF?Apparently you dont understand the 80% rule.. Ask an R/C pilot.
11-23-2008, 07:32 PM
#1379
5.0 * 28 = 140A continuous
5.2 * 24 = 124.8A continuous
The 5000 28C pack will provide you more punch, better performance across the run and not heat up as much.
17.5 and 13.5 you're looking at least 15-18mins runtime when geared hard.
4.0 you wont have capacity issues with either (I use 3.5T and it pulls 3900mAh in 5mins when geared hard on a large outdoor track). I think you'll make at least 7 mins runtime with the 4.0 (depending on which one you're referring to), but you'll find that the 5200 pack will heat up more than the 5000 pack as its not going to handle the constant high current requirements of low wind modified motors as much as the 5000 can (due to its higher continuous current rating).
-Mark
5.2 * 24 = 124.8A continuous
The 5000 28C pack will provide you more punch, better performance across the run and not heat up as much.
17.5 and 13.5 you're looking at least 15-18mins runtime when geared hard.
4.0 you wont have capacity issues with either (I use 3.5T and it pulls 3900mAh in 5mins when geared hard on a large outdoor track). I think you'll make at least 7 mins runtime with the 4.0 (depending on which one you're referring to), but you'll find that the 5200 pack will heat up more than the 5000 pack as its not going to handle the constant high current requirements of low wind modified motors as much as the 5000 can (due to its higher continuous current rating).
-Mark
