SMC 28C 4000/5000 Hardcase Lipo part 2
03-04-2008, 03:38 PM
#346
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Hey Danny/SMC, any plans on making a Lipo cell for 1/12th scale??
03-04-2008, 03:50 PM
#347
I'm not really sure that a 3.7v pack would be good for 12th scale. Maybe we should go with a 7.4v Lipo and use this with a high turn BL motor. The weight of a 7.4v Lipo is close to a 4 cell pack so there would be no need to add weight.
03-07-2008, 09:01 PM
#351
I have been doing some more testing and one of the tests I have decided to do was to cycle a pack through the connectors and then cut the wires as they are fairly long on our pack and get the readings from the wires which would be the same as hard wiring a NiMh pack.
Connectors: 527 - 7.40 - 6.1
Wires: 528 - 7.44 - 4.9
Connectors: 527 - 7.40 - 6.1
Wires: 528 - 7.44 - 4.9
03-07-2008, 09:20 PM
#352
I have been doing some more testing and one of the tests I have decided to do was to cycle a pack through the connectors and then cut the wires as they are fairly long on our pack and get the readings from the wires which would be the same as hard wiring a NiMh pack.
Connectors: 527 - 7.40 - 6.1
Wires: 528 - 7.44 - 4.9
Connectors: 527 - 7.40 - 6.1
Wires: 528 - 7.44 - 4.9
03-07-2008, 09:45 PM
#353
Danny, if you're looking for low-resistance connectors consider these ones:
http://www.rctoys.com/rc-toys-and-pa...RS-WIRING.html
To my knowledge, they are the lowest resistance connector in the R/C market.
http://www.rctoys.com/rc-toys-and-pa...RS-WIRING.html
To my knowledge, they are the lowest resistance connector in the R/C market.
03-08-2008, 08:30 AM
#354
I'm running out of tests to do so I may have to get out of my room. LOL
Next test is comparing a heated pack versus a regular cycle pack. When I originally tested this it was on my original offroad 22C packs that had fallen off in capacity , voltage and IR. The difference was very big on this pack and I know that it won't be as much on a new pack that is in good shape so I want to know the difference.
Should have the results tonight.
Next test is comparing a heated pack versus a regular cycle pack. When I originally tested this it was on my original offroad 22C packs that had fallen off in capacity , voltage and IR. The difference was very big on this pack and I know that it won't be as much on a new pack that is in good shape so I want to know the difference.
Should have the results tonight.
03-08-2008, 07:22 PM
#355
Here are the results of warming up a pack to 140 degrees prior to discharging it.
The pack used is the one I tested with no connectors and cycled out 528 - 7.44 - 4.9 at 70 degrees.
I put it in the oven for an hour and when I took it out the case was in the 140 range but was cooling done relatively fast. Not sure of the actual cell temp.
The pack cycles out at 527 - 7.53 - 3.4
What I find interesting is that when I do this to one of my older 22C packs that has fallen off some it has a much better improvement when heating it up. So heating up a Lipo seems to give better results but the results will be even better on an older pack that has some degradation.
My next test which will take a long time to do is figuring out the effects of storage charge in Lipos. In some of my testing I believe that leaving storage charge in a pack will create a drop in runtime with an increase in IR and drop in voltage. It will take some time to figure out how long we can keep a Lipo discharged with no storage charge and how low it can go before it gets damaged. In one of my original tests I have left a pack for 4 months with no storage charge and it was fine when I cycled it.
The pack used is the one I tested with no connectors and cycled out 528 - 7.44 - 4.9 at 70 degrees.
I put it in the oven for an hour and when I took it out the case was in the 140 range but was cooling done relatively fast. Not sure of the actual cell temp.
The pack cycles out at 527 - 7.53 - 3.4
What I find interesting is that when I do this to one of my older 22C packs that has fallen off some it has a much better improvement when heating it up. So heating up a Lipo seems to give better results but the results will be even better on an older pack that has some degradation.
My next test which will take a long time to do is figuring out the effects of storage charge in Lipos. In some of my testing I believe that leaving storage charge in a pack will create a drop in runtime with an increase in IR and drop in voltage. It will take some time to figure out how long we can keep a Lipo discharged with no storage charge and how low it can go before it gets damaged. In one of my original tests I have left a pack for 4 months with no storage charge and it was fine when I cycled it.
03-08-2008, 08:14 PM
#356
I was looking at the dimensions on the 4000 and was excited about getting that into a T2 07 until I got a look at the wiring exit. The exact reason I went away from core and to a Trackpower...very impractical wiring exit from pack. Leaving the balance plug dangling and dealing with interference with the "out the side wires" I just dont get. I really hope the reason isn't "terminal corrosion and resistance"....thats proven a non-issue over and over IMO.
People are cutting and grinding Core packs to move wires for this exact reason. Why go that route instead of the clean, more trouble free route of out the top...even the end would be better in most cases.
Here is another good one. I have a Trackpower 4900 and an Orion 3600 race spec. They cant even standardize the side the positive comes out!
Add that to the 4mm bullet connector that goes either way and POOF...you got smoked cuz someone is used to going the other way with red wire. This type of blind manufacturing practice is sad to see...oh...BTW...I'm a tool design / manufacturing engineer by trade...so excuse the anal tirade if you could care less.
People are cutting and grinding Core packs to move wires for this exact reason. Why go that route instead of the clean, more trouble free route of out the top...even the end would be better in most cases.
Here is another good one. I have a Trackpower 4900 and an Orion 3600 race spec. They cant even standardize the side the positive comes out!
Add that to the 4mm bullet connector that goes either way and POOF...you got smoked cuz someone is used to going the other way with red wire. This type of blind manufacturing practice is sad to see...oh...BTW...I'm a tool design / manufacturing engineer by trade...so excuse the anal tirade if you could care less.
Last edited by Verndog; 03-08-2008 at 08:27 PM.
03-10-2008, 09:46 AM
#357
Due to our cells being 28C the size of the tabs where the wires must be soldered are fairly big there was no way to get them to come out on top. As far as using tubes that reguires a cicuit board that will increase the IR and since our packs are high performance packs using a circuit board makes no sense.
03-10-2008, 10:41 AM
#358
Danny
Any chance of cycling out a standard over the counter energ matched pack on your gfx so the numbers can be compared to the results of the lipo pack.
Just curious on difference in performance kinda of apples to apples test. Lipo guys tend to be slower at my local track but I am not really sure if it is a result of the pack or drivers
Cheers
Jamie
Any chance of cycling out a standard over the counter energ matched pack on your gfx so the numbers can be compared to the results of the lipo pack.
Just curious on difference in performance kinda of apples to apples test. Lipo guys tend to be slower at my local track but I am not really sure if it is a result of the pack or drivers
Cheers
Jamie
03-10-2008, 11:24 AM
#359
EnerG 4600 at 6 volt cutoff 448 - 7.39 - 10.7
I have had some tell me that our new Lipos are faster than there EnerG packs and others who have told me they are slower. I think it will take some more testing to truly figure it out.
The Lipos do seem to have real good voltage at the higher amp loads but at a lower load like 20 amps which is probably what a stock motor pulls on the straight the Lipo will have lower voltage than NiMh. I think that motor setup and gearing may need to be different with Lipos.
I have had some tell me that our new Lipos are faster than there EnerG packs and others who have told me they are slower. I think it will take some more testing to truly figure it out.
The Lipos do seem to have real good voltage at the higher amp loads but at a lower load like 20 amps which is probably what a stock motor pulls on the straight the Lipo will have lower voltage than NiMh. I think that motor setup and gearing may need to be different with Lipos.
03-11-2008, 04:59 PM
#360
Danny et al.
Just to let those interested know, I bought a 28c 4000 and 28c 5000 and have managed to fit both into the Losi JRXS R. It is a very tight fit for both and the 5000 will only fit when placed sticker side down. The slight taper on the one side of the pack is enough to clear the topshaft. So far I've been happy with the performance but I do wish the wiring solution was different. As it is my wires come out on the left front of the car through the drive belt. Just makes me a little nervous but so far so good.
Just to let those interested know, I bought a 28c 4000 and 28c 5000 and have managed to fit both into the Losi JRXS R. It is a very tight fit for both and the 5000 will only fit when placed sticker side down. The slight taper on the one side of the pack is enough to clear the topshaft. So far I've been happy with the performance but I do wish the wiring solution was different. As it is my wires come out on the left front of the car through the drive belt. Just makes me a little nervous but so far so good.