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SMC 28C 4000/5000 Hardcase Lipo part 2

SMC 28C 4000/5000 Hardcase Lipo part 2

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Old 04-22-2008, 01:05 PM
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Yes we will have a 28C saddle pack. Should have the samples in a few weeks. At first we were going to go with the same size as Trakpower but from what I heard it's to tall for some of the cars. So we changed the size which is creating a small delay.
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Old 04-22-2008, 01:12 PM
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Sweet!

What is the best way to warm a Lipo pack? High amp discharge? Heating pad? What are your recommendations Danny?
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Old 04-22-2008, 01:30 PM
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Someone told me they use a heating pad that has a digital temperature adjustment and he wraps up the pack and sets it at 120 degrees Farenheit which gives him great results.

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Old 04-22-2008, 01:33 PM
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Cool.Thanks...BTW nice work on the Lipos and cant wait for the saddles.
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Old 04-22-2008, 02:31 PM
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Originally Posted by Danny/SMC View Post
At first we were going to go with the same size as Trakpower but from what I heard it's to tall for some of the cars. So we changed the size which is creating a small delay.
YEAH SMC!!!
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Old 04-22-2008, 02:46 PM
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Are there small enough heating pads that will fit into a lipo sack? Or do you preheat the lipo and then charge it using the lipo sack?
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Old 04-22-2008, 03:08 PM
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I think you can get a heating pad that once it's wrapped up it will fit into a Lipo sack.

You can also charge your pack in a Lipo sack then once it's charged wrap it with the heating pad.

To heat prior to charging will not be as good as heating after charging as the pack will cool down while charging.
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Old 04-22-2008, 03:42 PM
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Hey Danny--can you share what the dimensions of the saddle pack WILL be?
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Old 04-22-2008, 03:58 PM
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I should have the dimensions of the saddle pack in a few days.

Now that I can graph with my GFX I decided to graph a 5000 with the voltage sensing leads attached to the connector on the charger side and to graph one without the connector and the wires cut.

With connector: 530 seconds - 7.39 avg. voltage and 6.2 IR

No connector: 531 - 7.45 - 4.9
Attached Thumbnails SMC 28C 4000/5000 Hardcase Lipo part 2-500028cnoconnector.jpg  
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Old 04-22-2008, 07:10 PM
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I got 3 new SMC 4000 hard case packs today. I checked the cell voltages before doing anything. All were unbalanced:

Pack#1
Cell#1: 3.20V
Cell#2: 3.35V

Pack#2
Cell#1: 3.36V
Cell#2: 3.24V

Pack#3
Cell#1: 3.31V
Cell#2: 3.41V

Is this typical, or should I be concerned?
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Old 04-22-2008, 07:29 PM
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That's why I use my balancer.
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Old 04-22-2008, 08:21 PM
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Those storage voltages are much lower than other lipo manufacturers use.
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Old 04-22-2008, 10:47 PM
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Originally Posted by ta_man View Post
I got 3 new SMC 4000 hard case packs today. I checked the cell voltages before doing anything. All were unbalanced:

Pack#1
Cell#1: 3.20V
Cell#2: 3.35V

Pack#2
Cell#1: 3.36V
Cell#2: 3.24V

Pack#3
Cell#1: 3.31V
Cell#2: 3.41V

Is this typical, or should I be concerned?

The reason why your getting different voltages is because our first batch of Lipos were sent out with no storage charge as the demand was so big that we knew they would be sold real fast. Our second shipment will be sent with 25% storage charge.

I have left packs for 4 months with no storage charge and I have yet to see an issue. I reccomend keeping a bot of storage charge but to much will make the packs capacity drop and the IR and voltage will deteriorate some. Once again this is based on racers wanting to keep there packs at the top. If your just an RC enthusiast who isn't concerned about 2 milliohms and .08 in voltage then you can keep your packs stored with 50%.

If you own a balancer and it has discharge mode like mine just balance the packs prior to the first charge.
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Old 04-23-2008, 05:02 AM
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Originally Posted by Danny/SMC View Post
The reason why your getting different voltages is because our first batch of Lipos were sent out with no storage charge as the demand was so big that we knew they would be sold real fast. Our second shipment will be sent with 25% storage charge.

I have left packs for 4 months with no storage charge and I have yet to see an issue. I reccomend keeping a bot of storage charge but to much will make the packs capacity drop and the IR and voltage will deteriorate some. Once again this is based on racers wanting to keep there packs at the top. If your just an RC enthusiast who isn't concerned about 2 milliohms and .08 in voltage then you can keep your packs stored with 50%.

If you own a balancer and it has discharge mode like mine just balance the packs prior to the first charge.
What is the minimum storage charge you recommend that will not compromise IR and voltage? None? (If "None" what does that mean in terms of discharging before storage? 6V cutoff at 35A?)
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Old 04-23-2008, 10:37 AM
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Originally Posted by ta_man View Post
What is the minimum storage charge you recommend that will not compromise IR and voltage? None? (If "None" what does that mean in terms of discharging before storage? 6V cutoff at 35A?)

On some of the previous Lipos I had tested discharging them down to 6 volts at 35 amps and leaving them like that was fine for long periods of time. Since the IR is real low on our new 28C packs I would store them with some charge to be safe. I would not exceed 50% but if you race frequently 10% will be fine. For longer periods of time like 1 to 2 month I would put 25%. If you store them in a cool enviroment they will selfdischarge even slower.

Once again all of this is based with racing in mind where you want the voltage and IR to stay as good as possible.
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