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Old 08-28-2006, 08:49 AM   #166
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Quote:
Originally Posted by syndr0me
Are there charts somewhere that show the voltage discharge curve of the Orion LiPo packs vs a quality NiMh pack? Perhaps something similar to the charts at the bottom of this page.

It's good to hear you guys are still aiming for mid-Sept. That's rapidly approaching. :-)
This is all we have.
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Old 08-28-2006, 08:52 AM   #167
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Originally Posted by Lonestar
What exactly am I missing?
If you're not careful, they're dangerous... But same with NiMH. You can wire cells together in parallel to increase the run time too, but so can nimh but it will just add a ton of weight.
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Old 08-28-2006, 09:07 AM   #168
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Originally Posted by Lonestar
Hi all, Rick,

so in a nutshell: LiPo's are better, lighter, less maintenance, more convenient, etc etc etc... which is all good - but where's the catch? I mean, my mom always told me, if it looks too good to be true then it probably is... not trying to be a smarta$$ here, just to understand whether I should ditch my NiMH and charger and invest into a complete new technology, or sit wait and relax for another little while and watch others be guinneapigs for this technology. For the moment it kinda looks like the brushless technology, fantastic on paper but still not really picking up after a couple of years of market availability...

What exactly am I missing?

Thanks!
Paul
The fact the technology is so good does lead many to question it. There is a trade-off with brushless motors. What you gain in efficiency and overall power but you lose with a less drivable powerband and different braking characteristics.

There are no trade-offs with the LiPo techology itself. It is simply better. However there are some issues that exist, but are easily overcome.

The first is the basic dimensional requirements of LiPo. Since there are rectangular, they may not fit in some cars. The second is the fact they are lighter. This is good in many ways, but in some cars the chassis may require adjustments.

In off-road car, you may have less weight on the rear wheels which can cause a loose condition. By adding weight, the car will be the same as with NiMH. Cars can also be tuned to work with less weight, but when a driver uses both types of batteries, it is easier to add weight when using LiPo and remove it when using NiMH.

In a touring car with weight on one side (Losi is the exception because the battery is in the middle), the balance change. We weighed the electronics of my car versus a NiMH and the NiMH was abour 3oz heavier. This means the car is heavy on the battery side. But with the LiPo, the battery side is 3oz lighter. The balance is no different. All that changes is which side carries the extra 3 oz.

However to make minimum weight in sanctioned races, you need to be sure to add the weight to the appropriate side depending on the battery type.
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Old 08-28-2006, 09:09 AM   #169
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Quote:
Originally Posted by MK_Arbiter
If you're not careful, they're dangerous... But same with NiMH. You can wire cells together in parallel to increase the run time too, but so can nimh but it will just add a ton of weight.
There is a danger factor. They are not a danger when used properly. When misused, they can be more dangerous than NiMh.

But we have seen many instances of NiMh cells exploding, so I am not sure if one is really more dangerous than the other.
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Old 08-28-2006, 10:02 AM   #170
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Quote:
Originally Posted by syndr0me
Are there charts somewhere that show the voltage discharge curve of the Orion LiPo packs vs a quality NiMh pack?
Here's one: 20 amp discharge on a IB3800 pack with less than 10 runs on it. This pack was taken down to 0.9 V per cell after every run and it was only used for 19 turn. Notice the HUGE drop in runtime. The Peak/Kokam pack has been run maybe 30 times already and was used extensively in the last Tamiya Enduro.
The "blip" in the plot is when the Internal Resistance was measured.

Note, this plot only tells half the story. Lipo's really begin to shine at even higher discharge rates.
Attached Thumbnails
Team Orion 3200mAh Race Spec LiPo-orion_lipo.jpg  
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Old 08-28-2006, 10:26 AM   #171
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Quote:
Originally Posted by Rick Hohwart
There is a danger factor. They are not a danger when used properly. When misused, they can be more dangerous than NiMh.

But we have seen many instances of NiMh cells exploding, so I am not sure if one is really more dangerous than the other.
The danger factor for NIMH is all user error. Charging at 10 amps and letting it peak. The danger factor in lipo is a little bit mechanical error with a bit of user error. Overcharge is a user error but you can't predict over discharge unless you know exactly when to unplug or you have the led indicators. I hope i got my facts right.
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Old 08-28-2006, 01:18 PM   #172
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Quote:
Originally Posted by Rick Hohwart
This is all we have.
Now this says you can charge Kokam cells all the way up to 3C so why Orion does not recommend charging the new battery with more than 3.2A? (I know it does not give you more runtime and/or voltage but still you want to get it done as fast as you can and 6.4A would finish the CC phase in about 20 minutes).
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Old 08-28-2006, 01:28 PM   #173
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Quote:
Originally Posted by cvt01
Now this says you can charge Kokam cells all the way up to 3C so why Orion does not recommend charging the new battery with more than 3.2A? (I know it does not give you more runtime and/or voltage but still you want to get it done as fast as you can and 6.4A would finish the CC phase in about 20 minutes).
Unlike with NiMH, charging them faster only charges them faster. There is no difference in performance when charged at higher rates. Even though the battery will accept higher rates, this will reduce the cycle life of the battery.
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Old 08-28-2006, 01:51 PM   #174
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I've been hearing some talk recently that LiPo is slower for stock (and maybe 19T) racing than good NiMH packs. I know a lot of testing is done on these with hot mod motors, and that shows better performance, but what about for the slower motors with lower amp draw? Do you guys still find that they perform at least equal to NiMH?
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Old 08-28-2006, 02:15 PM   #175
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Quote:
Originally Posted by syndr0me
I've been hearing some talk recently that LiPo is slower for stock (and maybe 19T) racing than good NiMH packs. I know a lot of testing is done on these with hot mod motors, and that shows better performance, but what about for the slower motors with lower amp draw? Do you guys still find that they perform at least equal to NiMH?
NiMH packs seem to have a slight advantage initially, but the LiPo takes over with better performance over the last 3 -4 minutes.
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Old 08-28-2006, 02:16 PM   #176
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Quote:
Originally Posted by Rick Hohwart
it will not fit without some modification. Same with Tamiya MSX.

edit: It will fit the MSX with no modification although removing a very small bit of alloy material may make the pack easier to take in and out of the car. It should fit the T2 the same way.

Rick I just picked up the MSXMR edition, will the 4800 LiPo pack fit this car? Iam planning on running the KO GP and dont want to be let down buy having to purchase NiMH's

thanks
T
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Old 08-28-2006, 02:20 PM   #177
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Originally Posted by tboned_2002
Rick I just picked up the MSXMR edition, will the 4800 LiPo pack fit this car? Iam planning on running the KO GP and dont want to be let down buy having to purchase NiMH's

thanks
T
It can be made to fit. But you will need a few parts from the MSX stick pack conversion kit. If you use the top deck and left side rear bulkhead from this kit, it will fit in the standard battery location. You might have to grind the bulkhead a bit for a "perfect" fit.

The 3200 LiPo, when released, requires no modifications to the chassis.
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Old 08-28-2006, 02:29 PM   #178
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Quote:
Originally Posted by Rick Hohwart
It can be made to fit. But you will need a few parts from the MSX stick pack conversion kit. If you use the top deck and left side rear bulkhead from this kit, it will fit in the standard battery location. You might have to grind the bulkhead a bit for a "perfect" fit.

The 3200 LiPo, when released, requires no modifications to the chassis.
Is there a concrete release date for the 3200 LiPo? All Ive seen on this thread is mid Sept? Is this correct?

thanks again,
T
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Old 08-28-2006, 02:34 PM   #179
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Quote:
Originally Posted by tboned_2002
Is there a concrete release date for the 3200 LiPo? All Ive seen on this thread is mid Sept? Is this correct?

thanks again,
T
This is still the planned date.
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Old 08-28-2006, 02:41 PM   #180
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Quote:
Originally Posted by Rick Hohwart
NiMH packs seem to have a slight advantage initially, but the LiPo takes over with better performance over the last 3 -4 minutes.

This is what I have found also. I have been running 19t a lot recently and have been able to put down lap times right there with everyone else running pretty good 4200's. Like 1.22 and 1.6 IR. I do have hte battery balanced with extra solder too, to eliminate the weight advantage.
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