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Old 03-02-2007, 11:08 AM   #16
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Had mine for 6 months or so... no probs and works great. I think mine is a 15C where the new ones are 20C.... so using mod with a 4000 could draw a little more than it should. I know a guy running a 4000 with mod that it got hotter than it should but no fire or other issues. The 15C 6000 could possibly have an issue with mod but the 20C (120 amp continuous) should be fine I would think. I charge mine with an ICE and it works great. I also have a balancer which I plug in occasionally and the pack has never been out of balance. Running a 4300 foam TC I have gotten 35 minutes of run time before it drops off. We have 5 guys running MaxAmps at our track and all are sold on their packs.
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Old 03-02-2007, 11:53 AM   #17
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Whoooaa. I’m a huge proponent of Lipo’s, but bad information that has potentially dangerous consequences must stop.

”You don't need the hard case. Waist of money”

HARD CASES ARE GOOD FOR LIPOS!
The internal construction of the high discharge type lipo that we use in RC cars/planes are essentially a bunch of little lipo batteries stacked together in parallel. These batteries are constructed with layers of copper graphite coated anodes and aluminum metal oxide coated cathodes and they are separated by a very THIN polyethylene film. It’s extremely important that the seperator maintains integrity or some of the cathode/anode layers will short out. A LiPo cell is MOST vulnerable at the edges where the seperator is not continuous. A dent on the side of a Lipo may move the seperator and cause an internal short. Sometimes the short burns off a little material, creates a little gas, and you have a puffy cell with less capacity. Othertimes, the short can melt enough of the seperator which causes shorts in other areas of the cell and the chain reaction causes a flame situation. A hard case prevents dents, which prevents internal shorting, which prevents a dangerous situation.

”...After about 10 mins the swelling went down. I tried charging it...”

IF LIPO CELL SWELLS UP – STOP USING IT!
Once a cell swells up, you already have an internal short. The internal mechanical construction of the cell is already compromised and you have a fire hazard. Not all the layers may be affected so the cell might still take a charge, but doing so is a highly dangerous. Any Lipo cell manufacturer or cell distributor MUST warn against this ”obvious” sign.
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Old 03-02-2007, 12:08 PM   #18
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This is why I picked up 2 of the Peak 3200s in the hard case. This is also why I'm excited about running lipo in my BK2 and soon to be JRXS-R, both run the batteries down the center of the car. This seems to be the safest solution to the lipo hazards. The hard shell is icing on the cake. The hard shell should be considered required in a car where a side impact could directly impact the battery. With some of the dangers involved, a few extra bucks is worth the added safety. It isn't like their going to go bad in 50 cycles. People are claiming 100-200+ cycles on these high quality packs. People have more money in shiny aluminum crap on their car that does nothing, then the cost difference over a couple batteries.
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Old 03-02-2007, 12:18 PM   #19
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Quote:
Originally Posted by linger
Whoooaa. I’m a huge proponent of Lipo’s, but bad information that has potentially dangerous consequences must stop.

”You don't need the hard case. Waist of money”

HARD CASES ARE GOOD FOR LIPOS!
The internal construction of the high discharge type lipo that we use in RC cars/planes are essentially a bunch of little lipo batteries stacked together in parallel. These batteries are constructed with layers of copper graphite coated anodes and aluminum metal oxide coated cathodes and they are separated by a very THIN polyethylene film. It’s extremely important that the seperator maintains integrity or some of the cathode/anode layers will short out. A LiPo cell is MOST vulnerable at the edges where the seperator is not continuous. A dent on the side of a Lipo may move the seperator and cause an internal short. Sometimes the short burns off a little material, creates a little gas, and you have a puffy cell with less capacity. Othertimes, the short can melt enough of the seperator which causes shorts in other areas of the cell and the chain reaction causes a flame situation. A hard case prevents dents, which prevents internal shorting, which prevents a dangerous situation.

”...After about 10 mins the swelling went down. I tried charging it...”

IF LIPO CELL SWELLS UP – STOP USING IT!
Once a cell swells up, you already have an internal short. The internal mechanical construction of the cell is already compromised and you have a fire hazard. Not all the layers may be affected so the cell might still take a charge, but doing so is a highly dangerous. Any Lipo cell manufacturer or cell distributor MUST warn against this ”obvious” sign.
Question ..... If you have a Lipo with a hard case will you be able to see a damaged pack swelling? (which is the sign to stop using it before it blows up). If you don't have a case on it then you would easily be able to see if it was swelling and get an early warning that something is wrong and get rid of the battery BEFORE it explodes. If you have a protective case and your lipo get damaged and starts swelling, but you cant see it because of the case, the battery could potentially build up alot of pressure inside the case before it blows. Then when it does blow up you have shards of the case and battery remains flying at dangerous velocity in all directions .... Just provoking some more conversation
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Old 03-02-2007, 12:35 PM   #20
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Quote:
Originally Posted by shaggys40oz
Question ..... If you have a Lipo with a hard case will you be able to see a damaged pack swelling? (which is the sign to stop using it before it blows up). ...
Shaggy - great observation. The hard case needs to be designed correctly. Let's take the Peak/Orion hard case as an example. It's a two part design and the top and bottom case are held together with nothing but a sticker. They also use a thin double sided sticky tape to fix the battery in case to prevent the battery from bouncing around. Any swelling of the cell will cause the case to pop open. It's important for any case not to rigidly confine the battery which would cause a pressure buildup which causes even more heat.
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Old 03-02-2007, 12:48 PM   #21
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I think linger has the hard shell case nailed.
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Old 03-02-2007, 03:27 PM   #22
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does anyone know if any of the 2cell maxamp lipos fit into the tamiya m-chassis'? i was thinking of getting one and perhaps make a bottom plate for it made out of or some other strong materiel.
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Old 03-02-2007, 04:23 PM   #23
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Quote:
Originally Posted by SSJChar
does anyone know if any of the 2cell maxamp lipos fit into the tamiya m-chassis'? i was thinking of getting one and perhaps make a bottom plate for it made out of or some other strong materiel.
I know that the 4000 will, it is the same lenght and width as a stick pack, and not as tall. I believe the 6000 is the same size lenght, width, and height as a std stick pack
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Old 03-02-2007, 04:55 PM   #24
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Me and my friends all use Maxamps 6000mah lipos in our mod class or almost 1 year now without issues...

Only problems is that the solder inbetween the cells has come off on some and required resoldering.

We have used them with so far novak 5.5, 4.5, 3.5 and currently with mamba max 7700.

But I have never gotten more then 10mins out of a pack. how do you guys get up to 20-30mins out of a battery using a mod motor.

Maybe Im geared too low? Who knows, but works fine for 5min heats. Also I read that u are not meant to discharge them as they do not have a memory effect. Is this correct or do they required to be discharged.

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Old 03-02-2007, 06:17 PM   #25
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I recently picked up a Maxamps 3s2p 4000 pack for my rustler and it's a great pack. It's defintly underrated at 4000 (which it's supposed to be). I can have it down to where it cuts off (9.6v's I believe) and then charge it and I can put in more than 4000 before it's done charging.
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Old 03-03-2007, 12:17 AM   #26
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I think maxamps has jack up the price of 6000 from 69.99 to 79.99 ( soon after winning a 24 hours enduro race ).
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Old 03-03-2007, 12:35 AM   #27
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Quote:
Originally Posted by mattnin
Maybe you ran into problems because the novak GTB does not have LIPO voltage cutoff protection built into their ESCs. Even if the LIPO is fully charged, the Novak GTB can draw so much juice from the LIPO that the voltage will drop below the cutoff voltage thereby causing damage to the battery.

I have been using a maxamps 4400 mah saddle pack lipo for almost a year now racing with a novak 5.5r, but I used a LVC for lipos. I am now using the same saddle pack with a mamba 7700kv that has lipo protection. I am using the same battery racing weekly, sometimes bi-weekly in up to 3 heats and one main.
I was running a LVC, I checked the voltage on each cell and and they weren't out of balance. I think you would deffinitely feel a drop off if the pack went below 6V. Maybe I got a dud pack or something.
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Old 03-03-2007, 05:21 AM   #28
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I think MetalMan (he's on a lot of other forums) had one of his first lipos puff up like you said and it still ran. But then he sent it back and got another one.
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Old 03-03-2007, 08:54 PM   #29
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Hi

WARNING:
NEVER discharge cells below 3V per cell when under load. Most recommend a CUT OFF of 3.2Vper cell under load.
NOTE: The voltage quickly comes up after the load is removed.

There is a lot of good info in the Flying forums (RCGroups, ..) They have been using them before cars.

The new high C rated cells have a low internal resistance and can discharge below 3V per cell still giving a good discharge current (Amps).
The old lower C rated cells would dump before the Voltage got too low - NOT the new cells.
All fliers use ESC's or separate LVC's for Lipo cells.

CHARGING:
Use only chargers designed for Lipo.
NEVER charge Lipo's unattended. Keep a watch on them.
Balancing the cells is important. You could be overcharging a cell if they are unbalanced.
I always charge through the balancer with my Hyperion Charger and Balancer

LIPO's are great cells and technology. They are all I use for my RC.
. Lipo packs are not cheap but can outlast NiMH if they are looked after correctly.
BUT .... you have to look after them

Jeff
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Old 03-04-2007, 12:10 AM   #30
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are maxamp lipo batts oem? i saw these

premium power 4700mah 7.4v lipo

and they look a lot like maxamp batts, but with lesser mah & built in tamiya plugs
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