Zippy Flightmax Lipo??

[squeeforever]

Originally Posted by Chadworkz

I have 10 of them, ranging from 2S @ 500mAh to 4S @ 5000mAh, and I couldn't be happier...they are some of the best batteries on the market, and are THE best in their price range.

I have nothing against MaxAmps batteries, but their packs are way over-priced for what you get...the Zippies are much better, and far cheaper. I also don't have anything against TrueRC batteries, but their pack just don't put out the amps (C) that is needed and are also way over-priced. Just get the Zippy Flightmax batteries, and get the 30C packs if you can (if they are in stock).

I'd have to disagree. TrueRC aren't really overpriced. They ARE underrated though, and they offer packs that you really can't get elsewhere, at least not for the quality and price, such as the 8000mah packs. There a tad big, but very nice packs.

[jsr]

Originally Posted by lincpimp

Did you fix them? Or send them back? I would like to see the internals of those packs...

Yeah, I opened up the hardcase on every pack and resoldered the cells. After doing so, most of them continue to re-open under any load near their "100A" rating. Since then, I use them for setups that don't draw as much current, but I've had them open on a 60A setup (that never got past just warm, so I doubt it was even drawing 60A). The tabs on the cells does not allow solder to wet. This was the case when they were first put together and also when I resoldered them. I even sanded down one of the cell tabs that didn't wet well to get clean metal and it still wouldn't take solder. Because the tabs don't wet solder very well, most of the joints that opened were because the factory knew this and all they did was blob enough solder so that it made a pressure joint against the tab (meaning the solder blob just pressed against the cell tab to make electrical contact). Any mechanical vibration (like in a RC truck) or heavy thermal stress (like big current draws heating up a crappy high-resistance electrical connection) would easily open a pressure connection. I took a picture of the solder joint before, but am too lazy to find it. I posted it on RCU or somewhere.

[squeeforever]

Originally Posted by jsr

Yeah, I opened up the hardcase on every pack and resoldered the cells. After doing so, most of them continue to re-open under any load near their "100A" rating. Since then, I use them for setups that don't draw as much current, but I've had them open on a 60A setup (that never got past just warm, so I doubt it was even drawing 60A). The tabs on the cells does not allow solder to wet. This was the case when they were first put together and also when I resoldered them. I even sanded down one of the cell tabs that didn't wet well to get clean metal and it still wouldn't take solder. Because the tabs don't wet solder very well, most of the joints that opened were because the factory knew this and all they did was blob enough solder so that it made a pressure joint against the tab (meaning the solder blob just pressed against the cell tab to make electrical contact). Any mechanical vibration (like in a RC truck) or heavy thermal stress (like big current draws heating up a crappy high-resistance electrical connection) would easily open a pressure connection. I took a picture of the solder joint before, but am too lazy to find it. I posted it on RCU or somewhere.

Thats because your not using the right type of solder and I'm gonna guess your not using flux as well...

[Metallover]

You need aluminum solder and other aluminum soldering supplies.

[Chadworkz]

Lead-free, silver solder and brush-on flux paste is your friend...don't use solder with flux already in it, that always results in a bad connection. Also, it sounds to me like your soldering iron does not have enough wattage...60w will get the job done, but 100-120 watts is much better, and allows you to get the job done quicker so as not to heat soak the batteries or other electronics.

[jsr]

I did use paste flux. I have various solder types (including tin silver) and none of them worked well. I've never had any problems soldering any other batteries, including other LiPos, just these. My joints ended up looking the same as the stock solder joints (with a bit better reflow). Perhaps the factory isn't using the correct type either. Regardless, the consumer shouldn't be needing to redo what should be correct from the factory.

[Chadworkz]

That's true, jsr, I agree...

Hmmm...maybe some sort of chemical has soaked into the bars stopping them from accepting the solder?

[Martin]

Anyone tried a higher charge rate than 1C ?

[suicideneil]

If the cell is rated at 1c charge, the thats all you should do. Newer cells with safer chemistry can accept upto 5c, though 2c is more the norm; follow the instructions on your specific packs.

Generally, a 4900mah pack could be done at 5amps and be safe, but if you cant wait one hour for the pack to charge (at a race for example), then you need to buy some more packs so you have a continuous supply..

[phildogg]

Originally Posted by jsr

They're fine batteries. Just AVOID the 4000mAh Flightmax 2s Hardcase ones. Those are ok if your application won't demand more than 50-60A continuous, but the terrible soldering makes them far below their rated "100A". Stay away from those and you should be fine. I ordered 6 packs and ALL 6 packs opened circuited.

I bought 4 of the 2s 4000 25c hardcase (new version with better solder ) They run great for me.. I have run them in my 1/8 ofna buggy with mmm/2200 combo on 4s and they performed great.. runs right around 40 mph with them.. never run hot either. great in the rustler also.. mine are the ones tey have now seems they fixed the solder issue and made a update on the site about it.
phil
phil

[Jason]

I ordered these one for my slash :

http://www.hobbycity.com/hobbycity/s...idProduct=8583

[Martin]

Found this on Hobbycity`s website about Flightmax lipo:

Product Config Table:
Capacity(mAh): 5000
Config(s): 4
Discharge(c): 30
Max Charge Rate (C): 2

Has it allways been max charge rate 2C?? Or is this new info??

[nitrostarter]

Thats nice to know!

But I wouldn't recommend charging at 2C all the time. It will reduce the life of the packs.

[Chadworkz]

Maybe just charge at 2C 2 or 3 times total throughout the pack's life? Like only when you absolutely HAVE to?

[starscream]

I just picked up a couple of the 2S 4000mAh hard case packs.
No soldering problems and they ran very well. I used them last night for qualifiers in my rc10b. They do not have the punch the RCM 5200 mAh packs have but they were good for qualifiers and practice.