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Stryfe Batteries Heating Up!?


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#1 Jonathan Lim

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Posted 06 March 2015 - 10:53 PM

Hi guys.
At this point I'm a little worried because something is happening to my Stryfe.

After I replaced them with the Tamiya Sprint Dash motors, I rewired them like the stock motors.

I'm running them on 3 Ultrafires +1 Dummy.

At first, the performance was solid. I really liked it.

Then the next day, I tested them out again. They were rather weak and suddenly the Ultrafires became really hot. Is it a short circuit?
Soon, I thought the Ultrafires were almost dead, so I decided to charge the batteries. 2 of them worked perfectly but one just couldn't charge(my charger has an L.E.D indicator). What's wrong with my stryfe?

Am I gonna blow up my Ultrafires? (All my Ultrafires are 14500 protected cells)

I need help urgently. Thanks.
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#2 snakerbot

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Posted 07 March 2015 - 01:07 AM

Am I gonna blow up my Ultrafires? (All my Ultrafires are 14500 protected cells)

The protection PCB should keep them safe. That's kind of the entire reason it's there.

That said, ultrafires are very unfit for this purpose. A brief google search fails to find their official safe discharge rate. Similar li-ion cells are rated to about 1-2C, which means these can really only deliver about 1A continuous. Those motors ask for 2.8-3.8A at 2.4-3.0V. You're feeding them 11.1V, so they're actually probably drawing somewhere in the ballpark of 10A or more at times. This is for one motor, you're driving two, so double that. 20A is something that even unprotected ultrafire 14500s will never, ever be able to do unless you run something like 10 or 15 of them in parallel.

Ultrafires and their cousin trustfires have their place, but driving motors is not it. Feeding 11.1V to motors rated for 3 is not a good place to be either. Sure, the Tamiyas might be able to handle it, but I'd be very careful. What you really should do is get a 1S (lithium) or 3cell (nickel) battery pack that can deliver enough current.

So back to the beginning question. Are your batteries safe? I'd say probably, but you're abusing the hell out of them, and I'm really not sure how the protection PCB will react.
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#3 Lunas

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Posted 07 March 2015 - 03:10 AM

The protection PCB should keep them safe. That's kind of the entire reason it's there.

That said, ultrafires are very unfit for this purpose. A brief google search fails to find their official safe discharge rate. Similar li-ion cells are rated to about 1-2C, which means these can really only deliver about 1A continuous. Those motors ask for 2.8-3.8A at 2.4-3.0V. You're feeding them 11.1V, so they're actually probably drawing somewhere in the ballpark of 10A or more at times. This is for one motor, you're driving two, so double that. 20A is something that even unprotected ultrafire 14500s will never, ever be able to do unless you run something like 10 or 15 of them in parallel.

Ultrafires and their cousin trustfires have their place, but driving motors is not it. Feeding 11.1V to motors rated for 3 is not a good place to be either. Sure, the Tamiyas might be able to handle it, but I'd be very careful. What you really should do is get a 1S (lithium) or 3cell (nickel) battery pack that can deliver enough current.

So back to the beginning question. Are your batteries safe? I'd say probably, but you're abusing the hell out of them, and I'm really not sure how the protection PCB will react.

When higher than normal current is drawn the protection shuts down the cell that cell that is not taking a charge either got discharged below or tripped the circuit. If you must go up to at least imr batteries they will be better off than the ultrafires which i would dispose of at this point or store them in a fire proof box. It sounds like the op over discharged them.

The best option would be a lipo 1s with the highest amperage he could find. Next a single purple efest 18650 30A. after that efest v2 14500 if possible 2 in parallel i have been toying with the idea of reworking my stryfe's battery box to have 2p2s efest 14500 v2 also i would recommend a voltage monitor addition to prevent over discharge in the future.
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#4 darthskids

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Posted 07 March 2015 - 04:54 AM

I wouldn't count on those protection circuits. They are made with all the same love and care that goes into the rest of the battery.

*edit*
Now that I have time to sit down and think about it, those protection pcb's only protect from low voltage. They won't do anything for current draw.

The tamiya motors just pulled too much out of the *fires and one shorted internally and the others are half cooked.

Edited by darthskids, 07 March 2015 - 03:52 PM.

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#5 BlasterHacker

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Posted 07 March 2015 - 03:26 PM

Might I slip a Q in here requesting a good guide (with a shopping list) for someone totally new to modding electronic blasters?
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#6 jwasko

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Posted 08 March 2015 - 12:46 AM

Might I slip a Q in here requesting a good guide (with a shopping list) for someone totally new to modding electronic blasters?

Not sure if there are any zero-to-hero writeups available. A lot of guides out there give outdated, incomplete, and/or wrong info. But a suggested read is http://torukmakto4.b...ated-guide.html

And a 2-cell (2.4V) NiMH battery pack will work fine for tamiyas, actually; 3-cells NiMH push their rating a bit.
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#7 Azrael0987

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Posted 09 March 2015 - 12:39 AM

As an alternative for someone who doesn't want to invest in lipos and their respective chargers (its not that much cash but little bits here and there add up), running 3 or 4 18650/26650 li-ion batteries give pretty good performance for their cost. They are cheaper than lipos and have a 30-35 amp limit on 18650's and usually a 50 amp limit on 26650's. The only thing you really have to look out for in these is which brand you buy. The cheap blue cased batteries or protected ultrafire batteries are garbage and I can say now the extra few bucks for a good set of e-fest or sony vtc's are very much worth it. Unless you are just a diehard use 14500 sized cells and do not want to modify the battery tray, they make a great option instead of lipos.
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