Max voltage for a P7?

SR.GRINGO · Jun 6, 2010

I have a couple of 10.8 volt packs consisting of NIMH elite. The max for a P7 is 2800mah..so at 2000 mah I should be good in that department. They are 2000 mah 4/5A. I have taken the pack apart which consists of 4 unprotected 18,500's with a cardboard top with some resistors and stuff. So if I solder the wires to the contacts in the pack I should be good right? The pack that came with my magic shine was DOA(bad cell) and I live in a different country...so it is hard to get replacement parts.

The other option is...

the magicshine came with 4 unprotected 18500's(one is bad)
I have 8 AW 18500's for my elephant
I would rather use the 10.8 packs becuase I'm not using them for anything

I just want to be able to use my bike at night when it is cool enough to ride. Any thoughts?

COAST · Jun 6, 2010

Hmm.... If you're not planning on using a driver, 10.8 volts is WAY too much voltage for a P7 to handle safely. It all depends on the bin, but 3.7v is the norm.

SmurfTacular · Jun 10, 2010

Yeah at 10.8 volts I'm pretty sure it would flash then burn out.

Unless you use a heatsink like this

[hotlinked image removed - please read Rule 3. - DM51]

COAST · Jun 10, 2010

SmurfTacular said:
Yeah at 10.8 volts I'm pretty sure it would flash then burn out.

Unless you use a heatsink like this

[hotlinked image removed - please read Rule 3. - DM51]

M@elstrom · Jun 10, 2010

I'm not sure that'll be a big enough heatsink!

Bottom line... unless you intend to direct drive off 3 NiHM/NiCD cells you'll require some kind of electronic regulation

fivemega · Jun 10, 2010

SR.GRINGO said:
I have a couple of 10.8 volt packs consisting of NIMH elite. The max for a P7 is 2800mah..so at 2000 mah I should be good in that department. They are 2000 mah 4/5A. I have taken the pack apart which consists of 4 unprotected 18,500's with a cardboard top with some resistors and stuff. So if I solder the wires to the contacts in the pack I should be good right? The pack that came with my magic shine was DOA(bad cell) and I live in a different country...so it is hard to get replacement parts.

The other option is...

the magicshine came with 4 unprotected 18500's(one is bad)
I have 8 AW 18500's for my elephant
I would rather use the 10.8 packs becuase I'm not using them for anything

I just want to be able to use my bike at night when it is cool enough to ride. Any thoughts?

---
You are mixing up current draw which is measured by Amp or mA with battery capacity which is measured by Amp/Hr or mAh
Battery capacity does not do anything with current draw directly.
Direct driving a P7 at 10.8 volt without any controller will fry it regardless of heat sinking.
You mentioned:

SR.GRINGO said:
I have a couple of 10.8 volt consisting of NIMH

In this case, your each pack must have 9 cells connected in serial. (1.2x9=10.8)
Then you mentioned:

SR.GRINGO said:
They are 2000 mah 4/5A. I have taken the pack apart which consists of 4 unprotected 18,500's

18500 is 18mm diameter with 50mm length while 4/5A is 17mm diameter with 44mm length.
If your pack of four serial is NiCad or NiMH, then total nominal voltage is 4.8 volt. (1.2x4=4.8)
If your pack of four serial is li-Ion, then total nominal voltage is 14.8 volt. (3.7x4=14.8)
I still don't know where is 10.8 volt coming from.

COAST · Jun 25, 2010

I guess that answers it!

Max voltage for a P7?

SR.GRINGO

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COAST

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SmurfTacular

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COAST

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M@elstrom

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fivemega

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COAST

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