NiCad tool battery overheating

[John Doe]

With some help from this and other groups, I built a cool little
push stick for inline skating.

http://www.flickr.com/photos/27532210@N04/
http://www.flickr.com/photos/27532210 N04/ (sign removed)

I am planning to make many improvements, including upgrading the
batteries from NiCad to lithium ion.

The DeWalt XRP NiCad batteries get hot during use, should I be
concerned about them rupturing or otherwise self-destructing?

I can go for lithium-ion batteries, or do other improvements if
the NiCads will last for a while. Upgrading the batteries is a
no-brainer improvement that can be done at any time, so I would
rather put my limited resources into other experimental
improvements, like building another push stick with a lighter
structure.

Would lithium-ion batteries improve performance in my high current
application somehow? Would they be safer?

Thanks.

 

[Martin Riddle]

With some help from this and other groups, I built a cool little
push stick for inline skating.

http://www.flickr.com/photos/27532210@N04/
http://www.flickr.com/photos/27532210 N04/ (sign removed)

I am planning to make many improvements, including upgrading the
batteries from NiCad to lithium ion.

The DeWalt XRP NiCad batteries get hot during use, should I be
concerned about them rupturing or otherwise self-destructing?

I can go for lithium-ion batteries, or do other improvements if
the NiCads will last for a while. Upgrading the batteries is a
no-brainer improvement that can be done at any time, so I would
rather put my limited resources into other experimental
improvements, like building another push stick with a lighter
structure.

Would lithium-ion batteries improve performance in my high current
application somehow? Would they be safer?

Thanks.

High rate discharge Nicads. Li-ions cant compare. Next up is Li-Poly.
I would post the question on an RC group. They commonly run batteries at
their max discharge rate,
or above for short periods.

Cheers

 

[John Doe]

For the record, about DeWalt lithium-ion battery protection.
Thanks to the replies.





DC9180 Battery Shut Down

The DC9180 have electronics in them that are designed to shut the
battery down if it gets too warm. Once this occurs, the battery
will not work in any tool until it is put back into the DC9310
charger, this will then reset the electronics in the battery.

The battery is designed this way to protect the cells in the
battery pack and results in a battery that will last far longer
than a NICAD battery pack.

 

[John Doe]

Have you come up with electric brakes yet?

Inline skates come with a brake. My Motail does not interfere with
normal skating, except for having to carry 6 extra pounds.

Were you planning on marketing this as a product?

So far, I am very busy having fun using it.

Wouldn't the legal liabilities for such a product
be absurd even aside from batteries blowing up?

Street skating is risky, best done by someone who is unusually
aware of his surroundings. I get the impression that the Roller
Cycle guy ran into liability problems.

When used without propping it against my rear thigh, it is
reminiscent of climbing stairs with both legs and hands as a
child.

I will make sure the batteries do not blow up, that is why I
asked.

 

[Kevin McMurtrie]

With some help from this and other groups, I built a cool little
push stick for inline skating.

http://www.flickr.com/photos/27532210@N04/
http://www.flickr.com/photos/27532210 N04/ (sign removed)

I am planning to make many improvements, including upgrading the
batteries from NiCad to lithium ion.

The DeWalt XRP NiCad batteries get hot during use, should I be
concerned about them rupturing or otherwise self-destructing?

I can go for lithium-ion batteries, or do other improvements if
the NiCads will last for a while. Upgrading the batteries is a
no-brainer improvement that can be done at any time, so I would
rather put my limited resources into other experimental
improvements, like building another push stick with a lighter
structure.

Would lithium-ion batteries improve performance in my high current
application somehow? Would they be safer?

Thanks.

You can improve the peak current capacity of NiCd by running them
completely dead after use and delaying charging until immediately before
use.

Do NOT use standard Lithium-ion cells unless you want to die in flames.
You'll need LiFePO4 or special high-current LiPo. I've used
http://www.batteryspace.com/ for hobby projects. Buy the correct
charger too (to again avoid the dying in flames thing).

 

[Robert Roland]

The DeWalt XRP NiCad batteries get hot during use, should I be
concerned about them rupturing or otherwise self-destructing?

As a general rule of thumb, NiCd batteries can safely reach 40C
without damage. During discharge, it is extremely unlikely such
batteries will fail in a spectacular fashion. If fast charging and
overchariging, however, they can explode.

NiMH batteries perform much like NiCd, but they provide more charge
per weight.

Would lithium-ion batteries improve performance in my high current
application somehow? Would they be safer?

Li-Ion batteries provide much more charge per weight, but are much
less safe than Ni-based batteries.

There are also batteries known as Lithium-Polymer (LiPo), although
they are actually Li-Ion-Polymer. These batteries have become very
popular among RC modellers, since they provide even better charge per
weight performance than Li-Ion. Also, they can deliver very large
discharge currents. Some models can be safely discharged in five
minutes or less, and still be only warm to the touch. You can get
batteries than can be charged in 15-20 minutes, which is a great
advantage for some applications. LiPo batteries have a great risk of
fire. If a charged battery gets pierced (they have no metal casing) by
a conductive object, they will catch fire. If you put water on the
fire, you will make it burn faster. Search Youtube for "LiPo fire" to
see what it's about.

There's also the LiFePo battery. This battery provides somewhat less
charge density than LiPo, but is much safer. The selection of LiFePo
batteries is much smaller than for LiPo, and they are more expensive.

All Lithium batteries will need a specialized charger. Do not try to
charge a Li battery with a charger that is not designed for that
specific type of battery.

 

[John Doe]

As a general rule of thumb, NiCd batteries can safely reach 40C
without damage. During discharge, it is extremely unlikely such
batteries will fail in a spectacular fashion. If fast charging
and overchariging, however, they can explode.

NiMH batteries perform much like NiCd, but they provide more
charge per weight.

Panasonic has an 18 volt 3.5 amp hour nickel metal hydride
battery.

Thanks.