High power but low weight batteries?

  • Thread starter Daniel Kelly (AKA Jack)
  • Start date
D

Daniel Kelly (AKA Jack)

Guest
Hi,

Please could you recommend a supplier for high power (but low weight)
batteries? Ideally I need something that can beat these specs:

12V
6Ah
400g

I'm building a wearable system for recording many many hours' worth of
video. I need any voltage upwards of 5v.

Thanks,
Jack
 
"Daniel Kelly (AKA Jack)" <d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote in message
news:c3sn82$25v4$1@uns-a.ucl.ac.uk...
Hi,

Please could you recommend a supplier for high power (but low weight)
batteries? Ideally I need something that can beat these specs:

12V
6Ah
400g

I'm building a wearable system for recording many many hours' worth of
video. I need any voltage upwards of 5v.

Thanks,
Jack
Click to expand...
Lithium Polymer batteries are currently the best at this on the market. If
they won't work you'll need to wait for fuel cells. They require special
care and feeding and they can burst into flame if mistreated. Check
Batteries America for batteries and charger.
 
"Daniel Kelly (AKA Jack)" <d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote in message
news:c3sn82$25v4$1@uns-a.ucl.ac.uk...
Hi,

Please could you recommend a supplier for high power (but low weight)
batteries? Ideally I need something that can beat these specs:

12V
6Ah
400g

I'm building a wearable system for recording many many hours' worth of
video. I need any voltage upwards of 5v.

Thanks,
Jack



There are two choices: Lithium rechargeable are the highest energy density
Click to expand...
currently available but they have two problems. First, as another poster
mentioned, they need special care and feeding. This makes them difficult to
use as a DIY project. Second, although they start life as a very high
energy density, they decay over time and their effective capacity can drop
alarmingly over a relatively short period of time. The decay is accelerated
with high storage temperatures and it is quite possible that they can drop
to 50% capacity inside a year.

The second choice is NiMh. We have just completed a project that involves
runnig a Sony camcorder with additional components for 8 hours from a single
charge. The batteries we chose were 7 C size to give me a nominal 8.4V
output with 3.5 Ah capacity. To reach your 5V output you will need 5 of
them with a weight of just under 400g. Using D size can give you 7Ah
capacity but at a rather higher weight.

The manufacturer is GP who seem to offer the highest capacity batteries
right at the moment. Charging takes a bit over one hour for the pack and
the batteries are expected to last for more than 300 full charges. Due to
various design constraints, we also needed to provide an external power
supply that would charge the batteries while in circuit, so we have now
designed and built a high speed, software controlled charger that will fully
supervise the power supply system. This means we make up sealed packs of 7
cells rather than expecting the user to remove individual cells for recharge
every day. NiMh batteries do not have the same memory effect that NiCad are
kown for, so repeated partial use does not affect them adversly. We have
been monitoring the capacity of our pack over the past 6 months and we have
seen no degredation in performance over that time despite the camera systems
being used for 5 or 6 days each week. Other than avoiding overcharging,
these batteries work well in almost any situation.

As an aside, having done an amount of commercial video work, I have worn a
variety of battery belts, most of which are in excess or 1Kg. Normally, I
can wear them for several hours as a time without them getting
uncomfortable. If you can achieve 7Ah at under 1Kg, you will be doing
fairly well. You might also want to consider the use of multiple AA size
packs (2.2Ah). Having several battery packs means that you can have one or
two on charge, be wearing one and have the facility to add a second pack to
the belt to provide a changeover without losing power.

Good luck with your project
 
soundman <ph@nowhere.com> wrote:
"Daniel Kelly (AKA Jack)" <d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote in message
news:c3sn82$25v4$1@uns-a.ucl.ac.uk...
Hi,

Please could you recommend a supplier for high power (but low weight)
batteries? Ideally I need something that can beat these specs:

12V
6Ah
400g
snip
There are two choices: Lithium rechargeable are the highest energy density
currently available but they have two problems. First, as another poster
Click to expand...
Zinc-Air is several times better.
Not rechargable though.
 
On Wed, 24 Mar 2004, Daniel Kelly (AKA Jack) wrote:

Hi,

Please could you recommend a supplier for high power (but low weight)
batteries? Ideally I need something that can beat these specs:

12V
6Ah
400g

I'm building a wearable system for recording many many hours' worth of
video. I need any voltage upwards of 5v.

Thanks,
Jack
Click to expand...
try lipoly. they have crappy design and shitty lifespan and personally
I wouldn't spend a nickel on them unless it was forced but they should
match the weight. what dimesions?

moose

 
Thanks everyone for your great input!

Jack



"john" <jmuielewicz@yahoo.com> wrote in message
news:pine.LNX.4.58.0403250411560.718@libretto.cool.org...
On Wed, 24 Mar 2004, Daniel Kelly (AKA Jack) wrote:

Hi,

Please could you recommend a supplier for high power (but low weight)
batteries? Ideally I need something that can beat these specs:

12V
6Ah
400g

I'm building a wearable system for recording many many hours' worth of
video. I need any voltage upwards of 5v.

Thanks,
Jack


try lipoly. they have crappy design and shitty lifespan and personally
I wouldn't spend a nickel on them unless it was forced but they should
match the weight. what dimesions?

moose
Click to expand...
 
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