Battery Power

Hi,

I've had a good search for a Video Link that uses batteries, but
couldn't find any, so I bought one that uses plug-in adapters, but
would like to hook up batteries to make them portable.

The devices have the following power specs:

12V DC, 200 mA
9v DC, 400mah

I would like to use rechargeable batteries to power these devices for
no more than an hour.

I thought for the 12v device I could use a 12v sealed lead acid
battery.

For the 9v device, would rechargeable NiMH batteries do the job
without a problem? As there are no 9v sealed lead acid batteries that
I can see, this seems the only alternative

Hope someone can give me confirmation that this is possible.

Cheers
Sean

 

[Pat Ziegler]

Find yourself a good 12V Lithium Ion cell phone battery. Most are 600mah or
bigger so you should get at least an hours time out of your video sender.
Charging the battery will be your next hurdle.


Pat Ziegler
Wholesale Electronics Inc.


www.weisd.com











<noen@no.mail.com> wrote in message
news:6assc1di177e45l96vjph2e00u56j4mrap@4ax.com...

Hi,

I've had a good search for a Video Link that uses batteries, but
couldn't find any, so I bought one that uses plug-in adapters, but
would like to hook up batteries to make them portable.

The devices have the following power specs:

12V DC, 200 mA
9v DC, 400mah

I would like to use rechargeable batteries to power these devices for
no more than an hour.

I thought for the 12v device I could use a 12v sealed lead acid
battery.

For the 9v device, would rechargeable NiMH batteries do the job
without a problem? As there are no 9v sealed lead acid batteries that
I can see, this seems the only alternative

Hope someone can give me confirmation that this is possible.

Cheers
Sean

 

On Fri, 8 Jul 2005 11:02:03 -0500, "Pat Ziegler" <pzig@weisd.com>
wrote:

Find yourself a good 12V Lithium Ion cell phone battery. Most are 600mah or
bigger so you should get at least an hours time out of your video sender.
Charging the battery will be your next hurdle.


Yes, a lithium battery is a good idea in terms of being light and

compact, I'll have a look around.

I have a 12v lead battery to power a small monitor which works great
with a standard 12v charger, but it is rather bulky which is the only
problem with it being portable.

I think the 12v battery won't be a problem either way, its the 9v I'm
looking for that is my main problem

Cheers,
Sean

 

[Alan the Tech]

You could use a 12v battery with an adjustable voltage regulator a
LM317 3 pin regulator would work just fine. You only need 2 resistors
to set the output voltage and it has a 1 amp capacity which would be
more than enough for your needs.

On Fri, 08 Jul 2005 17:53:05 GMT, noen@no.mail.com wrote:

On Fri, 8 Jul 2005 11:02:03 -0500, "Pat Ziegler" <pzig@weisd.com
wrote:

Find yourself a good 12V Lithium Ion cell phone battery. Most are 600mah or
bigger so you should get at least an hours time out of your video sender.
Charging the battery will be your next hurdle.


Yes, a lithium battery is a good idea in terms of being light and
compact, I'll have a look around.

I have a 12v lead battery to power a small monitor which works great
with a standard 12v charger, but it is rather bulky which is the only
problem with it being portable.

I think the 12v battery won't be a problem either way, its the 9v I'm
looking for that is my main problem

Cheers,
Sean

 

[John Fields]

On Fri, 08 Jul 2005 23:36:57 GMT, Alan the Tech
<mymail@is_a_secret.com> wrote:

You could use a 12v battery with an adjustable voltage regulator a
LM317 3 pin regulator would work just fine. You only need 2 resistors
to set the output voltage and it has a 1 amp capacity which would be
more than enough for your needs.

On Fri, 08 Jul 2005 17:53:05 GMT, noen@no.mail.com wrote:

On Fri, 8 Jul 2005 11:02:03 -0500, "Pat Ziegler" <pzig@weisd.com
wrote:

Find yourself a good 12V Lithium Ion cell phone battery. Most are 600mah or
bigger so you should get at least an hours time out of your video sender.
Charging the battery will be your next hurdle.


Yes, a lithium battery is a good idea in terms of being light and
compact, I'll have a look around.

I have a 12v lead battery to power a small monitor which works great
with a standard 12v charger, but it is rather bulky which is the only
problem with it being portable.

I think the 12v battery won't be a problem either way, its the 9v I'm
looking for that is my main problem

Cheers,
Sean

--
John Fields
Professional Circuit Designer

 

[John Fields]

On Fri, 08 Jul 2005 12:38:33 GMT, noen@no.mail.com wrote:

Hi,

I've had a good search for a Video Link that uses batteries, but
couldn't find any, so I bought one that uses plug-in adapters, but
would like to hook up batteries to make them portable.

The devices have the following power specs:

12V DC, 200 mA
9v DC, 400mah

I would like to use rechargeable batteries to power these devices for
no more than an hour.

I thought for the 12v device I could use a 12v sealed lead acid
battery.

For the 9v device, would rechargeable NiMH batteries do the job
without a problem? As there are no 9v sealed lead acid batteries that
I can see, this seems the only alternative

---
I'd go with either lead-acid or NiMH and get the 9V with a buck
converter so you wouldn't waste power in a linear regulator.

Assuming about 80% conversion efficiency in the switcher and that your
load will draw 400mA at 9V means that for:

P = IE = 9V * 400mA = 3.6W,

the input to the converter will need to be about 4.5 watts, or,

P 4.5W
I = --- = ----- = 0.375A
E 12V

So, if your loads are going to be conncted for an hour, the 12V load
will take 200mA and the 9V load 375mA, so your battery will need to
be rated at about 575mAH. But, batteries are usually rated to deliver
their capacity at C/10 (or C/20), so you'll need to use batteries with
about 25% greater capacity than what the load will impose on them.

For 575mA, that means that the battery should be rated at about
719mAH, so rounding up to 750mAH should get you there easily.

--
John Fields
Professional Circuit Designer