I am trying to build, or at least cobble together, a battery pack for a
receiver. I will only need one (1) amp of power. The battery will have a one
(1) amp fuse on both the lead in and out of the radio just for safety. What
I have not been able to understand is what amp hours are. I need a twelve
(12) volt battery that will last a while, or at least five hours, and be
rechargeable. I have been looking at UPS battery pack, or even small car
batteries. Any help? Thanks.

Matthew
KC2KEI
Scars are the proof that man can survive his own stupidity.


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On Sat, 30 Aug 2003 23:07:50 GMT, "Matthew and Wendy Plante"
wrote:

I am trying to build, or at least cobble together, a battery pack for a
receiver. I will only need one (1) amp of power. The battery will have a one
(1) amp fuse on both the lead in and out of the radio just for safety.

That might be a bit close, you might want a 1 1/2 amp fuse just to
allow for turn on surges.

What
I have not been able to understand is what amp hours are. I need a twelve
(12) volt battery that will last a while, or at least five hours, and be
rechargeable.

One thing you can do is to compute amp hours by saying: I need 3 amps
for 5 hours" That implies you need a 15 amp hour battery at least.

the good news is that a 20 amp hour battery would supply 1 amp for 20
hours...

I'd get a 10 amp hour battery at least, just because... I'd also go
with a gell cell because the will not leak and can be used in any
position. Gell cell chargers are easy enough to come by.

There was an article in 73 magazine about how to charge gell cells
that did a nice job of it.

Harvey



I have been looking at UPS battery pack, or even small car
batteries. Any help? Thanks.

Matthew
KC2KEI
Scars are the proof that man can survive his own stupidity.

On Sat, 30 Aug 2003 23:07:50 GMT, "Matthew and Wendy Plante"
wrote:

I am trying to build, or at least cobble together, a battery pack for a
receiver. I will only need one (1) amp of power. The battery will have a one
(1) amp fuse on both the lead in and out of the radio just for safety.

That might be a bit close, you might want a 1 1/2 amp fuse just to
allow for turn on surges.

What
I have not been able to understand is what amp hours are. I need a twelve
(12) volt battery that will last a while, or at least five hours, and be
rechargeable.

One thing you can do is to compute amp hours by saying: I need 3 amps
for 5 hours" That implies you need a 15 amp hour battery at least.

the good news is that a 20 amp hour battery would supply 1 amp for 20
hours...

I'd get a 10 amp hour battery at least, just because... I'd also go
with a gell cell because the will not leak and can be used in any
position. Gell cell chargers are easy enough to come by.

There was an article in 73 magazine about how to charge gell cells
that did a nice job of it.

Harvey



I have been looking at UPS battery pack, or even small car
batteries. Any help? Thanks.

Matthew
KC2KEI
Scars are the proof that man can survive his own stupidity.

On Sat, 30 Aug 2003 23:07:50 GMT, "Matthew and Wendy Plante"
wrote:

I am trying to build, or at least cobble together, a battery pack for a
receiver. I will only need one (1) amp of power. The battery will have a one
(1) amp fuse on both the lead in and out of the radio just for safety. What
I have not been able to understand is what amp hours are. I need a twelve
(12) volt battery that will last a while, or at least five hours, and be
rechargeable. I have been looking at UPS battery pack, or even small car
batteries. Any help? Thanks.

Matthew
KC2KEI
Scars are the proof that man can survive his own stupidity.

Amp-hours are the capacity of the battery. A 10 amp-hour battery can
provide 1 amp to a load for 10 hours, 2 amps to a load for 5 hours,
etc. You need at least a 5 amp-hour battery, and more would be
better.

A couple things to remember: At high current draw you get less than
advertised capacity. That 10 amp hour won't give 20 amps for 1/2
hour. The battery will last much less than 1/2 hour at that rate.

Also, lead-acid batteries don't like to be discharged until dead.
That reduces battery lifetime. Some batteries are made to tolerate
this better than others. In any case you want something more than 5
amp-hours.

There's a fellow who did a great lead-acid battery FAQ page. Don't
have the link around, do a search or perhaps someone around here would
have it.

And finally, if the radio draws 1 amp you may want a 1.25 or 1.5 amp
fuse. There could be peak current draw of over 1 amp.

Good luck and 73,
Jim

On Sat, 30 Aug 2003 23:07:50 GMT, "Matthew and Wendy Plante"
wrote:

I am trying to build, or at least cobble together, a battery pack for a
receiver. I will only need one (1) amp of power. The battery will have a one
(1) amp fuse on both the lead in and out of the radio just for safety. What
I have not been able to understand is what amp hours are. I need a twelve
(12) volt battery that will last a while, or at least five hours, and be
rechargeable. I have been looking at UPS battery pack, or even small car
batteries. Any help? Thanks.

Matthew
KC2KEI
Scars are the proof that man can survive his own stupidity.

Amp-hours are the capacity of the battery. A 10 amp-hour battery can
provide 1 amp to a load for 10 hours, 2 amps to a load for 5 hours,
etc. You need at least a 5 amp-hour battery, and more would be
better.

A couple things to remember: At high current draw you get less than
advertised capacity. That 10 amp hour won't give 20 amps for 1/2
hour. The battery will last much less than 1/2 hour at that rate.

Also, lead-acid batteries don't like to be discharged until dead.
That reduces battery lifetime. Some batteries are made to tolerate
this better than others. In any case you want something more than 5
amp-hours.

There's a fellow who did a great lead-acid battery FAQ page. Don't
have the link around, do a search or perhaps someone around here would
have it.

And finally, if the radio draws 1 amp you may want a 1.25 or 1.5 amp
fuse. There could be peak current draw of over 1 amp.

Good luck and 73,
Jim