Wanted: "fuel gauge"-like meter for deep-cycle batteries
 

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I like the idea of the Whatt Meter, and I've seen them for sale at
hamfests and they look great. I started looking at the specifications
and I discovered some limitations which make it much less useful for
my needs.

The deep-cycle batteries I use have much more capacity than the ones
they use for electric flight (that's the original target audience for
Astro Flight's products), so that's a minus. Also, the battery
system I have currently installed will charge when it's not
discharging, which doesn't fit the NiCad model very well.

Ideally, the meter I want to use would resemble an automobile fuel
gauge in that it would have some idea of what "full" was (whether by
testing via full discharge or by entering in data somehow) and it
would be able to handle charging and discharging without being
rewired. The latter is the truly crucial bit, as the former can be
implemented with a PIC. The PIC could do much more, of course, but as
a bare minimum, I'd like to know how much capacity remains and how
quickly I'm using it.

Is there anything out there like this? Is there a schematic for the
charge/discharge data collection which would be suitable for my needs?
I appreciate any help with this idea, as it might turn out to be
useful for more than just me.

Jack.
- --
Jack Twilley
jmt at twilley dot org
http colon slash slash www dot twilley dot org slash tilde jmt slash
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I am a boater who uses deep discharge marine batteries. I purchased
from West Marine a gauge that measurea percent discharged, based on a
narrow voltage band. Voltage itself is not a good indicator. A battery
can show 12V and be almost dead.

Check out West Marine or Defender Industries.

kip


On Sun, 27 Jun 2004 14:56:07 -0700, Jack Twilley
wrote:

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I like the idea of the Whatt Meter, and I've seen them for sale at
hamfests and they look great. I started looking at the specifications
and I discovered some limitations which make it much less useful for
my needs.

The deep-cycle batteries I use have much more capacity than the ones
they use for electric flight (that's the original target audience for
Astro Flight's products), so that's a minus. Also, the battery
system I have currently installed will charge when it's not
discharging, which doesn't fit the NiCad model very well.

Ideally, the meter I want to use would resemble an automobile fuel
gauge in that it would have some idea of what "full" was (whether by
testing via full discharge or by entering in data somehow) and it
would be able to handle charging and discharging without being
rewired. The latter is the truly crucial bit, as the former can be
implemented with a PIC. The PIC could do much more, of course, but as
a bare minimum, I'd like to know how much capacity remains and how
quickly I'm using it.

Is there anything out there like this? Is there a schematic for the
charge/discharge data collection which would be suitable for my needs?
I appreciate any help with this idea, as it might turn out to be
useful for more than just me.

Jack.

"evans" wrote in message
...
I am a boater who uses deep discharge marine batteries. I purchased
from West Marine a gauge that measurea percent discharged, based on a
narrow voltage band. Voltage itself is not a good indicator. A battery
can show 12V and be almost dead.

Check out West Marine or Defender Industries.

kip


On Sun, 27 Jun 2004 14:56:07 -0700, Jack Twilley
wrote:

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...Ideally, the meter I want to use would resemble an automobile fuel
gauge in that it would have some idea of what "full" was (whether by
testing via full discharge or by entering in data somehow) and it
would be able to handle charging and discharging without being
rewired. The latter is the truly crucial bit, as the former can be
implemented with a PIC. The PIC could do much more, of course, but as
a bare minimum, I'd like to know how much capacity remains and how
quickly I'm using it.

Is there anything out there like this?

The lead-acid battery does show capacity by measuring voltage, but it
MUST have "rested" for some time. That is, no discharge or charging.

I don't know how long, for sure, but I think it is on the order of
hour(s); perhaps one or two. A fully charged battery will show just over 13
volts...13.2 or 13.3 I don't remember the exact number, I always go on the
web for the exact numbers, or I just use the approximation. A dead one will
be on the order of just under 12 volts. Around 11.9 or 11.8. There's lots
of info on the web. No other common type of battery has this type of a
voltage characteriscic.
73,
--
Steve N, K,9;d, c. i My email has no u's.