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Yet Another Battery Question



 
 
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  #1  
Old April 24th 06, 04:13 AM posted to rec.aviation.soaring
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Default Yet Another Battery Question

What is a sensible and safe FLOAT charge rate for a 14 V, 12 AH sealed
lead acid battery?

Thanks in advance,

Paul
  #2  
Old April 24th 06, 04:55 AM posted to rec.aviation.soaring
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Default Yet Another Battery Question

What is a sensible and safe FLOAT charge rate for a 14 V, 12 AH sealed
lead acid battery?

I am not clear on the question, so I will expand on the answer and hope to
cover the question. First, you mention a 14 volt battery rather than a 12
volt battery. The float voltage would be 16.1 volts. The float charge rate
would be equal to the self discharge rate of the battery , which is
typically .001 times the battery capacity, or .012 amps (12 ma).

The sealed lead acid battery can be left on float charge indefinitely.
However, that is assuming that there is no load on the battery. Putting a
load on complicates things.

Colin


  #3  
Old April 24th 06, 12:13 PM posted to rec.aviation.soaring
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Default Yet Another Battery Question

P. Corbett wrote:
What is a sensible and safe FLOAT charge rate for a 14 V, 12 AH sealed
lead acid battery?

Thanks in advance,

Paul


The "classic" glider "gel cell" which is 12 v and 7Ah typically likes to
see 13.8 volts if you're going to leave it on charge all the time.

I've used constant voltage battery chargers set at 13.8 volts for 10
years and never had a battery issue in flight. Plug it in and forget it.
  #4  
Old April 24th 06, 02:57 PM posted to rec.aviation.soaring
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Default Yet Another Battery Question

If you are talking about a 12 volt battery, then the float voltage is 13.8
volts and the current required to overcome the losses would be 12 ma.

You can use a constant 13.8 volts to charge it and then keep it charged,
however you should limit the initial charge rate to 1/10 of the total
capacity - which would be 1.2 amps.

You said 14 volt battery in your post, and the float voltage would be 16.1
for that.

Colin


  #5  
Old April 24th 06, 03:13 PM posted to rec.aviation.soaring
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Default Yet Another Battery Question


P. Corbett wrote:
What is a sensible and safe FLOAT charge rate for a 14 V, 12 AH sealed
lead acid battery?

Thanks in advance,

Paul


Why guess? The battery manufacturers post very detailed spec sheets for
their batteries, telling you exactly how to charge, float, etc.

John Cochrane BB

  #6  
Old April 26th 06, 02:22 AM posted to rec.aviation.soaring
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Default Yet Another Battery Question

The short answer is ZERO. Well, not exactly. Float charging is to
replace the charge lost by internal discharge, which is on the order of
2-3% per month.

The voltage mentioned by others is valid only at 25 C. This goes up
significantly in cold weather and drops in hot. This means your battery
is under charged when it is cold and you are over charging it when hot
- not particularly good for battery life. Panasonic specifies a voltage
of 14.1 V @ 0 C, 13.7 V @ 25 C and 13.4 V @ 40 C. A temperature
compensated battery charger should be used if you are charging at
extreme temperatures.

Tom

 




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