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Author Topic: radio set charging  (Read 828 times)

guitar man

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radio set charging
« on: August 13, 2011, 10:38:28 AM »

Hi all

I recentally purchased a charger to charge the 6volt lead acid in my boat though i don't seem very happy with it but that another story.My question is this, the  charger can switch between 6 and12 volt it came with a plug type adaptor which would fit my radio could it be used for charging the batteries in that I.e 8 times 1.5 volt AA size rechargable equals 12 volts or does it not work like would it still be a 1.5 volt charger required. Thanks in advanced for any help or information.


                              Regards Tony
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chingdevil

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Re: radio set charging
« Reply #1 on: August 13, 2011, 10:46:23 AM »

I am no expert but I would say no due to the different charging rates between a gel battery and nimH/nicads found in transmitters.


Brian
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Shipmate60

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Re: radio set charging
« Reply #2 on: August 13, 2011, 10:55:14 AM »

Tony,
Gell Cells and "Dry Batteries" require different types of charges ie constant voltage or constant current.
So unfortunately with that charger the answer is no.

Bob
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guitar man

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Re: radio set charging
« Reply #3 on: August 13, 2011, 10:57:52 AM »

Thanks both that was something that I had not even thought about, but seems obvious now it has been stated.



              Regards Tony
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malcolmfrary

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Re: radio set charging
« Reply #4 on: August 13, 2011, 11:04:05 AM »

It isn't 8*1.5 for rechargeables.  It's 8*1.2=9.6 volts.  Unless the charger has current limiting built in, rather than just having a transformer that goes bang when too much is asked of it, it will need something extra to limit the charge current.
The cells will charge to more than 1.2 volts, and can approach 1.5, but can also be damaged by charging at excessive current for too long.
Lead Acid requires a supply with limited voltage as well as limited current.  Nickel cells require limited current, but usually at a different value to that required by lead.
My RX charger consists of a 1.99 (back than) battery eliminator with a 50Ω several watt resistor inserted in one leg of the lead and covered in heatshrink.  As the voltage of the charging battery approaches that of the supply, the current drops.
Incidentally, to ensure charging of a 12 volt SLA, the charger will need to put out rather more voltage.  The 12 volt SLA will likely charge up to about 14 and a bit volts, the charger, to ensure that it can reach this, will need to offer a volt or two more.
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