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Old Dec 30, 2012, 02:40 PM
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Help!
12 Volt on 10.8 circuit?

I have Futaba FG FP-T7FG/K FM radio that is used to remote control a moving target.
The radio is on for several hours during the course of the match. I'm not getting a long life of of the "normal' battery pack and as you know they are not "quick-swappable"
My battery pack is 10.8 V DC. Is it possible to run this radio off of an external 12 V DC portable battery without hurting the radio?
This radio has been a great work-horse and has a very good range which is ideal for my club shoot.
Thank you for any info.I did a search and found no info.
Rob.
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Old Dec 30, 2012, 02:53 PM
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United States, CA, Brentwood
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Someone's going to ask, so I will first, what MA is the stock battery? Might just be a low Ma battery and throwing a LiFpo high capacity might just be the ticket.
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Old Dec 30, 2012, 02:55 PM
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2500 mAh
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Old Dec 30, 2012, 03:01 PM
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United States, CA, Brentwood
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Have you tried cycling it to see if it's still at 2500? I can fly for a month on my radio with a 2600..
Having said that, yes you could hook up 12vdc to the trans, but I'd probably put a diode in line to drop it a volt.
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Old Dec 30, 2012, 03:20 PM
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Haralson County GA. USA
Joined Oct 2004
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Sanyo Eneloops.
Do a search.


A 12V Pb (Lead acid) charges to over 14V and would damage the transmitter. You could modify the transmitter but 8 Sanyo Eneloop AAs and a Raduio Shack cell holder is only around $20.

Charles
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Old Dec 30, 2012, 05:07 PM
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The problem is the lack of room in the battery compartment. The original battery cells are 1.2 V DC and there are nine of them.
I have batteries at work which are sealed medical grade 12 V DC lead-Acid and use a voltage regulator to drop the output voltage to 10.8 V DC. These batteries are the size of your fist and can produce 2.5 Ah.
I'm not sure what the current draw of the radio transmitter is.
Thanks for the ideas so far..
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Old Dec 30, 2012, 07:08 PM
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The Northeast Kingdom, Vermont
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If the radio uses a 9 cell battery, then there is absolutely no problem with running it directly off of a 12V lead acid battery. A 9 cell Nimh packs nominal voltage is 10.8V, but its full charge voltage in a bit over 13V, very close to the full charge voltage of the lead acid battery. If the radio uses an 8 cell battery, then using a regulator is a good idea.
Not to be a kill joy, but there's more than a good chance that radios on an old frequency and no longer legal for use in the US.
Pete
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Old Feb 08, 2013, 04:16 PM
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Thank you for the replies. I went with a 12 volt voltage regulator adjusted down to 8.5 volts. The batteries lasted for six hours of "on" time which worked out just right for my shoot.
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