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[aprssig] Kenwood TH-D7 Batteries (and Icom,Alinco,Yaesu)

Greg D. ko6th_greg at hotmail.com
Tue Aug 19 04:46:00 UTC 2008


Hi folks,

A related question...  If I do use the internal charger, is it going to be enough?  I received an off-list rememberance that NiMH batteries don't like being charged slowly, and by my measurements I'm getting about 69ma of charge current out of the radio.  That works out to a charge rate of C/39 if I fill the battery pack with Sanyo 2700 mAh batteries.  

If it's too slow, is the "charger" circuit simply a diode and resistor (that I could modify)?  Anybody ever look inside a D7 for modifications?  I don't see anything relevant on the Web...  Any clue where it would be?

Greg  KO6TH


----------------------------------------
> From: ko6th_greg at hotmail.com
> To: aprssig at lists.tapr.org
> Date: Mon, 18 Aug 2008 17:31:59 -0700
> Subject: Re: [aprssig] Kenwood TH-D7 Batteries (and Icom,Alinco,Yaesu)
> 
> 
> Hi folks,
> 
> Recalling this thread from long ago...
> 
> I understand that the BT-11H pack from Batteries America has a charge-inhibiting diode built in, to protect standard AA cells from inadvertent destructive charging.  But if I only am using NiMH cells, and promise to be good, would it be possible to short out the diode and properly charge NiMH cells from the radio?  I know it will take a while (two days, perhaps), but I'd rather not have to carry the charger around.  
> 
> Thanks,
> 
> Greg  KO6TH
> 
> 
> 
> ----------------------------------------
>> Date: Thu, 8 May 2008 11:15:35 -0500
>> From: schiers at netins.net
>> To: aprssig at lists.tapr.org
>> Subject: [aprssig] Kenwood TH-D7 Batteries (and Icom,Alinco,Yaesu)
>> 
>> A frequent concern of Kenwood D7 (aprs dual bander with built-in TNC) 
>> owners is batter life. I have found dramatic improvement in battery life 
>> using the item(s) described below.
>> 
>> While perusing May QST, I ran ran across a nice 6 cell AA battery case 
>> for the D7 and G7 handhelds at Batteries America. Unlike the 4 x AA 
>> battery case that has been available for quite a few years, this one has 
>> six slots, and can be ordered with a spring belt clip that fits all the 
>> standard D7 battery cases.
>> 
>> The problem with the 4 cell case is if used with NIMH recharging 
>> batteries, the D7 only runs for a very short time, no matter how high 
>> the capacity of the batteries, as 1.2 x 4 = 4.8v, and even at the peak, 
>> 1.4 x 4 = 5.6v. The intended purpose for the original 4 cell AA pack was 
>> alkalines where 1.6 x 4 = 6.4v, which is much more acceptable for the D7.
>> 
>> With this 6 cell case and NIMH batteries, one gets 1.2 x 6 = 7.2v, which 
>> even at the terminal (low end) voltage of the recharge cycle life is 
>> adequate for the D7, and I have found that after recharging my 2500 maH 
>> AA NIMH Energizer camera batteries produces about 8 volts from the pack, 
>> and will run my D7 in packet mode, dual receive all day and then some. 
>> (I'm on my 2nd day, shutting down just to sleep)
>> 
>> Another nice feature of the pack is that it uses a sliding drawer access 
>> to the batteries, and of course, fits both the d7 and g7 just fine.
>> 
>> I own several of the high current 7.2v 1800 maH Maha packs which work 
>> well, but not nearly as well as this 6 cell AA pack with 2500 maH AA 
>> cells. The model number is BT-11H for the Kenwood D7/G7 Handhelds. 
>> $24.95 (no batteries).
>> 
>> I  have a dozen 2500 maH batteries laying around, which gives me two 
>> packs, one for the radio, the other for the charger. I no longer run out 
>> of battery power for my D7...and have been experimenting with the 
>> Energizer 15 minute charger (with AC & Car Cord) and find it works very, 
>> very well. I do have reservations about how hard this is hitting the 
>> batteries (even with the built in cooling fan on the charger) and their 
>> ultimate lifetime, but only time will tell. (Wal-Mart, $30.00 with 4 AA 
>> cells)
>> 
>> I ordered on line from Batteries America, and received my cases/clips 
>> within 3 days.
>> 
>> www.batteriesamerica.com is the web site. I have no connection to them, 
>> other than being very pleased with this new 6 cell AA case for the D7 
>> and G7.
>> 
>> I'm also going to test the newer MAHA MH-C9000 Advanced Battery Charger, 
>> which has a large display, 4 independently configurable charging slots 
>> (AA and AAA only), and loads of other features like the C777 model. It 
>> recharges AA cells in one hour, which should be easier on the batteries 
>> than the Energizer 15 minute unit.
>> 
>> http://www.thomas-distributing.com/
>> 
>> Price: $59.97
>> 
>> I hope someone finds this info useful, even for other handhelds, as 
>> Batteries America lists similar custom AA cases in their May QST ad for 
>> Icom, Alinco and Yaesu handhelds, many models. (4th from last page, left 
>> hand column, adjacent to the Index of Advertisers)
>> 
>> 73,
>> 
>> ...hasan, N0AN
>> 
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> 
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