[Motorola] NTN1171A Rapid Charger for HT1000 Radios

[KB0NLY]

I know of 1171A's being used to charge NiMH batteries but I don't know for 
sure if its Motorola recommended.  I do know that generally the ones with 
four contacts are rapid chargers with the thermal sensor input that can 
handle NiMH, the three contact models are just dumb slow chargers though 
some of the three contact models had a circuit in them that would light an 
LED and turn it green based on battery voltage or current draw to indicate 
fully charged, its been a long time since I went over the schematics for 
one.

One thing I always hated about the 1171A is that when the light goes green 
the battery is only about 80% charged, so most people that are in a hurry to 
charge it won't ever fully charge the battery.  You have to let it go green 
then wait another hour or so.  What I would do is put your NiMH battery in 
the 1171A and closely monitor it and see if it starts getting hot, if it 
does then don't use it for NiMH.  The NiMH chargers really only add a 
thermal sense input to let the charger know if the battery is too cold or 
too hot and stop charging.


73,

Scott KB0NLY


-----Original Message----- 
From: eric lemmon
Sent: Saturday, July 5, 2014 9:20 AM
To: Motorola-Radius at yahoogroups.com ; 'Discussion of equipment manufactured 
by Motorola'
Subject: [Motorola] NTN1171A Rapid Charger for HT1000 Radios

I have several NTN1171A Rapid Chargers for HT1000 portable radios.  I
noticed that some of them have four spring contacts while others have only
three.  I opened one of each to see what was different.  The three-contact
PCB has a part number of 8480648C01-P6, while the four-contact board has
part number 766V-A.  There are significant differences between them in
component count and layout.

I know that the NTN1171A charger is to be used only with NiCd batteries, and
was replaced by the RPX4747A charger, which can charge both NiCd and NiMH
batteries.  The RPX4747A is now NLA, so I can't examine its PCB to see if it
might resemble the 766V-A PCB.  Neither my HT1000 nor my Visar manuals
include any information about the NTN1171A or the RPX4747A chargers.

I am well aware that a NiMH battery can be toasted if placed in a NiCd-only
charger, and I don't want to risk damaging a new NiMH aftermarket battery.
I wonder: Is it possible that the four-spring version of the NTN1171A is
actually an early embodiment of the RPX4747A?  Moreover, is it safe to use
the four-spring NTN1171A to charge NiMH batteries?

73, Eric Lemmon WB6FLY


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