MV21CV charger question

[Joe123]

Hello and new to the board.
I have a MV21CV radio that needs a charging unit for it. Will the Motorola desktop unit HTN9046D work with this radio? It is a Spirit model VHF.

Thanks,
Joe

[RadioSouth]

Yes, will work. Not all of the Spirits have the bottom contacts and in that case could not use as a drop-in, the battery alone will also work in that charger so you're still good. There was a drop-in retrofit to convert those without bottom contacts as well. As an alternate that radio will also work with transformer alone plugged into the side accessory connector (from memory HtN8232 ?) and sells for about $6. (10 hr. charge)

[Joe123]

Thanks for the reply's. I have not been able to find a adapter in stock any where yet as every one keeps telling me it is back ordered. I have noticed on the adapter it states 11vdc and 55ma is the output. Was wondering if I could use something say like a 12vdc 200mah adapter would it work without messing anything up? I have plenty of 12vcd adapters laying around, could just wire up a end. Would the 1 volt extra hurt anything? Also I am assuming if this were to work the battery would charge at 200mah correct?

Thanks,
Joey

[Tom in D.C.]

You can use a 12VDC transformer with no problems.
The current doesn't work that way. Current is drawn
by the battery charging circuit as required, so the
transformer you're going to use can supply UP TO
200 mA. As the battery's charge gets higher and higher
the internal resistance of the battery increases, and this
lowers the current as the resistance increases. Just don't
leave the transformer when directly connected to the radio
on for more than about 12 to 14 hours.

[Joe123]

Tom,
Thanks for responding. I now understand what your are saying about the charging circuit. If I understand correctly the original battery was only 600mah so the charge time would be about 10hrs correct? I purchased the newer higher capacity battery 1200mah so charging time would be about 20hrs correct assuming that the battery would be completely dead, am I correct on this?

Thanks,
Joey

[Tom in D.C.]

Yes, a higher capacity battery will require a longer charge time, but it won't be an exact linear relationship. In the absence of an automatic charger that will cut off the high charge when the battery's resistance reaches a certain level you can make good use of a cheap digital voltmeter. Your radio's battery probably has a nominal rating of 7.2 volts and has six cells, which works out to 1.2 volts per cell. In practice the actual cell voltage can run up to about 1.45 volts or 8.7 volts for the pack. What you want to do is to read the voltage after, say, ten hours of charging and if it's anywhere around 8+ volts to start using the battery because it's fully or nearly fully charged.

[Joe123]

Thanks for all the replys. I did wire up a adapter 12vdc and 200mah. On one radio I used the original Motorola adapter 11vdc and 55mah. After a 10hour charge I checked the batts and the one with 200mah adapter was warm to the touch and showed 8.7volts on the meter while the one the 55mah charger showed around 8.0 and was not warm at all to the touch. Also in another test I left both radios on for the same amount of time and the radio that I charged with the 55mah adapter went dead before the other. I am going to do another test hopefully tonight or in the next day or so. Can I safely assume that the radio with the 200mah charger is actually charging at 200mah or close to it? I did read through the reply's and i sort of understand about the linear charging thing. Am I right on this or somewhat off?

Thanks,
Joey