charging voltage for handheld vhf

[actionoptics]

My Silva Star m-298 vhf has a mains charger with the output stated as 10.5 v 190mA
Will I do any damage if I charge it onboard through the 12 volt system which my battery monitor says sometimes the voltage is up to 13.6 v ?

 

[misterg]

My Silva Star m-298 vhf has a mains charger with the output stated as 10.5 v 190mA
Will I do any damage if I charge it onboard through the 12 volt system which my battery monitor says sometimes the voltage is up to 13.6 v ?

Almost certainly: "Yes"

Pretty good chance it would go with a bang, too. I believe they have nicad batteries which need control of current and/or voltage when charging.

 

[nigelmercier]

Almost certainly: "Yes"

Almost certainly: "No"

The voltage from the charger is likely to be a nominal voltage, and regulated in the unit itself. Measure the output with a voltmeter.

 

[maby]

Almost certainly: "No"

The voltage from the charger is likely to be a nominal voltage, and regulated in the unit itself. Measure the output with a voltmeter.

I would agree - most handies have the necessary charging regulators built into either the case or the charging base. I've never come across one that could not be charged on a standard car/boat 12v outlet.

If you are really concerned, have a look in Maplins - they have a range of adjustable regulated power adaptors designed to plug into a 12v car socket - one that can drive the charge input of a handie should not be expensive.

 

[Ruffles]

My Silva Star m-298 vhf has a mains charger with the output stated as 10.5 v 190mA
Will I do any damage if I charge it onboard through the 12 volt system which my battery monitor says sometimes the voltage is up to 13.6 v ?

Navtronics are selling a 12v adapter for £6 which suggests it just a lead.

 

[VicMallows]

Almost certainly: "No"

I would measure the open-circuit voltage from the charger (preferably with an analogue meter). Most likely it will be anything in the region 15-20v in which case I would happily connect the device directly to 12v DC. If I measured a voltage close to the stated 10.5v I would be much more wary.

 

[maby]

I would measure the open-circuit voltage from the charger (preferably with an analogue meter). Most likely it will be anything in the region 15-20v in which case I would happily connect the device directly to 12v DC. If I measured a voltage close to the stated 10.5v I would be much more wary.

I'm sure that the supplied charger is just a standard "wall-wart" crudely regulated brick. NiCad (or NiMh) chargers are relatively complex devices designed to deliver a constant current charge up to a defined point, then fall back to a maintenance charge level - not the sort of thing you get in a wall-wart. I would be as near sure as I can be that the charger circuitry is in the radio or docking base and probably able to accept input in a range as wide as 9v to 25v.

 

[William_H]

HH charger

Much depends on different types of chargers and batteries.
If it has niCad batteries and if a full charge is expected to take 24 hrs then the charger is a simple constant current type whose charge current is less than 10C (ie 1/10 of mAhr capacity of batteries) so giving a full charge and no harm if left on charge too long. In this case fit a resistor between the 12v supply and the radio charge input wire to reduce current to about 180 ma. A ressistor of around 22ohms rated at 1w max dissipation or more should do nicely.
If it has a fast charge capability then I would suggest a voltage regulator like an LM317 which can be adjusted to give 10.5 volts to feed into the radio. Or as said buy a regulator converter to give 10.5 volts.
The comments about "wall worts" does not always hold true these days as it is cheaper to make a wall wort with switch mode power supply and very good regulation compared to the old transformers. So if the plug pack or power supply is surprisingly light in weight then it is a switch mode type and thus the radio may be expecting a very well regulated accurate 10.5 volts. (so use a regulator from12v).
good luck olewill

 

[ChrisE]

My Silva Star m-298 vhf has a mains charger with the output stated as 10.5 v 190mA
Will I do any damage if I charge it onboard through the 12 volt system which my battery monitor says sometimes the voltage is up to 13.6 v ?

Yes or maybe no.

My HH VHF, an ICOM, needs a specific charger as the voltage is regulated by the charger not the unit. Others may be different.

 

[tawhiri]

Charging voltage

I would think it is similar to mine. I opened my battery case and there are 9 NiCad 1.2 volt batteries wired in series. These need 1.4 volts or more each to charge. 1.4V * 9 = 12.6V. In fact most modern chargers use a pulsed voltage with slightly higher voltage. In my case 16V.
NiCad batteries are no longer available in Europe since 2013. However NiMH are a good replacement.
If you have have either NiCad or NiMH then no worries, but if you have lithium-ion, you will have to use the correct charger as they can explode.