Simple Electronics Question

[bighammer]

I got a handheld marine radio cheap. It takes 8 AA batteries instead of a rechargeable pack. Since 8 batteries would make 12 volts, can I just remove the AA cells and run a line to the boat's battery? or would it be too much current?



I just don't want to fry it before I get to use it.

 

[Will24]

The radio only draws as much current as it needs, just make sure you have the proper fuse in the feed to the radio from the boat.



Is there an AUX power jack on the side you could just get the proper plug for so the thing's not hardwired?





-Will

 

[bighammer]

Thanks Will, that's what I thought. There is a jack, but the radio has been discontinued, and doesn't include much info. I haven't used it yet, so it might be crap anyway. It was about half the price of other ones. I don't need anything loaded with features, or even a real long range. It's just to keep in contact with other boats in our group.

 

[illflem]

Just because there are 8 batteries it doesn't necessarily mean it's 12 volts. Make sure the batteries are in series, positive to negative on all of them or you could fry the radio.

 

[Motorhead]

Because the radio is old doesn't mean that you can't get a power jack. Go to Radio Shack and they can fix you up. GENERALLY..... the center pin is positive but take it apart and make sure or it will FRY . I look on the internet and research sealed lead acid batteries. They are cheap and rechargeable and could be attached to the back for portable use. Try this site.

www.batteries4everything.com Chris

 

[bighammer]

I bought it brand new, it's just a discontinued line. It's a Hummingbird VHF5. I just opened it up and the jacks are for speaker and microphone.



I might open the case and see if there is room for a jack someplace. I think it would be pretty easy to add and if done right would disconnect the batteries from the outside source.



I got 2 of them for gifts for a couple boating friends I run with. I get tired of trying to use sign language at 50mph They were about half the price of any other hand held radio.

 

[Motorhead]

I would open up the battery compartment and trace where the two wires(+,-) hook to and tie in a female battery jack with a short pig-tail bringing it out of the battery compartment and then build up a fused extension with the cig liter jack on one end and the male plug on the other.

 

[Rotty]

This almost sounds like an engineering joke, that can even catch the best of them. You have a 12v unit and connect a 12vdc 1000 amp power supply to the UUT (unit under test). Does it burn up?



Start with a volt meter and check to make absolutely sure of what the polarity is.

Them make the proper connections with an inline fuse at ~ 1. 5 times the max current. You may also have to install an power inductor (noise filter) if it is to noisy from the boats alternator.

You can also use nicads but the max power will be less because of the lower voltage of nicads. DO NOT put in more than 13. 6 volts ever if it is max rated for 12vdc. Just be methodical and absolutely sure of the polarity before you connect to any power source. There are tricks to get around this, send me a PM and I can give other possible solutions. This is a sure way to fry your purchase before you even get to use it.

Always ASSUME the worst and hope for the best.

Also, don't assume that the cigarette lighter socket is wired correctly, a multimeter(DMM) is your best friend. Learn how to use it properly and you can troubleshoot most electrical problems.