Can I run Navtex from a smallish dry battery?

[Guest]

I would like to leave my Navtex permanently receiving but don't really want to leave it connected to a main battery.
Will this instrument run from a "small" battery e.g. PP3 ?

Any experience/suggestions welcomed....

Bernie
HEXIE

 

[bedouin]

It's not really feasible to run Navtex from dry cell batteries - typically a Navtex seems to draw about 50mA - or about 1Ah/day. A PP3 battery - even if you could convince the Navtex to work off 9V, would power it for less than 10 hours. Even a pair of 6V lantern batteries could only power it for about 10 days - and that would get expensive.

Why don't you want to leave it connected to the main battery? The most likely alternative would be a dedicated lead/acid battery.

 

[billmacfarlane]

The NASA dual frequency Clipper Navtex consumes approximately 50 ma. Left on for 24 hrs means that it will consume roughly 1.2 A . Why would you want to use a dry battery ?

 

[Budgie]

I have my Navtex wired to a permanently live terminal on my circuit panel, i.e. directly to the battery, and I have an in line switch to turn the set off if required. Navtex sets are very low power and are designed to be left permanently on.

A separate battery would only seem to add complication.

 

[Guest]

Thanks for your tech help.
I want to leave it on to
1. have the latest info available when I go aboard and
2. avoid having to reprogramme the stations and messages

I'm just a little uneasy about leaving anything switched on that might flatten the main batteries or cause a short.

Am I right to assume that having all electrics turned off stops the electrolytic action and anode erosion?

Regards
Bernard

 

[bedouin]

Firstly - no the boat electrics have little or nothing to do with electrolytic action. I'm afraid your anodes will continue to corrode with or without batteries/shore power.

I would hope that any modern Navtex will retain its memory indefinitely after being switched off (at least for stations and messages) so leaving the navtex switched on is only useful for always having the latest messages. If you're coming to the boat from home then there are many other (better) sources of up-to-the-minute information you can bring with you.

There is nothing wrong with leaving equipment permanently switched on, provided that the wiring is correctly installed. Flattening the batteries may be an issue if you are leaving it for weeks - but assuming you've got 100Ah domestic batteries, that would power it for a couple of months without damaging the batteries, and adding say a solar panel would keep it topped up anyway. Shorts ought not to be a problem - that really is what the fuses are there for.

If you are concerned about the electrics then running a dedicated supply directly from the battery with a low-current in-line fuse (250mA) near the terminals is pretty well as safe as you can get.