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VHF Lo Battery warning

Old 08-31-2011, 11:27 AM
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Default VHF Lo Battery warning

Hey all!

I recently installed a standard horizon gx 1600 vhf. Love it, have connected it with my HDS 5, seems to be all set up great. Only issue, I noticed when I press the transmit button for a radio check, the lo battery warning lit up. I did get a successful check, but from relatively close range (about a mile), and it took a while to get a response. Not sure if that meant it was not transmitting, or if nobody bothered replying.

Anyhow, tested voltage at the batteries, and both batteries seem to be decent, with 12,7 and 12.8 volts. My motors fire up great, no other symptoms of low battery/voltage. It would be surprising to me that they drop down to <10 volts, which is supposed to be the trigger for the warning, when transmitting, yet have no other issues with other electronics or starting the motor.

I am thinking that a reasonable trouble shoot would be to check the voltage at the connection of VHF to battery switch during rest and transmission. Any other ideas, recommendations, etc...I am new to electronics, but trying to learn as much as I can as I go. Don't plan to be dangerous, but I do want to understand what is on my vessel, how it works and how to fix it when possible. Thanks in advance!

N
Old 08-31-2011, 11:31 AM
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Yes, check the voltage at the connections to the VHF while transmitting. You are getting a voltage drop from poor connections or wire that's too small for the distance and current. The voltage may be fine at the battery but low at the VHF when drawing enough current to transmit.
Old 08-31-2011, 01:09 PM
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Hey Ron, thanks for the reply!

Interesting wrinkle. I just got out there and checked...when I power up the VHF, all is well, no issues transmitting, no lo battery warning, 12.5 volts across the board. However, when I turn on my Lowrance HDS 5 and try to transmit, I get the lo battery signal when I try to transmit. They are connected via NMEA connection, but that is it. Why would the HDS 5 cause a lo battery signal on my VHF?

Would love to sort this out, as I don't think it is reasonable to turn of the HDS to transmit, and that would seem to defeat the purpose of DSC...

thanks
Old 08-31-2011, 01:12 PM
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Is the VHF and the HDS connected to the same fuse/distribution block?
Old 08-31-2011, 01:14 PM
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Originally Posted by ncor33 View Post
Hey Ron, thanks for the reply!

Interesting wrinkle. I just got out there and checked...when I power up the VHF, all is well, no issues transmitting, no lo battery warning, 12.5 volts across the board. However, when I turn on my Lowrance HDS 5 and try to transmit, I get the lo battery signal when I try to transmit. They are connected via NMEA connection, but that is it. Why would the HDS 5 cause a lo battery signal on my VHF?

Would love to sort this out, as I don't think it is reasonable to turn of the HDS to transmit, and that would seem to defeat the purpose of DSC...

thanks
Does the voltage actually drop to the VHF when the other device is powered up of does it stay the same but you have the message?

You probably have a #10 or so wire from the battery switch near the stern to the helm and another back to the battery negative. Everything at the helm is powered through these wires so if something is drawing a lot of current or there's too much resistance, the voltage will drop.
Old 08-31-2011, 01:22 PM
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I have 14g wire from the HDS and the VHF to the helm switch panel, running about 7 ft from my T top to the panel at the helm.. It is a panel with 8 toggle switches, wired to the battery. Not sure the gauge of the main wire from the panel to the battery switch, but both batteries and the perko switch at at the center console, wire does not run more than 3-4 feet from the battery to the toggle switch panel. HDS and VHF have their own switch and fuse. The panel really has nothing else turned on. The livewell and washdown pumps are wired to the toggles, as are my running/courtesy/anchor lights. But nothing else is operational when I have been using and testing.

I will get back aboard tonight and test what happens at the VHF with the HDS on and VHF transmitting. I am assuming the message is accurate and the voltage drops below 10, as it seems it would be odd to get that specific of a message without some change in voltage (as it works normally without the HDS on).

Thanks for your patience, new to electricity/12v stuff, but enjoying the learning. Hopefully my status as a novice did not lead me to a shoddy install.
Old 08-31-2011, 01:42 PM
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Try to get an estimate for the length of the wire from the panel to the battery switch along with the guage. The guage should be "inked" on the side of the wire including the wire type. I ran a separate fuse block for my electronics as the wire size from the battery to the factory installed panel was 12 guage that was 25' in length (actually 50' when computing voltage drop). I ran 8 guage to the new fuse block as I have 2 screens, 2 black box digital sounder units, VHF and a Radar connected to it.
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Old 08-31-2011, 01:55 PM
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you know what, now that I think about it, i have had funny issues with the washdown pump coming of that distribution panel. sometimes the sucker does not fire up. today it worked fine on the trailer....but, i am wondering if i have more than one unit operational off the panel if the voltage drops enough to keep the pump from functioning, trigger the low bat warning on the VHF, etc...

if that is the case, a wire to the battery of insufficient gauge could be the culprit, right? too much resistance on the smaller wire to power multiple electronics/pumps off one distribution switch? does that make sense? if so, and i find 10 or 12 or even 14 g wire connecting the panel to the battery, just switch it out to 8 g for a quick and easy fix, right!?

thanks
Old 08-31-2011, 02:06 PM
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Originally Posted by ncor33 View Post
you know what, now that I think about it, i have had funny issues with the washdown pump coming of that distribution panel. sometimes the sucker does not fire up. today it worked fine on the trailer....but, i am wondering if i have more than one unit operational off the panel if the voltage drops enough to keep the pump from functioning, trigger the low bat warning on the VHF, etc...

if that is the case, a wire to the battery of insufficient gauge could be the culprit, right? too much resistance on the smaller wire to power multiple electronics/pumps off one distribution switch? does that make sense? if so, and i find 10 or 12 or even 14 g wire connecting the panel to the battery, just switch it out to 8 g for a quick and easy fix, right!?

thanks
Or corroded connections that were not properly heat shrunk.
Old 08-31-2011, 02:15 PM
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good times.

my plan is to rewire this vessel one wire at a time. already put in 2 auto bilge pumps with new, clean wiring and to dedicated 3 way switches at the helm, cleaned up nice, safer and fully functional. was planning to do the same with each wire, as the boat is 15 years old. so, i get to spend some quality time under the console! it is fun to know exactly where every wire goes, how it was connected and that it is new and non-corroded. doing it slowly is pretty straightforward as well. it is nice to see that this will likely improve performance immediately, as well as be cleaner, easire to maintain and more aesthetically pleasing.

N
Old 08-31-2011, 02:32 PM
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There is more than just running new wire to the panel. You will need a fuse within 3 feet of the battery, and the fuse being used now especially if it is an in line fuse, the wire guage maybe too small as well as the fuse. You will need to calculate your total electrical draw, voltage drop and size the wiring and fuses accordingly. I believe West Marine has a form on their website to do the calculations. This is just a couple of examples of some things you will need to know and would suggest the help of a qualified electrician or at the least purchase a book on marine wiring such as a BOATERS ILLUSTRATED HANDBOOK TO WIRING buy Charlie Wing. I received this book from one of the Electrical Engineers who works in one of the departments I manage as I was constantly asking him for advice. All wiring needs to conform to ABYC standards. A little home work up front on your part will ensure your project will go smoothly and prevent frustrations along with problems later on.
Online help on a forum can only go so far as each situation is a little different.
PS: Only use wire and connectors that are rated for marine use (tinned) along with sealing all connections with heat shrink. I bought a heat gun at Harbor Freight Tools for $10.00 and it works great for heat shrinking connections.
Old 08-31-2011, 02:35 PM
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Originally Posted by The Hat Island Pirate View Post
There is more than just running new wire to the panel. You will need a fuse within 3 feet of the battery, ...........
Seven inches per ABYC. Unless it's in a "sheath".
Old 08-31-2011, 02:43 PM
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Originally Posted by rwidman View Post
Seven inches per ABYC. Unless it's in a "sheath".
Thanks Ron.

Thats why you need to seek professional help or buy an updated book that is ABYC compliant.
Old 08-31-2011, 02:55 PM
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thanks for the recommendation on the book!

for "re wire", my plan has basically been to simply replace with newer wire, using marine safety wire. got a big 'ol roll of the duplex tinned wire from west marine. currently, there are fuses within 7 inches of the batteries currently. i have been using waterproof butt splices with a crimper and heat shrink already.

i know this is a job for experts, but i plan to be as safe and thorough as possible. on a 1996 21' center console, the good news is that there is not a lot of wiring to deal with, all 12 v. the original wiring will be used as a template.

basically, i have the following done:

2 new auto bilge pumps installed, to dedicated toggle switches, straight to power with in line fuses (each to a different battery) with marine grade bilge pump wire from west marine. fully functional, looking good if i do say so myself
replaced all gauges on the instrument panel
installed the HDS 5 and VHF to the distrubution panel

work left to do
rewire the washdown and livewell pumps with the duplex safety wire back to distribution panel
likely new wires from distribution panel to power.

the wiring from battery to switch looks ok, no signs of corrosion, no excess play at the connections. the perko switch works fine. there is a nice panel with ring connections for all the ground wires.

thanks for the advice, and wish me luck!

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