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Discussion Starter #1
I'm installing a ham radio in my 2017 Volt and purchased a low voltage disconnect box which will start a timer below 12.8 volts and either disconnect the radio after 2 mins or when voltage hits 12.4 volts, whichever comes first. Thinking into this prior to installation, I realized this system is designed for 12v ICE cars with an alternator that continually supplies 13+ volts to charge the battery.

Does anyone know the charging logic of the 12v system in the G2 Volt? Will my voltage ever drop below 12.8 volts while the car is on? If so, any ideas as to protect the battery with the ham radio connected directly to it? I cannot connect it through the fuse panel due to current draw concerns. I'd just hate to accidentally leave it on one day and return to a dead battery.

Thanks!
 

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I'm installing a ham radio in my 2017 Volt and purchased a low voltage disconnect box which will start a timer below 12.8 volts and either disconnect the radio after 2 mins or when voltage hits 12.4 volts, whichever comes first. Thinking into this prior to installation, I realized this system is designed for 12v ICE cars with an alternator that continually supplies 13+ volts to charge the battery.

Does anyone know the charging logic of the 12v system in the G2 Volt? Will my voltage ever drop below 12.8 volts while the car is on? If so, any ideas as to protect the battery with the ham radio connected directly to it? I cannot connect it through the fuse panel due to current draw concerns. I'd just hate to accidentally leave it on one day and return to a dead battery.

Thanks!
When the car is running, 12v is supplied by a DC to DC converter that never drops below 14.5v. Therefore is should meet your requirement of 12.8v since it is actively supplying power to the 12v all the time it is on.

When powered off and plugged in, the 12v battery is actively maintained as well.
 

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The volt is the wife's, I highly doubt my icom would be installed. But if I did, it would mimic my other gm install where a run a 100a relay controlled by a key-on source. This way, you get all the current you need direct from 12v battery and have protection from battery drain with RAP auto power off.
 

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Buy one of the Volt meters you can find on Amazon that plugs into the 12V adapters and watch it run.
I have one, and did the same.
It is different on the Volt as they keep the SOC at a lower target than traditional cars.
 

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When the car is running, 12v is supplied by a DC to DC converter that never drops below 14.5v. Therefore is should meet your requirement of 12.8v since it is actively supplying power to the 12v all the time it is on.

When powered off and plugged in, the 12v battery is actively maintained as well.
That voltage is true for the Gen 1, but the Gen 2 can be more like 13-13.5V when the vehicle is on. It does float around a bit though depending on conditions.
 

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I have a voltmeter plugged into the accessory power port all the time on my 2017 Volt. I have noted voltage readings while the Volt is powered on from 12.4V to 15.4V depending on the temperature and electrical accessories that are in use. The typical voltage observed is 12.6V to 14.4V. Based on a reading taken with a DVM I believe the plug in voltmeter is accurate to within +/- 0.15V.
 

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If you have Kenwood TM-D710, you can set it to auto-power off after a while. That what I did for my older Gen1. Other rigs may have this option.

73, N2GH
 

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The volt is the wife's, I highly doubt my icom would be installed. But if I did, it would mimic my other gm install where a run a 100a relay controlled by a key-on source. This way, you get all the current you need direct from 12v battery and have protection from battery drain with RAP auto power off.
+1

If you want to make things fancy, put a timer on the relay to keep it energized for a couple minutes after the accessory bus ("key on") shuts down.

Don't power the radio directly across the battery - the ground side has a current sense resistor between the chassis and Batt neg. Ground the radio to the chassis instead. The Volt monitors the state of charge of the 12V.

Short story: My brother was having trouble getting his truck to start when leaving work. The battery was getting well discharged from all the starter activity. I jumped my volt 12V to his truck battery, and just let the Volt run for about half an hour to charge his battery. Afterwards, the volt started showing error codes related to the 12V battery, but they cleared after a couple days.
 

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I use the cigarette lighter adapter to power my HT at 5w and the second one powers a small MFJ amp that outputs 35w. I don't remember the current draw, but seem to remember it was less than 10amps. At any rate, I've never blown a fuse.
 

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Discussion Starter #11
Thank you all for the responses. I apologize for the long delay in getting back to the thread, however I was away on business and didn't have time to post.

So a bit of a follow up, I installed the radio. So far everything has been working great. The Icom ID-5100 I installed has a built in voltage meter, so I can see the state of the battery at all times. On the Gen 2 this seems to bounce around a lot from as high as 14.5 volts, to as low as 12.5 while I'm driving the car. About 90% of the time the battery is at 12.8 volts, that seems to be it's happy spot. I didn't end up using the voltage cutoff device since it cuts off the radio at 12.8 volts and the Volt will drop below that while driving. I may eventually get a relay tied into the ACC bus, but I currently have a dashcam on what I believe is the only switched fuse in the drivers compartment. Also, the radio as an auto-off feature, so I can just use that.

I do have one final question though, as @brett_cgb mentioned the Volt has a current sense resistor between the batt and ground. I didn't take this into consideration before I installed the radio and wired it directly to the battery. I know very little about current sense resistors and Googling offers a mind-blowing amount of information. Basically my question is this; how important is it I bypass the resistor and ground directly to the chassis? So far everything seems to work fine with the car both on and off, however I don't want to be limiting my power or doing permanent damage to the electrical system.

Thanks again for all the great information. I'm happy to post pics of the install if anyone is interested in seeing them.
 

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I installed a 50W VHF/UHF (also and Icom 5100) and just wired direct to the battery and have never had any issue at all. In fact, I also installed that EV Power wiring mentioned on this site and have a 1kw Xantrex inverter in the car. This also runs off the 12v battery, which is kept charged by the DC/DC converter. I think you may be worrying too much.
 
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