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jocoman
Samba Member
Joined: August 11, 2016
Posts: 427
Location: Ottawa, Canada
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 Posted: Fri Apr 28, 2017 12:15 pm Post subject: radio parasitic drain problem |
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Hi
I have been head scratching for a while on this one, so I am hoping someone has solved it.
My radio gets 12v from fuse 3 , but that is not enough as it needs another 12v on the remote line. I supply this additional 12v via the key switch circuit.
Life is good. If the key is not in the ignition no draw and if the key is in the ignition it pulls 95ma but who cares when the engine is running.
Now the problem:
I want to set up my camping battery. I plan on removing fuse 3 and running 12v from the camper battery to the fuse panel and "spade it into fuse 3. Now my lights will work but the radio will not as it needs that additional 12V! I don't think it is wise to run another 12v to another fuse location to supply the remote 12v. Can't figure out how to sort this out.
I hope this makes sense, any comments are appreciated. |
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chimivee
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Joined: September 23, 2009
Posts: 741
Location: Orange, CA
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| Posted: Fri Apr 28, 2017 1:02 pm Post subject: Re: radio parasitic drain problem |
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How about a switch?: Switch position 1, connected to ignition, for day-to-day driving; Switch position 2, connected to aux battery, for camping. Tap into the same circuit (formerlyl Fuse 3) that connects to the aux battery. This is how I have mine set up.
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86 Syncro Westy, etc |
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jocoman
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Joined: August 11, 2016
Posts: 427
Location: Ottawa, Canada
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| Posted: Fri Apr 28, 2017 1:18 pm Post subject: Re: radio parasitic drain problem |
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| I considered that but my concern is forgetting to flip the switch. That would have the radio connected to two different 12 v sources. I'm sure it would happen but maybe that does not cause any damage? Also you are going to have a 95 ma drain on the camper battery when in camper mode with radio off. |
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chimivee
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Joined: September 23, 2009
Posts: 741
Location: Orange, CA
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| Posted: Fri Apr 28, 2017 2:00 pm Post subject: Re: radio parasitic drain problem |
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| jocoman wrote: |
| I considered that but my concern is forgetting to flip the switch. That would have the radio connected to two different 12 v sources. I'm sure it would happen but maybe that does not cause any damage? Also you are going to have a 95 ma drain on the camper battery when in camper mode with radio off. |
I don't think it matters where the 12v supplies are coming from.
Yes, I suppose if you forget to flip the switch, then you'll drain the battery. But if you want to have the radio on, when the engine is off (battery not charging), I don't think there's any way around this risk. At least in camper mode, you kill your aux battery, and not your starter battery. Seems like 95mA would take a while - maybe at least a week - to drain (don't quote me on that). You might consider a battery alarms or low-voltage disconnect.
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-James
86 Syncro Westy, etc |
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jocoman
Samba Member
Joined: August 11, 2016
Posts: 427
Location: Ottawa, Canada
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| Posted: Fri Apr 28, 2017 2:08 pm Post subject: Re: radio parasitic drain problem |
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Another alternative is to have both the 12v main connection and the 12v remote connection tied together and go thru a switch and connect to fuse 3.
Switch off ->no drain, switch on -> radio from fuse 3 whether it is powered via the starter battery or the camper battery. Maybe have a blinking switch so when you turn the car off or turn in for the night you will notice the switch is on so you turn it off to avoid any drain.
Kind of a pain, but I don't think there is any elegant solution with today's modern radios with this remote lead. thanks |
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chimivee
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Joined: September 23, 2009
Posts: 741
Location: Orange, CA
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| Posted: Fri Apr 28, 2017 4:13 pm Post subject: Re: radio parasitic drain problem |
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| jocoman wrote: |
Another alternative is to have both the 12v main connection and the 12v remote connection tied together and go thru a switch and connect to fuse 3.
Switch off ->no drain, switch on -> radio from fuse 3 whether it is powered via the starter battery or the camper battery. Maybe have a blinking switch so when you turn the car off or turn in for the night you will notice the switch is on so you turn it off to avoid any drain.
Kind of a pain, but I don't think there is any elegant solution with today's modern radios with this remote lead. thanks |
I'm not sure I follow... but it's Friday, and I usually start fading by Tuesday. 
Blinking light certainly could help as a reminder. But with or without light, in the above scenario, are you saying that you wouldn't ever have it switched to the ignition? If you have it switched so at least one position is controlled by the ignition, then at least your battery is "safe" in that position. If not, then you must always rely on remembering the switch. Or am I misunderstanding?
Also, on many modern radios, the constant +12v wire is required to retain the memory. So, if this wire was also switched, you'd lose your settings each time.
For what it's worth, here's my experience with the radio switch:
In day-to-day driving, the switch is in the ignition-controlled position. So it shuts on/off w/ the van. I never think about it. When I camp, I flip it to the aux-battery position. Turning the radio on, coupled with other accessories is going to be a much bigger draw than 95mA, so that's the least of my battery draw concerns. Once I'm driving again, the aux battery will start charging, regardless of which position the switch is in. So the only real risk (for me) is after camping, when I come home, park the van, and forget the switch in aux mode. But, that's not likely, because I almost always have the radio on when driving. So if I shut the van off, and the radio is still going, I know I have to flip the switch.
Your mileage may vary.
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86 Syncro Westy, etc |
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kbeefy
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Joined: March 10, 2006
Posts: 600
Location: Central Oregon
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| Posted: Fri Apr 28, 2017 9:03 pm Post subject: Re: radio parasitic drain problem |
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95mA seems like alot for a radio turned off in sleep mode. Most modern vehicles, complete with radio and a dozen computers drawing a little current to keep everything alive only draw 30-50mA.
I'd suggest wiring it direct for a trial run.
The draw if the radio is off is very minimal. I have my radio wired to my house battery, so I have to turn it on and off manually. Ignition and starting battery are not part of the circuit at all.
My van can sit a month and still start fine. There is a small draw from the radio, sometimes I'll pull the fuse if it's sitting for a long time, or hook up a trickle charger occasionally. It hibernates for about 4 months during the winter.
If you find having it wired direct doesn't work for you, add a switch to the circuit. If both batteries share a common ground (chassis) the source won't matter much. Make sure the constant 12v is routed to the house battery to avoid drawing the starting battery down while jamming out and camping.
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Ace
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Joined: July 07, 2003
Posts: 1903
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| Posted: Sat Apr 29, 2017 4:15 am Post subject: Re: radio parasitic drain problem |
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| Having the radio ignition line always on will make it draw high standby current. |
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chimivee
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Joined: September 23, 2009
Posts: 741
Location: Orange, CA
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| Posted: Sat Apr 29, 2017 6:45 am Post subject: Re: radio parasitic drain problem |
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| kbeefy wrote: |
| 95mA seems like alot for a radio turned off in sleep mode. Most modern vehicles, complete with radio and a dozen computers drawing a little current to keep everything alive only draw 30-50mA. |
A modern aftermarket radio typically has a switched +12v wire (in addition to a constant +12v wire) intended to be connected to the ignition's ACC position. When power is going to this wire, it's not uncommon for the stereo to draw a lot of power, even when off. My Kenwood (circa year 2000) draws ~110mA when off, but switched power is on.
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86 Syncro Westy, etc |
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bluebus86
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Joined: September 02, 2010
Posts: 11075
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| Posted: Sat Apr 29, 2017 8:11 am Post subject: Re: radio parasitic drain problem |
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| jocoman wrote: |
| I considered that but my concern is forgetting to flip the switch. That would have the radio connected to two different 12 v sources. I'm sure it would happen but maybe that does not cause any damage? Also you are going to have a 95 ma drain on the camper battery when in camper mode with radio off. |
i got a radio like that, would drain the battery in several days, added a rocker switch next to radio. I now remember to never shut off radio with the stock radio knob, takes a change in habit, but for decade or more I have not forgotten.. a small light or bright color becoming visible when switch is on may help as a reminder to turn it off. just like remembering to turn off the headlights or the glovebox map light. an added bonus is I can play the radio without leaving the keys in the van!
good luck
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jocoman
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Joined: August 11, 2016
Posts: 427
Location: Ottawa, Canada
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| Posted: Sun Apr 30, 2017 5:05 am Post subject: Re: radio parasitic drain problem |
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| I think I will go with Chimivee's suggestion. (thank-you) The worst case is having the key in the ignition with the switch set to camping mode. Then the radio would be supplied with 12v from two different sources. Not sure what would happen. I'm thinking that maybe when I am in camping mode I would put tape across the ignition key to prevent me or anyone else from inserting the key. |
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Wildthings
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Joined: March 13, 2005
Posts: 50352
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| Posted: Sun Apr 30, 2017 9:19 am Post subject: Re: radio parasitic drain problem |
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| You can hook up many stereos so that both wires have full time power, but there is a special way to turn the stereo off so it is depowered. Sometimes you just hold the normal "off" button for a couple of seconds and sometimes there is another button to use. Check your owners/installation manual to see if your unit has this function. |
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jocoman
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Joined: August 11, 2016
Posts: 427
Location: Ottawa, Canada
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| Posted: Sun Apr 30, 2017 10:47 am Post subject: Re: radio parasitic drain problem |
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| No, mine unfortunately does not operate like that. however I was thinking of adding a 1 amp fuse on the switched remote lead so if the key ever goes into the ignition when in camping mode it should protect the radio and would not allow the batteries to equalize thru the radio before blowing . (I would think) |
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sciroccojim
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Location: NJ
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| Posted: Sun Apr 30, 2017 11:47 am Post subject: Re: radio parasitic drain problem |
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I've noticed that most modern head units draw a lot of power in the "off" position. Kenwoods and Pioneers (and probably others) require that you hit and hold the "source" button to truly turn it off....or push the button and pop the face out enough to disconnect it from the main unit. After that, the current draw is much lower.
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vwwestyman
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Location: Manhattan, Kansas, USA
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| Posted: Sun Apr 30, 2017 8:37 pm Post subject: Re: radio parasitic drain problem |
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I believe most all modern radios pull most of their power through the "memory" wire, and the other wire is just used to tell it to turn on.
If it were my van, I would wire the "memory" wire to a circuit powered by the camping battery.
I would then wire the "turn on" wire to the door chime circuit. This will, in all likelihood, only use a very small amount of power from the main battery, but will not require you to turn the van on to listen to the radio.
If you are really concerned, then have the door chime circuit trigger a relay that provides camping battery power to the "turn on" wire. That way, you'd be certain that the only juice coming through the starting battery was triggering the relay.
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1978 Champagne Edition Westy, repowered to '97 Jetta TDI
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Wildthings
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| Posted: Mon May 01, 2017 1:20 am Post subject: Re: radio parasitic drain problem |
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| The problem with using the "key in" circuit for the stereo is well, it requires that you leave the key in the ignition in order to get the stereo to work. This is something I wouldn't be comfortable doing in many locations. A lighted rocker switch gets around this or you could use a dummy key that would fit in the switch but not be able to be turned. |
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vwwestyman
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Location: Manhattan, Kansas, USA
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| Posted: Mon May 01, 2017 4:42 am Post subject: Re: radio parasitic drain problem |
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I guess I figure if I'm letting the key sit in the ignition with the radio on while camping, I'm also going to be very close to the bus and able to monitor it. Though it is pretty rare that I'd be camping and sitting and listening to the radio with music playing, so my needs may be different.
Though occasionally I do enjoy having a baseball game on in the background while relaxing by the campfire. However, again, I'm right there next to the bus.
You're right, that a strip of metal or plastic or something inserted into the switch would server to turn the radio on for these situations. Maybe a key blank kept in the Van as the "camping switch" and then it would go back to more normal use later with the regular key.
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President, Wild Westerner Club
1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
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