Remote start messing up avic

[joegr]

You would need 2 relays to properly isolate.

 

or just a relay & a diod, diods only allow power to flow in only one direction eliminating any back flow and isolating the circuit, also if you are using the constant power circuit as the source of power for the relay and ACC to trigger the relay and the acc wire on the AVIC is just hooked up to the relay and not multiple sources, 1 relay will be enough

 

Back to the battery issues...when I said deep discharge will occur in a previous post, there was no mention of a diode at the time, without a diode "DEEP DISCHARGE WILL OCCUR". But depending on where you vehicle's voltage regulator's voltage cutoff is, keep in mind by adding a diode into the circuit to isolate the battery from the rest of the car, may not allow the GELCEL to charge properly. This is due to the forward voltage drop of the diode which is typically .7 volts. The vehicle voltage regulator is monitoring the voltage of the vehicle without the diode, and won't see the GELCEL's voltage isolated by the diode. A 12V GELCEL(lead acid without venting) requires 13.7 volts to charge it and 13.4v to float it. So add .7v to this and we have 14.1v to 14.4v. The vehicle voltage must achieve at minimum of 14.1 volts to float the GELCEL and 14.4v or better is ideal to charge it. And if your vehicle doesn't provide these minimums, the GELCEL will have a shortened life cycle. But if you know for sure the ACC is losing power during crank...which is what also happens to my vehicle put in the 528T delay relay because it won't matter what the cranking voltage is or how long it takes to crank because the AVIC will never be powered up before crank or during crank. The battery..is much bigger, too heavy even a small GELCEL weighs several pounds(its lead!) so it requires a strong mount, you must fuse it, too expensive, needs an additional relay anyway, requires periodic replacement and the diode charging issue. Why go through all this hassle with a battery/fuse/diode/relay combo??? I say again go with the 528T for the only viable, reliable, cheapest, easiest solution!!!

 

That's funny, my solution (with a NiCd battery) has been viable, reliable, and very cheap for the last year or so. The added benefit of the slightly shorter boot time (since it continues to boot while the engine is starting) has been very minor. The added benefit that I can stop for gas, and then restart the car without ever having to reboot the AVIC has been major. I have also never experienced any of the flash corruption type issues that some in the forums have. I can't say that this is only because of the clean, no dropout power provided to the AVIC, but it can't be a bad thing.

People who say that their way is the only way for everyone are almost always wrong!

[ot1]

Its a nice idea to be able to pull into a gas station and shut off the car to fill up while the AVIC is still running. What timer are you using to control the shut off time since a fillup will last more than 5 minutes? Im guessing a fillup takes 8-10 minutes on average. We are not taking about having NASCAR fillup capability.

 

Also charging a NiCAD directly from the car's charging system is very risky. The vehicle charging system is designed for lead acid cells not NICADs. A charger specifically designed to operate off the vehicle voltage but have the correct charging characterics for NiCads should be used to prevent thermal runaway, hydrogen gas build up, cell destruction, fire, etc. Keeping this in mind, I dont see how a NiCAD charger, 12v NiCAD battery pack, and relay is cheaper than just a suggested 528T. A diode is no longer needed because the NICAD charger will isolate the battery pack but you still need a fuse.

 

So the NICad IS viable with the proper charger, but how is it cheaper? and it certainly isnt smaller, and if your goal is to power the AVIC for 10 minutes after the car is shut off you still need a delay relay too.

 

For that matter you could use a GELCEL to accomplish the same thing, eliminate the diode, eliminate the special charger[the vehicle charger is designed for GELCELs], and use a relay to isolate the GELCEL from the vehicle voltage while the vehicle is off, and a time delay relay on the output to cutoff the AVIC after 10 minutes or more. This would be cheaper that the NICAD solution, because no special charger is required, and a 4 amp GELCEL will be half the price of a 2 amp NICAD pack and about the same size.

 

The drawbacks for a battery backed AVIC are cost, and size[space and mounting locations available in the vehicle], BUT I DO ADMIT USING A BATTERY WITH THE PROPER DESIGN IS VIABLE.

 

My design would use an input relay instead of a diode. I don't have to fuel up very often[diesel] but there are days when I am in and out of the vehicle alot, so I would need 20-30 minutes of AVIC UP time. I would use a DPDT input relay to control the mute wire too, so the audio is silenced while the vehicle is OFF for that 20 minutes drawing even less power from the GELCEL, this would also charge the GELCEL properly when the vehicle is running. Maybe even use a 3PDT to dim the display too while the vehicle is off and AVIC is UP.....

[joegr]

1. The timer is built into the car. Radio power stays on until the driver's door is opened, or ten minutes after the key is turned off, whichever is first. However, when stopping for gas, I turn the key to the engine off, accessory on position, so none of that matters. Does you car not have this simple feature?

2. The NiCd is being correctly charged via a cheap circuit with a current limit resistor and a diode. It's not like I am an EE with many years of experience, oh wait, I am.

3. From your earlier post, I would like to correct your notion that gel-cell batteries don't vent. They do indeed vent when abnormal circumstances arise, such as a short circuit on the output or a overvoltage charge condition. Consider yourself warned.

 

The whole point here is that it is absurd for me to claim that my solution is the best one for everyone out there. It is also absurd for you to claim that yours is the best solution for everyone out there. Grow up. Present the options, leave out the "my way is the only way" crap, and let people choose.

[ot1]

Hi Joegr,

 

If your built in timer allows the radio to operate for 10 minutes after you turn your car off and you turn the ignition back to ACC position before you open the door within this interval, do you even need a battery backup to provide uninterrupted music/GPS during a fillup?

 

No, I do not have such a timer built into my vehicle, the only timer that exists is one that keeps the courtesy light on for 30 seconds after you open a passenger door, the driver door opening does not start courtesy the timer. None of the cars or trucks I drive have the simple timer feature you describe.

 

I like others, dont pay with a card(many diesel pumps dont even have a CC swiper on them) thus requiring one to leave the vehicle unattended, with the keys left in the ignition....another safety issue which could lead to your vehicle being stolen, leaving the keys in the ignition wouldn't work for me.

 

Sorry for using the words "My"...but I wanted to differentiate "My" idea for a design vs. others.

As I admitted the battery was viable but I somehow thought cost played a role in the design, and NOT whether there was any UP time after the vehicle was turned off, after rereading my post...it did sound a bit arrogant, that was not my intention. I was trying to present a design with the least overhead and provide the most safety to readers who are not engineers, a design flexible enough to work for most.

 

The original poster did say "the battery was overkill", but to others I realize function and not cost is a consideration.

 

 

Back to the GELCELs...I said "lead acids without the venting" which is still true, not sure why you are correcting me. The GELCEL battery is sealed non-vented battery as described by the manufacturer. As a matter of properly designed use, they do not vent, external venting is not required in the design, and the manufacturer does not provide a venting line attachment. The GELCEL is recombinant battery requiring positive internal pressure, and if it were to have venting, the battery perfomance and life would be greatly reduced. Its vent seal is only a safety feature to keep the battery from exploding if it is overcharged, or yes short circuited but, as I mentioned in a previous post, one needs to install a fuse on/next to the battery. But under nomal circumstances they do not vent as opposed to the lead acid car wet cell battery which does require venting to the outside of the vehicle at all times to allow hydrogen to escape during normal charging. Wet cell car batteries mounted within the interior of the vehicle all provide a vent line attached directly to the battery for external venting to the outside. Most car batteries also require an upright mounting position, while the GELCEL mounting position is not demanded by the manufacturer of the GELCEL(of course depending on terminal configuaration). Even NICADs will vent if they are improperly charged but like the GELCEL are not considered vented batteries.

[joegr]

"If your built in timer allows the radio to operate for 10 minutes after you turn your car off and you turn the ignition back to ACC position before you open the door within this interval, do you even need a battery backup to provide uninterrupted music during a fillup?"

 

The whole point is not to have music during the fill-up, it is to have working navigation when leaving the gas station, instead of two minutes later.

 

The battery is needed because the car's main battery's voltage goes below 10.5V while the starter is going. That's the whole problem that started this thread. If the AVIC is running or booting, and its power voltage goes below 10.5V, then it does a sudden, improper, shutdown and this can corrupt its FLASH memory. Normally, when you switch off the accessory lead, the radio still has full 12V power that it uses for part of a second to do a proper shutdown.

 

Actually, the simple feature I referred to is the accessory position on the ignition switch, not the timer. The switch has four positions. Off, accessories on, engine on, and start. Therefore, there is no need for the timer when switching from engine on to accessories on. I do pay at the pump, however I do sometimes also lock my car while the key or the engine is on. There is a keypad on the outside of the door that will unlock it if I enter the right code. That is a very handy feature.

 

Sorry about the gel-cell comment. It stems from a misunderstanding that some people that I know have with those sorts of batteries. My car has the battery in the trunk. The OEM battery has a vent tube connected to it that runs to the outside of the car. This reduces the possibility of an explosion in the trunk. Several people go out and replace the stock battery with one of the "sealed" gel-cell batteries, not realizing that the battery will still vent hydrogen should something go wrong.

 

 

 

Re cap:

Problem: AVIC crashes when power voltage falls too low when it is running or booting.

 

Solutions: (1) Wire the AVIC so that it is never powered while or just before starting the engine. Relays may be required. (2) Use a backup battery so that the AVIC always gets a full 12V, even when the engine is starting. Electronic components required.

[gschade]

Another easy solution to the gas station problem if you have a diesel is to leave your car running.

 

I am planning to install a Avic in a TDI and I would like to have it powering up while the glow plugs are warming up. The battery option listed here with a diod sounds interesting. I'm not an EE major so I might need a little more help to make it work. Joegr, thanks for the idea (I already had a simillar idea, and had already come to the conclusion that a separate battery rather than a capacitor is what I would need).

 

Joegr, can you give us a parts list and a simple diagram for how you created your solution? I would very much like to try to recreate it on my setup.

[joegr]

See attached

 

AVIC.pdf

[ot1]

Although its pretty safe filling up diesel with the engine running, out of habit I usually shut off the engine because i go inside to pay, and I can't lock it with the remote with it running....but im thinking more about the battery idea because whenever I go to a drive up window, I have to shut off my vehicle when i order because they cant hear me. Or if I want to pull over into a rest stop or talk on the phone...and switch to ACC the AVIC wont have to reboot. Glow plugs...mine take 30-40 secs in the winter...and sometimes i have to cycle them 2 or 3 times if its cold out like below 10F, the battery really makes sense in the winter..something I didnt think about yet.

[gschade]

Thanks for the awesome diagram. You rock!

[gschade]

Sorry to go a little off topic here. Looking at the diagram I am wondering if I could somehow use the door locks or dome light to power the acc line. Then my remote unlock would startup the AVIC. Then by the time I'm in the car belted in and ready to start I might already have navigation and music.

 

I'm just not sure how I would make it stay powered once the dome goes out from closing the door. Also how to make it actually turn off when I turn the key off.

 

I'm also not sure from the diagram how the 2x transistors work and why they are necessary. I wasn't expecting them (which led to me question above as I pondered what they were for)

[1loudls]

the transistors are to use the cars ACC trigger to turn the radio on and off by using the power stored in the battery.

the dome light idea wouldnt work because it would reset when you go to start the car and you would still have the same problem, either makeing the battery device or geting a remote start would be a better option

[gschade]

the transistors are to use the cars ACC trigger to turn the radio on and off by using the power stored in the battery.

the dome light idea wouldnt work because it would reset when you go to start the car and you would still have the same problem, either makeing the battery device or geting a remote start would be a better option

 

If I understand you correctly, transistors are so the ACC is powered from the supplemental battery (but still controlled by the ignition key). This prevents the cranking of the engine from dropping voltage on the ACC and causing the radio to shutoff. The transistors basically cause power to remain constant on both ACC and 12V. I'm not sure the drop in ACC would cause it to shut off. I thought it was just the main line that was the problem. Anyone tried it without the transistors? Why don't the transistors turn off, are they just more sensitive than the stereo?

 

I didn't mean the dome instead of the battery, I mean in addition to the battery. I think if I just wire the dome in with a diode, then when the dome goes on, the radio will start up. provided the ACC goes on before the dome goes out, the radio should stay booted (I guess I would have to start the car before closing the door), maybe there is another source for power that stays on up till start, like a door unlock line. Do I need a diode then on the ACC line too (I think I do to keep current from flowing from dome back into the battery)?

[joegr]

...

If I understand you correctly, transistors are so the ACC is powered from the supplemental battery (but still controlled by the ignition key). This prevents the cranking of the engine from dropping voltage on the ACC and causing the radio to shutoff. The transistors basically cause power to remain constant on both ACC and 12V. I'm not sure the drop in ACC would cause it to shut off. I thought it was just the main line that was the problem. Anyone tried it without the transistors? Why don't the transistors turn off, are they just more sensitive than the stereo?...

 

Yes, I did some bench top testing. The AVIC would shut down if the continuous power input went below 10.5V, or if the switched (accessory) power input went below 10.5V. For that reason, I had to add the transistors. Of course, you could use a relay instead, but the transistors were smaller and simpler for me.

[ot1]

the transistors are to use the cars ACC trigger to turn the radio on and off by using the power stored in the battery.

the dome light idea wouldnt work because it would reset when you go to start the car and you would still have the same problem, either makeing the battery device or geting a remote start would be a better option

 

My dome light stays on for about 30 seconds even after I start the car (Ford). It works the same for both driver and passenger doors, if you open the door from outside the vehicle(switch in the handle) or if you unlock the car with the remote. My vehicle has the Illuminated Entry Module which powers the dome lights and provides the delay. You would connect this output (pin 4, black/lt blue wire) to the AVIC ACC lead through a 1N4004 diode. The AVIC gets all of its power from the MEMORY lead, the ACC lead only carries 2.6 mA when the AVIC is powered up and playing music.

 

So with this idea in mind, you would not need the NiCAD batteries, nor the transistor circuitry or diodes, provided the domelight works in a similar fashion. Another thought here is that if the driver turned on his dome lights from the dash dimmer switch, you could keep the AVIC powered up while you ran into the bank or pumped gas thus eliminating the 528T delay relay and the external UPS battery(GELCEL) that I suggested in an earlier post. One drawback is that the alarm probably wont set with the dome light on and you have to remember to shut off the dash switch when parking over night! However the batteries would be necessary if your cranking voltage is low as previously discussed. I don't have a problem with this now, but in the winter I probably will have, since it gets mighty cold, and car batteries don't output as much juice.

 

I read the datasheet on the Schottky diode SDP10S30. It has a forward voltage drop of two silicon diodes thus putting the drop at 12.0 - 1.7(max) = 10.5v - 10.3 volts, somewhat low to be powering the AVIC. This may not be an issue once the vehicle is started and the alternator is suppling 13.4v, but under a heavy amp load such as headlights, A/C, heater or defroster on at the same time, the voltage power the AVIC could again drop to 10.3v at idle, depending on how beefy your alternator is. JoeGr you didn't find this to be a problem yet?

[gschade]

Thanks for the help, buying the componenets now. Will install on Monday.

 

A couple more questions:

1. Is it ok for the HD and XM modules to be hooked up to normal old acc? Will it mess up the AVIC if these powere up and down while the avic is on?

2. Should I install the bateries in a place like the glove compartment so I can change them out? How long will they last before they die from constantly being charged?

3. Do I need to hookup a relay to the battery so that it won't be charging while the car is off? I sometimes don't drive for weeks and I don't want the main battery dead ever. If I do this, how long will the cells keep enough juice to survive a crank? In my application would a SLA be better?

4. Could I rearange the diodes to eliminate the diode going back to the main battery. I think this would work because the resistor would limit the charge going to the main battery during crank. But the two diodes would allow current to flow to the AVIC as needed (main when not cranking, NICD when cranking):

main -----Diode>-----------------Avic

|....................|

R....................|

|....................|

|-------Diode>-------|

|

|

Backup

 

Thanks for the help