Has anybody allready done a mod for the ignition signal?

I mean when you turn the ignition on (without starting the engine) maybe to set up a new target for the navigation and after that you start the engine it will result in a reboot of the F900BT.

I've heared about a mod with a diode an electrolytic capacitor to keep the voltage on the ACC input high enough during the engine start to prevent the F900BT from rebooting. But I do't know what capacity would be needed and what current there is on the ACC line.

Could somebody give me more information or do I have to test it by myself?

I've done this, but a capacitor is not enough. I had to add a NiCd battery pack. Some transistors were also required. Another member on here has done the same mod and reported that it worked well for them too.

Yes, please post more details. I never start my car until fuel pump is done priming so this makes the Avic reboot.

I've done this, but a capacitor is not enough. I had to add a NiCd battery pack. Some transistors were also required. Another member on here has done the same mod and reported that it worked well for them too.

I'm one of those members that Joe shared his solution with, and as Joe said it worked out great for me. Picked up all the parts from Radio Shack.

Since it's Joe's solution I'll leave him to post the details.

I just found something that would fit perfectly with some litte modifications:

Switch-Off delay, the 3rd schematic on the page.

S1 will be the ignition switch, the radio (ACC in) should be at point A.

Modification 1:

The relais contact KX will be connected to 12V, not to S1.

Modification 2:

The value of C1 is to high. The delay would be 53s with the original value of 0,47µF, that's also the time the radio will play after switching the ignition off. I think 0,047µF will be enough, that should be about 5,3s delay. - Time to start the engine and short enough to switch it off before you leave the car.

The biggest problem with getting the AVIC to continue to run will starting the car is that usually the car battery voltage will fall below 10.5V while doing so. The AVIC will shutdown if the voltage on the red or the yellow wire goes below 10.5 V.

See attached schematic for one solution.

The car_acc_pwr line has to be one that is on when the key is turned to run or start. The ignition power lead would be one example of such a signal.

AVIC.pdf

This looks good Joe, I am in the process of trying to find a suitable arrangement to get rid of the bloody PITA re-boots all the time. At the moment I have a switch and relay wired up, but if I forget to press the standby switch on the Avic before leaving or getting back in the car and turning on ignition then I gota suffer the re-boot again

Think I will see if your idea will work with a small lead acid battery, I'm assuming the aux battery pack gets charged by the car?

if you're not concerned with the power surge that may occur during cranking, why not just change the acc line? instead of using the acc wire in the stock harness, just run a line to the vehicles ignition line? ign remains powered while cranking..

if you're not concerned with the power surge that may occur during cranking, why not just change the acc line? instead of using the acc wire in the stock harness, just run a line to the vehicles ignition line? ign remains powered while cranking..

I tried this myself at one point but found out that the +12V constant also experience a dip during cranking.

I think this is a car-related issue.

My car does not interrupt the battery power during starting. (SAAB)

All functions (headlamps / radio included) continue functioning.

I think this is a car-related issue.

My car does not interrupt the battery power during starting. (SAAB)

All functions (headlamps / radio included) continue functioning.

The starter on my car, and I suspect most cars, causes the battery voltage to dip during the cranking process. The voltage then recovers once the alternator kicks in. It is during this dipping that the voltage falls to an unacceptable level for the HU.

Yes I understand.

Most cars therefor try to not burden the battery by switching off some items. (As headlights)

Nevertheless some cars are equiped with some kind of buffer or condensator in order to not have this issue. (as a SAAB 9-5 has)

I see the same thing often with (European) cars fitted with a factory fitted HID lightsystem.

IDK if this has been discussed yet but what about a relay and a diode?

85 goes to a ground

86 goes to the vehicle's starter wire

30 goes to a consant 12v source, preferably the constant at the ignition cylinder because it doesn't cut out during start-up.

87a will not be used

87 goes to the constant and ACC of the radio, of course after being diode isolated.

-OR-

85 groes to ground

86 goes to vehicle's accessory wire

30 goes to ignition constant

87a goes to radio constant and ACC, of course after being diode isolated

87 will not be used.

In theory, doing either of these methods should keep the radio powered up when starting the vehicle.

Joe's circuit looks very interesting, but I think the voltage drop caused by a Schottkydiode still is about 0,4-0,5V and that would result in some watts of heat when the F900BT needs some power. I also don't like the idea of having a additional battery located somewhere under the instrument panel. - It can cause a shortage or run out, two things that are not very funny in a car.

@paQ: I think a lot of new cars (especially the ones with a CAN BUS or something similar) here in Europe switch off the headlights during the engine start, my Opel Corsa does this too.

I think I have to measure the permanent voltage at the F900BT during the engine start, but maybe it is also affected by switching off the power.

Bascally, a starter motor draws 150 - 200 amps cranking the engine.... That's what causes the voltage drop.

Joe's circuit looks very interesting, but I think the voltage drop caused by a Schottkydiode still is about 0,4-0,5V and that would result in some watts of heat when the F900BT needs some power. I also don't like the idea of having a additional battery located somewhere under the instrument panel. - It can cause a shortage or run out, two things that are not very funny in a car.

 

@paQ: I think a lot of new cars (especially the ones with a CAN BUS or something similar) here in Europe switch off the headlights during the engine start, my Opel Corsa does this too.

 

I think I have to measure the permanent voltage at the F900BT during the engine start, but maybe it is also affected by switching off the power.

It is not necessary to locate the battery under the instrument panel. I chose to locate it under the Door sill. This made it easily accessible in the event I needed to perform any future service.

Regarding the issue of the battery "running out", this circuit uses a NiCD rechargeable battery that is charged only when the car is running. So it is pretty maintenance free.

Finally the issue of short circuit can be easily over come by placing an inline fuse in the positive of the NiCD battery. In fact for safety I highly recommend this addition.

Finally I'd like to add that Joe's circuit works pretty well. I implemented it and have not had any trouble with it to date.

I considered using a Capacitor before using Joe's solution but realized that the size of the capacitor would be too large as to be feasible solution.

Yes, that's clear but when the Radio is on the current will flow through the diode that also causes about 0,4-0,5Vand the Avic-F900BT/F700BT can take up to 10A from the 12V line. That would result in up to 4-5W at the diode.

Yes, that's clear but when the Radio is on the current will flow through the diode that also causes about 0,4-0,5Vand the Avic-F900BT/F700BT can take up to 10A from the 12V line. That would result in up to 4-5W at the diode.

The particular diode selected is rated to be able to handle that. In practice, the average current to the AVIC is usually less than 2 amps. I can assure you that this solution does work, and is being used in at least two cars.

Yes, the warnings about fusing the circuits is very valid. I just assumed that didn't need to be pointed out. Car electrical fires are no fun. Another good battery location (in my case anyway) is in the spare tire compartment of the trunk, next to the car's main battery.

What do I need to change in order to get this thing work with F500BT? The F500BT has a 5V (3A max) power input from a DC-DC cigarette adapter. I'm think about hard wire the ACC to a power supply like this

http://store.mp3car.com/ProductDetails.asp?ProductCode=PWR%2D022&Show=ExtInfo

to get rid of the cigarette adapter, and I would like to also remove the reset problem during engine start (yes, F500BT also got reset problem when ACC drop during engine start, even it come with internal battery).

Mine is hard-wired with the almost-impossible-to-figure-out loom. This connects the F500 to the ND-G500 amp, which gets it's power from both the +12V Batt. and +12V Acc.. The amp then supplies the +5V to the F500. So this should work for me, now I just need to source the components......

Edit -

Will this circuit also work for a sealed lead acid batt. or a series of Ni-Mh batts.?

if you're not concerned with the power surge that may occur during cranking, why not just change the acc line? instead of using the acc wire in the stock harness, just run a line to the vehicles ignition line? ign remains powered while cranking..

 

I tried this myself at one point but found out that the +12V constant also experience a dip during cranking.

if your voltage is dipping that low during crank, you might want to get your electrical system checked.. starters draw a fair amount of current, but it shouldn't be enough to dip things that low unless you've got a bad cell or two in your battery.

if you're not concerned with the power surge that may occur during cranking, why not just change the acc line? instead of using the acc wire in the stock harness, just run a line to the vehicles ignition line? ign remains powered while cranking..

 

I tried this myself at one point but found out that the +12V constant also experience a dip during cranking.

 

if your voltage is dipping that low during crank, you might want to get your electrical system checked.. starters draw a fair amount of current, but it shouldn't be enough to dip things that low unless you've got a bad cell or two in your battery.

The allowable voltage range for the Pioneer is 10.8V to 15.1V. Considering I have a 12V battery that only allows me a drop of 1.2V during cranking, quite tight. I think the problem is this tight tolerance not the electrical system in my car. If it is the electrical system in my car then it is highly contagious since several members in this forum are also reporting this problem.

Nonetheless, I've resolved this issue with the circuitry posted in this thread. My comments were only intended to be helpful to the starter of this thread not to start this debate all over again.

Edit -

 

Will this circuit also work for a sealed lead acid batt. or a series of Ni-Mh batts.?

Yes.

if you're not concerned with the power surge that may occur during cranking, why not just change the acc line? instead of using the acc wire in the stock harness, just run a line to the vehicles ignition line? ign remains powered while cranking..

 

I tried this myself at one point but found out that the +12V constant also experience a dip during cranking.

 

if your voltage is dipping that low during crank, you might want to get your electrical system checked.. starters draw a fair amount of current, but it shouldn't be enough to dip things that low unless you've got a bad cell or two in your battery.

I can assure you that it is common and within spec for most cars to drop to as low as 9V during cranking. (My experience applies to V8 cars.) I have seen this with new 900+ CCA batteries. Very high end cars have two batteries, one for the starter and one for the electronics. Remember, it is not just the voltage drop due to the internal resistance of the battery, there is also some drop in the wiring due to wiring resistance and contact resistance. While the average starting current might be 100 to 300 amps, the current surge when the starter is first engaged is easily 500 to 700 amps (for a fraction of a second only).