Ignition Mod on F900BT?

[nkosi]

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.

[jb79]

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.

[joegr]

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.

[StupidPig]

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).

[dumpystig]

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......

 

[dumpystig]

Edit -

 

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

[ubernewb]

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.

[nkosi]

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.

[joegr]

Edit -

 

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

 

Yes.

[joegr]

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).

[johnnyfidgets]

i was raeding this and i think it would be safe to just add and on off switch and just turn on the avic after the car is on.. if no harm comes from this reboot then just live with it.. a battery pack should need a switch to not over charge..

[joegr]

i was raeding this and i think it would be safe to just add and on off switch and just turn on the avic after the car is on.. if no harm comes from this reboot then just live with it.. a battery pack should need a switch to not over charge..

 

The resistor limits the charging current to what is allowed continuously by the battery pack. It won't over-charge.

 

I'm not sure about the reboots not being dangerous. Many people on this forum have had flash corruption problems. Flash can be corrupted when power fails (or falls too low) while the flash is being written. This is one of the two main reasons I did this.

[lobelsteve]

Hey Joe,

 

Excellent PDF electrical diagram. If I knew what all that meant I'd just go out and do this. Any chance you can post the parts list. I see on the diagram:

 

SPD10s30 x2 Diode

R1 resistor 10.0 Ohm 10.0 w

R2, R3 (same size resistor) 1000.0 Ohn .25w

Q1 2N4401

Q2 2N4403

C1 capacitor 10uF 25v

C2 capacitor 100uF 25v

Battery x10 500mA/hr NiCd

[rcxracing]

they do make someting called a power tamer my current job is building and modifying police, emergency, and federal vehicles. what this does is once you turn the key on the power tamer is activated and when you turn off the car the timer starts and you can set it from 30 min. to 4 hours. so the output side of the power tamer can hook up to the ignition wire of avic and you cap off the ign. on the car side. you can hook up variuos other after market electronics this device. on the cars i do the power tamer is running our custom fuse panels by turning on and leaving on a 150 amp military grade electronic relay for certain amount of time.

[JLeach12]

there are two power wires at almost every ignition switch in cars. one the accessory in most vehicles loses power during crank. the other which is actually an ignition wire remains at 12v during crank. instead of wiring relays, just run a fused wire to the ign switch and find the wire that maintains power during crank. i appreciate relays and diodes, but fuse holders and 18-14 ga wire is less expensive.