I was advised to use a 7.5 amp fuse for the main ignition supply. Does the permanent live supply for the real time clock etc also require a 7.5 amp or smaller say <1amp ?
I’ve measured the combined amp draw for both the ignition and constant to be in the milli-amps, like 50.
You’ll be fine with tiny fuses provided the ADU is the only thing on the circuit and wiring/install is correct.
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Thanks Flooritgarage,
I’ll try a 500 mA fuse for the permanent supply (I have this fuse).
It looks like there is some confusion about which pin does what.
Pin 12 - Supply 12V
This is a power supply pin.
Everything in ADU is supplied from this pin, including the RTC.
The maximum current draw is below 1 A, but it can be above 500 mA.
Current draw mostly depends on the LEDs and screen brightness.
Pin 11 - Switched 12V
This is only a signal input to turn on the display.
The current draw of that pin is less than 5 mA.
Mkuklis,
Thanks for the reply.
Are you saying, both pins 11 and 12 can be ignition switched? There is therefore no need for a permanent and separate live supply?
From what you said above, it reads like Pin 12 is permanent live and Pin 11 is switched live.
Hope you can clarify.
Yes, there is no strict requirement for a permanent supply. However, a permanent supply is required to keep the real-time clock running and allow for delayed turn-off.
Yes, but how you use the word “live” is very confusing.
You should be using “positive” instead of “live”.
“Live wire” means a wire that has voltage on it.
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Thanks again, so Pins 11 & 12 can be switched positive +12v supplies.
Any idea how long the internal battery can keep the RTC when there is no permanent +12v to Pin 12?
Aside from the RTC and the delayed shutdown, are there any disadvantages to supplying both Pins 11 and 12 with Ignitions switched +12v supplies?
is there still current draw, when pin11 is off? I thought the device is completely off.
btw i had it without battery for months, still had track data, RTC was off by a few minutes (not sure, it was updated automatically on first laptop plug-in, but i guess not)
Don’t remember exactly, but it’s over 2 years.
There might be power backfeeding if you use outputs and flyback diodes.
Other than that, no disadvantages.
Was that question for me? If so, I’m still in the process of wiring up my dash and hence why I want to make sure I get the wiring right first time.
Presumably if Pin 12 is given +12v switch supply it’ll still charge the battery when the dash is in use?
I wasn’t suggesting not connecting Pin 12 at all.
I just checked, and you are correct.
The device is completely off when there is no switched 12V signal, so not even RTC current.
If the switched signal is off, the RTC current is taken from the internal battery even with constant power at pin 12.
No, the battery is not rechargeable.
if the internal battery dies, it only affects the RTC clock?
Yes, it’s used only for RTC.
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Did you mean you had the battery disconnected for months and when you reconnected it the RTC was only out by a few minutes?
Did you wire your dash with a separate permanent +12v to Pin 12 and a switched +12v supply to Pin 11? Or switched +12v to both pins 11 and 12?
disconnected the whole battery for winter storage.
i just had my first trackday last weekend, and the RTC was 5 min off. Had it on the laptop a lot before, but never did manual sync. I don’t know if there is any background sync or something.
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Thanks for the reply LSL1337, so how did you wire Pin 11 and 12? Ignition switched +12v for both?
did it 2 years ago, so not sure. but i would guess 12 is not switched, only 11., but based on what they said, not much difference between the two.
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