My energy is being drained...

Flatulentoldgoat

Just hooked up my multimeter to measure draw. Positive lead to the negative battery terminal, negative lead to the chassis. Am I doing it right? Looking at the YouTube vids I should've touched the negative clamp rather than the earth. Nonetheless I still appeared to have a reading. Dodgy fuse in = 0.8A Dodgy fuse pulled out = 0.14A....

Fancy radio if anyone's curious....

williamgriffin

How long had everything been off before you tested?

Flatulentoldgoat

williamgriffin said:

How long had everything been off before you tested?

Nearly about a day. Battery was @ 12.5v (it's nearly new was fully charged three days ago and ran for a couple of hours yesterday)

facade

williamgriffin said:

How long had everything been off before you tested?

+1

The problem with these modern cars is that they are full of com-puh-tahs, which use vast amounts of current, when you don't expect.  You need to connect the ammeter and leave it in circuit for an hour or so and read it again, the act of breaking the circuit and reconnecting it resets something.

My Renault Nissan had a flat battery on Saturday, and I mean flat, as in I could hear a relay faintly clicking, it read 7V and the CTek refused to charge it.

Which was odd, as it had started easily and driven for about 45 minutes the Saturday before, and it stood 4 weeks in the Summer with no effect

So I was looking for something taking current.

Connecting the ammeter, after the initial surge, it read about half an amp for a couple of minutes, which dropped to 150mA.  Pulling  the audio and horn fuses made no difference, I wouldn't dare pull the ecu fuses on a Renault with the battery connected though!

Ah well, 150mA means it needs charging every couple of days, so I left it a couple of hours, and the current had gone down to 6mA.

So I've no idea why the battery went flat- except it has Renault electrics, something must have come on, like the fan, or maybe the door locks stayed on. I even had the top off the dash to see if Nissan's failure to make the windscreen rainproof had filled the BECM with water, but amazingly it was bone dry.

(Yes I checked the interior light was off, and wasn't the cause of the flat battery)

Goudy

Flatulentoldgoat said:

Fancy radio if anyone's curious....

Who wired this in?
It could be the radio's switched live has been connect to a constant live. It's quite a common issue with aftermarket headunits.

They need two lives, a constant live that pulls very little power to store the presets when everything is turned off.
And
A switched live that powers the unit with the ignition on.
(sometimes this is an inhibited live, so will stay live for X minutes after the ignition is switched off).

If the switched wire on the head unit is connected to a constant live they tend to pull around 0.5 or 0.6 amp even when the radio is turned off, add in a few other, normal small power draws and that could easily add up to 0.8 and cause the battery to drain.

A telltale that they are wired in wrong is either the unit loses it's presets every time the ignition is turned off.
Or
The headunit stays live all the time when the ignition is off (though you need to account for a certain amount of time in case this circuit in inhibited).

You'd think the wiring and connectors would be pretty much standard, plug and play.
But I have noticed a few older (early to mid '00's) models over the years that have needed the constant and switched swapping over

Flatulentoldgoat

Goudy said:

Flatulentoldgoat said:

Fancy radio if anyone's curious....

Who wired this in?
It could be the radio's switched live has been connect to a constant live. It's quite a common issue with aftermarket headunits.

They need two lives, a constant live that pulls very little power to store the presets when everything is turned off.
And
A switched live that powers the unit with the ignition on.
(sometimes this is an inhibited live, so will stay live for X minutes after the ignition is switched off).

If the switched wire on the head unit is connected to a constant live they tend to pull around 0.5 or 0.6 amp even when the radio is turned off, add in a few other, normal small power draws and that could easily add up to 0.8 and cause the battery to drain.

A telltale that they are wired in wrong is either the unit loses it's presets every time the ignition is turned off.
Or
The headunit stays live all the time when the ignition is off (though you need to account for a certain amount of time in case this circuit in inhibited).

You'd think the wiring and connectors would be pretty much standard, plug and play.
But I have noticed a few older (early to mid '00's) models over the years that have needed the constant and switched swapping over

Ah most helpful. Unfortunately I was the installer. The thing is, the unit works as it should. When I turn the key, it comes off standby mode (this is meant to be very low powered) and the screen comes on immediately. So the switched live is working as it should.

I couldn't find a constant live for the original radio so I tapped the fuse board and found a 10A constant and used this. If I disconnect this, the unit cold boots each time as expected. Can take 20-30 secs to get fully started which is a pain in the !!!!!!.

I'm wondering if it's the steering wheel controls adapter that is actually accessing another constant live. But I'm really not sure and it's most frustrating taking the whole thing out and playing Tarzan with the wires.

facade

Measure the current that is actually going into the radio when it is off as well as the battery drain. It may be the radio is somehow keeping the car ecu awake.

I wired a device  to the ignition live and accessory live on my Corsa-C once, tapping the wires at the ignition switch. The device worked perfectly, but the battery went flat.  It was doing something to the ignition live that kept the ecus powered up.

The engine switched off, and all the panel lights went out as normal though, I've no idea what it was, but moving the device to different live feeds sorted it.

AdrianC

Leave the earth terminal alone.

Pull the head unit fuse. Put the multimeter probes across it, and check current there.

If the head unit connection has switchable yellow and red, then check across each of those.

born_again

facade said:

My Renault Nissan had a flat battery on Saturday, and I mean flat, as in I could hear a relay faintly clicking, it read 7V and the CTek refused to charge it.

Which was odd, as it had started easily and driven for about 45 minutes the Saturday before, and it stood 4 weeks in the Summer with no effect

Slight difference in temp between summer and last week...
And cold is a real battery killer.

facade

born_again said:

facade said:

My Renault Nissan had a flat battery on Saturday, and I mean flat, as in I could hear a relay faintly clicking, it read 7V and the CTek refused to charge it.

Which was odd, as it had started easily and driven for about 45 minutes the Saturday before, and it stood 4 weeks in the Summer with no effect

Slight difference in temp between summer and last week...
And cold is a real battery killer.

I considered that, but the battery is only 3 and says Yuasa on the side. I will see what the voltage is tomorrow- and if it starts

blackdog2220

I do work non older smaller motorcycles and am often fighting to gain power so n that decent h/light can be used , those bike are kick only , not elec start , this tool , mine came from cpc is fantastic https://www.amazon.co.uk/Generic-CF-02-CURRENT-TESTER-AUTOMOTIVE/dp/B008B1GXYM

in my case changing dash bulbs (5 x 4w) to t10 leds , and changing 21/5w stop tail to led can allow you to go from a 25/25 w headlight to a blistering 35/35 
the tool is made for your job , checking currant flow thru fuses 

the unit can read negative or posative flow , without vbeing reversed ,