Control unit current consumption - anyone measured?

[WelshGas]

Thanks. Was more about accessibility. Can I get to said wire through the small circular access hole in the cupboard under the hob. Don’t need a ground / earth for charger and anyway would need to take out fridge to access shunt (I believe). Unit has a diode so one way only leasure to starter so no problem when engine running. By running through load out on solar controller I can choose to charge starter only once leasure on float and also see how much Amp-hour starter is needing each day.

Are you sure your Charger is under the Fridge. On my 2014 it is above the Rear Leisure Battery. I think they changed the position around about MY 2014, so about mid 2013.

 

[Skewif]

Mine is a MY13. Charger under the fridge. Well 99% sure as I put my solar controller in battery compartment and didn’t see the charger. Pretty sure charger under fridge when I had a look through access hole. Don’t mind running wire to under the passenger seat if needs be but if starter connection easy to access under fridge it would save a lot of faff. Will have a look and report back.
Isn’t it the later models have it in battery compartment and early has under fridge or do I have it the wrong way round?

 

[WelshGas]

Mine is a MY13. Charger under the fridge. Well 99% sure as I put my solar controller in battery compartment and didn’t see the charger. Pretty sure charger under fridge when I had a look through access hole. Don’t mind running wire to under the passenger seat if needs be but if starter connection easy to access under fridge it would save a lot of faff. Will have a look and report back.
Isn’t it the later models have it in battery compartment and early has under fridge or do I have it the wrong way round?

No, that’s the correct way. Charger was moved because of the problems of excess heat from Charger and fridge heat exchanger causing problems.
Some owners put extra vents in the kitchen side wall to aid ventilation and even small 12v fans to help.

 

[Roger Boeken]

On my 2014 SE, the Contro Panel shows -0.2 v with Backlight On.

You do realise that the Mains Charger will trickle charge the Engine Battery once the 2 Leisure Batteries reach a certain level. So I would expect the Engine Battery Voltage to rise.

OnT6 and even late T5 models engine battery is charged with 1A when on hookup don't remember the exact year they started doing this . Not sure if this is only after leisure battery has reached certain load level..

 

[Roger Boeken]

Hi,

I have -0.4A, sometimes -0.6A showing on the central control unit with nothing on + no plug in the inverter socket etc.

I have just measured the actual consumption which is much lower, as below....

CCU off = 25mA (0.025A)
CCU on = 68mA (0.068A)
CCU on with backlight = 114mA (0.11A)

Has anyone else made this measurement?

I still think the 25mA is highish if it is in sleep mode, and strangely when I put it on hookup I noticed the main engine battery voltage creeping up a little (a few 10's of millivolts), so am concerned there is some leakage current between the 2 systems.

Also tested with fridge on and CCU shows 4.4A, whereas actual is 4.0, so there is a 400mA offset.

Thanks!

Can you tell us how and where exactly you measured these values ? So we can measure the same way and share our findings ?

 

[thehorse]

Can you tell us how and where exactly you measured these values ? So we can measure the same way and share our findings ?

Hi Roger,

I measured on the rear battery under the wardrobe.

Use a coin to open the battery compartment
You have to undo the bolt securing the battery, then you can slide it out.
Remove the smaller brown wire on the negative terminal
Connect meter in between the brown wire and the negative terminal. (in series)
(or you can disconnect both wires on the negative terminal and connect in between the brown and black to make the circuit and not have a connection to the negative on the battery)
Make sure you change the meter probes into the current measuring sockets.

Very interested if you are able to do this measurement!

ps- don't disconnect the red wire on the battery as risk it could touch the metal wardrobe and blow the fuse.

 

[Roger Boeken]

Hi Roger,

I measured on the rear battery under the wardrobe.
Remove the smaller brown wire on the negative terminal
Connect meter in between the brown wire and the negative terminal. (in series)
(or you can disconnect both wires on the negative terminal and connect in between the brown and black to make the circuit and not have a connection to the negative on the battery)
Make sure you change the meter probes into the current measuring sockets.
Very interested if you are able to do this measurement!
ps- don't disconnect the red wire on the battery as risk it could touch the metal wardrobe and blow the fuse.

I'll make some measurements myself later but I have 1 remarks so far:

I observed the display of the control unit and it jumps between 0,0 to 0,2 A. I think 0,2A is the resolution of the meter. So all values it can show are multiples of 0,2A. If you use 0,25 A it may show 0,4A. If you use 0,05 A it may show 0,0 A and if you use 0,10A it may show 0 or 0,2...
Somehow your control unit has a offset of 0,2A not 0,4A : if you measure 0,11A with ccu on with backlight it must show 0,2A. With an offset of 0,2A it will think there is 0,31A and will show 0,4A on the display. Maybe there is a way to trim this offset away or there may be bad shunt or bad contact at the shunt or bad wring to the ccu .. It would be interesting to measure the voltage at the shunt yourself. I'll keep you updated of my findings in my cali.

 

[Roger Boeken]

sorry, pushed 'reply' twice

 

[sidepod]

Why measure in the negative and not the pos?
Ameters are connected in the positive. Are you not including the battery in the measurement? Not my area of expertise but I’d take the readings in the positive.

 

[Loz]

More for convenience, the shunt which is an ammeter is on the negative, but you are still only measuring the draw from 1 battery.

If you want to be more accurate then remove the shunt and measure there as that is where the control panel takes it from and you will have like for like then.

 

[Ian Robinson]

If as the thread title suggests that you are only interested in the drain of the control unit. Then maybe measure the current across the fuse supplying the unit (fuse removed) with a fused a ammeter? However if you want the total current drain on the leisure batteries then as Loz says - the shunt is the place to measure this.

 

[sidepod]

A shunt isn’t the most accurate or stable means to measure current and will be affected by temperatures (resistance alters with temp).

Perhaps try a clamp meter (Hall effect) around the positive for more accuracy.

 

[Loz]

I meant disconnect the shunt and put your meter in place..

 

[thehorse]

Why measure in the negative and not the pos?

The current flowing in the circuit will be the same wherever you measure, so it makes no difference. It is however safer to measure on the negative as the bodywork will be tied to the negative and if you undo the positive wire there is a risk it could touch the body and cause a short. 800A+ isn't going to do your wiring any good!

More for convenience, the shunt which is an ammeter is on the negative, but you are still only measuring the draw from 1 battery.

As long as the other battery isn't in the loop it won't matter as the current with one battery would be the same as with 2 batteries

 

[Loz]

As long as the other battery isn't in the loop it won't matter as the current with one battery would be the same as with 2 batteries

I thought the OP mentioned measuring off the rear battery, hence my suggesting using the shunt location.