voltage

[edam]

After a problem with a flat battery I have been checking the charging using a meter which plugs into the cigarette lighter/power socket.
With the engine idling the only time the voltage was above 14v was when the blower was running in the 3 position or the headlights were on otherwise the voltage was just above 12v.
So if you want to get some charge into the battery run the engine with either the blower on 3 or your headlights on
I have seen this posted on the forum before but I thought I would post the readings I have got

[culzean]

After a problem with a flat battery I have been checking the charging using a meter which plugs into the cigarette lighter/power socket.
With the engine idling the only time the voltage was above 14v was when the blower was running in the 3 position or the headlights were on otherwise the voltage was just above 12v.
So if you want to get some charge into the battery run the engine with either the blower on 3 or your headlights on
I have seen this posted on the forum before but I thought I would post the readings I have got

I have noticed this for a long time because I have had a 'Ring' cigarette lighter socket expansion gizmo in the cat ( turns 1 socket into 3 ) and it has 4 led indicators on it ( red, orange, yellow and green ) for different voltages, the top 2 led only come on with engine running,  sometimes when I am driving along the top to leds will go out for a while and then come back on, I can keep them on all the while if I switch various loads on, like headlights ( limited success because my LED headlight bulbs only draw about an amp each, compared to 5 amps each for filament bulbs ),  much better to turn heated rear screen etc on.

[edam]

It was only tjhe blower or headlights which increased the voltage. Surprisingly switching on the rear screen heater/wing mirrors did NOT increase the voltage.

[BadgerMk3]

I suspect your 'reading' is indicative of the 'smart' charging system which distributes voltage depending on importance of the circuit and the load on the battery.

Also, when idling the alternator would not be running at full capacity.

[Jocko]

Did a check today and with blower on I saw 14.6-14.8 volts. Switched off blower, let voltage recover to 12.5 volts then as soon as I switched on rear screen heater, back up to 14.8 volts.

[edam]

Switching the rear screen on does not increase the voltage on mine which seems odd . I have checked the screen and it does get warm

[Jocko]

You did switch off the blower and let the voltage settle back to 12.5 volts? No matter what load you put on it won't get any higher than the 14.6 - 14.8.

[edam]

Yes I did let it settle to about 12 and the engine slowed slightly when the screen heater was put on but the voltage did not increase.
It could be useful to know come winter that the voltage does not incrase unless the fan/headlights are put on. Thats if I still keep the MK3

[BadgerMk3]

Did a check today and with blower on I saw 14.6-14.8 volts. Switched off blower, let voltage recover to 12.5 volts then as soon as I switched on rear screen heater, back up to 14.8 volts.

Just an observation for clarity seeing as this thread is in the Mk3 section.

Is the Mk1 charging system and battery the same as the Mk3?

Despite the obvious best intentions, there is a danger of comparing systems which are not actually comparable.

[edam]

Did a check today and with blower on I saw 14.6-14.8 volts. Switched off blower, let voltage recover to 12.5 volts then as soon as I switched on rear screen heater, back up to 14.8 volts.

Is this on your MK1???

[Jocko]

Yes it is on the Mk1 but the heated screen on the MK3 draws similar current and should trigger the charging current as both systems are controlled in a like manner.

[edam]

Yes it is on the Mk1 but the heated screen on the MK3 draws similar current and should trigger the charging current as both systems are controlled in a like manner.

I understand that on the MK4. to save petrol. the battery is not charged all the time. There is some Gizmo connected to the battery which limits the charging . I dont think this was on either of my MK1,s so they would not behave the same

[Jocko]

It is the MK3 that is being discussed, not the MK4.

[culzean]

Smart alternators have been around since the 1980's.  Even in the 1990's fitting the 'wrong' battery to your Ford would result in it not getting charged because the smart charging was 'tuned' to a certain battery chemistry.  Smart charging mainly to reduce load on engine, but also makes batteries last longer because the smart charging also senses ambient temperature and alters charging to suit. There is an added gizmo on the battery as well to allow 'coulomb' counting, so current in and out of battery is sensed to determine state of charge rather than just battery voltage.  The reason some retrofit 'smart' ( voltage sensing ) daylight running light ( DRL ) kits did not work on more modern cars is that the light control unit was programmed to sense when engine was running, they did this by voltage level, with <13 volts the engine was assumed to be stopped,  and when voltage was above 13.5 v the engine assumed to be running,  but as we have seen that depending on load the system voltage varies even with engine running from <13v to 14.7v, so DRL were switching themselves on and off at random in response to system voltage changing.

https://www.motor.com/magazine-summary/are-you-smarter-than-a-smart-charging-system/

[BadgerMk3]

It is the MK3 that is being discussed, not the MK4.

Not wishing to appear rude, but that statement also applies to the Mk1 versus the Mk3...

I appreciate you're trying to help, but you're quoting references for the Mk1 system when the OP is specifically looking for advice on the Mk3.

I haven't looked in any detail but I strongly suspect the Mk3 charging system has advanced quite significantly since the Mk1.

The simple fact that the Mk3 has a stop/start system and associated battery would tend to confirm that theory.