On 12/19/2023 at 10:07 AM, TomsFocus said:

very first point you attach the Maypole, it does show battery voltage.

You're right Tom it does, but usually 0.4 more than the actual battery terminal voltage as measured with a meter. I suspect that this could be due to the internal reverse protection of the charger. Some day I'll take mine apart to investigate just out of interest.   Of course the moment the charger is switched on it begins its sensing and charging routine which further adds to the voltage being displayed as inaccurate.

@unofix I suspect you're thinking of the forward-bias voltage of a series-connected diode but until the charger is powered up a series diode would be reverse-biased so the measurement must be being made on the output side of it.

11 minutes ago, unofix said:

You're right Tom it does, but usually 0.4 less than the actual battery terminal voltage as measured with a meter. I suspect that this could be due to the internal reverse protection of the charger. Some day I'll take mine apart to investigate just out of interest.   Of course the moment the charger is switched on it begins its sensing and charging routine which further adds to the voltage being displayed as inaccurate.

That is very interesting.  I had been relying on that instead of trying to carry the multimeter downstairs with the Maypole and the powerbank as well.  So only used either Maypole or multimeter at any given time so far.

I wonder if the Maypoles vary between each one.  I connected mine yesterday after about 8 weeks since a 15 minute idle and it showed 12.1v.  Surely it couldn't actually have been 12.5v after all that time? 

I then left it plugged in for almost 6 hours.  Drained 80% of the powerbank.  (Approx 360Wh, inc conversion losses and cooling fan).  And Maypole was still in the red background with 4 solid bars and 1 bar flashing when disconnected.

I'll try to take the multimeter down later today to see what the resting voltage is now.

6 hours ago, mjt said:

but until the charger is powered up a series diode would be reverse-biased

Until the charger is powered up there is no display regardless of how the reverse polarity protection is configured 👍

6 hours ago, TomsFocus said:

I wonder if the Maypoles vary between each one.  I connected mine yesterday after about 8 weeks since a 15 minute idle and it showed 12.1v.  Surely it couldn't actually have been 12.5v after all that time? 

Can't answer that one Tom. I just know that if I connect my Fluke multimeter to the battery terminals at the exact same point as the Maypole charger leads, the display is 0.4V different. I'll try and get some measurements (and photos) over the next couple of days. It's just one of those things I've accepted without delving too much in to.

3 hours ago, unofix said:

Until the charger is powered up there is no display regardless of how the reverse polarity protection is configured

Fair point. I'm a bit confused now. When you make the comparative measurement is it with the Maypole charging? If so then if the reverse-polarity protection is a simple blocking diode and the measurement is being taken on the supply side of it the voltage would be higher by the forward bias value. If measured on the output side it wouldn't be affected by the forward-bias voltage. Either way since it's microprocessor-controlled the programming should correct for that.

What I'm trying to say (badly) is that I doubt the error is due to the protection. Maybe 0.4V is simply within the accepted calibration error. If you do get inside I'd be interested to know what you find. I'm almost tempted to get one even though I've already got a Ctek and have a look myself.

22 minutes ago, mjt said:

Maybe 0.4V is simply within the accepted calibration error.

That is a strong possibility.

The moment you switch the Maypole on it begins the charging process so the measurements are taken while the Maypole is supplying a charge.

Just to add my tuppence worth to the debate, I have a Lidl special Charger that looks remarkedly like a Maypole one and when I charged up my new Battery I did check the Voltage several times whilst charging with my equally cheap Multimeter and they were within 0.1 of each other.

It is possible that my Multimeter is not very accurate though. 

Glad you technically minded sorts are on top of this!! 
 

anyway, my ford pass app is still advising ‘battery saver mode’ however the car location on the app appears to be working ?

maybe As Tom suggested I need to have a few trips to get things reset?

On 12/19/2023 at 10:50 AM, TomsFocus said:

That is very interesting.  I had been relying on that instead of trying to carry the multimeter downstairs with the Maypole and the powerbank as well.  So only used either Maypole or multimeter at any given time so far.

I wonder if the Maypoles vary between each one.  I connected mine yesterday after about 8 weeks since a 15 minute idle and it showed 12.1v.  Surely it couldn't actually have been 12.5v after all that time? 

I then left it plugged in for almost 6 hours.  Drained 80% of the powerbank.  (Approx 360Wh, inc conversion losses and cooling fan).  And Maypole was still in the red background with 4 solid bars and 1 bar flashing when disconnected.

I'll try to take the multimeter down later today to see what the resting voltage is now.

Just taken a multimeter reading - 12.2v.  (Approx 48hrs since charging)

So my Maypole definitely doesn't over-read.

Hopefully it under-reads, otherwise that was a lot of hassle for an increase of just 0.1v resting voltage.

Well I don't have any answers as to why "my" Maypole does this but here are some photos.

On 12/19/2023 at 10:30 AM, unofix said:

You're right Tom it does, but usually 0.4 more than the actual battery terminal voltage as measured with a meter.

CORRECTION to my post of Tuesday 19th Dec 2023.

I originally said less than, which was just a typo. Sorry if this has caused confusion.

11 minutes ago, unofix said:

CORRECTION to my post of Tuesday 19th Dec 2023.

I originally said less than, which was just a typo. Sorry if this has caused confusion.

Ah, that does make more sense.  (PS - Just realised I also put underread & overread the wrong way round in the post above!)

So I think the general consensus is that the Maypole display can't be relied upon for an accurate or even a consistent reading.  I will have to find a way to check the voltage with a multimeter before deciding whether it's worth plugging in the Maypole or running the engine for 15 minutes in future.

On 12/18/2023 at 3:34 PM, Andyr55 said:

Even though my present battery is only 2/3 years old? 
 

battery fully charged with maypole but still in battery saver mode! 
 

any suggestions?

If the battery is messed up its messed up no matter how old it is.  Voltage may be fine but as soon as you out a proper load on it the battery could be failing.  Its not unheard of to replace a battery at 3 years, there's a reason some are only warrantied that long!