Battery voltage 12.2

[Stewart7]

I just had to leave my car standing for 2 weeks, so I plugged one of those small solar panels that Maplin used to sell, into the front 12 volt socket.  I just went out to the car today and measured the battery as only 12.2 volts.  It seems the solar panel can't even keep up with what the car uses when everything is switched off  and just standing.  Have I wasted my money?  Or is there another explanation.

 

Thank you for any comments

Stewart

[SuperbTWM]

2 weeks is fine to leave a car without a solar panel so why are you wasting your time with one?

 

Also, you don't seem to have done a very fair test as you haven't left your car 2 weeks without a solar panel to compare the readings?

Edited 11 June, 2018 by SuperbTWM

[Stewart7]

That's a fair point.  I may have to leave it again for 2 weeks in the not too distant future, so I'll leave the solar panel disconnected and make the measurement again.  I'll report back.  Thanks for the suggestion.

 

Stewart

[SuperbTWM]

47 minutes ago, Stewart7 said:

That's a fair point.  I may have to leave it again for 2 weeks in the not too distant future, so I'll leave the solar panel disconnected and make the measurement again.  I'll report back.  Thanks for the suggestion.

 

Stewart

 

Also would be good to do some testing and see how much current the solar panel is pushing out with a multimeter, and at the same time cover the panel to make sure when it gets dark its not sucking power out of the battery.

[Stewart7]

Another good point.  Thanks.  It is supposed to have a diode in series to stop current flowing from the battery, but I can get an ammeter in series to check output, and to see if anything flows in reverse when the panel is in the dark.

Thanks for the suggestions.

S

 

[vegit8]

We often leave our car for this long, we use the citigo for journeys of less than 60 miles. All that concerns me is that it will start when I need it to.

It has never let me down yet. 

There was one occasion where I left the rear facing crash cam plugged in and I got a warning on the Maxidot that battery was low.

Car still started - have now fixed cigarette sockets so that they are switched with the ignition. 

[Gabbo]

I recently left my car for 4 weeks unused.

The Kessy was disabled when I returned to it (as it states it should be switched off automatically to save power after 2 weeks or something like this) but it unlocked fine with the remote fob buttons & there were no signs the battery was low.

Fired up like normal without any cranking problems.

 

I think with modern power saving electronics, you can leave for many weeks without any issues.

[SC03OTT]

Cars are sat on dealer forecourts and storage yards for months at a time. A few weeks is nothing. 

[Breezy_Pete]

19 hours ago, Stewart7 said:

Have I wasted my money?

Probably not entirely, assuming that testing shows that it does give some positive output current, and never consumes any.

I had one years and years ago, measured its output at about 10 or 11mA max, in sunlight behind the windscreen, against a claimed 1.5W (which is closer to 100mA by my maths).

So not going to cancel out the quiescent draw of the car, but it will reduce/offset it, and so slow down the discharge rate.

 

I didn't bother moving it across to my next car...

[flybynite]

First-off the batteries fitted as standard are not the best, done to a cost as many things. These can be improved on when it comes time to replace, even fitting a larger capacity, especially on smaller petrols. Been detailed on here a few times.

 

A lot can do with the weather and what kind of driving you do. Mine does short trips and often a lot of standing.

 

Mine (untouched from new) was disabling KESSY in a few days, giving battery warnings now and again, and once would not start the car. I was going to just put a new AGM on it and be done but when it would not start the car I needed to charge it anyway.

 

A good day on charge with one of my CTEKs in recon mode, and it seemed to behave better even in the cold. Now the weather has warmed up it has not missed a beat, recently went a fortnight and KESSY still worked on return. A good Varta 096 AGM is certainly going on before next winter, however it seems fine at the moment, even with continued abuse.

 

How long it will last will depend on the temperature and the abuse it has had up to that point but the modern chargers do put a bit of life back in them that I could not do by giving the car a long run.

[Rodge]

One way to keep the battery charged when you do use the car is with engine braking, as that is apparently when the alternator operates at maximum capacity.

[ChoonDoode]

Good way to keep your battery healthy is to use a battery conditioner. These monitor the voltage and over the stages, can determine what state the battery is in. My track bike sits with one on over the winter months, but come the warmer months, it fires up first time no problems.

 

As has already been said, it sitting up the drive for a few weeks shouldn't do it any harm. It's only the alarm which will be constantly in use and they're designed to keep an eye on what the battery's voltage is.

 

Short journeys are what does damage to batteries, certainly in the winter. The energy needed to crank it on start gives it such a kicking and then if you've got the vents on hot, the heated rear screen, the heated front screen and the heated seats, it takes a good while after the engine is up to temperature for the battery to be recharged properly.

[Stewart7]

Dull weather today, but hopefully tomorrow, I'll be out there with my ammeter to see what current the panel produces when connected to the car, and also to see any current flow when the panel is in darkness.

My thanks to all who replied.

Stewart

[ords]

Left mine for 4 months over the winter in a garage & it fired up with no problem

[Rodge]

15 hours ago, tunedude said:

... if you've got the vents on hot, the heated rear screen, the heated front screen and the heated seats, it takes a good while after the engine is up to temperature for the battery to be recharged properly.

I hope that under those circumstances it turns the alternator and up boosts the engine revs to meet the extra demand, which would also have the benefit of generating more heat sooner, but I have no idea if it actually does.

[ChoonDoode]

5 hours ago, Rodge said:

I hope that under those circumstances it turns the alternator and up boosts the engine revs to meet the extra demand, which would also have the benefit of generating more heat sooner, but I have no idea if it actually does.

 

It does, but only when idle. When you're driving, the revs will be the same as normal

[Stewart7]

Just went for a 20 mile drive and measured 14.7 volts at the 12v socket when the engine was running.  When I got back and everything was off, I still had only 12.2 volts at the socket.  Shouldn't it have been about 12.6, for a fully charged battery?

 

Sunny this afternoon, so made some checks with ammeter.  When in full sun, the panel could only provide 50mA.  When cloudy, 15mA.

With the panel in complete darkness, (face down under a thick blanket), meter showed zero current flow in either direction.  That was on a range that could show 1 microamp, so charge isn't leaking back into the panel during the night.

 

As tunedude previously suggested, I think I'll go back to my battery conditioner when the car isn't being used.  I thought the solar panel would save me having to keep connecting and disconnect the charger.

 

I know most of you guys think I'm worrying too much, but I'm a pensioner and I know that lead acid batteries like to be kept as close as possible to fully charged at all times, and I've seen some really scary prices for new batteries.

 

Thank you again for all the very helpful comments

Stewart

 

 

Edited 13 June, 2018 by Stewart7
'Scale' should have read 'range'

[SWBoy]

13 hours ago, Stewart7 said:

Just went for a 20 mile drive and measured 14.7 volts at the 12v socket when the engine was running.  When I got back and everything was off, I still had only 12.2 volts at the socket.  Shouldn't it have been about 12.6, for a fully charged battery?

The battery isn't taking and/or holding charge, I would start saving for a new battery

[xman]

EFB (enhanced flooded battery) are fitted in cars with stop/start. These cars also feature energy recovery (called micro hybrid use) and its normal for these batteries to be part charged- around 75% as the ecu controls energy recovery (using the alternator as a brake and switching off charging under certain conditions to improve fuel economy). Also EFB shows slightly lower voltage than old standard batteries in standby and it varies on the make of battery (and battery manufacturer needs to b coded in the ecu)

 

An overnight charge with an external charger is only way to ensure a fully charged battery. Take care though, follow the instructions in the manual regarding chargers, use the ground point and not the battery negative terminal. Don't use cheap unregulated chargers as these will often cause expensive damage.

 

The battery will have a big E or EFB printed on the top if it is an EFB.

 

As for solar panel chargers, these really need to be on the outside of the car as under glass, their efficiency usually drops dramatically.

 

Also check if the 12 volt socket disconnects when the ignition is off or after a certain time. I doubt its a direct feed.

 

Its often quoted that quiescent consumption when everything is off is around 50mA on average and that seems to be what I see on my cars.

Edited 14 June, 2018 by xman

[BigEjit]

It takes 5 mins for the vehicle ecu's to power down after locking the car. During this time there is a higher current draw when compared to everything fully asleep. Leaving the car unlocked prevents the ecu's from going to sleep quicker. With the ECU's awake and ignition off, the current draw will lower the voltage reading and give an impression theres a problem. With Kessy, its harder for the ecu's to go to sleep as they are primed and waiting for an engine start signal.

 

The best way to get a true battery voltage reading is to fully charge the battery, let it stand for a few hours to stabilise then take a voltage reading with it disconnected so that there is no current draw affecting the reading. Any other reading taken is subject to the effects of current draw from the vehicle systems.

 

 

[Stewart7]

A big thank you to xman and BigEjit.

Lots of very interesting info. there.

 

It seems that battery technology has moved on in leaps and bounds since I bought my last lead-acid battery from Halfords for £40.

 

I hear what you say about solar panels behind glass.  Thanks for that.

I know the 12v sockets are always live because I once left the dash cam plugged in to the front one overnight and captured footage of cats, foxes and bin-men going about their business.  I've also used the rear one to connect my maintenance charger (it does have a stop-start battery setting).

It's interesting to know about the 50mA current draw when everything is off.

 

Thank you Gentlemen, and everyone else who replied.  I can sleep a bit easier now, and thank you also, for your patience with an old duffer who worries too much.

Regards

Stewart

 

[pist0nbr0ke]

And I thought EFB was End of Family Brat 

 

Some very knowledgable members on here - thanks for sharing that info,  @xman and @BigEjit