Your specialist subject..battery chargers..cheap and not so..

[B21]

We had a recent major power outage courtesy of Storm Isha with 20 hours or so no mains power.

Pressed into service a mixture of car batteries with inverters and my back up generators.

Embarrassingly my main back up battery a big 110 ah leisure battery was flat!

After mains power was restored I started charging the batteries up with my two Lidl chargers and my BMW aka CTEK charger.

What was interesting was that both the Lidl chargers considered both wet batteries charged quite early on..whereas..the CTEK would huff and puff for a lot longer on each battery.

Looked up and essentially most chargers are 3/4 stages..

First step: BULK phase

In the bulk phase, the battery charger delivers its maximum current, e.g. 50 amps for a ChargeMaster 12/50 and battery voltage increases. The duration of this phase depends on the battery capacity, charger capacity and any consumers connected to the battery during charging. The bigger the battery, the longer this step takes; the larger the charger, the shorter the stage. If consumers such as a refrigerator is connected, they will also need to be powered by the charger, reducing the charge current going into the batteries and increasing the time necessary for charging.

Second step: ABSORPTION phase

The second step, the absorption phase, begins once the battery has reached its maximum voltage. At this point the battery is around 80 % full, and the charge current begins to slowly decrease. At 25 °C, the maximum voltage is 14.25 volts for a 12 V battery and 28.5 volts for a 24 V one. In this stage the battery is charged to the full 100 %, which takes approximately three to four hours, depending on the battery type, the battery charger and the charge amount.

Third step: FLOAT phase

Once the battery is fully charged at the end of the absorption phase, the float phase begins. The Mastervolt battery charger switches over to a maintenance voltage so that the battery remains fully charged and in optimum condition. Any existing consumer loads are also powered. The charger remains in the float phase until the battery voltage falls due to a major load, or the battery charger is unplugged because the power connection was removed.

Then there's some optional stuff about either doing a burst of absorption charging and /or desulphonation mode to get rid of sulphates on plates.

The CTEKs have many stages..how much of its mumbo jumbo I'm not sure..

Does it matter?

For recovering and using some big leisure batteries probably so and cars with early electrics..if you have an E89/G29 probably not..its going to be a new battery and a 'simple' charger will suffice..

The reason why my big battery was flat was that I kept in on trickle charge with a Lidl charger and it had tripped offline and then was slowly draining the battery..one good reason for a CTEK..albeit 5 times more expensive..

Sorry to waste everyone's time..

[axelleveau]

I had issues with the CTEK supposed to "maintain" my motorcycle battery so would be on float most of the time. It seems the issue was that it goes on float and then does not manage to go back into charge (it was relevant for me as I had a GPS tracker always draining the battery, might have been what tricked the charger by draining too fast). I had to use a mechanical 24hrs clock thingy to make the charge reset everyday and now it is happy

[TitanTim]

I've used CTEKs for years so can't really compare them to similar cheaper makes. Only reason I use them is its nice to see at what stage the charge is at, don't know if that's unique to CTEK. Only issue I've had with them is the mode button can stop working or becomes intermittent after a few years. Fixed mine by taking the charger apart and lubricating the button with WD40.

Interestingly I had my M140i hooked up to a CTEK for 8 months and when I went to start the car it started but then gave a battery discharge message pretty much straight away and to charge the battery immediately which was strange as the CTEK was saying the battery was fully charged when I disconnected it. Would the battery discharge that quickly. Unsure therefore how accurate the charging status lights are in reality.

Tim.

[1536Z4]

Would the battery discharge that quickly. Unsure therefore how accurate the charging status lights are in reality.

I have a CTEK and it says fully charged and on maintenance but if I disconnect it to start the car and move it and then reconnect the CTEK the charge lights start at the 3rd light in so much the same as you are seeing .

[TitanTim]

Would the battery discharge that quickly. Unsure therefore how accurate the charging status lights are in reality.

I have a CTEK and it says fully charged and on maintenance but if I disconnect it to start the car and move it and then reconnect the CTEK the charge lights start at the 3rd light in so much the same as you are seeing .

Yes the same, although it doesn't take too long to get back upto a fully charged state.

I have noticed with my Hyundai i20N which is brand new if I connect the CTEK and wait until it says fully charged then go for a drive and connect the CTEK back up it will stay on the Bulk stage for quite some time, same for the absorbption stage before finally going to fully charged state. I think it took well over 8 hours to show the battery as fully charged and the battery is supposed to be brand new. I know some of Hyundais models have suffered premature battery failure which could be down to Bluelink which is equivalent to BMWs remote app as the car is continously pinging with the app to give its status etc i.e. whether the car is locked, fuel status etc which all requires the cars battery power.

Tim.

[ronk]

I’ve got a £25 “Maypole“ Charger connected on the under bonnet pins - it sits at 13.6v all winter long and returns to that same stage if the power goes off.
I was in the car the other day for about 15mins so interior lights and systems were on - the charger then showed 12.6v and then increasing back to 13.6v after about two hours.

I had a Lidl charger some time ago and it coped ok with power outs - it only gave up the ghost when it was put onto a neighbours car and I think she attempted to start her car while it was connected

[B21]

I’ve got a £25 “Maypole“ Charger connected on the under bonnet pins - it sits at 13.6v all winter long and returns to that same stage if the power goes off.
I was in the car the other day for about 15mins so interior lights and systems were on - the charger then showed 12.6v and then increasing back to 13.6v after about two hours.

I had a Lidl charger and it coped with power outs - it only gave up the ghost when it was put onto a neighbours car and I think she attempted to start her car while it was connected

The Maypole gets good reviews

[B21]

Would the battery discharge that quickly. Unsure therefore how accurate the charging status lights are in reality.

I have a CTEK and it says fully charged and on maintenance but if I disconnect it to start the car and move it and then reconnect the CTEK the charge lights start at the 3rd light in so much the same as you are seeing .

Yes the same, although it doesn't take too long to get back upto a fully charged state.

I have noticed with my Hyundai i20N which is brand new if I connect the CTEK and wait until it says fully charged then go for a drive and connect the CTEK back up it will stay on the Bulk stage for quite some time, same for the absorbption stage before finally going to fully charged state. I think it took well over 8 hours to show the battery as fully charged and the battery is supposed to be brand new. I know some of Hyundais models have suffered premature battery failure which could be down to Bluelink which is equivalent to BMWs remote app as the car is continously pinging with the app to give its status etc i.e. whether the car is locked, fuel status etc which all requires the cars battery power.

Tim.

Most new cars with regenerative braking will initially let a fully charged battery drain down a bit so that the regenerative braking can be used..so it’s behaviour and that of the CTEK all accord…

[Pondrew]

These 'maintenance' or 'smart chargers' are not really all that smart. All they do is constantly measure the voltage and adjust their output accordingly. They have set parameters of voltage which will kick in and out their charging amperage/ voltage. The different 'modes' or 'sequences' will just add a time frame into that.
Voltage on a DC battery is directly proportional to stored amperage, at rest. That's the only real way you can sensibly measure stored electricity. Stored electricity is not measured in amps, amperage is the measure of current flow. At rest there is none, so it is 'potential amperage'.

Starting a car takes a LOT of energy from a battery, initially, but they do 'recover' quite quickly afterwards to some degree. Everybody must have tested it at one time, or another. Cranking a car that won't start drains the battery so it won't turn the starter motor after a while. Leave it a couple of minutes and it will crank again. Like magic!

[Pondrew]

Most new cars with regenerative braking will initially let a fully charged battery drain down a bit so that the regenerative braking can be used

Indeed, otherwise the electricity can't flow into the battery. You need a difference in voltage for the current to flow. Same as all the basic laws of physics....pressure difference.

If your alternator was producing 12 volts and your battery was sitting a 12 volts, nothing would happen. It can't.

[ronk]

Waking up the car simply by opening the door, then starting it necessarily drains power - so there’s nearly always a wee bit of room for some more electrical energy,
However, if the the battery is fully charged, Ie on a decent journey, the system doesn’t allow the alternator to over charge the battery,