Replacement car battery charger - shows wrong voltage again

Thread Starter

johnnybaloney

Joined Feb 6, 2021
8
Hi,

I had a Einhell CE-BC 4M "intelligent" (!) car battery charger that would display voltage value going up and down and well below the actual voltage of the battery. I returned it, received a replacement and managed to charge a flat battery once. Now the same thing is happening again.

Here is what the display shows while charging:

And here is the point in the video when I measure the battery voltage with a multi-meter:

Would this be another faulty unit or am I doing something wrong?
 

LowQCab

Joined Nov 6, 2012
2,506
It depends on your definition of "flat" (dead).

If a "12-Volt" Lead-Acid-Battery stays below ~12 actually measured Volts,
for more than about a ~week, ( sometimes just a couple of days ),
it will be permanently damaged, and may never recover.

There's probably nothing wrong with the Charger,
it's trying to get the Battery to recover, but it probably won't happen.

A Lead-Acid-Battery MUST be kept above ~12.6 to 12.7-Volts at all times,
preferably higher than that.
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Thread Starter

johnnybaloney

Joined Feb 6, 2021
8
Thanks for your reply. I use 'flat' as in 'car not starting up'.

It's strange because that would mean the charger 1 was also trying to recover the battery and was apparently unsuccessful at that. It looks like the battery wasn't very dead back then as the car was starting at the time (and is still driving today). When a month later charger 2 arrived and the battery was indeed 'flat' and the car wouldn't start it actually managed to bring it back to life! Now we are back to the situation as with charger 1, the car starting but charger 2 unable to pump juice.

Trying to understand those "intelligent" chargers is quite a job! This one has a Battery Fault indicator for when it thinks (!) there is a problem with the battery, it never came on during use. Sadly the manual says nothing about the behaviour from the video...

Here is the timeline:

  • 2nd December - Attempting to top-up the (less than 1 year old) battery with charger 1. The charger is showing fluctuation in voltage as seen in the video during the 12 hours it's connected to the battery. Contacting a garage about the warranty for the battery, they say they would do a "drop check" when I bring the car over for the annual service.
  • 3rd December - Service done, they find nothing wrong with the battery. I check with a multi-meter, it shows 12.45V and the car is starting up fine.
  • 6th December - Warranty claim for the charger assessed, authorisation given to send replacement charger 2 to me.
  • 14th January - Charger 2 arrives.
  • Soon after can't start the car, connecting charger 2, charging all the way to 'FULL' (according to charger 2 display), car starting again. Driving the car since then no issue.
  • Some time in February - hooking up charger 2 to do a top-up. Still looks to be working fine.
  • 16th February - hooking up the charger, same symptoms as with charger 1. Voltmeter shows 11.94V.
 

LowQCab

Joined Nov 6, 2012
2,506
Sounds like you've got a bad Alternator,
or possibly the Car is only driven ~once or twice a week for a very short distance.
If the later is the case,
the Battery should be kept on a "Battery-Maintainer" any time it is not being driven.

How "old" the Battery is is almost irrelevant, I've seen Car batteries last for ~5-years, or one month.
If it is not kept completely Charged, it will fail.
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Rich2

Joined Mar 3, 2014
242
Where's the negative charger wire connected? Is it on the chassis? Connect it straight onto the battery negative terminal.
 

Thread Starter

johnnybaloney

Joined Feb 6, 2021
8
Yes, you are correct, the car isn't used frequently. The idea was to periodically top the battery up with a charger, but it turns out the charger is not "intelligent" enough, ugh!

I'll try again even though the display of the charger shows gibberish and check if there is any progress with the voltmeter. Hopefully the battery has not reached the doors of the Creator yet!
 

Rich2

Joined Mar 3, 2014
242
Yes, the negative wire is connected to some metal bit just as they say in the manual.
Earth straps can fail or it can be a dirty connection. Put it on the battery and squeeze it closed so it's a good connection. It's odd how it's reading 8v and the multimeter reads 11.94 v
 

Thread Starter

johnnybaloney

Joined Feb 6, 2021
8
Thanks Rich, will try that! It sparks when I stick it onto metal which I took as a confirmation of good connection.

Yep, that's the confusing bit, and it's two devices of the same make displaying the same erratic readings, which led me to believe that it was the charger that was faulty.
 

Ylli

Joined Nov 13, 2015
1,058
My first thought is that the OP doesn't have the leads properly connected to the battery. Since the charger likely does not have any smoothing cap, the meter is reading the average of the rectified waveform. Put the red lead on the battery positive and the black lead directly on the battery negative. If you are concerned about a local spark, then connect the leads before powering up the charger.
 

Thread Starter

johnnybaloney

Joined Feb 6, 2021
8
Welcome to another episode of my Chargers from (Ein)hell story!

In the last episode the voltmeter displayed 11.94V while the charger was being funny showing all sort of things below 9V.

Later in the day the car was taken for a return trip of about 10 miles.

Today I started with a voltmeter which read 12.04V so the alternator seems to be doing its job. I then hooked up the charger the same way as always and it displayed 13.5V and proceeded with charging the battery! Once the charger showed 'FULL' I checked with the voltmeter again with the charger still connected and the reading was switching between 13.14V/13.31V presumably due to the charger now working in the maintenance mode. Disconnected the charger, did the final measurement with the voltmeter and it showed 12.67V.

Not sure what to think about it. I don't rule out poor connection, although yesterday I repositioned the clamps several times and it made no difference. Today it worked first time. It's a mystery...
 

LowQCab

Joined Nov 6, 2012
2,506
Start the Car, let it warm-up for at least ~10-Minutes,
Turn-On ALL accessories, All Lights, Blower on "High",
measure the Voltage at the Battery Terminals,
if it is not at least ~14-Volts, You need to replace the Alternator.
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Thread Starter

johnnybaloney

Joined Feb 6, 2021
8
It's been a while but finally the stars aligned and I checked this. The results from the voltmeter:
  • lights on - 14V
  • + blower on max - drops to 13.8V
  • + rear screen defroster - drops to 13.3V

I've added a recurring entry to my calendar and top up the battery weekly now. I'm still observing the erratic behaviour of the charger and leaning on the poor connection suggestion now. Maybe the charger clamps are too weak or insubstantial for the job. When I notice the charger is being funny I keep rejigging until it becomes happy. Unfortunately sometimes it means hours kind of wasted with the charger only pretending to be doing something before I get the positioning right.
 

dl324

Joined Mar 30, 2015
15,117
I'm still observing the erratic behaviour of the charger and leaning on the poor connection suggestion now.
What makes you think it's behaving erratically?

My battery maintainers vary the charging voltage frequently when charging. Sometimes they'll be charging at 14V or higher and then they'll switch to a different mode to check battery state, then go back to charging. They do that until the battery is deemed charged, then the voltage stabilizes in maintain mode.

When I notice the charger is being funny I keep rejigging until it becomes happy.
Could it be defective wiring?

EDIT: I have several vehicles that don't get driven very often or are in storage (not driven at all). I have 4 of these battery maintainers to try to keep the batteries charged:
1651084191346.png
4 vehicles are outside and I can't keep them constantly connected. I plan to make up some cables so I can...
 
Last edited:

bassbindevil

Joined Jan 23, 2014
563
Modern cars have a lot more junk that can drain a battery if not driven regularly, and things that can malfunction (perhaps a trunk light that doesn't turn off). Cars may also have improperly installed aftermarket gadgets that are wired to "always on" 12V instead of "ignition" or "accessory".
I'd strongly suggest adding a digital voltmeter to the dash. It tells you a lot about the health of the electrical system. I can't recommend the very cheap "waterproof" voltmeter I bought on ebay; it goes nuts when I start the truck and never reads correctly afterwards; the Schumacher gauge that plugs into a lighter jack works fine (though I had to replace the voltage regulator on it once).
 
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