Battery charging device with 12.5 volts?

Hi,

My dad has a device that, when connected to the battery, only outputs 12.5 volts.

The battery was just barely able to start the 2.0 16V Opel engine, and it had the same voltage at idle (of the battery, not the engine).

According to my understanding, the electrons don't use anything, because they are not actually pressed into the battery.

In order for something to charge, there should be a few more volts available, right?

I would have expected >13.

Should I scrap the battle gear?

m;

Depends on the battery's charge level.
The charger also has a higher voltage when idle, but when you connect it to the battery, a different voltage value is established, which depends, of course, on the charger itself, but also on the state of charge of the battery. If it is very low, the voltage will only be slightly above 12 volts (at least with my simple charger). Over time, the voltage also continues to increase. I've measured voltages as high as 14 volts there, once the battery is fully charged.

For simple chargers, you also need to consider that the voltage is a rectified AC voltage. This means you get "positive sine wave half-cycles". If you measure it with a multimeter, you only see the average value, but the peaks are still slightly higher.

dieselmartin wrote:

My dad has a device that, when connected to the battery, only outputs 12.5 volts. In order for something to charge, there should be a few more volts available, right?

The clamping voltage is determined by the "relationship" between the battery's state and the internal resistance of the charger.

Could it, for example, deliver 90 A like a TDI LiMa? In that case, the charging voltage would also quickly rise to ~ 14.4 volts even with a discharged battery.

However, with the few amperes of current produced by common "high-impedance" chargers, one only increases the open-circuit terminal voltage of a battery by a few mV.
While charging, the voltage rises to 14 volts or higher over time, and it is recommended to disconnect at 14.5V to prevent unnecessary gas buildup in the battery.

Quote:

Should I scrap this battle gear?

Only when the battery is in good condition and fully charged, and after approximately 30 minutes of operation at less than ~ 14 volts.

Edit:
Parallelposting with Holger . . .

I would also expect a bit more (13 to 15 volts)!

However, if the battery has been so deeply discharged that even at the maximum charging current, no voltage can be achieved,

Can't you also measure current?

What kind of charger is this, a large one with a transformer, or a mini one with a 'wall wart'?

Is there any intelligence present?

Best regards, Georg

This is such a cheap ABSAAR part.

Trafo - thanks, mainly because of the weight.
Intelligence - probably not present in the charging device.

Dad got a new battery. After 25 months of battery life, I told him not to pay anything.
A BOSCH should "last" for a longer period.

BOSCH wants to "check" something further.

m;

dieselmartin wrote:

This is such a cheap ABSAAR part.

Ah, something like that, I have too.

If the device has a (functional) charging indicator, you can estimate how it's charging.

Roughly, you also perform a spark test: Connect the device and gently pull a clamp over the battery terminal.
If you observe a slight "wonder candle effect" in the process, you can also charge a relatively intact (!) battery with a few amperes, which, depending on the charge level, can usually be fully recharged within a day.

Hi,

Before using the spark method, I would advise against it. An empty, freshly discharged battery can still look quite nice...

Roger wrote:

I would like to warn you before using the spark method. An empty, freshly cleaned battery can still look quite nice...

Oh - I haven't noticed this before, but you're right, of course.

And I always thought that batteries only gassed when charged above 14.5 volts

Before using the spark method, I would advise against it. An empty, freshly cleaned battery can still look quite nice...
Oh - I haven't noticed this before, but you're right, of course.

And I always thought that batteries only gassed when charged above 14.5 volts

Hello Ulf,
Take a look at a battery during startup; in comparison, a bottle of mineral water is practically 'asleep'!
Best regards,
Günther

Hi! Yesterday, I bought a battery for my neighbor. It already had 12.65V in the store. Then, I charged it again for 2 hours at 3A up to 14.45V, and then it had a resting voltage of 12.85V. Today, it still had 12.8V

On the side, below the upper edge, there is a small hole that leads into the inside. If you press on the wobbly side walls, the battery 'breathes' through this hole. Is there perhaps a labyrinth or a valve, so that the acid does not leak out when tilted?

Greetings
Holger

Quote:

Might be a labyrinth or a valve to prevent the acid from leaking out when tilted?

More likely a venting system with a retaining function for electrolytes (recombiner) that are carried away during gas cooking, often with a backfire protection (frite). The term "labyrinth" is approximately correct in terms of function . But it will still leak when tilted.

In some car batteries, one or two nipples are present for a venting hose, but they are often sealed with plugs. If you simply install the battery without removing one of the plugs and connecting the venting hose, the battery can swell and explode. This happened to my father when he replaced the battery at the Daimler factory. Battery case cracked at the positive terminal and leaking - what a mess!