What charger do I need for this battery?

[Aleksandar91]

Hi all.
I know pretty much nothing about electronics.
Some time ago I lost the charger for my son's toy car (the type of car that a 3 year old can ride).
I want to get a replacement charger, but I can't see any branding information on the toy itself, so I cannot find the original creator.
I opened the toy and took a few photos of the battery and the socket for the charger plug.

The socket size was tricky, so I compared the closest size screwdriver tool I had.
This one is 5 mm, so the socket hole should be ~5mm too.

Can you please tell me which charger to buy?

[Mr.B]

It looks like a standard 6v SLA battery to me.
An automotive shop should have a charger that would be suitable.
Some motorbikes use a 6v SLA.

[Aleksandar91]

Thanks.

[Digorion]

Hello.
As described on the side, its pretty standard lead acid battery, which may be charged with constant voltage. Requirements described in the table. In your case it is "cyclic use", so the voltage must be within the 7.2-7.5 volts and charging current less than 1350 mA (1,35 A). Practically any wall-socket PSU with adjustable to 7.5v voltage and max current about 1A must be suitable (ROBITON DN1000, SN1000S or like), if there is no additional charging circuitry inside toy, of course.
Before charging your MUST check the polarity of the PSU connector and charging socket on the toy, wrong polarity may cause damage of battery or/and PSU! Typically center pin is positive, but sometimes may be negative too. Try to find pinout on the labels or in the documentation. I think that wires from the socket (on your first photo) goes directly to the battery terminals, so in this case positive terminal of the battery must be connected to the positive pin of PSU connector.
Also, at least first time, regulary check the temperature of battery during the charging, its MUST not exseed 50°C. If it is about 40 degrees or more, disconnect the psu and let the battery cool down (actually, if battery in good condition and voltage and current set right they not heating so much).
Also, as say Mr.B, you can find suitable charger for 6v automotive batterys, but its like overkill for this case.

[Aleksandar91]

Thanks for the detailed reply.

Initially I was hoping to just buy something that fits the hole and passes the right voltage, but if there could be parts that change the power before it reaches the battery...
...It might be best to simply take out the battery and charge it directly from time to time.

Is it a common practice for gadgets to have charging curcuitry inside them, instead of in the charger only?
Is there a simple way to check if the toy has that (is such circuitry big enough to be obvious)?

Do you recognize the socket/port type itself?

[james_s]

Lots of chargers sold for RC models have a lead-acid mode, or you can buy dedicated lead-acid chargers. Most lithium-ion powered devices have build in battery management circuitry but lead acid batteries normally do not need anything like that, typically the charge port connects directly to the battery, maybe with a diode in series to keep the charging jack from being live in case something shorts it.

[Digorion]

The socket is pretty standard, like as the battery. Adapters mentioned before does have a plug for each type of this socket (about 10 pcs or so), its not a problem.
These chinese toys made as cheap as possible, i really dont think so this one have a charging circuitry inside. Only possible reason to do this - using standard 12v PSU for charging, instead of 7.5v. Even in this case you can just switch PSU from 7,5v to 12v output voltage.
If you could disassemble toy and take some photos of wiring inside (from socket to battery), it will be helpful.