I have a battery that looks like a lead acid battery, contains lead, and it's from one of those little electric cars that kids can ride on, so it should be chargeable, but it says on the casing not to charge it:

Nonchargeable lead battery

Is this battery really not chargeable, or did they just write that so that I'd have to buy a new battery every time?

  • \$\begingroup\$ What's the voltage across the battery right now? A 12 volt SLA suffers damage when discharged below 10.5V, so I guess a 6V battery is damaged below 5.25V If the battery has less than 4V in it, then just replace it. \$\endgroup\$
    – Criggie
    Commented Sep 14, 2023 at 1:59

3 Answers 3


It's a lead acid battery. The second bullet point wraps to the third line (terrible layout).

Do not charge in a gas-tight container

In other words, you can charge it, just ensure that it can properly vent.

  • 15
    \$\begingroup\$ OMG, it's so obvious when you point it out. Doh! \$\endgroup\$ Commented Sep 12, 2023 at 9:03
  • 9
    \$\begingroup\$ The correct phrase really should've been "Charge only in a well-ventilated area". Look at the Wikipedia article for more details. \$\endgroup\$
    – Nelson
    Commented Sep 13, 2023 at 0:50
  • 1
    \$\begingroup\$ HEH hilarious ! \$\endgroup\$
    – Fattie
    Commented Sep 14, 2023 at 21:39

As other answers have stated, do not charge in a gas tight container.

Since this is Electrical Engineering, might I venture a guess that you have a benchtop power supply with adjustable voltage and current? If so, set volts for 6.9V and current for 100 mA max. Actual current will diminish with time. Connect supply's (+) to battery (+) and (-) to (-).

This will fully charge the battery within about 24 hours unless the battery has already reached end-of-life through internal shorting, sulfation or loss of electrolyte. Other, faster charging regimens are possible, but this one is safe and effective.

  • 3
    \$\begingroup\$ If you don't already have a bench supply, a car battery charger with both a 6V mode and a manually selected float charge mode will also work and likely be cheaper. The full charging current is likely to be too high for this little battery, but the float mode will get there in the end. This type of battery is the same as used on some classic motorcycles, and (old) motorbikes are why car battery chargers have a 6V mode \$\endgroup\$
    – Chris H
    Commented Sep 13, 2023 at 8:49

Do Not Charge in a Gas Tight Container

--> Reason is lead acid battery will react during the charging & discharging so definitely it will emit some gas so that was they mentioned.


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