So I plugged in my new nearly full charge SLA battery (12 Ah) into a new charger designed for 12V batteries and within about 30 seconds the bottom blew out a corner, which I assume was the vent, out came about 15 drops worth of liquid which I assume is battery acid. This is an AGM Deep Cycle by the way.

This is my charger: Amstron 12V / 3A SLA Battery Charger - LC1-12-3A

I read online that the charger gave it too much power, but this charger is rated for this battery. What went wrong? I measured the battery the day before, brand new with no charging done at almost exactly 12 V.

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    \$\begingroup\$ Did you connect the red terminal to the positive? if not you have just reverse connected the charger , it should have shutdown but some dont detect this.also this will be closed unless the question can be shown to be related to electronics design. \$\endgroup\$
    – Spoon
    Mar 2, 2017 at 0:19
  • \$\begingroup\$ @Spoon Yes, red->red and black->black, I connected them before I plugged the charger into AC. \$\endgroup\$ Mar 2, 2017 at 0:20
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    \$\begingroup\$ 12V is nothing like full charge for an SLA battery. \$\endgroup\$ Mar 2, 2017 at 0:37
  • \$\begingroup\$ @LeonHeller After about 15 seconds of charging, the charger lit up green which according the the manual means it went into float charge mode. I was surprised as well, but figured I had misread information online or my voltimeter which is garbage was off. \$\endgroup\$ Mar 2, 2017 at 0:41
  • \$\begingroup\$ Charging a sealed battery is something you need to be careful with. Charge too fast and gasses will build inside the battery and if you are lucky the button will pop out. If you are not, it can explode throwing acid everywhere. \$\endgroup\$
    – Trevor_G
    Mar 2, 2017 at 3:03


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