I came across batteries with mAh rating, which says mA amount of current can be supplied for an hour; if we pull more power more discharge for less time. Some batteries are rated with voltage and output current; does that mean its current output is fixed?
For some batteries its output current rating is not mentioned but mAh rating and voltage is specified; does that mean current can be discharged according to the resistance in circuit?

I have a GSM module that needs 9v and 1 amp current to start transmission; it works with 12v 1.0 amp dc adapter but when I use a 9v dc battery with no indicated current rating it starts but turns off as soon as I try to make a call. Can I use a mAh rating 9v battery so that the GSM module takes current as it needs? If not, what can I use to take 1 amp current from the DC battery? Is there a way? I'm not a electronics engineer, I'm a software guy who doesn't know about electronics. I'm working with bus tracking project for my college, but unfortunately I couldn't find help for electronics side.

  • \$\begingroup\$ Provide a link to the battery in question and, while you are at it, search for the data sheet for that battery and read it. It will more than likely answer your question OR raise more relevant questions. \$\endgroup\$
    – Andy aka
    May 24, 2017 at 12:10

1 Answer 1


The mAh rating of a battery is not directly related to the maximum amount of current it can supply. It specifies capacity, not current.

The problem with your application is that typical 9V block batteries can only supply very little current (maybe like a few hundred mA - notice difference between mA and mAh!).

The maximum current is largely determined by battery type. Different battery types have different internal resistance, which limit the maximum current. Lithium batteries for example can generally deliver a much higher current than standard alkaline batteries. But batteries usually don't tell you their maximum discharge current like power bricks do.

  • \$\begingroup\$ Out of curiosity, do you know of a way to check internal resistance of a battery? \$\endgroup\$
    – Ifusaso
    Nov 15, 2017 at 13:42

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