Replacing the battery in my GBA SP and I'm confused!

(I'm not going to do anything until I get a concrete answer so I won't burn my house down by accident)

I don't know anything about electricity. I have a GBA SP (the second model that has the backlight, not the older frontlight model) and I bought a replacement battery for it. The white battery I took out is 3.8V 600mAh. The replacement I got from Amazon is green and is 3.7V 850mAh. Both are Li-ion.

Shouldn't they be the same thing? I'm afraid to put the new, green battery in there because I don't know what will happen. I would really appreciate the help so I can finish my game of Pokemon Gold. Thanks.

It is safe.

3.7v vs 3.8v doesn't make much of a difference. The voltage will fluctuate a lot more than that simply during it's normal discharge cycle. Also from quickly looking around, it seems 3.7v is the typical voltage for the gba sp battery replacement kits, so you should be ok.

600mAh vs 850mAh is just the overall capactity of the battery. Bigger number = last longer.

@gorkamorkaorka: If it makes you feel better, voltage varies considerably in a rechargeable as it runs down and charges up. In a NiMH AA battery, for example, they charge at 1.5 V and are dead at 0.9 V, even though it says 1.2 V nominal on the side of the battery. The other number is milli Amp hours, a measure of the battery's capacity (which is a function of voltage and only comparable between batteries of the same voltage).

It's totally a fine swap.

Oh okay thanks guys! That makes me feel a lot better.

Batteries are weird. I think it was only six years ago that I learned batteries in series add their voltages, so two 12 volt batteries lined up is 24 volts; but they only have the capacity of a single cell. Where as, batteries in parallel just have the voltage of a single cell, but the the capacity of the battery pack is the sum of the capacities of the individual batteries. It all makes sense, it follows an easy to understand logic, but it was just stuff I never knew....it made me feel dumb for not knowing that earlier in life.