Can I recharge a battery that I don't know anything about?
If you know nothing about them then be aware that some batteries are not designed to be recharged and can explode if charging is attempted. 

For rechargable batteries there is a different charging scheme for each technology. Do it wrong and the battery is likely to explode or catch fire. 

I strongly urge that, since by your own assertion that you know nothing about these batteries, STOP experimenting around before you end up hurting yourself, others or destroying property.