3d Printer Heated Bed is Slow to Heat Up

[2DPrinter]

Hey all, 

For those who know stuff about 3d printers, I have a question. 

My monoprice select mini pro's (a discontinued printer) heated bed heats up pretty slowly. I have noticed it takes like 3 minutes to get up to 60-65C where as my nozzle is quite a bit faster. Sometimes as it is trying to heat up, the temp will go down a few degrees and than keep going up. I don't remember it being this slow when I first got it, but maybe this is normal? Just want to make sure that nothing is going to break because I want to possibly invest some money into getting an enclosure possibly. 
I have the printer in a garage and the temperatures have gotten down to 30-40 Fahrenheit before. But even at around 50 Fahrenheit outside it still is slow to heat. 

Anything possibly wrong with the bed? 

Thanks!  

[Levent]

If its a 12v bed, they do tend to take forever to heat up. I have a layer of insulation on my anet a8's beds underside. It still takes forever (around 20 minutes) to hit 90-100c required for ABS but at least I am able to take some strain off the mosfet and PSU that way.

[2DPrinter]

5 hours ago, Levent said:

If its a 12v bed, they do tend to take forever to heat up. I have a layer of insulation on my anet a8's beds underside. It still takes forever (around 20 minutes) to hit 90-100c required for ABS but at least I am able to take some strain off the mosfet and PSU that way.

Wow, yours takes quite a while to heat up. Good to know. Thank you for your help. I think it might just be slow.