inexpensive and safe isn't normally used together. But the only thing i can suggest is the icharger 106b which is what i would call safe. Also a para board for the batteries you have.
Cheap, easy and safe...look at the onyx 245. There are better deals out there, if you want to piece a set up together, but the 245 is pretty straight forward.
If you do choose the onyx 245 it only comes with one balance plug lead and if you want to charge 2 LiPo packs at a time you will probably want to also purchase a second balance plug lead. The newer chargers for safety will error out if the balancer is not plugged into the battery when you charge a LiPo battery pack.
Also read the battery manufactures maximum charge rate for the battery pack. LiPo battery packs can catch fire if they are charged to fast. A fire bag such as these are recommended. I own one and use it while charging my battery packs.
A good starter lipo charger is the Thunder AC6 which can be had for about 44 bucks. It has a nice selection of of adapters, comes with a balance board, does storage charges and basically does everything you would want a lipo charger to do. Its only a 50W charger though but it doesn't require a DC power supply as it plugs straight into the wall. It can do 2-6S lipo and also your other common battery types NiXX and I believe LiFe too although it can't reach a full 5A doing 5 and 6S lipo packs. For an additional $4 you can get the Thunder AC680 which is basically the same thing but it is an 80W charger instead of 50W for a little extra help for those bigger lipo packs.
I'm using a IMAX but here lately , been noticing that it's not counting the voltage right at all, idk if it's just mine or what . But I'm looking in to gettin a Icharger or a onyx 245
I like everything about the onyx 245 but the price and lack of recomendation / reviews.
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I have also read about the IMAX and there is a cheap CLONE and a real one. Any idea which you have? A quick look on ebay and you can tell there are 2 fif ones going by the same name.