Electric Power batteries are pretty good, and stand up to their ratings pretty well compared to other brands.
Just make sure that if this is going into anything other than a mini that you use a 2p setup.
SH Z-Car, Custom Crawler, 8s Savage, 12s XTM XLB 1/7 buggy, 4wd 4-link rear/IFS Pro4 truck, Custom Hyper 10 Short Course, Belt-Drive Mammoth ST 1/8 truggy, 4s 17.5 MM Pro HPI Blitz
I've never heard of ewatts. If you can't find any info. on them, then it might be best to stick with other batteries that you or others have heard of and/or used.
SH Z-Car, Custom Crawler, 8s Savage, 12s XTM XLB 1/7 buggy, 4wd 4-link rear/IFS Pro4 truck, Custom Hyper 10 Short Course, Belt-Drive Mammoth ST 1/8 truggy, 4s 17.5 MM Pro HPI Blitz
It is possible that it uses cells that are sold in more expensive packs, but I wouldn't count on it. Usually these packs are so inexpensive because the cells used are rather cheap and can't stand up to what they are rated at.
SH Z-Car, Custom Crawler, 8s Savage, 12s XTM XLB 1/7 buggy, 4wd 4-link rear/IFS Pro4 truck, Custom Hyper 10 Short Course, Belt-Drive Mammoth ST 1/8 truggy, 4s 17.5 MM Pro HPI Blitz