When you upgrade from the bat-pack to the suits, you trade staying ability for mobility and protection. What if power using tools (possibly mining lasers/nanoswords too) could draw some energy from the suit, in the same way as the bat-pack.
Now you are probably saying "omgz overpowerdz the tradeoff is the point!!!!!!11111oneoneone", and you would be right. Kinda.
The thing, is, the tradeoff is still there. If you decide to turn on the (toggleable!!) ability to have tools draw from the suit, your suit energy depletes quicker, meaning you trade staying time for staying time. It sounds a bit ridiculous, but I think in usage it would be quite balanced, and also allow for a higher end tradeoff for the bat-pack.
Either the (AFAIK "useless") chestplate could be used for this energy flow, or the whole suit could be drawn from equally (better).