Balancing Cells - RC Charger or connect in parrallel?

The fastest and easiest way is with a Prolong Battery Charger. There is a one time car harness installation and then the battery can be easily reconditioning (and cells rebalanced) at home as often as needed for the rest of the life of the vehicle:
Prolong Battery Systems - Hybrid Automotive

Also, in case it helps, here is a good how to on load testing the modules:
Prolong Battery Module Load Tester - Hybrid Automotive

 

Keep in mind that reconditioning and re-balancing is a major undertaking and one should have good understanding of the batteries and their operation before attempting! Read up on all of the threads on Priuschat about reconditioning before attempting! This is a good one to start: Prius Battery rebalance thread | PriusChat

To answer your questions:
1. Series and parallel circuits - Wikipedia, the free encyclopedia However hooking cells in parallel will only balance their output voltages, it will not balance the state of charge which is what is desired to be balanced. It's a huge misconception that the battery voltage indicates how much charge a battery has left (this will only provide one a rough estimate). In general there's no need to hook the cells of the Prius' batteries in parallel during reconditioning.
2. Re-balancing usually involves doing near full discharge and recharge of all the 28 batteries at least 3 times, and recording the capacity of discharge on each cycle. Batteries that do not recover a certain capacity are then replaced, and those that show improvement but are still below average can often be cycled another 2-3 times to get back capacity. Cells that are replaced must be very close in capacity to the other cells, otherwise imbalancing will occur with normal Prius operation and the car will throw an error code within a short amount of time afterwards.
3. No, you would fully cycle all of the cells to determine the capacity of each individual battery per my comment in #2. What I've written here is just a general overview. See other PC threads for a full procedure.

Using a charger like Jeff mentioned can help re-balance your battery before it throws a code. If you're already getting a code, it's probably too late and you'll need to do full battery reconditioning at a minimum. If you're not getting a code, I wouldn't recommend messing with individual cells unless you really know what you're doing.

 

You are correct that the most benefit from our products will be obtained if they are used BEFORE the battery fails. This is true 100% of the time.

However, around 75% of the time people wait until they encounter the 'red triangle of death' before purchasing our products. In about 60% of these cases, reconditioning the pack by charging/balancing and deep discharging three times is enough to restore it to serviceable condition and extend the life of the battery. Around 40% of the time, reconditioning alone is not enough and a module or two needs to be replaced. We are happy to help our customers locate good quality tested used modules to complete their rebuilds. Rebuilding one's own pack takes a bit of work and is not for everyone, but it is much less expensive than a new battery replacement and much lower risk than buying an unknown history rebuilt pack from a local craigslist seller. I agree with Kevin that unless a module has failed and must be replaced, changing/rearranging the cells (modules) is not recommended.