What is a Break-in? Do Eneloops need it?
No, this has nothing to do with burglars or with your breakfast. But a Break-In for batteries is referred to as maximizing the performance or capacity of a battery. (However, this is different from a Refresh or Analyze mode)
The Maha Powerex MH -C9000 for example has a Break-In option.
Warning: A break-in cycle should always start with an empty battery.
The charger will charge for 16 hours 0.1C charge rate, then rest for an hour, do a 0.2C discharge, rest again, and at the end again charge for 16 hours at 0.1C according.
(I don`t know to what Voltage the Powerex will discharge, but according to the IEC standards, section 7.1 it should be 1V.)
If you do an Analyze or Discharge, you should be able to know the capacity, do NOT look at the “charge capacity” during the Break-In!
When to use a break-in with Eneloops?
Only with an empty battery! When using rechargeable NiMH batteries people advise doing a Break-In right out of the package. I personally don`t think you need to do this with Eneloops. It`s a great feature for old rechargeable AA or AAA batteries that are almost useless or completely dead.
My advice would be to not use the Break-In mode (too often) with Eneloops, especially not with Eneloop Pro. Eneloops don`t really need it unless you want to have the extra 5+% capacity.
Ps. New Eneloop batteries need a few cycles to get to max capacity… (This is also written in each battery product specification.

More questions about charging (Eneloop) batteries
+ Is slow charging better than fast charging for Eneloops?
+ What do mA and mAh stand for? And what’s the difference?
+ How many times can Eneloop rechargeable batteries be recharged?
+ Do Eneloop batteries need a special charger?
+ How long do Eneloop batteries hold a charge?
+ What is the recommended charge current for Eneloops?
+ What’s the best Eneloop charger?
+ Eneloop Voltage – what’s the deal
+ Can you overcharge Eneloop batteries?
+ What is the maximum charge voltage for Eneloops?
+ Do I need to charge my new Eneloop batteries before I start using them?
+ Should I discharge my Eneloops completely before charging them?
+ How long does it take for Eneloop to charge?
+ How do I need to Refresh my Eneloops?
+ Can I refresh Eneloops if I don’t have a charger with a refresh option?
+ How many years do Eneloops last?
Advanced Eneloop charging info
+ What is -dV/dt charging? (termination)
+ What is 0 dV/dt termination?
+ How are Eneloops tested to claim a 2100 cycle life? (IEC 61951/ JIS 8708)
+ Non-charge related questions can be found in the Eneloop FAQ