if so, you can just make the cells in different packs be in parallel by connection its balance wires... But way do you disconnect them while discharge? Why not to leave them connected forever?
If the packs are identical and are going to be charged and discharged in parallel, there is no reason why the balance leads should need to be disconnected.
I mainly use a 25.9V 7S2P 10Ah pack made up of 2 x 3S 5Ah and 2 x 4S 5Ah, and this pack is permanently connected on both the power leads and the balance leads, apart from when I have to disconnect the balance leads to reconfigure it to a 51.8V 14S1P pack.
Failure to disconnect the balance leads usually causes big sparks and melted connectors when you attempt to connect the power leads in series while the balance leads are still paralleled!
I made up a simple balance board connector unit using Veroboard that allows me to connect the balance leads of up to 8 LiPo packs
(4 x 3S and 4 x 4S) for simultaneous balanced charging. This board has a separate balance lead
(made from balance lead extentions), which is needed for balanced charging and monitoring the cells, without having to disturb any of the balance leads from the individual packs.
Here are some photos of my setup showing how it all goes together:
The completed balance board:
Fitted and connected to four battery packs
(with connectors for four more packs):
Power cable "Y" adapter to connect both 7S packs together in parallel:
Here's the complete pack ready to use, but without any physical protection:
Home made gender changers are required to allow the watt meter to be reversed for monitoring the pack's charging capacity instead of just its discharge capacity.
Watt meter is fitted in normal direction to measure consumed current etc.
The Simple battery monitor device plugged into the balance lead at the top of the picture beeps very loudly if the pack voltage falls too low during use.
I unplug this when the battery is not being used to prevent it from slowly discharging the pack while it sits unused.
This adapter/extension lead converts 1 x 3S and 1 x 4S to 1 x7S plug to suit the charger:
My charging setup, shown without the usb lead that I use for monitoring on the PC using
LogView.
The pack is tucked inside a Jiffy bag, which is taped inside a cardboard box before being placed into the foam padded pannier for added shock absorption, and it seems to be protected well enough to cope with all the punishment I've subjected it to so far!
And this is the ideal result for a properly balanced 7S LiPo pack pack after a full charge:
I must apologise to anyone who is trying to read this post using a dial up connection instead of broadband.
Alan 
