You can do a no-solder battery pack:
(1) Find the largest 6V sealed lead acid battery that fits the battery compartment.
(2) Disassemble Portable so you can see the underside of the battery compartment. The gold-plated battery contacts are simply clipped into place and connected via slip-on terminals. Remove, wrap in some non-conducting material and tape somewhere inside the Portable so you can't lose them.
(3) Make battery extension cables to reach from SLA battery to those existing slip-on terminals. Might have to hunt around a little to find the appropriately sized terminals. If you can't solder, crimp them and insulate if need be.
(4) You probably will have extra space in the battery compartment. Fill it with whatever material you have on hand so nothing rattles around and causes damage: Closed cell foam, corrugated cardboard, block of wood, etc would all be workable.
Voila! New off-the-shelf battery pack that fits the stock Portable with no permanent modifications needed.
One thing tricky about the Portable is that there's a constant current draw, even when it's "off", so if you are going to leave it unplugged for a long time, remove the batteries or consider rigging up a small solar trickle charger or something.
(1) Find the largest 6V sealed lead acid battery that fits the battery compartment.
(2) Disassemble Portable so you can see the underside of the battery compartment. The gold-plated battery contacts are simply clipped into place and connected via slip-on terminals. Remove, wrap in some non-conducting material and tape somewhere inside the Portable so you can't lose them.
(3) Make battery extension cables to reach from SLA battery to those existing slip-on terminals. Might have to hunt around a little to find the appropriately sized terminals. If you can't solder, crimp them and insulate if need be.
(4) You probably will have extra space in the battery compartment. Fill it with whatever material you have on hand so nothing rattles around and causes damage: Closed cell foam, corrugated cardboard, block of wood, etc would all be workable.
Voila! New off-the-shelf battery pack that fits the stock Portable with no permanent modifications needed.
One thing tricky about the Portable is that there's a constant current draw, even when it's "off", so if you are going to leave it unplugged for a long time, remove the batteries or consider rigging up a small solar trickle charger or something.