Lead-acid is the best bang for your buck, but heavy and bulky.
LiPoly and LiFePoly are the best weight and size to energy density, but expensive, and require precision charge/discharge controllers to prevent damage (potentially catastrophic damage).
LiFePos are less prone to bursting into flames than LiPo.
NiMHs are in the middle between PbA and lithium for cost vs weight vs energy, and safer to DIY than lithium.
NiCads are about the same as NiMHs, but have one advantage (able to deliver higher current) and two disadvantages (not as readily available in high capacities like 2000+mAh, somewhat more expensive per mAh).
If you are considering lithiums, check out the charge/discharge controller kits available from Adafruit. I've been looking around recently and these are about the best out there for smaller projects (like cellphone size and upwards)
A MiniITX DC-DC board might be a useful component, too. They're very small, and even the cheapest ones should have enough power (check the current ratings for each voltage line, though). You can then run a single 12V line to the board. The "intelligent automotive" ones from that link have beefed up protection from unpredictable voltage spikes on the input (ie, when the car starts up for example).
If you also need say -5V, and that's not available on the DC-DC, you can pick up a separate converter for that for not much.
/ETA/ The very simplest hack would be to use a small UPS (rather than an inverter) - you get your batteries, charger, and AC inverter in one unit. Though that means leaving the SE/30 PS in place, cutting into your room for internal additions.
LiPoly and LiFePoly are the best weight and size to energy density, but expensive, and require precision charge/discharge controllers to prevent damage (potentially catastrophic damage).
LiFePos are less prone to bursting into flames than LiPo.
NiMHs are in the middle between PbA and lithium for cost vs weight vs energy, and safer to DIY than lithium.
NiCads are about the same as NiMHs, but have one advantage (able to deliver higher current) and two disadvantages (not as readily available in high capacities like 2000+mAh, somewhat more expensive per mAh).
If you are considering lithiums, check out the charge/discharge controller kits available from Adafruit. I've been looking around recently and these are about the best out there for smaller projects (like cellphone size and upwards)
A MiniITX DC-DC board might be a useful component, too. They're very small, and even the cheapest ones should have enough power (check the current ratings for each voltage line, though). You can then run a single 12V line to the board. The "intelligent automotive" ones from that link have beefed up protection from unpredictable voltage spikes on the input (ie, when the car starts up for example).
If you also need say -5V, and that's not available on the DC-DC, you can pick up a separate converter for that for not much.
/ETA/ The very simplest hack would be to use a small UPS (rather than an inverter) - you get your batteries, charger, and AC inverter in one unit. Though that means leaving the SE/30 PS in place, cutting into your room for internal additions.