Adding a second battery

[holy_crap]

Has anyone tried adding a second battery to a Gen II Prius? I don't mean adding it in parallel, but in series mode, kind of like a flashlight is. I would think that you would at the very least have a longer use time on EV mode.

I have seen some of these batteries on eBay for $300 to $700.

[bwilson4web]

Originally Posted by holy_crap

Has anyone tried adding a second battery to a Gen II Prius? I don't mean adding it in parallel, but in series mode, kind of like a flashlight is. I would think that you would at the very least have a longer use time on EV mode.

I have seen some of these batteries on eBay for $300 to $700.

Unfortunately, putting another battery in series would initially double the voltage. The control electronics are not likely to handle going from 200 VDC to 400 VDC without bad things happening to the capacitors and power electronics. But we could start by discharging both battery packs to half of their normal voltage causing another problem.

The energy storage voltage range for NiMH batteries is narrow, ~1-1.2 V. If you cut the operational voltage in half to 0.5-0.6 V., the batteries would have almost no energy storage capabilities. They would appear to be completely exhausted. Then there are the control and management problems faced by the battery ECU.

This is probably not a very good idea.

Bob Wilson

[statultra]

you probably mean paralell, series it would mess up alot of parts, youd end up giving out 400 volts DC rather than 200 as said above.

Paralell would give you an improvement, but minimal, with stock battery.