Quote:
Originally Posted by broski499
Fantastic job. Amazing how stock it all looks. How long does it take to charge it 100%. Are you able to gauge the percentage of the pack's charge state? I have a 2008 prius and have wanted to do this but the cost is a tough sell. has anyone tried rigging up a system that allows for grid charging of the stock battery so you always start at 100% charge state. I'm in California, wonder if a solar roof could trickle charge the stock battery while at work... I know small solar panels can't do much, just curious. Anyway, bravo for doing what I have always wanted to do and doing such a nice job.
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Great way to cause cycle wear with no benefit. Usable capacity of the Prius NiMH pack is almost identical to the total capacity of the 12V, so conceptually, you're trying to gain some benefit by adding additional energy equivalent to the capacity of your 12V battery.
The good thing is that your battery will probably be very balanced most of the time.
The bad thing is that your battery will sustain accelerated cycle wear due to you forcing the battery to 100% SoC. This increases the depth of discharge and adds battery cycles where there otherwise wouldn't be any. This generally equates to reduced battery life.
Additionally, the repeated forced over-charge would likely cause accelerated capacity loss due to inducing voltage depression and would require you to periodically discharge the battery via an external means to recover lost capacity.
The mpg benefit would likely be very hard to measure given that you're adding very little stored energy.
Grid charging is very beneficial as a preventative maintenance tool, but this is typically done on a once per 90 days time frame.
Calcs:
HV battery:
6.5Ah * 201.6V = 1.31kWh
40% usable = 0.52kWh
12V battery:
45Ah * 12V = 0.54kWh