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Old 06-05-2010, 10:32 PM   #140 (permalink)
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Prius C - '12 Toyota Prius C
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Originally Posted by Formula413 View Post
What about a simple float charger for the 12v battery? I use one for my motorcycle battery in the winter, it's really a tender as opposed to a charger. And it was cheap.
Yep, I have a 1A 12V trickle charger that automatically tapers off the charge to zero as you approach 100% SOC, so as not to overcharge the battery. I've measured it at only 60-something percent efficiency, versus the 84% efficiency of this charger that I assembled. *shrug*. It'll do.

Originally Posted by MechanicalRandall View Post
Can you please tell me where you are finding the circuit diagrams? I am trying to figure out how to build a replacement module with different chemistry and I need to learn about the interface between the BCM and the rest of the car.
Download 2000-2006 Insight Service Manual PDF and Others - Insight Central: Honda Insight Forum

If you check out electrical troubleshooting / IS0006202173A.pdf, you'll find there are four BCM wires that communicate with the rest of the car - two to the MCM, two to the gauge cluster. Unfortunately, they're "serial communication".

You'll want to read up on Peter Perkins' work. Search for posts by Retepsnikrep on InsightCentral. He has a 40Ah lithium pack in place of the stock battery. If I understand his work correctly, the Honda BCM sits there with its battery temperature sensors someplace cool and its ten battery voltage sensors looking at a ten-way voltage divider resistor array hooked across the real battery pack. Basically, instead of building his own BCM, he fooled the existing one, then added a custom BMS to watch the temperature and voltage of his battery. A MIMA is required to control assist and regen.

Speaking of MIMA, I really need one to make good use of the charger. I went shopping today, 7mi round trip, making liberal use of assist. I was only able to run my battery down by five bars out of twenty. I got 76.4mpg instead of my usual sub-60 on that route, which I have to say is pretty disappointing. I would have preferred 20 bars used and >100mpg indicated.
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