most recent MPG with new plug-in pack from Plug-in Supply

Are you able to monitor the actual OEM battery SOC? I never really understood how PIS dealt with the SOC issue. I thought you connected the PHEV battery directly (in parallel) with the OEM battery. So the Prius will be all confused when it tries to track the SOC with it's Hall sensor. I'm assuming PIS spoofs the SOC on the CAN bus somehow. So why would the SOC you're seeing be all over the place? It should be whatever PIS is spoofing, no?[/quote]

 

Nope, no way:

Every time I pull out one of those noisy/crinkly plastic grocery bags, my cat takes off for the hills!

On the other hand, some kind of heating pad might keep the batteries in their operating range.

 

I'm able to track both the spoofed and the 'real' SOC with my Scangauge.

I set one display to show 'passive' SOC reading (xgauge = soc) and another to show 'active' SOC reading (xgauge = SOC). The spoofed value stays pretty stable at either 74 or 79% SOC reading, but the 'real' value was all over the place.

[edit]The PIS system doesn't do anything to/with the Hall sensor. You are right that the PHEV battery is connected directly to the OEM battery, but current flow to the OEM battery is controlled by a contactor unit that mechanically opens/closes based on commands from the PIS control board. That current does NOT go through the Hall sensor, which is why there is a need for spoofing the SOC. That's as much as I know about how the system works, I don't understand everything about it.[/edit]

 

My understanding is that the current always goes through the hall effect sensor in one direction. In the Enginer case it goes through the current sensor when going into the stock battery. In the PIS/calcars case it goes through the current sensor when going to the inverter. I wonder if the effect you were seeing was caused by the PHEV current being large when the stock system was trying not to use much current out of the stock battery due to its low temperature. That could be just a case of false reporting, as the stock system may be confused by seeing much more current coming out of the battery than expected, but doesn't know that most of that current is coming from the PHEV pack not the stock pack. It would be interesting to know what PIS makes of this observation.

Rob

 

That was my understanding, too -- the Hall sensor will be sensing the current flow to/from both the OEM and PHEV batteries, which are connected in parallel. The only current it won't see is any current between the two batteries.

I still don't see how the Prius ECU could have any chance at an accurate SOC reading on the OEM battery in this scheme. Maybe the Prius ECU is "recalibrating" the SOC reading continuously based on voltage readings, and that is what Frog is seeing?

 

Yeah, that's the part I don't quite get either. With both current assumed to be going in/out of the stock battery it would think its charging and discharging a lot faster than it really is. You could be right about it recalibrating. Cold temps also could shift the voltages around and make it more pronounced, or the stock ecu behavior could change at cold temps.

I guess ultimately the stock SOC value doesn't really matter as long as the PHEV controller is managing the add-on SOC, and the PHEV battery is effectively buffering the stock battery from charging/discharging significantly while the system is engaged. If the PHEV system switches off, the stock SOC should recalibrate the first time it hits max or min V.

Rob

 

Update on my experience over the winter and up to now (7/24/13).

10/7--11/7 - some hwy driving plus cooler weather got 146 mpg on that tank
11/7--12/4 - cold weather driving mpg way down. Using space heater, but not much improvement: 108 mpg
12/29/2012 - removed batteries for the duration of the winter. 96.9 mpg
Early April 2013 - reinstalled batteries mid tank (84.7 mpg) but removed again for cross country trip to OK
Late April 2013 - reinstalled batteries mid tank (68.9 mpg)
4/25--5/25/2013 - more hwy driving than I like. 149 mpg
5/25--6/16/2013 - lots of hwy driving...but during commute I notice pack capacity only 40% of normal. 107 mpg
6/16--7/8/2013 - same as above. 108 mpg
7/8--7/23/2013 - same as above but even worse mpg. 104 mpg. Tried some trouble shooting on the pack and found one BMS board is dead...there may be other problems...pack is currently disabled/inoperable.

I called Rob @PIS and he walked me through some additional trouble shooting. He indicates rear controller is bad. He is sending me two BMS cell boards (one as a spare in case I find another bad one) and a replacement controller board. The 4kwh system is adequate so far...certainly better than the 2kwh Enginer system I had. Support from Rob has been good as well.

...to be continued. If this gets too long I'll open my own thread.

 

Update...the boards arrived yesterday pm. Installed the controller board, but not the BMS cell boards (not enough time to remove/replace them...will do soonest though!).

On this morning's commute, the pack still dropped out after about 7-8 miles, but was able to restart it later after it had 'rested' and recovered some power. When I recharged it I got 2.10kwh into it where before I was getting <1.75kwh per charge.

An improvement, but still some problems with the pack capacity. Will update on progress...

 

every aftermarket plug in user wannabe should read this thread. 'read this before proceeding'.

 

DITTO

 

Hi MJFrog,

I suspect that a fault on the rear controller board has caused a fault on one of the BMS cell boards from the little info given.

I would expect that the cell the faulty BMS cell board was supose to protect may also have to be replaced. The cell was probably damaged by being exposed to a voltage exceeded 3.8 volts at the end of charging. This is the usual cause of losing a lot of battery pack capacity.

Good luck.