Assist at 3 bars, thermostat-based charge current limiting
Folks,
Does anyone's Insight "sit" at three bars while allowing Assist for a long time before starting to limit assist after a grid-based recharge (w/ an Idle Relearn immediately following that recharge)?
That's what mine does, and I'm assuming it's from the BCM thinking a full charge is achieved at what is actually a 75% absolute charge (80% for original BCMs), when it's actually usually near 100% charged, and it can't see and/or account for the difference. The BCM then tracks the pack depletion to what is supposed to equate to a 35% absolute charge (20% for original BCMs) at the 3 bars basement level but is actually 50% (100%-75%+35%) (or 100%-80%+20% = 40% for original BCMs). Assuming the Assist gets limited only when the BCM sees bi-stick voltage tap levels significantly increasing their negative slope and/or going below a threshold voltage, Assist would be allowed longer than expected given the higher than expected actual SOC.
(I'm also remembering newer replacement BCMs such as mine as keeping the pack in a Prius-like 35% to 75% SOC window, which could be off a bit, and of course many folks here probably haven't had Honda replace their packs because they found a better way to address pack issues , letting them keep the wider 20 - 80% SOC window via their original BCMs, which would also reduce the BCM's SOC calculation error I suspect I'm seeing.)
Does that resemble the experience of anyone else doing grid-based recharging, and are my assumptions reasonable?
Also, for summer months at least, would including at least a simple pack fan exhaust -based thermostat (i.e. attic fan t'stat -case) perhaps be a good idea for early exit of the high-current charging circuit in a bi-level charger? I suspect it certainly wouldn't hurt.
On those lm 317's ..... you need the lm317hv. The LM317 will burn out if you try to span to great of a voltage range. I know as that was the first one i tried. I also tried the higher current version and they also burned out. The 317hv's have been running almost 2 years with no issues.
I noticed that on the spec sheets, but then I noted that both versions were spec'd the same. in that they said as long as you didnt exceed 40V from input to output that it was fine. But...BOTH are spec'd at 40 volts. Since I am using it with a power supply string voltage regulated to 175 volts that means the battery can drop to 135 volts before its over spec. I will never have a battery under 144V in the car and on the bench I will be using a different charger that is designed to start at 100Volts, I dont see it as a problem, but maybe I missed something.
What voltage difference were you working with when they burned out??
__________________
Jim Isbell
2000, 5 speed, 250,000 miles
"If you are not living on the edge, well then,
you are just taking up too much space."
The same range ..... ~140v - ~172v. The lm 317 ran fine for about a week then pop ... did that with 2 in a row. The same with the high current version that had a different number. The HV version however works fine.
Btw, I think normal version is good for about 37 volts. The HV version is good for over 50, I would have to look up the specs.
For this cleaner charger I just decided to use the led current limited supplies due to the cheap ebay deal. I'll actually be building up 5 units, 2 for myself, 2 for a friend who is in the process of getting a car that will also be dual packed, and one spare.
Also another note on the LM317's, I also tried two limiting circuits in series to split lower voltage load, but that didn't work. The circuits would randomly split the difference from 50 - 100% ea. However they work fine paralleled to stack current.
Roger,
I had the first ECM "cold Weather" recal done to my 2000 back in about 2002, and after that, my car would sit at 3 bars for some time before finally limiting the charge, and this was before MIMA or grid charging, so you may be seeing that issue.
During the first MIMA pack whack, we had strong assist with no SOC showing. http://99mpg.com/Projectcars/mimapackwhack/
So while the car is relearning, strange SOC readings can be expected.
There are several threads about the 3 bar bug as some call it.
I like the LED CC supplies for several reasons, that they are pretty cheap for what they do, are off the shelf, and have UL and CSA safety approval, and are isolated input to output.
Roger, mine does the same thing. I don't have MIMA and I'm not even grid charging it but when I drive and provide enough regen and drive to avoid assist to get all 20 bars and then run it down with heavy assist, it hangs at 3 bars for a short period of assist longer than it normally would for a few bars to go by and then assist cuts and it slowly drops the final bars indicating empty. I was then able to regen and get it charged all the way full. I haven't had any recalibrations in the 2000 miles or so that I've owned mine either. The battery is 3 years old, has an updated BCM from the recall and has about 65,000 highway miles on the battery based on what the previous owner had to say about it.
Since it seems that it's in good shape, I think adding a buddy pack wouldn't be a bad idea, but I'm waiting for the warranty to drop out in June before I proceed with a grid charger. For all I know a grid charger(slightly higher powered) and MIMA might just be all I need to accomplish what I want to do.
Thanks... The conditions (_fully_ charged pack) do resemble the MIMA Pack Whack conditions. I'll read up on the 3 Bar Bug threads. I figured it was the BCM governing the situation, was unaware of the ECM's role.
Getting full sustained Assist at 3 bars, sometimes with the car wanting background charging when possible and sometimes not (even with only 3 bars showing) seems an odd, but potentially understandable reaction to a higher than expected pack SOC.
Something I'm going to see if I can brew up is a charger that automatically disconnects (if desired, depending on settings) when the charger power consumption rises a bit, suggesting full sticks.
I use a Kill-A-Watt to track charger power consumption and (including the backyard fountain) the power will stay at 72W and then eventually gradually rise to 74 or 75W before slowly descending down to 15W if not lower (I know from a forgetting to unplug it). There has to be a way to detect that peak in the power consumption, leading to tripping out of its own power source.
It should probably be voltage-based, since the current doesn't change from 350mA until the pack is beyond the voltage dip. It could however detect a post-dip current drop below 350mA, either via the voltage across a shunt resistor or via an R-C circuit noticing a negative voltage slope across the shunt resistor.
Having it essentially automatically unplug itself at just the right time would be great, IMHO, for unsupervised charging. If op-amps can reliably trip with millivolt-level sensitivity, not only could the charger go from high current to low at the right point, but also take it a further final step by disconnecting completely at just the right point.
It's something I'll see if I can develop, so perhaps my role here can extend beyond asking questions. ;>
Roger, from my testing, the 350MA can stay there for hours once the cells are topped off, and that is required for the first full charge just to make sure that all cells get filled.
This is why I recommend having the a fan running.
If the grid chargers open circuit voltage is set too low, so the CC drops voltage before the weaker cells get fully charged, some cells will not get balanced, and you will see decreased current on your killawatt.
When the charger open circuit voltage is set to say 175 or so, the pack will never reach that voltage, and the AC current draw will stay the same throughout.
IMHO A simple timer to stop the whole charge process may be the easier solution if you want to stop the charge if you forget.
Having it essentially automatically unplug itself at just the right time would be great, IMHO, for unsupervised charging. If op-amps can reliably trip with millivolt-level sensitivity, not only could the charger go from high current to low at the right point, but also take it a further final step by disconnecting completely at just the right point.
I'm not just interested in saving gas on the road, but also in saving electricity at home. A three-stage charger (6A, 0.35A, 0A) would be ideal. But since the final stage would require dV or dT detection, which is beyond my ability to implement, I'll just go with the proposed charger plugged in to a light switch/timer.
Mike, what would happen if someone set the setpoint wrong or built the circuit poorly, and a 1A charge was applied to an already full Insight pack for many hours?
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Assist at 3 bars, thermostat-based charge current limiting
