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Discussion Starter #1
Well, I started writing out a long explanation of my story, but I had a power flash and my UPS backup sucks so here we go again. Scroll to the bottom if you just want to see my pictures!

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The Story:
I installed MIMA and found that my battery was nearly dead all the time, due to my extreme hypermiling style (I hardly ever use the brakes and override the parasitic charging as it is extremely inefficient).

I tried to read through the entire grid charger article, but my OCD and ADHD combination isn't always conducive to learning. I got a good amount of help from Mike Dabrowski, who I scared a couple of times. Thanks again, Mike - you rule! :cool: I settled on the basic 350ma charger/balancer design.

I ordered four RS-25-48's on eBay for $25 shipped, took a trip to Radio Shack for about $10 in parts and followed it up with an order from Jameco for the CCV 350ma supply. All in all I spent around $65 on parts that guys like us wouldn't already have lying around their garage. I used a 12v wall wart for the fan.

I had a lucky break when a friend ran into computer problems. I'm no longer a PC tech, but no one else seems to think so... :rolleyes: Anyway, their power supply was bad, so I swapped in a spare. Inspiration hit, and I started tearing it apart to see if my components would fit. Luckily it was almost perfect! This was great, as it gave me a built in switch, ability to use the fan, and is a decent size, as well as some LED action.

I measured carefully, drilled, and used some old PC screws to mount the power supplies. I ended up using very sticky double sided adhesive like Mike gives for the MIMA joystick mounts for the CC PSU. I mounted all four of the 48v power supplies in there even though I'm not using the last one - so I can put a 12v one in there later and make it all cleaner.

I decided that I was going to keep the 120mm fan to cool the charger (even though it probably won't need it, but I live in FL and may be charging on hot days). I ended up pulling a small daughter board from the power supply to split the current between that fan and the one in the car. I played around with it, and found out how to make it output about 9.6v to both fans, also giving me a couple of LEDs lit when it's on (in addition to the bright blue fan). It sat on top of the constant current supply with some more of the double sided super-sticky tape, just clearing the fan.

After giving Mike a call because I wasn't getting any voltage, I found the 1A fuse had blown. This had continuously been giving me problems. I ended up switching to a slow blow fuse today and it's working wonderfully. I adjusted the power supplies to 177v on the bench per Mike's instruction.

After sorting that all out, I had to get the terminals set for the battery. I crimped ring terminals to the diodes in the appropriate direction (with some solder for good measure), also soldering on a ceramic fuse on the positive end and covering them with heat shrink tubing. I connected them to some spare decent speaker wire that I had lying around. Next, I used some ULTRA fluorescent green wires from a modular computer power supply to pretty up the connection in the power supply and provide the molex connector to attach to the battery. This is similar to the trailer connection that many use, and is also keyed.

In the back of the Insight, connecting to the negative terminal of the battery was easy, but the positive was tough. I see from the solarvan.co.uk site, that he must supply some type of an extender for the spade connection. I didn't have anything to fashion that out of, so I talked to Mike, and he suggested what I was thinking - tracing the wire, unscrewing the other end, and putting a ring terminal there. But unfortunately, it's a tight fit. He suggested actually removing the battery but I thought NOOO WAY! So I used a philips head bit and some vice grips to undo it from the side. A 1/4" racheting open-ended wrench would have made it a lot easier, but it wasn't terrible. I had to work hard to get it tightly back on there.

I connected the two wires for for the fan connector with some taps. I had to cut back the covering a bit, but it's in an inconspicuous place, for if I ever need to go back to stock. I then connected all four to another green wire from the ULTRA computer power supply to run out of the battery box. I decided to use the holes on the bottom of the box, which the wire fit through exactly. I used a zip tie to not allow it to be pulled any further than necessary and others in strategic places to make sure that there would never be any strain on the connections that I had made to the fan and battery.

I was able to connect and charge my quite low battery overnight without any real problems in the process. I didn't do a full balance, as I got up early to get some things done, but it did charge up to around 168v and showed a full charge on the gauge after driving for a few miles.

I used assist liberally, and was able to get around 105MPG without much effort for over 50 miles and six stops, with a decent amount of city driving. I used most of it about a third of the way into the trip or less, but it seemed to stay at three bars and not force charge for a very very long time... so I'm assuming it simply wasn't reading the charge properly. I did almost totally drain the battery on the way home.

After the maiden voyage, seeing that everything is set, I put things back together. I'm running the wire currently through the left hand side, squished in-between the styrofoam and between the velcro into the storage compartment for now. It's doing great, with my only real problems being the stupid fast-acting fuse blowing on power up. Does anyone else have this problem? :mad: After exhausting all of my fuses, I went to Radio Shack and picked up a handful of slow blow ones at the same rating and it's charging happily!

Check out my pics below. This is before I put all of the pieces back together. I'm not sure how I'm going to permanently mount the charger in there. It will stay with the car, as I'm hoping to do some charging at work as well. 9 hours there will give me over 3AH - most of the usable charge. There is a great amount of space to the right of the cubby for storage, but i'm getting some leakage and the last thing I want is a wet charger.

I'm currently charging, pulling around 72 watts last I checked (including about 6w from the wall wart side pushing the LEDs and fans). I figure it costs me less than a penny per hour to charge, and should pay off by raising my MPG, but moreso just in sanity by letting me have a decent amount of charge at my disposal.

I never take pics as I'm working on something but always wish I had. I'll disassemble and snap a few of the innards a little later. I also plan on taking out the dummy PSU and swapping in the 12v one, cleaning it up, and also allowing the LEDs to tell me that the unit is getting power and doing it's job (vs now, just telling me that the fans are working).

If anyone has any questions or comments, please post! I'd be happy to help anyone who is a novice like me. Anyone who has patience and is very thorough and careful can do this. But as Mike pointed out time and time again, it can be very dangerous, so be careful!

And now, the pics:

Link to pics on Flickr (for larger view)

[pics on next post due to forum restriction]
 

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Nicely done.

I may have to steal your idea of using a Molex for a voltage tap. Just be very careful where your high-voltage wires are, don't let the sharp edges of the IMA box cut them, and don't drop your luggage on them. There are a couple of convenient entry points on the passenger side of the box too.

168V may be full, depending on battery temperature. And of course, a NiMH pack's voltage will peak and then decline after it's 100% full. So a voltage versus time plot may tell you SoC, but V alone does not.

Is that power brick in your spare tire well unrelated?

I presume you start every day with three bars indicated on the SoC gauge, and a 100% full battery. How do you stimulate a recal with minimum FE impact?
 

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Nice solution for a case. I am an IT tech and didn't even think of that, though my focus was on fitting everything inside the electronics bay and in my situation I needed the equivalent of two chargers.

I still have my chargers set to 170 volts including the voltage drops from the isolating diodes and all seems to be working fine. This constantly gives me the 168+ volts required for a daily positive recal (SOC reset). Once summer is over I might bump it up a few volts. However I think 177 is too high as the charger will theoretically never 'shut off'. The highest pack voltage I have ever seen is 173 - 174 volts and that was in the dead of winter with sub zero temps. In hot weather with a hot pack 166 volts seems to be the top end. If you forget to unplug in hot weather you could overheat your battery pack. Once about a year and a half ago I did that and the packs got up to 130F. That is still within spec, but I even hate breaking 110F.
 

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Nicely done.
I presume you start every day with three bars indicated on the SoC gauge, and a 100% full battery. How do you stimulate a recal with minimum FE impact?
Just turn on the key but don't start the car. A soc recal will occur within ~2 minutes if the pack is at 168v or higher. If you need to warm up the car for longer than 2 minutes then just start the car.
 

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Discussion Starter #8
Nicely done.

I may have to steal your idea of using a Molex for a voltage tap. Just be very careful where your high-voltage wires are, don't let the sharp edges of the IMA box cut them, and don't drop your luggage on them. There are a couple of convenient entry points on the passenger side of the box too.

168V may be full, depending on battery temperature. And of course, a NiMH pack's voltage will peak and then decline after it's 100% full. So a voltage versus time plot may tell you SoC, but V alone does not.

Is that power brick in your spare tire well unrelated?

I presume you start every day with three bars indicated on the SoC gauge, and a 100% full battery. How do you stimulate a recal with minimum FE impact?
I actually found that the holes at the bottom of the IMA box are nicely cut and don't appear to have sharp edges. I saw the smaller holes on the right side of the IMA box, but those were shearing the wire as I passed it through them. Also, the green wire that I'm using is very thick. It would take years for it to even think about making an impact on it.

I have yet to give it a full recharge and balance, so I need to sit down and plot voltage. But I know just from the beginning charge and rate of charge vs time that I should still have some time to go. I could have been wrong about the 168v, because I forgot to write it down.

However, note that I'm measuring what's coming out of the charger, not the actual battery voltage. With the diodes in place, doesn't that cause a bit of a drop, approx 3v? I believe I read that. I set them to 177v on Mike's suggestion, as he seems to be the authority on this. To my understanding, that's the max - it's not going to get that high unless the pack wants it, right?

The power brick is actually for the 12v (fans). I cheapened out and the 4th power supply in the case is actually a placeholder RS-25-48 that I will replace with a RS-25-12 later to clean things up.
 

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Discussion Starter #9 (Edited)
Does anyone know if there's a way to step down the RS-25-48 to output 12v or less? If I can use off the shelf resistors or something from Radio Shack, that'd be amazing. Sorry if this is a stupid question, so stop me if it's not possible, but please explain why so I can learn - thanks!
 

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Discussion Starter #10
Just turn on the key but don't start the car. A soc recal will occur within ~2 minutes if the pack is at 168v or higher. If you need to warm up the car for longer than 2 minutes then just start the car.
WOW. THIS IS AMAZING!! I want to give you a big freaking bear hug if this is true!

I had to drive to the gym last night with a PATHETIC 65MPG. It made me want to run over myself. I never got a recal, and eventually just overrode it and used up the whole charge on the way back to get myself near 90MPG.

This is a lifechanger - thanks so much, friend! :D
 

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Another tip dealing with the 3 bar bug.

If you charge up while the soc is at 3 bars or higher soc you can skip a soc reset. The car will keep soc at 3 bars until the batteries hit a ~145volt lower limit. The last 3 bars will then do a negative recal to zero.

This comes in handy if your pack is hot and you can't get 168 volts to force a positive recal. But it only works if you started out at 3 bars or higher or if you can force it to 3 bars using manual recharge.

Peter from the UK also designed a BCM fooler that puts a voltage of 168 volts or higher across the BCM to force a SOC Recal at will. Check out his PHEV thread for information.
 

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I had to drive to the gym last night with a PATHETIC 65MPG. It made me want to run over myself.
Well, if you find yourself in the market for another car, at least you know what kind of car it's gotta be: first-gen Insight, 5MT. There's nothing else on the market as far as I'm concerned.
Does anyone know if there's a way to step down the RS-25-48 to output 12v or less? If I can use off the shelf resistors or something from Radio Shack, that'd be amazing. Sorry if this is a stupid question, so stop me if it's not possible, but please explain why so I can learn - thanks!
No, it's a ~35-54V power supply. You need the RS-25-12.

It would be nice if you could find a 1A linear voltage regulator that could handle 48V input, but the ones I've seen can't handle more than 32V or so.
 

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Discussion Starter #13
Another tip dealing with the 3 bar bug.

If you charge up while the soc is at 3 bars or higher soc you can skip a soc reset. The car will keep soc at 3 bars until the batteries hit a ~145volt lower limit. The last 3 bars will then do a negative recal to zero.

This comes in handy if your pack is hot and you can't get 168 volts to force a positive recal. But it only works if you started out at 3 bars or higher or if you can force it to 3 bars using manual recharge.

Peter from the UK also designed a BCM fooler that puts a voltage of 168 volts or higher across the BCM to force a SOC Recal at will. Check out his PHEV thread for information.
I checked out his thread, but he is using his secondary HV pack to supply most of the voltage to the BCM to force the recal. How would I supply that kind of voltage?

Is there a way for us single-battery folk to be able to do that?
 

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Discussion Starter #14
Well, if you find yourself in the market for another car, at least you know what kind of car it's gotta be: first-gen Insight, 5MT. There's nothing else on the market as far as I'm concerned.No, it's a ~35-54V power supply. You need the RS-25-12.

It would be nice if you could find a 1A linear voltage regulator that could handle 48V input, but the ones I've seen can't handle more than 32V or so.
I chatted with Mike, and it seems like there'd be a way to drop it down to 12v, but the problem is that it only outputs 570ma, and the fan wants almost an amp, so it's a no go. Plus, I'm running an additional fan on the grid charger. I went ahead and ordered an RS-25-12 for $18 shipped from Sumoha (or something similar) to clean up the install.

Note that an RS-15-12 would also work, but it's not the same shape, and I don't want to have to drill another hole. Plus, I like the headroom, incase I want to run anything else on the 12v circuit...
 

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Discussion Starter #15
Just turn on the key but don't start the car. A soc recal will occur within ~2 minutes if the pack is at 168v or higher. If you need to warm up the car for longer than 2 minutes then just start the car.
I'm not having any luck with this :(. I charged from pretty much a dead pack for around 19 hours and my multimeter read 169.x volts coming out of the charger. I put the key into the on position without starting the car for a few minutes and no luck.

I also decided to try pulling the 18 fuse with the car off and trying the same thing with no luck. Incase it takes longer than I'm expecting, I have the key in with it sitting in the driveway now, just incase.

Am I doing something wrong? Any tips to make this work? I'd do about anything to make this work about now!

Thanks so much for your help!
 

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If you run power to the BCM while you're charging, it does tend to come off the charger with 19 or 20 bars SoC. I think you should try a wire that goes: RS-x-12 -> diode -> IGA1.
 

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As far as resetting the soc gauge .... you see 169.xx off the charger, is that including the drop due to the isolating diode? That diode can drop any where from .7 - 1.5 volts depending on type. I've never had issues with resets as long as the pack voltage is ~168 volts or higher.

I might try powering up the bcm. Does anyone know if it actually counts amps or if it simply watches for the 168 volt threshold when you do this?
 

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I powered up everything on the IMA fuse: current sensor, MCM, BCM. I went to key on every few hours to check on the SoC gauge, which rose gradually.

I haven't been plugging in more than twice a week, because when my only way to use the charge is to mash the gas pedal, I'm not saving enough gas to justify the KWh. MIMA will change that.
 

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Discussion Starter #19 (Edited)
If you run power to the BCM while you're charging, it does tend to come off the charger with 19 or 20 bars SoC. I think you should try a wire that goes: RS-x-12 -> diode -> IGA1.
Thanks for the great info... now I wish I hadn't put it all back together!

I've been tending to use the full charge with my "lead hand", meaning that I might not get to a full capacity with my available charge time, so this would be A HUGE GODSEND.

Would you mind explaining IGA1? Where is this connector? to tap into? And would I be using the same diode as I would for the connections to and from the HV battery?

And can I run from the RS-25-12 to the fan, then right from that directly to the BCM? Or does it need to be a separate run?

Excuse my ignorance, I'm learning as I go along.
 

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Discussion Starter #20
I powered up everything on the IMA fuse: current sensor, MCM, BCM. I went to key on every few hours to check on the SoC gauge, which rose gradually.

I haven't been plugging in more than twice a week, because when my only way to use the charge is to mash the gas pedal, I'm not saving enough gas to justify the KWh. MIMA will change that.
Is all of that done with the connection you mentioned above? If not, what is the upside of running just the BCM vs all of the other items above?

Also, have you compared current draw to see how many additional watts this draws? IIRC, I think my fans were drawing 6-9 watts (case and pack fans) depending on voltage and the whole thing is around 72 watts.
 
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