Sunday, January 30, 2011

PakTrakr issues

Another thing that's been nagging at me is the fact that my PakTrakr system fritzes out during part of the charging cycle.  The 6th battery's voltage in each remote drops to 4 volts at the peak charging voltage, so it's forever saying that "Battery 6 is failing."  Manually checking the voltage of that 6th battery showed that it was approximately the same as the other batteries, just over 16 volts.
Looking at the PakTrakr serial logger output, each remote maxxed out at around 86.5 volts.  Six batteries at 16.4ish volts each is just over 98 volts.  If the remote can't detect over 86-87 volts, that would cheat the last battery by around 10 volts.  The reduced readings make sense, then.

According to Ken Hall at KJH Motor Company (maker of the PakTrakr system), the remote is designed to be limited to 90 volts (although mine clearly were limited to 86-87 volts).  That means the remote can only measure the 36 cells (6 12V batteries that have 6 cells each) up to 2.5 V/cell.  AGM and Gel lead acid batteries are charged at up to 2.45 and 2.4 volts respectively, so the remote can (barely) monitor 6 of those types of batteries.  Flooded lead acid batteries are charged up to 2.7 V/cell, beyond the capability of the remote.  Fortunately he also told me that there's no problem monitoring 5 batteries per remote (it will not mess up the display or serial logger).  Since I have 13 batteries I already had 3 remotes, so I'll be able to use a 5-5-3 monitoring scheme and eliminate the out-of-range problem.

Unfortunately, I killed my third remote (the one that was monitoring the 13th battery).  Apparently, one of the unused leads contacted another battery terminal while I was reinstalling it after some battery maintenance that burned out something inside it.  I've sent it back - hopefully it can be repaired...  Until then I'll be limited to monitoring 10 of my batteries.

Vacuum system repair

Last week, having gotten the batteries warm and the receptacle fixed, I started working the batteries up to be able to start commuting again.  Driving around I noticed that the vacuum pump was running a bit more than normal.  By the time I returned the pump was running continuously.

I had wanted to change the vacuum reservoir anyway, because I had to cut away some of the splashguard where the tie rods came through to make room for the reservoir.  This unfortunately allows water to splash into the engine compartment, and I have been worried about the DMOC and some of my other electrical connections.

$5 at a local junkyard got me a new splashguard.  The original reservoir is a 10" length of 4" ABS pipe.  In it's place I constructed a "U" shaped construction of 2" PVC pipe.  This construction has a smaller volume than the original, but I think it'll do the job and the smaller pipe fits nicely between the tray holding the DMOC and water heater and the firewall.
With the new system, the pump takes about half the time it did for the initial draw down.  It comes on more frequently than before, but for less time.  Every indication is that the system is now relatively leak-free.  Once again I appear to be ready to commute again.  It starts tomorrow.

Tuesday, January 25, 2011

Improving the plug

I haven't been totally happy with the receptacle in the fuel filler area of the car.  Because the Saturn's body is plastic there wasn't really much to attach the receptacle to.  Just a single mounting hole where the fuel filler pipe was mounted (above and to the right of the receptacle in this picture).  Because it is only held on with a single bolt it is difficult to fully engage the turn-lock connector.  Sometimes I even had to reach behind the fender liner to hold the receptacle to make the connection.  Not good.
From the back you can see the exposed terminals.  I don't really like that, either.  Especially when I have to reach back there to steady it when making the connection.  It might get splashed, too, so corrosion may be a problem down the road.
So, instead of a receptacle I decided to make a pigtail that could be pulled out when I want to plug it in.
Once it's connected I can stuff the connection back inside the car so the fuel filler door can be almost shut.  Hopefully that'll keep the snow out.
I might consider notching the door so it can be closed completely.  I'll have to wait and see how much water and snow gets inside.

Monday, January 24, 2011

Battery Warmers

With the drivetrain vibration fixed (sort of), the next problem is that the batteries have been so cold that they just won't give me enough juice.  Using a surface thermometer, I measured the temperature at 33 degrees F.  Brr.

I ordered battery warmers from KTA Services, one for each battery.  Farnam Battery Heater Pads, thin mica sheets sandwiching a ribbon heater.  They run on 120V AC, so I wired them so that they will be powered only when the car is charging.  For once, I actually successfully planned ahead when I brought a neutral line into the car in addition to the two hot wires and ground.  In case anyone's interested, here's the wiring diagram for the heaters.  As you can see, I split the power for the heater between the two hot leads of the 220V AC coming into the car.
The worst part about installing the heaters is that the batteries have to come out.  Ugh.  Heavy.  Here are the batteries from the rear box in all their weighty glory.
Here are the heaters laid out in the bottom of the rear battery box.
And with the batteries in place.
In this view you can see the the wiring for the heaters.  I ran the wires along the sides of the box so the batteries can come out without affecting the heater wiring.  And here the batteries are back in place.  Finally.
Here's the control box wiring.
And the box in place in the trunk of the car.
Notice the temperature of the batteries?  The controller on the left is for the rear box, the one on the right for the radiator box.  The outside temperature was about 15 degrees F at the time.  Nice.

Sunday, January 23, 2011

Checking in

Almost 3 months since my last post.  I'd like to say it's because I have been commuting gas- and problem-free for all this time.  Alas, no.  After commuting for a week or two I decided to fix the vibration in the drive train.  So began a series of setbacks and missteps.  Then winter set in.

Here's the sad picture of my engine compartment with everything taken out.
With the motor and transmission separated I measured the runout of the flywheel with a gauge indicator.  Less than .003" range on both the axial and radial directions.  I think most of that runout was just because of the rough surfaces, too.  So the flywheel was installed true.  The only other explanation would be that pressing the starter ring off the flywheel caused it to go out of balance.  So I took it and a new clutch and pressure plate to an automotive machine shop to have them balanced.  Here are a couple of pictures of some of the holes they put in the flywheel to bring it into balance.  The large hole in the first picture (at about 7:00) existed prior.
With the newly planed (notice the shiny front surface!) and balanced flywheel reinstalled on the motor shaft, the dial indicator showed less than .001" runout.

It's now been over a month since I took the car off the road.  It took another 2 weeks to get the car back together and on the road again.  The good news is the vibration in the drivetrain is much better.  There are still a few speeds where the car gets loud, but I think those are related to the fact that I eliminated the rubber mounts and not from imbalance issues.  The bad news is that after a few shifts the clutch stopped working.

The automotive machine shop had wanted to make sure the taperlock hub was balanced as well, so I took the extra effort to get it off.  It was stuck on the motor shaft pretty good, not the least because of some rust on the inner hub surface.  So when I reinstalled it after the flywheel balancing I put a small amount of anti-seize on the motor shaft.  My initial thought about the clutch problem was that perhaps the lubricant had allowed the taperlock hub to be pushed toward the motor by the force of the clutch.  So, out everything came again.

Well, the hub had not moved.  However, it looked like the new pressure plate was taller than the old one by about .12" so I shifted the hub out a bit, thinking that maybe I was at the end of the throw for the clutch.  Put everything back together again.  Same result.  Clutch works for a few times then nothing.  So, maybe the clutch is failing.  Before investing in a new clutch, a friend suggested bleeding the clutch hydraulics - maybe some air got in one of the lines while the slave cylinder was hanging free (I had it tied up near the fuse box to keep it out of the way while removing the motor-transmission).  Took the cap off the clutch cylinder and pumped the clutch pedal 10 times.  Miraculously, the clutch started working again.  Sigh.

By now winter had set in, and this year's winter is the real deal.  Lots of snow and lots of cold.  So even though my drivetrain problems seem to be solved, the cold is really taking a bite out of my batteries.  I am not able to get more than 120 amps out of them before the voltage sags below the cutoff for my DMOC controller.

Next entry: battery warmers....