1987 MK 1 Electrical System Upgrade - Feedback Requested

[J_Sail]

Regarding your possibly bad 6-volt battery and your plans to charge it for a few hours and then measure the voltage...
Generally the batteries need to be left for 12-24 hours with no load after charging for the "at-rest" voltage to give a good indication of the state of charge, though you may get some useful info from an immediate measurement if it differs excessively from its mates.

Unfortunately the only reliable way to determine battery health is to fully charge them and then run a controlled discharge test.  MaineSail has written some good materials on the subject, including an analysis of the failings of the fancy impedance testers that many electricians have to come to rely on for rapid battery condition analysis.
http://www.pbase.com/mainecruising/battery_state_of_charge
http://www.pbase.com/mainecruising/impedance_testers

[Jon W]

Checked Saturday afternoon and got the green light that the batteries are good as is. I let the now cold refrigerator run with temp set in the middle range overnight with no AC. According to the BMV-700 ~12 hours later, the fridge used ~25A. What a great addition. Another great result is the SmartGauge and BMV-700 read within .03 - .04V's of each other. Voltage drop from the house to the distribution panel is almost zero. I'll be checking house to starter voltage drop next weekend.

The engine started on the house bank immediately. I then shut it down, switched to reserve battery, same result. My reserve may be at the low end, but a Group 24, 12VDC, 80Ah, 650 CCA starts the M25-XP just fine.

So Della Jean is now put back together. Next weekend I install the external regulator, add House or reserve labels to the battery selector switch and BMV-700. Some final photos attached.

Except for posting the write-up of this project in the Tech WIKI, I think this brings this project to a close. Thanks everybody, couldn't have done it without all the help.

Jon W.

[KWKloeber]

NICE!


Bravo!!! 

kk

[Noah]

Excellent! Congrats my friend. Well done, you should be proud!

[Stu Jackson]

Great job.

So, when are you gonna remove the Micrologic 8000? 

[Jon W]

It goes when I upgrade the instruments, autopilot, add radar, and get new standing rigging later this year. For now I plan to go sailing for a couple of months, and use my roll and half of butyl tape to re-bed the chainplates, the drains and opening portlights in the cockpit.  Jon W.

[Stu Jackson]

Jon,

That sounds like a right good plan.  I was, of course, just kiddin', my PO had one of those, cleverly hidden behind the sliding black door just forward of the nav station!  I finally removed it and thrashed it.  Maybe shoulda saved it for an electronics museum!    The programming steps on it were so complicated that I had to write my own "How To" manual!!!    Something that must have come out of the original B52 designs.  The West Marine V2.0 Loran I had on my Catalina 25 was far simpler and more intuitive to operate, and worked better to boot!

[Rick Allen]

Great Job Jon!!!!!

[Noah]

Micrologic was "The King" in its day...Some oldies age, and/or hang on tighter than others. I am amazed to see Signet Instruments still advertising in the Catalina Mainsheet! That's a blasted from past, too. They were hot stuff during my 1980's IOR racing days.

[Jon W]

Thought I'd give one more update after hooking up the external regulator and voltage check I did.

On Saturday I set the regulator to FDC (flooded batteries), belt level 4 (20% reduction), and long display. Started the engine. At idle the alternator was putting out 7-8A to the house bank. I brought the engine up to 1,500 rpm, checked the display and the alternator is now putting out ~82A to the house bank, alternator temp was 32 deg C, and the house bank was 18 deg C. Just like advertised!

Today I went to the boat to compare voltage between the battery and the alternator for the house bank, and starter for both house and reserve. I used a voltmeter purchased at Sears that lists a +/- 1.5% accuracy. The AC charger was off, no other loads on.

Turned the battery selector switch to position 1. The house was 13.21 VDC which matched the BMV-700. When I measured the alternator it was 13.21 VDC. I then measured the starter it was 13.21 VDC.

Turned the battery selector switch to position 2. The reserve was 13.18 VDC. When I measured the starter it was 13.18 VDC.

If this method is correct, my voltage drop at rest is between .2 VDC (-1.5%) and zero VDC depending on how you want to look at the voltmeter.

Is this the correct way to take this measurement? Thanks for the help.

Jon W.

[J_Sail]

Jon,
I am doing this reply quickly without re-looking at your schematic, but my recollection from having studied it in the past is that you have the alternator output connected to the house battery and use an EchoCharge to charge the starting battery. Thus with the battery selector set to the Starting battery, it has load on it, but is being charged by the EchoCharge rather than the alternator. The output voltage of the EchoCharge is likely slightly different than that of the alternator.  It's not that there is a voltage drop per se, it's that the circuitry in the EchoCharge has its own idea of what an ideal output is, and there is no reason to expect it to be identical to what the Balmar external regulator has decided on for the alternator.

In other words, all is fine.

Jeremy

If I have mis-recalled anything about your design, I may need to revise my answer, but until then, don't worry, and enjoy the results of your great work!

[Jon W]

That's the set up.

By no loads I mean engine off, all AC and DC accessories are off.

I measured the voltage of the house battery and it was 13.21 VDC. Then I measured the voltage at the positive cable connection at the starter and the engine ground and got 13.21 VDC. Similar story for the reserve battery measurement. I read this to mean I'm getting the full voltage available from the battery to the starter. So no voltage loss/drop.

Is this a correct interpretation?

Jon W.

[KWKloeber]

That's the set up.

By no loads I mean engine off, all AC and DC accessories are off.

I measured the voltage of the house battery and it was 13.21 VDC. Then I measured the voltage at the positive cable connection at the starter and the engine ground and got 13.21 VDC. Similar story for the reserve battery measurement. I read this to mean I'm getting the full voltage available from the battery to the starter. So no voltage loss/drop.

Is this a correct interpretation?

Jon W.

That's a correct interpretation -- if the amperage is the near zero that your meter draws.   You need to measure voltages with the load applied for which you want to know the voltage drop.  i.e., your mileage is basically infinite with your idling in your driveway, but you know it;s not so at 65 mph.

kk

[Jon W]

Would that mean I need to measure while I'm starting the engine?

Jon W.

[KWKloeber]

Would that mean I need to measure while I'm starting the engine?

Jon W.

When you did your spreadsheet of amperages, looses, and required cable sizes -- the size(s) you chose to minimize V loss wasn't based on only LED lighting on, right?  It was based on the amperage draw for whatever you would have on.   So, to verify that assumed or calculated loss, you want to have the same things running (drawing the same amperage as you assumed.)  So, if you want to know the loss for amperage of lighting load, you need lights on.  If you want know the loss while charging, or starting, preheat, and so on and so on......you need to have the charger on --- or so on and so on.  The starter motor is obviously going to be your highest amperage draw and result in the greatest voltage loss thru that circuit/cable.

kk