1987 MK 1 Electrical System Upgrade - Feedback Requested

[Jon W]

Getting ready for the next big event. I've looked through lots of info on this site and others, have copied others ideas, modified to fit my needs and attached a draft schematic to this post.

Currently I have little to no electronics installed on the boat. However, one of the next projects is to add electronics (radar, chart plotter, wind/speed instruments, depth), and auto helm. So need a design that will accommodate.

The wire and fuse sizes in the attached are a blend of what I found in others schematics. Not sure they are correct for my application. I'd like to take advantage of all of the experience and knowledge on this forum, and get feedback on the attached first draft. What did I miss, where am I over or under designed? Thanks for all of your help and insight.

Jon W.

[Stu Jackson]

Jon,

Very nice job.  Well done.

You forgot the starter off the C post.

No comments on wire sizes or fuses.  With everything in the "Electrical Systems 101" topic, you should be able to and most likely have done that.

[Jon W]

The start solenoid label off the C post of the 1-2-B switch is meant to represent the starter.

[Stu Jackson]

The start solenoid label off the C post of the 1-2-B switch is meant to represent the starter.

Sorry, I missed it.

Doh...

[mainesail]

*I'd really like to see all battery wiring 2/0

*Alt fuse is too small, should be 150% of alt rating

*Battery fuses are a bit on the small side for engine starting, I like to see 250A minimum

*SmartGauge should ideally be wire across house bank not just off first set

*30A fuse on 4GA starter cable won't last very long. Start cable should be protected by the battery fuses this is why 2/0 is important all the way through the system so it can be well protected by the bank fuse

*I'd prefer to see some consolidation of the negatives. Perhaps home run start and engine ground to batt compartment busbar

*You could probably do away with the start battery positive busbar and just place Echo and feed to switch on load side of ANL fuse and SG on battery post side or battery post....

Looks like a very good diagram overall...!

[Jon W]

Thanks for the quick response. What about the alternator output to the house bank?

"all battery at 2/0" would include from the house bank and reserve bank buss's to the 1-2-B switch, and from the starter to "C" post on the 1-2-B switch? What do you mean by "home run" start for negatives?

I need to look closer at length of runs to match 3% voltage drop and where to run them, but not sure all that large 2/0 wire has room to be run.  Jon W.

[Stu Jackson]

...................What about the alternator output to the house bank?

"all battery at 2/0" would include from the house bank and reserve bank buss's to the 1-2-B switch, and from the starter to "C" post on the 1-2-B switch? What do you mean by "home run" start for negatives?

I need to look closer at length of runs to match 3% voltage drop and where to run them, but not sure all that large 2/0 wire has room to be run.  Jon W.

Jon,

Here's a discussion Maine Sail & I had over on co.com about wire sizing.

http://forums.sailboatowners.com/index.php?threads/alternator-b-to-starter-post-or-combine-post.170778/page-2

The basic concept is BOTH voltage drop AND fusing.  You might want to read both pages of that link.

That is covered well in the referenced Blue Sea tables, available in their reference library.

Here's another one (scroll up to the top and then down to read Main Sail's excellent contributions):

http://forums.sailboatowners.com/index.php?threads/old-battery-cable.135133/

[J_Sail]

Jon,
Great work so far. I designed an electrical retrofit for my brother who owns a C34 in San Diego. In the process I engaged in lots of discussions with other forum members including MaineSail and Stu and am happy to share that.

Couple comments below:
Your #4 AWG wire from the alternator output to the House Battery busbar is undersized with regards to voltage drop for efficient battery charging if using an internally-regulated alternator. The output wire from an internally-regulated alternator has to meet a much tighter spec than other wiring. That is because even a small (0.3v) change in charging voltage significantly impacts charge time/efficiency.

It is extremely important that your alternator deliver the proper charging voltage all the way to the actual batteries. Any uncompensated-for drop will result in slow/undercharging of your batteries, which is the leading cause of premature failure.

There are two ways to address:

  1) Run sufficiently heavy wiring from the alternator to the batteries on both the positive and negative (ground) side so that the voltage delivered to the batteries is extremely close to what comes out of the alternator (within 0.2v). If your alternator outputs 80amps (sustained*) and the round-trip path is 20' (10' positive and 10' negative), then you would need to use #1 AWG wire to keep the total drop to 0.2v volts. Even that drop will reduce the bulk charge rate somewhat.

  2) Use a regulator that supports "External Sense" and run the necessary additional sense wire back to the House battery busbar. The sense wire can be very small gauge as it carries almost no current; it's just used by the regulator to detect the actual voltage at the battery so that the regulator can tell the alternator to increase its output to compensate for the drop across the charging wire from the alternator to the battery. In some cases, where your negative return is undersized, you may need to run the regulator negative back to the battery to get the equivalent of a negative sense lead. See further below for details.

If you implement solution #2 (my recommendation), it's okay to use your #4 red wire from the alternator to the batteries, as the regulator will adjust the alternator output to produce the proper charge voltage at the battery. However; you still need to address the negative return side. The preferable approach is to make sure the negative cable is heavy enough to introduce less than 0.1v drop at your max sustained charging current (likely 80-90 amps or less). Since you already need to run heavy (at least 1/0) cable from the engine to the batteries to handle the starter current, it's trivial to run a 1/0 cable from the alternator to the lug/busbar at the engine end of the negative battery cable.
If for any reason, you don't have a low-enough resistance negative path to maintain its drop to less than 0.1v, you can run the regulator's negative lead directly to the battery negative (instead of to the alternator). With a 1/0 negative return and carefully implemented connections, however, you should not need to do so.

If you are willing to spend the money and do the proper installation/configuration, I strongly recommend an external regulator that supports external sense, such as the Balmar MC-614. It could easily end up paying for itself in longer battery life. If you go that route, you should install the optional alternator and battery temperature sensors and triple-check that you enter the right configuration parameters for you battery type, etc.

* For this case we only care about the alternator current that will be sustained over many minutes. That's because it's about the efficiency of battery charging, not wire heating/safety. A 105A alternator is unlikely to output over 80-90amps for more than a few minutes due to both rising battery voltage and alternator heating.

Notes:
1. The negative path from the Alternator to the Battery negative terminal is at least as important as the red-wire positive path, yet the negative is often overlooked, sometimes relying on the case of the alternator being in electrical contact with the engine block.  It is important that there be a good heavy-gauge wire run from the alternator's negative output (there should be a bolt on its case) back to the battery (via a busbar or other heavy-duty cable-to-cable connection post is fine).
2. For reference, at 80amps a #4 wire will drop ~0.2v for each 10' of length.

[KWKloeber]

Couple comments below:
Your #4 AWG wire from the alternator output to the House Battery busbar is undersized with regards to voltage drop for efficient battery charging if using an internally-regulated alternator. The output wire from an internally-regulated alternator has to meet a much tighter spec than other wiring. That is because even a small (0.3v) change in charging voltage significantly impacts charge time/efficiency.

It is extremely important that your alternator deliver the proper charging voltage all the way to the actual batteries. Any uncompensated-for drop will result in slow/undercharging of your batteries, which is the leading cause of premature failure.

2. For reference, at 80amps a #4 wire will drop ~0.2v for each 10' of length.

J-Sail,

Is it not true that the OEM internal regulator is simply an on-off switch? 
In other words, it puts the alternator into an "output"  or "no output" condition -- it doesn't control the output current?

kk

[mainesail]

Couple comments below:
Your #4 AWG wire from the alternator output to the House Battery busbar is undersized with regards to voltage drop for efficient battery charging if using an internally-regulated alternator. The output wire from an internally-regulated alternator has to meet a much tighter spec than other wiring. That is because even a small (0.3v) change in charging voltage significantly impacts charge time/efficiency.

It is extremely important that your alternator deliver the proper charging voltage all the way to the actual batteries. Any uncompensated-for drop will result in slow/undercharging of your batteries, which is the leading cause of premature failure.

2. For reference, at 80amps a #4 wire will drop ~0.2v for each 10' of length.

J-Sail,

Is it not true that the OEM internal regulator is simply an on-off switch? 
In other words, it puts the alternator into an "output"  or "no output" condition -- it doesn't control the output current?

kk

Ken,

The regulator does essentially control the output current by controlling the duration the field is energized vs. de-energized. This is called PWM regulation and solar controllers and battery chargers do the same. By varying the width (time) of the on and off pulses we get a regulator that holds voltage very, very steady. In early absorption the pulsed on time is much longer than at very high SOC's. The only time it will go to zero output, for long enough for a human to see it, is if another source is driving the limit voltage above the regulators set point. Even at high SOC the PWM time is so fast that even the best and fastest DVM will still show a steady voltage.


I think the main point being made was about voltage drop and everyone only tends to focus on the wire, but terminations, switches, fuses etc. all add to the voltage drop so calculating for wire does not tell the whole "as installed" story...

I tend to use 0.00025 Ohm per connection.... If we count the connections in the typical factory wiring, and include a fuse for house bank wiring, we have about 14 connection points plus the drop across the switch and the fuse..

If we just use the connections we have an approximate 0.0035Ω of additional resistance (this is with near perfect terminations) and then add the fuse and switch and we are looking at roughly 0.004Ω +/- of additional resistance beyond the wire itself... If we assume this is correct, or close, then the terminations switches etc. are adding another .32V of drop at 80A of charge current and even at just 30A we are still dropping an additional 0.12V.

Oh and I've only calculated for the positive side because calculating for the rusty engine block, well......... D'oh.....!!!  This is why I hear both pro's and DIY's complain their voltage drop calculations did not work correctly, after they measure the actual voltage drop "as installed". The wire is only part of the problem....

[KWKloeber]

Ken,

The regulator does essentially control the output current by controlling the duration the field is energized vs. de-energized. This is called PWM regulation and solar controllers and battery chargers do the same. By varying the width (time) of the on and off pulses we get a regulator that holds voltage very, very steady. In early absorption the pulsed on time is much longer than at very high SOC's. The only time it will go to zero output, for long enough for a human to see it, is if another source is driving the limit voltage above the regulators set point. Even at high SOC the PWM time is so fast that even the best and fastest DVM will still show a steady voltage.

RC,

Agreed it's essentially a very, very fast on/off switch, varying the on/off width.  Let's assume a given that the negative connections, etc., are optimized to the point we can't do any more, and that the Alt frame is directly connected to the negative cable (which Jon's is.)   

So we're talking about constant voltage charging -- where primarily the battery controls how much current flows?   

Where I am going with this is, the varying battery resistance (plus obviously the other resistance sources you mention) control the current, and thus the bulk charge time.  Granted you wouldn't want to charge with a 10 awg cable (well Universal wanted us to  ) but the V drop in the #4 cable is for a limited period, and is decreasing as soon as the battery begins taking on a charge -- resistance begins to increase, and current (and therefore voltage loss) begin to drop.  So, the cable size influences how long it takes to get to bulk charge, but the battery is the throttle after a given period of time?  And the regulator V setting controls whether the battery eventually gets undercharged, or conversely overcharged (This of course ass/u/mes that the battery SOC / available charge time / Alt capacity are such that the bank can reach full charge.)

If one only day/evening sails, has efficient nav lighting, etc., isn't running a 1000 watt boom blaster, no microwave, etc etc, and is back on shore power in a couple hours -- then a #4 should be way sufficient. If one is on a hook, extensively cruises, is relying on the Alt to return all the energy used, then the size of the charge cable is more important.  But because of the other voltage loss sources you noted, an adjustable voltage regulator, which Jon's is (to a limit of course) or a better externally sensed regulator becomes more important than upping the charge cable size.

**aside rant** - all marine/RV alternators should be externally sensed -- hell it's only providing a post and a jumper that one can chose to use or not use!

I maintain that one can't properly pick any single component of an integrated system, unless one has the complete picture -- and in the case of energy use/return (batteries, cables, alternator, shore charger), one has an accurate power and charge budget? Otherwise one might be way over spending or way under providing compared to the needs?

kk

[mainesail]

Ken,

If you tie to a dock after each sail the alternator performance is really nowhere near as important is when you are out cruising or you reside on a mooring and a dumb regulator can work pretty well for the weekender.

The problem of voltage drop becomes a time, performance & battery health issue. As the battery terminal voltage, at the battery end suffers from votlage drop, you hit absorption voltage considerably earlier in the SOC curve and the charge duration can extend rather dramatically.

A battery that may hit absorption voltage at 82% SOC at 14.4V may hit it absorption at 55% SOC at 13.8V. Once the limiting voltage is attained at the alt end the alt will begin cutting back because it believes it is at target absorption voltage all due to voltage drop.

By the time you get to the high 90's the voltage will have crept up, as current trended down, and will be "almost" good enough but now you have shortened the time in which you are at optimum absorption voltage, though you have theoretically been at it, at the alt end, for a long while already.

This leads to a capacity walk-down effect with each repeated cycle where you don't get back to full and the PSOC walk down will be considerably worse than what you will see with accurate voltage sensing. By the time you shut your engine down you have been robbed of sufficient time at 14.4V - 14.8V, for optimum battery health, as well as leaving considerable Ah's on the table not returned to the battery. If you tie back up to a dock at the end of a day, no big deal, if you don't your batteries will suffer....

For those who have not read it this article delves into why voltages sensing is important if you want optimal charging performance and optimal battery health.

Voltage Sensing - Why It is Important


.

[Jon W]

Thanks for the feedback and support in helping me navigate through this. I appreciate the compliments, but the foundation of my schematic is heavily based on the design work originally done by Noah and his brother Jeremy. They deserve the credit and "aata boys" not me.

2/0 is very expensive wire, and very large. I'm curious what path did others use to route it in their boat? I don't think the conduit under the shower pan has enough room for a couple of these 2/0's and the wires already in there. Did anyone route between the head and hull then through the hanging locker to the Nav Station? How about enlarging the bilge drain opening in the front of the engine compartment sideways and routing through there? Drill a couple more holes in the engine mount floor near where the water hoses to the head, and hoses to/from the heater come through?

The schematic modifications suggested by your feedback are attached in the revised copy below. I think I've captured it correctly. (I also added future place holders for electric windlass and solar).

Jon W

[Stu Jackson]

2/0 is very expensive wire, and very large. I'm curious what path did others use to route it in their boat? I don't think the conduit under the shower pan has enough room for a couple of these 2/0's and the wires already in there.

I agree that route is useless to use for anything else.  It's full with one or two #4s.  We have a Freedom 15, mounted on the outside (hull) wall under the nav station.  It came with two 2/0 wires connected to it (1998 model, rather than the "newer" ones with echo chargers built in where you had to supply your own 2/0 wires).  I drilled two holes in the aft end of the settee wall and ran those suckers under the macerator pump, across the bilge aft end to the forward point of the water heater.  Because of the "defined" length of the wires that came with the Freedom 15, I put a Power Post Plus in the wall of the heater area for the negative, and made that my NDP, and put a fuse on the positive side, then extended those into the battery compartment with more 2/0.

Having had a long discussion with the infamous Captain Al Watson who was doing the same thing to his 1986 C34 back in Connecticut, we determined it was pretty much the only way to run those huge cables on our boats.

Did anyone route between the head and hull then through the hanging locker to the Nav Station?

The only route I'm aware of is to go high.  Up and over the small sliding door cabinet, where the wiring to the cockpit panel goes.  One of our other infamous contributors, Steve Dolling, aka waterdog, ran his diesel heating system air duct UNDERNEATH the head mirror cabinet, an ingenious approach, since he says you never see it.  Think about it...  Very clever.

How about enlarging the bilge drain opening in the front of the engine compartment sideways and routing through there?

No, don't do it.  If you want to route anything there, go UNDER that pan directly from under the aft end of the heater.  After all, that's where the hoses to your head sink go anyway.  Two metal coat hangers are long enough to make that trip to pull wiring.  That's the route I used for our new alternator wiring.

You want to keep that pan as intact as you can, to catch drips.  Ours has a small hole that I can cork with a cork if there's any major leak, otherwise, it drains right to the bilge and is very handy.

From your hull #493 and the title of this post, you have an '87, right?  Should be the same stuff on yours as on ours.

Drill a couple more holes in the engine mount floor near where the water hoses to the head, and hoses to/from the heater come through?

I don't follow.  What more holes need to be drilled?  It's all open under there.

[Jon W]

Yes I have a 1987.

The "more holes" would be to route the alternator to the house battery box, the starter to the 1-2-B switch "C" post, the reserve battery 2/0 positive to the "2" position on the 1-2-B switch, and the 2/0 negative from the house battery box to the engine ground from the water heater area. Need to come up from below the sub-floor somehow/somewhere. The reserve positive to the "2" position is the one I was considering running between the head and hull through the hanging locker to the distribution panel.

Currently slots are drilled in the pan about ¾-1" wide by 3" long each side of the forward engine mount between the engine mount pedestal and the engine compartment bulkhead. This part of the pan is at floor level. On the port side, the hot and cold water lines come from the water heater area, up through the slot then aft to go around the corner to the head. On the starboard side, the water heater hoses route from the heater area up through the slot then connect to the engine. Sorry no pics, but think we are talking about the same path.

When you pulled the wires under the pan where did they come up to attach to the engine?

Jon W.