Looking for practical charging system refit advice

[roland stockham]

This may complicate your choice but I will suggest a different (cheaper) strategy. From the photos the wiring looks reasonably new and good quality so I would say it has been replaced at some point, needs a check but not automatic replacement. The alternator is fine and does not need replacing. Unless you have very high demands and large banks (600a/hr +) you will get no benefit from a larger alt. Using a diode splitter is fine provided the system is set up for it. A second hose bank has advantages although overall it is a less efficent use of battery capacity. If you have all the sensitive nav equipment and essential sailing stuff like nav lights it means you have less chance of problems with voltage fluctuation. There can be a problem withe house bank when, for example, a large inverter kicks in causing a voltage spike then dropping to 10.5v. I also means that if you use two much domestic power you sill have all the sailing stuff available as that battery is not flat. Finally it acts as a spare if either bank fails.
So I would say
1 decide whether you want just start and house or start, house, nav, banks.
2 Check the age and condition of all the batteries and replace as required
3 Fit a smart external regulator sensing from the house bank - This is ESSENTIAL, no internal regulators will give effective charging you must have a 3 step charge capability on the alternator charging system the same as on the shore charger.
4 Get rid of any 1/2/both type switches. They are unnecessary at best and can be a major problem. With a diode isolator each bank is kept independent anyway and the external regulator makes the charging process fully automatic. If you ever need to boost the start battery use a set of jump leads!
5 If you have the budget fit a battery monitor

Once you have do that and it is all set up check the voltages. You should have an initial charge voltage of 14.6 - 14.9 into a CHARGED battery (it will quickly drop to 13.8) Less than 14.6 means a lower or ineffective charge rate, more than 14.9 risks damage to connected electronics. you should have an initial charge current of about one fifth of the battery capacity so 20a for each 100a. This will be the MAX and will quickly drop but you need to know it. Make shore you batteries a well discharged to get the true max. Once you know the max continue to charge the batteries. If all is working the system should charge at between 20&10a per 100a/hr capacity until you reach the first set point. If it goes out of this range you have an alternator capacity or battery absorption problem. Assuming all is OK watch until you get to the next set point, the system should trip to float voltage at about the '20hr' charge rate (5a per 100a/hr capacity).
This is the most efficient charge profile for flooded L/A batteries. Don't mix batteries by using a 'sealed' start battery of any kind as they need different profiles.
There is no point trying to get high initial charge rates by fitting oversize alternators, even if they work they actually increase the overall charge time because the system switches to the next step earlier

[mitiempo]

Originally Posted by phaon

As one might surmise, not much of the mechanical and electrical systems in this boat are original with plenty of DIY fixes over the decades. We working on a "modest" nut reasonable budget. We have discovered some inconsistencies relative to the boats charging systems that result in insufficient charging of the house batteries.

Da Boot:
1970 Morgan 38, Yanmar 3HM 27 HP diesel.

Hitachi alternator (most likely a LR-155, but it's ID label was painted over during a engine rebuild) with internal regulator that was recently tested to be putting out 45 amps.

While the single starting battery and the 2 house batteries are all flooded acid batteries, they have little else in common ("one house battery" is actually two 6V batteries wired in series),

The 1/both/2/off battery selector switch currently switches between the two house battery banks,

There's a 3-post, diode isolator that distributes the alternator's charging output to each battery bank, but the alternator's sense wire is the original wiring off the ignition switch.

The shore power battery charger is smart and can charge up to 3 battery banks. It's charging output leads are currently connected to the battery posts on the isolator.

The solar panel is directly connected to one of the house batteries.

Our (perceived) challenges:
#1. The alt is sensing only the starting battery's charge, so when that battery is fully charged the alt effectively shuts down thus not fully charging the deep cycle house batteries.

#2. We'll never truly know what model Hitachi alternator we have due to the "nice" paint job, it seems to putting less amps than it's rated for, it's internally regulated, and generally believed to as a fellow sailor stated "not worth a pile of mouse poop".

#3. We're woefully ignorant as to how to effect improvements to this mess.

#4. The charging system is probably got more small, unaccounted for voltage drops due to the hodge-podge of cables and connections.

My humble thoughts:
#1. We should replace the current alternator with a good externally regulated model.

#2. Based on #1 above, we'll need to acquire a external, probably smart, voltage regulator/monitor and/or something else that monitors, prioritizes and charges all the batteries fully.

#3. Disconnect & remove the diode isolator totally.

#4. Connect the shore power battery charger directly to each battery bank.

My 20 questions:
#1 Anyone care to take a shot at ANYTHING I've written so far, particular the tentative fixes?

#2 Assuming an alternator replacement is a must, any recommendations for brands, sizes, regulation method, etc.

#3 Assuming a new externally regulated alternator, any thoughts/recommendations for what to buy? How to sense which batteries need charging? How best to save/reserve the staring battery?

#4 Best method for connecting in the shore power charger and the solar panel?

#5 Should the battery selector switch switch between either of the two house batteries or between the house bank and the starting battery?

#6 Anyone know any experts in these matters close to Punta Gorda, FL?

#7 What have I missed? Any additional thoughts, suggestions, recommendations or worse?

Some random comments:

Charging the batteries and measuring voltage the next day doesn't tell you the most important thing - their capacity. If they are 4 or 5 years old better to replace them. A single starting battery - say a group 24 with 1000 cranking amps will do fine and is not expensive.

The house bank size is hard to determine without knowing the expected loads. If you do not have refrigeration I would buy 2 golf cart 6 volt batteries and wire them in series. True deep cycle batteries and not expensive.

If you have higher loads - refrigeration being the highest - I would create a bank of 4 golf cart batteries for a total of 450 AH or so. You only should have one house bank - it's more efficient during both use and charging and the batteries will last longer as well. This will give you a theoretical 225 AH usable. Theoretical because it is unlikely they will reach full charge very often. Engine charging to about 85% capacity is all you can expect in a reasonable time period. From 50% to 85% will give you about 160 AH to use.

Solar can make up some or all of the charging deficit. You do not state how large the panel is not the type of regulator. My minimum would be 200 watts
of panels and a good MPPT controller. In the tropics this could get you as much as 70 or 80 AH per sunny day.

Hitachi alternators are notorious for de-rating their voltage output when warm. Couple this with the diode isolator which will cost .7 volts and I doubt you will get much more than 13 volts or so at the batteries when the alt heats up a bit. The solution is to lose the diode isolator and wire the alt directly to the house bank positive, fused of course. The house bank will always be in more need of current than the start battery. Buy an ACR (Blue Seas SI series for example) and wire it between the house and start batteries. This will charge the start battery whenever the house bank sees a charging current.

Wire the shore power charger and solar to the house bank only. ACR takes care of start battery automatically.

Wire one bank to position #1 on the switch and the other to #2. The common (output) goes to the DC panel for loads and the engine for starting.

If the budget allows you could look at a new alternator with external reg. But I would fit more solar first. If the money is available you could do both.

Hope this helps.

[mitiempo]

Originally Posted by roland stockham

From the photos the wiring looks reasonably new and good quality.....

What photos?

As far as I know the op hasn't posted any.

[mitiempo]

Led lights will save a lot of energy - in particular running, anchor, and any lights used often. If a light is used seldom and not for long - in the head for example - it's less of an issue.

A battery monitor is a good addition - Victron BMV-700 is probably the best value and it is easier to install than the other amp counter types. The Balmar SmartGauge is another option - more accurate on SOC but less information.

The 1/2/both switch can stay if desired. My choice would be separate on/off switches for start and house banks with a crossover switch for starting from the house bank. The crossover switch does not have to be visible as long as it is easy to get to.

[TranceNT]

Season's Greetings to all !

W3GAC has the goods, the money is on that arrangement.
VK4JC (inactive)
Cheers Terry

[socaldmax]

You've gotten a lot of good advice here, but some of the advice I don't agree with. I'll just post my thoughts and hope they help.

1. I see no reason to run 2 house banks. If you combined all batteries into 1 bank, it would run your loads for twice as long before needing recharging. Why run one bank down to 12v, then switch to the other bank? Better to have all of the batteries in one large bank sharing the load, they discharge less and they all last longer.

2. Someone suggested ditching the golf cart batteries and getting another 12v. I say the opposite. 6V GC batteries are the highest capacity, cheapest batteries you can get. 225AH rating for about $180 for a pair. I do agree with tossing them all if they're 4 or 5 yrs or older. Get at least 4, maybe 6 GC batteries and use boat cable with tinned, crimped lugs with adhesive heat shrink covering the crimp.

3. I'm a big fan of solar power (installing a 1200w dual MPPT controller system for a customer right now) but you didn't mention what size panel you're running. Anything under 80 or 100 watts is a battery tender, anything more really should have a decent solar controller on it, take a look at Renogy for reasonably priced units. Consider a larger solar system if possible, it's free energy once installed.

4. The best way to find out how much your alternator can put out is to take it to a shop and have it load tested. Any electrical shop or auto parts store can do it for you, and hopefully they can show you rpm vs output.

5. Get rid of any shaky looking wiring or connectors and replace it all with boat wire (oversized is better, we used 4/0 cable for the battery bank to main bus and 1/0 for interconnecting cables only 12" long) with crimped lugs and adhesive heat shrink.

I bought a great 16 ton hydraulic crimper for $36 on Ebay, came with 11 sets of dies that make a hexagon crimp for only $34, well worth the money.

[andyft]

This is a very informative thread, I am getting ready to upgrade my charging system. thanks all for the advice.

[socaldmax]

Correction, the crimper and dies was only $34 delivered, I don't want anyone to think the crimper was $36 and dies were $34.

[phaon]

I want to send all you marine "engineers" a giant, hardy THANK YOU!!!! for the the time and thought and wisdom you've put into your responses to my lengthy questions. The skipper and I have already started working some of your advice into our refit plans.

Happy New Year to All!!!

[TranceNT]

Hi Phaon, and the best of a New Year to you both,

There is no significant issue with that detailed post by W3AG and that is what I do. In particular, the matter of combining battery units in parallel is dealt with elsewhere in this forum.
Personally, the situation in boats that are not used in 'Live Aboard' mode is one which I would suggest is inappropriate for battery units to be solidly connected in parallel. You will find my post and others relating to this issue under my tag.
The reason is simply that unless the group is under continuous management, it has been shown that the variations present in each battery tends to drag the whole lot down if left that way for lengthy periods.
Having two house batteries (if room permits) and the normal 1,2, OFF, and BOTH style of selector gives you the optimum backup and life cycle cost.

It is a bit like having two 60+ alternators (driven separately of course) instead of one 100+ unit on one micro V belt. The smaller units are happy with a standard A or 10mm vee belt. I guess the old "All your eggs in one basket" is the difference from the "belt and braces" approach. There is a neat trick used in light aircraft engines involving fitting a spare belt out of service and tied safely out of the rotating parts --- beats the hell out of having to remove the prop to change the alternator belt. In boats, it is usually something like a crank-driven water pump">raw water pump, or some other accessory whose belt is usually in the way of a simple swap.

Good luck with the work,
Cheers, Terry

[phaon]

Well....post refit, post trip report: Again, thanks much to all those who contributed their expertise and advice.

We replaced the old Hitachi 55 amp (or so) alternator with a non-Hitachi, heavy-duty version of the same. It was definitely a plug and play replacement and designed for a Yanmar diesel, altho the new alternator's rated output was 80 amps. It was still internally regulated and used the same 3/8" v belt. It was definitely much heavier. Bought it from Maniac Electric Motors in Texas for $106.

We also installed a Blue Sea ACR between the house batteries on the 1/2/all/off switch and the starting battery. $76 at PKYS.com.

We also reran the alternator's voltage sense wire, which was originally connected to the positive side of the starting battery to house battery side of the new ACR. This allowed the alternator to sense the starting battery voltage when the ACR was closed (meaning all batteries connected together) as well as sense the house battery(s) voltage(s) depending on the position of the 1/2/all/off selector switch (generally left in the "all" position).

The redesign was relatively inexpensive, easy to install/change and seemed to work very well. The ACR would close whenever the alternator was running or we were on shore power. This allowed all the disparate batteries to charge fully. The beefier alternator allowed for quick battery charging when required. We did not connect the optional ACR lead to the ignition switch which would have opened the ACR, thus separating the house and start batteries when the engine was being cranked to start. Starting the engine did not reset the active electronics.

See attached wiring diagram for specifics.

Good winds!
Terry