Upgrading Generator Alternator for House Bank

[foggysail]

Ok, you love your solar panels. And for you that was a better alternative than getting a beefy reliable inverter charger.

But, for many of us big reliable chargers are onboard with sufficient cruising hours done during the day to be battery state happy. If I anchored for days on end in a solar friendly area I'd load up the top with Elon's favorites.

CHUCKLE, CHUCKLE! Elon is no favorite of mine, time to hide the subsidies

 

[ranger58sb]

Chris-- in post 12 I mentioned our illustrious 50 ampere charger which was just unable to recharge our batteries. The so called high output remained high for less than about 15 minutes instead of until the battery bank reached float. That forced me to seek a better charging technique....solar.

Again.................... please read post #12 in this thread. The over rated battery charger I purchased based on literature FAILED to charge at or near 50 amperes until the batteries had attained float. Sure.... I could have gone forward, done additional research, purchased another battery charger and maybe depleted battery problems would have ended.

I had enough of the battery charger bullpoop and went with solar.

Solar doesn't sound bad... except for the installation work and especially real estate.

But I think I'd have just replaced the charger first, anyway. Real estate already available, etc etc etc.

Maybe solar eventually, too, but probably only if a decent -- read: appropriately sized, and actually working -- charger still turned out to inadequate.

Different strokes, probably...

-Chris

 

[Ski in NC]

If you run a 7.5kW gennie for six hours and your batts are still not fully charged, your problem is a crappy or poorly sized charger.

 

[foggysail]

If you run a 7.5kW gennie for six hours and your batts are still not fully charged, your problem is a crappy or poorly sized charger.

I long ago suffered battery charge issues. I even purchased a Xantrex 50 amp charger....... will not express my regards to this *^%$# other than to say it was an unwise expenditure.

 

[O C Diver]

IMO, most cruising boats (that don't run a generator 24/7 when away from the dock) have too small a battery bank and a DC electric storage and charging system that is poorly engineered. My goal was to be able to sit for 2 days and have electrical needs covered with the exception of cooking and HVAC. Additionally, I wanted to be back to "float charge stage" after motoring for 4 hours. If I'm going to run the generator, I'd like it to be once a day and have the battery bank back to "float charge stage" when I'm done. All this was pretty easy to accomplish with a clean slate. Much tougher to accomplish if you don't have a plan and keep patching a failed design.

Ted

 

[kev_rm]

Using the noisemaker to power a good sized alt is a great idea for most diesel cruisers.

A 135A alt can be had from a big truck store (like Detroit diesel) brand new for under $150 ($135 here in FL)

A big advantage is it frees up perhaps 10A on the small noisemaker for other uses.

And it usually creates a good load so the noisemaker cooling can heat a HW tank.

Yes you will need a proper 3 or 4 stage V regulator with temp sensor , but the combo will charge faster and harder than most AC powered battery chargers.

The last 10-15% of charge is still best with solar as the battery is the slowdown , not the DC source.

This was essentially where I was going with the original thought. And now you've given me a good idea on swapping the hot water exchanger source...

 

[foggysail]

This was essentially where I was going with the original thought. And now you've given me a good idea on swapping the hot water exchanger source...

Years ago when I was an electrical circuit design engineer, it was common practice to cool high power devices by wrapping several turns of 1/2" copper pipe around the devices and securing them with silver solder. Cold water was circulated through this pipe for cooling. That worked. If you could do something similar with an alternator, you would have an efficient heat source.

 

[kev_rm]

IMO, most cruising boats (that don't run a generator 24/7 when away from the dock) have too small a battery bank and a DC electric storage and charging system that is poorly engineered. My goal was to be able to sit for 2 days and have electrical needs covered with the exception of cooking and HVAC. Additionally, I wanted to be back to "float charge stage" after motoring for 4 hours. If I'm going to run the generator, I'd like it to be once a day and have the battery bank back to "float charge stage" when I'm done. All this was pretty easy to accomplish with a clean slate. Much tougher to accomplish if you don't have a plan and keep patching a failed design.

Ted

+1 on two days of capacity is good design point for house bank.

 

[FlyWright]

Our requirements are not abnormal. And it matters not how large one's battery bank is IF THE CHARGE CANNOT BE REPLACED while the boat is away from a dock.

Regarding lead-acid batteries, I'd toss in another variable here that we might be overlooking. I think it's typical that those of us with LAs and no solar operate between 60-85% (25%) throughout most of our time at anchor. To charge much above 85% requires a lot of genset run time due to the tapering acceptance rate of typical lead acid batteries as we reach the later end of the absorption charge stage. This gets worse with battery bank age.

If I have a new 400AH bank, that 25% operating range equates to 100AH. If I continue charging beyond the 85%, my charge will reduce thereby extending the charge time accordingly. In theory, if I have a 50A charger and need 200AH per day, I'll need to charge twice per day for 2 hrs at peak charging rate. In real life, especially with aged batteries, that might equate to 5 or 6 hours.

With a 600 AH bank, it raises to 150AH of workable capacity. If I still use 200AH, I can charge in twice per day with that same charger and only run at peak charging of 50A and be topped off in 4 hrs. Even with older batteries, my workable capacity should stay well above 100AH, allowing a full rate charge into the bank for those two 2 hr periods.

With a larger bank, I can pump in more AHs in a given period of time using the same charger than I could with a smaller bank being operated at its limits.

 

[sunchaser]

Al

According to my house bank BMK my inverter charger stays in bulk mode until around 92% SOC. Up until then it has progressively dropped from about 135 to 85 amps. Generally our cruising day will top them off at 100% by the end of the day with genset off.

As an aside, our genset has about 1/4 the hours of the mains meaning we don't need much genset run time in comparison to cruising. At night on the hook all power is shut off except 12/110V fridge and lights.

 

[FlyWright]

Tom, are your batts lead acids?

As I recall, and correct me if I'm wrong, the following are the battery stages:

Bulk: Voltage increases to max while the incoming current remains at the rated max level.

Absorption: Voltage has reached max and remains constant while the incoming current amperage drops.

Float: Battery is essentially 100% (or very close) and the charge drops further to an amp or so, depending on your charger.

 

[sunchaser]

AL

Yes the batteries are LAs. Some confusion possible on my part. Probably as with the newer smart chargers, the amps are kept at near optimum acceptance rate as batteries - volts - will allow. The old designation of bulk, absorb and float are not necessarily a fixed amperage - just a point on the scale as amps auto drop.

Regardless, it all seems to work with my LA house batteries outlasting my thruster AGMs by a wide margin. That is a different story and largely irrelevant.

BTW, for interest of the OP, you may want to share your excellent story about your alternator moves of a few years ago. What you and OC Diver have done is well worth a read for anyone contemplating bigger alternators and associated work arounds.

Some technical stuff is fun to read about, keeps some of us coming back.

 

[FF]

"If you could do something similar with an alternator, you would have an efficient heat source."

Why bother ? 2/3 of the energy on a diesel is being lost out the exhaust and just to cool it.

Capturing that energy is fairly easy, the coolant can heat the boat , or just make hot water.

For most exhaust heat is harder to capture , but can be used for drying a wet gear locker , or with a wrap of tubing to create hot water .

Sadly refrigeration and air cond cant be powered by hot water , but it might make deck washing easier.

 

[foggysail]

"If you could do something similar with an alternator, you would have an efficient heat source."

Why bother ? 2/3 of the energy on a diesel is being lost out the exhaust and just to cool it.

Capturing that energy is fairly easy, the coolant can heat the boat , or just make hot water.

For most exhaust heat is harder to capture , but can be used for drying a wet gear locker , or with a wrap of tubing to create hot water .

Sadly refrigeration and air cond cant be powered by hot water , but it might make deck washing easier.

Cannot dispute that. I thought of cooling an alternator years ago when I considered modifying one for high output current. The technical problems I faced were ways to prevent both high internal temperatures which degrade wire insulation life along with a thermal runaway. I gave up on the idea of using an alternator because of the cooling challenge. Alternators do work, just have to be designed for the application.

 

[FF]

The Delcp DN50 is used on many buses.

It is oil cooled from the engine and can be had BIG !

Most are 250-250A 12v units but 300A 24 can be had.

As they are made for decades used or rebuilt is cheap and easy to come by.

Delco Remy 50DN Alternator Generator | eBay

All are BIG!!!and heavy , but if you need reliable they cant be beet.

 

[FlyWright]

BTW, for interest of the OP, you may want to share your excellent story about your alternator moves of a few years ago. What you and OC Diver have done is well worth a read for anyone contemplating bigger alternators and associated work arounds.

Some technical stuff is fun to read about, keeps some of us coming back.

Here's part of the story that I posted a few years ago.

http://www.trawlerforum.com/forums/s4/finally-balmar-120a-alt-installed-15652.html

The 110A (derated) Balmar alternator normally has the house bank at or near 100% after a couple hour engine run.

I don't have a genset installed on my boat so I carry a Honda eu2000i portable generator. It runs from the FB or bow and plugs into my shore power outlet.

My 55A Iota battery charger was chosen to be able to be powered by the Honda's 13.3A max output. It never seems to rev the generator very high so I could probably get by with a 75A model. At anchor, the 55A Iota takes a couple of hours per day to keep me in the 60-85% sweet spot for charging. I rarely see less than 70% SOC. When the acceptance rate drops below 20A, I typically turn off the gen.

Some of the biggest improvements to my boat electrically has been limiting the loads with the following upgrades:

LED lights including anchor light on photocell
Replaced old Norcold fridge with new Nova Kool refrigerator with Danfoss compressor

Before the fridge replacement, I consumed about 180-200 AH per day. Now I run in the 100-120AH range. This means my gen run times are reduced to 2-3 hrs instead of 4 hrs and my 660AH house bank can support me for 3 days on the hook without a gen run, if needed.

I do have a couple of high demand items in the galley that I prefer to operate on the gen. My microwave or electric skillet can run on the inverter but if they are used for more than about 5 minutes, it takes a chunk of power from the house bank that takes longer to replace than it takes to consume. IMO, I'd rather run the gen to operate them for short periods. Also, my Keurig coffee maker requires about 1500W which exceeds the output of my little 1000W inverter. I can always break out the Mr. Coffee and run it on the inverter but I have not had to revert to such drastic steps yet.

Every couple of days at anchor I'll run the gen for an hour or so just to heat water. This is a high electrical load that cannot be combined with charging and has that little Honda running at near full throttle.

My setup is far from optimum for many but it meets my needs. I am continually shuffling power demands in the "30 Amp Dance" but that's the price I pay for inexpensive solutions to potentially expensive workarounds.

Last summer I enjoyed an extended trip of 14 days solo on the boat with no plug-ins, pumpouts or reprovisioning. The electrical mods and efficient head made that possible. This year I'm seriously considering raising the bar to 3 weeks afloat with no marinas. The one system capability that may limit that attempt will be the 40 gal holding tank. Also, after 2 weeks of tank contents, it becomes a bit 'aromatic' downwind from the vent after flushing.

 

[FF]

"Also, after 2 weeks of tank contents, it becomes a bit 'aromatic' downwind from the vent after flushing."

Add air , a fish tank air bubbler or just a bigger vent pipe .

 

[O C Diver]

BTW, for interest of the OP, you may want to share your excellent story about your alternator moves of a few years ago. What you and OC Diver have done is well worth a read for anyone contemplating bigger alternators and associated work arounds.

Some technical stuff is fun to read about, keeps some of us coming back.

When I did the refit on my boat, I replaced the house battery bank with 8 Trojan T105s (almost 1,000 AH), added a second alternator (Leece Neville 220 amp) with a sterling 3 stage regulator to the engine, changed all light bulbs to LED, and have a Magnum Energy inverter / charger with 135 amp charging capacity. Typical consecutive days of cruising using a microwave and rice cooker for dinner and coffee maker in the morning, shows an at anchor power consumption of 10 to 15%. Cooking on the gas grill reduces consumption by about half.

Drawing the bank down to 70% over several days at anchor requires <4 hours of cruising to bring it back to "float stage charging". Typically, if I plan to anchor out for several days and cook dinner electrically, I'll run the generator to cook, make hot water (20 gallon water heater) and bring the battery bank back to "float stage each night. In my limited experience, this seems to be about 1 to 1.5 hours.

Last years cruising looks to have been about 12 weeks, 3,800 miles, 650 +/- engine hours, and about 100 hours on the generator. About 75% of the generator hours were climate control related. Based on this pattern, I just don't see solar paying for itself or significantly reducing my generator hours.

Ted

 

[ranger58sb]

About 75% of the generator hours were climate control related. Based on this pattern, I just don't see solar paying for itself or significantly reducing my generator hours.

I think that's similar to our situation: most genset time is about HVAC, cooking, and hot water. Battery charging happens as a matter of course.

I probably wouldn't turn down a solar installation, but it wouldn't bubble up to the top of my wallet anytime soon. Other nifty stuff that we'd gain more direct benefit from, first.

-Chris

 

[sunchaser]

When I did the refit on my boat, I replaced the house battery bank with 8 Trojan T105s (almost 1,000 AH), added a second alternator (Leece Neville 220 amp) with a sterling 3 stage regulator to the engine, changed all light bulbs to LED, and have a Magnum Energy inverter / charger with 135 amp charging capacity. Ted

Ted, you have almost the same setup we do. Our exception is twin engines with each having a 90 amp Prestolite alternator and fewer LEDs. Prestolite and LN are "parts" of the same company.

As well, your genset usage is about the same. We'll run the genset when hoisting anchor, our normal deep sets are a battery drainer otherwise. We do not have too many hours of AC time though but do wash and dry lots of clothes. Smelly Ts, jeans and sweat shirts seem common for this male, so says my wife.

 

[O C Diver]

Ted, you have almost the same setup we do. Our exception is twin engines with each having a 90 amp Prestolite alternator and fewer LEDs. Prestolite and LN are "parts" of the same company.

As well, your genset usage is about the same. We do not have too many hours of AC time though but do wash and dry lots of clothes. Smelly Ts, jeans and sweat shirts seem common for this male, so says my wife.

One of the things I had considered doing was adding a second inverter and reworking the other side of my AC breaker panel to be able to run loads off the second inverter. With the 3KW LN alternator, it would be very easy to do laundry while underway through the inverter. Could also run pilothouse air conditioning with that system. When one considers the all in cost per hour for a generator, a big alternator through a pure sine wave inverter is a very attractive supplement. Sadly, you have to draw the line somewhere and go cruising instead of boat projects.

Ted

 

[johnrupp]

One of the things I had considered doing was adding a second inverter and reworking the other side of my AC breaker panel to be able to run loads off the second inverter. With the 3KW LN alternator, it would be very easy to do laundry while underway through the inverter. Could also run pilothouse air conditioning with that system. When one considers the all in cost per hour for a generator, a big alternator through a pure sine wave inverter is a very attractive supplement. Sadly, you have to draw the line somewhere and go cruising instead of boat projects.



Ted

Ted,

How big of a air conditioning unit do you think you could realistically run with your 3KW alternator?

 

[O C Diver]

Ted,

How big of a air conditioning unit do you think you could realistically run with your 3KW alternator?

The issue isn't the alternator, it's the inverter / battery and starting surge of the compressor. That alternator can easily produce enough power for the inverter to make 18 amps 120 VAC continuously. This assumes a normal installation (pulley sizes) and the engine turning 1,500+ rpm.

On my charter boat, I have the same alternator hooked to a single 8D battery, feeding a modified sine wave Chinese inverter, running a 16K btu air conditioner. Been doing that for almost 10 years. You need a big enough battery and cabling to handle the momentary surge when the compressor starts. Originally had the inverter on the same alternator and battery as the navigation electronics. They didn't like the voltage drop when the piston compressor started on the original AC unit.

Ted

 

[twistedtree]

This article might be relevant

Adventures of Tanglewood: Alternator Reconfiguration for Improved Power

My boat came equipped with a large house alternator and not-as-large start battery alternator. The start battery alternator was spending most of its life doing nothing, so I combined the two alternators to run in parallel to charge the house bank, then added a 3-stage DC-DC charger to keep the start battery topped off. I now have about 30% more DC power available while underway, and a better charging scheme for the start battery. Plus a spare 3-stage regulator for alternators.

 

[johnrupp]

Thanks Ted and Peter, that's the info I'm looking for.

 

[MartySchwartz]

So this thread is most appropriate and the timing is perfect. Over the past few months I have been going through the this same mental exercise of trying to figure out how to decrease the generator run time to replace the 95-120 amp-hours and to do it in a manner that is cost-effective. Currently it takes about 3-4 hours of generator run time to replace ~100 amp-hours via the ProMariner 50-amp battery charger (House bank capacity is 745 amp-hours using six 6-volt wet-cell batteries.)

I thought about adding a big alternator to the engine side of my Westerbeake 8 KW generator but that seems to be a bad idea from what I have read here and the feed back I got when asking about it at the Seattle Boat show a few weeks ago.

Solar would be nice but that is still not really cost-effective for me now (or in the foreseeable future).

So far the best two options seem to be either (1) leave it as is and live with it or (2) go with a higher capacity AC-powered battery charger.

Any other options that I (and the OP) are missing?

Thanks
Marty........................

 

[O C Diver]

So this thread is most appropriate and the timing is perfect. Over the past few months I have been going through the this same mental exercise of trying to figure out how to decrease the generator run time to replace the 95-120 amp-hours and to do it in a manner that is cost-effective. Currently it takes about 3-4 hours of generator run time to replace ~100 amp-hours via the ProMariner 50-amp battery charger (House bank capacity is 745 amp-hours using six 6-volt wet-cell batteries.)

I thought about adding a big alternator to the engine side of my Westerbeake 8 KW generator but that seems to be a bad idea from what I have read here and the feed back I got when asking about it at the Seattle Boat show a few weeks ago.

Solar would be nice but that is still not really cost-effective for me now (or in the foreseeable future).

So far the best two options seem to be either (1) leave it as is and live with it or (2) go with a higher capacity AC-powered battery charger.

Any other options that I (and the OP) are missing?

Thanks
Marty........................

Marty, a 745 AH bank could probably be changed at a 20% of the capacity or about 150 amps. So replacing the charger with a new Magnum Energy inverter charger with a 135 amp charging capacity would cut your charge time by over 60%. But there's more, if you have a 10 amp draw (lights, pumps, electronics, and any othet 12 volt accessories) while you're charging, you're only putting 40 amps into the bank. Switching to a 135 amp charger would cut charge time by 70%. Now I'm not going to tell you that you will cut your 4 hour charge time to 1 hour. But I think based on my experience, you could expect to cut your charge time to between 1.25 and 1.75 hours.

Ted

 

[kev_rm]

I think another piece of information here is the cost per amp of input. An additional 50-70 amps as an add on to a mid size genny is almost an order of magnitude cheaper than solar or AC charger if you can bolt on without a bunch of mechanical problems - Which is why I started the thread in the first place.

 

[kev_rm]

ted had read your earlier message at discharging 70% not 30%.. 4 hours sounds about right, an hour bulk or so and 2-3 hrs accept. that's kind of a normal day in the life for lead acid.

 

[Ski in NC]

Have you looked at the front of that gennie and seen what it will take to put a big alternator on there? And what kind of alt and reg it will take to get good charging? The hardware alone will take some serious engineering and fabricating.

For the life of me I cannot see the logic in putting big DC charging hardware on the front of an 8BTD when it has a capable AC electrical end already installed that could easily drive an inverter/charger.

If you want a big alternator for good quick charging, it is best on the main engine where it can work when boat is going somewhere. If on the hook, let the gennie do it through it's more than adequately sized electrical end.