Reply
 
Thread Tools Display Modes
 
Old 02-27-2012, 07:08 PM   #21
Guru
 
C lectric's Avatar
 
City: Somewhere
Country: , Canada
Vessel Name: Island Pride
Vessel Model: Palmer sedan 32'
Join Date: Oct 2007
Posts: 1,864
RE: Understanding my genset alternator

You say your fridge is a Norcold.

The compressor is actually driven by a 20VAC motor. There will be a box somewhere on the back of the fridge which contains a relay, a transformer, several transistors and capacitors.. When on 120VAC supply the relay operates and isolates the 12VDC supply from operation and connects the 120VAC to the transformer. When you plug the fridge into a 120VAC outlet you will hear the click. The transformer drops the 120VAC down to 20VAC and away it goes.

On 12VDC , 120VAC not available, the relay is not actuated and the 12VDC goes through the transistors, which due to the caps. and a connection to the transformer are used as an oscillator [becomes an inverter] to produce a 60HZ ~12VAC which is fed to some other taps on the transformer which steps the voltage up to the 20VAC the motor requires.

It is no where near as efficient a setup as the Danfoss systems which have been around for over 20 years. Compared to the Danfoss compressors it is a power hog. They were reliable and long lasting if checked once in a while.

One of the things I found is an adjustable resistor in the box which is used to adjust the HZ. It does need to be adjusted periodically as the frequency falls off which results in a huge increase in inefficiency as the motor runs slower. You may find if you check this out that your ffridge has fallen of frequency and an adjustment will be worthwhile untill such time as you can or want to replace it. Don't be tempted to increase the HZ above 60 to 61.

Most mfgrs. use the Danfoss now due to the efficiency improvements over the older systems.

Several mfgrs make direct replacements for the Norcolds, box size for box size. Nova Cool is one. I still have my old Norcold and when $$ permit I will replace it as I have already picked out the unit I want .
__________________
Advertisement

C lectric is offline   Reply With Quote
Old 02-27-2012, 07:50 PM   #22
Guru
 
Fotoman's Avatar
 
Join Date: Nov 2009
Posts: 621
Understanding my genset alternator

I have the same concern with my fridge and I thought about a solution that may be interesting for you as well. I'm thinking about getting one of those 120v power bank you can get for your home and hook it up exclusively on the fridge when I am at anchor. I figure it will be able to power the fridge for an entire weekend with the bigger model (less than $200). Easy to install and to charge when I get back at the dock. Just a thought.

-- Edited by Fotoman on Monday 27th of February 2012 08:51:57 PM
__________________

Fotoman is offline   Reply With Quote
Old 02-27-2012, 08:33 PM   #23
Guru
 
Tom.B's Avatar
 
City: Cary, NC
Country: USA
Vessel Name: Skinny Dippin'
Vessel Model: Navigator 4200 Classic
Join Date: Jul 2009
Posts: 5,152
RE: Understanding my genset alternator

I hear ya' Tim! This isn't the kind of news I want to hear either. I just replaced my Norcold with... wait for it... another Norcold about two years ago. At $1600, I can't at all justify replacing it any time soon. Fast forward to today and I am now replacing my charging system. The last news I needed to hear is that my refrigerator is now a major DC hog on my boat. Well, at least I'll know to look for it. In the past, just out of paranoia, I will turn the fridge off before bed when we are at anchor.
Tom.B is offline   Reply With Quote
Old 02-27-2012, 09:25 PM   #24
Guru
 
Moonstruck's Avatar
 
City: Hailing Port: Charleston, SC
Country: USA
Vessel Name: Moonstruck
Vessel Model: Sabre 42 Hardtop Express
Join Date: Nov 2008
Posts: 7,848
RE: Understanding my genset alternator

The fridge and ice maker are the culprits. *However, the convenience is just too good to do without. *When we go to the Bahamas, we lift the arm on the ice maker and turn it into a freezer for extra food. *When that's emptied, we put the ice container back in and use it for that. *

I gave up fighting being too miserly on power consumption long ago. *LED lighting helps, but with music, TV, hot water, lighting and cooking producing enough power is a trade off I am glad to do. *1.5 hrs of generator time morning and evening takes care of it all. *If anchoring out for a week that's 21 hrs on the gen. *Not too bad.**Beats staying in marinas.
Moonstruck is offline   Reply With Quote
Old 02-28-2012, 01:09 AM   #25
Scraping Paint
 
City: -
Country: -
Join Date: Oct 2007
Posts: 13,748
Understanding my genset alternator

Quote:
timjet wrote:

Also what refrig unit do you suggest.
When we thought our Norcold was failing we conducted a pretty thorough search for a replacement with these requrements--- it had to fit the same space in the galley counter closely enough that only minor shimming/trim work would be necessary, it had to be AC/DC and connect to the same leads going to the Norcold.* It had to be a refrigerator/freezer, and it had to have a Danfoss compressor.

In the end, the hands down winner for us was a stainless steel Isotherm.* Our refrigerator is an under-counter unit, not as big or tall as yours.* But Isotherm makes a variety of refrigerator/freezers.

Actually, the Isotherm units we really like are their drawer-type refrigerator/freezers.* Unfortunately, the size that would fit our space would actually reduce our refrigerator/freezer volume from what we have now.* The Isotherm front door model we selected increases it even though it fits the same space.

Naturally, as soon as the Norcold realized its head was on the chopping block it "fixed" itself and has been running as flawlessly (and inefficiently) for the last three years as it did when it was new almost 15 years ago.* One factor in the longevity of the unit might be that from the day we took delivery of the boat in 1998 the refrigerator has never been turned off.* So it's been running 24/7/365 for almost 14 years now.*

A piece of advice we were given when we bought the boat by a person with a lot of credibility in this regard is never replace anything on a boat's that's working properly and doing the job you want it to do.* Electronics, toilets, anything.* So we have given the Norcold a stay of execution until such day as it truly does die.* At that point, we will go with whatever current stainless Isotherm model meets our rerquirements.


-- Edited by Marin on Tuesday 28th of February 2012 02:15:39 AM
Marin is offline   Reply With Quote
Old 02-28-2012, 08:19 AM   #26
Guru
 
koliver's Avatar
 
City: Saltspring Island
Country: BC, canada
Vessel Name: Retreat
Vessel Model: C&L 44
Join Date: Nov 2007
Posts: 2,165
RE: Understanding my genset alternator

Scott:

Danfoss compressor.
either a complete new fridge, that uses the DF unit, or a DF replacement for the guts of the Norcold.

In Vancouver, North Shore Refigeration, where "Freddy Freezer" will make the swap for a reasonable price.
koliver is offline   Reply With Quote
Old 02-28-2012, 08:33 AM   #27
Guru
 
Moonstruck's Avatar
 
City: Hailing Port: Charleston, SC
Country: USA
Vessel Name: Moonstruck
Vessel Model: Sabre 42 Hardtop Express
Join Date: Nov 2008
Posts: 7,848
RE: Understanding my genset alternator

What is the thing that makes a Danfoss compressor better?
Moonstruck is offline   Reply With Quote
Old 02-28-2012, 08:33 AM   #28
Guru
 
Codger2's Avatar
 
City: San Diego
Country: US
Vessel Name: "Sandpiper"
Vessel Model: 2006 42' Ocean Alexander Sedan
Join Date: Oct 2007
Posts: 5,420
RE: Understanding my genset alternator

Quote:
Moonstruck wrote:
*When we go to the Bahamas, we lift the arm on the ice maker and turn it into a freezer for extra food.
Quote:
__________________________________________________ ____
Quote:
I do the same thing. I've talked with guys who have ice makers who have never thought of doing this.
Codger2 is offline   Reply With Quote
Old 02-28-2012, 08:59 AM   #29
Guru
 
koliver's Avatar
 
City: Saltspring Island
Country: BC, canada
Vessel Name: Retreat
Vessel Model: C&L 44
Join Date: Nov 2007
Posts: 2,165
RE: Understanding my genset alternator

Don:

There may be someone here who can give you the technical niceties. That is not me.

I can tell you the results: 10.5 amp DC draw from the old Norcold AC/DC unit when running DC, compared to the 2.7 amp DC draw of a Danfoss. That makes it better.

That reduction to 25% consumption allows a similar reduction in charging capacity, batteries for storage, genset size, or conversely, allows more days on the hook between plug in days, or allows the addition of freezer capacity.

I credit Norcold AC/DC elimination with the following:

1; healthy batteries

2; fewer batteries: my boat now runs happily with only 4 Golfcart 6v in one house bank. I used to have 2 house banks, a pair of 8D, and a pair of 4D, which were never enough

3; we carry a 12v freezer (another Danfoss unit) which allows fewer trips to the grocers on long trips and allows fishing to occur.

4; more days continuously away from a plug-in to shore power. One summer holiday recently we unplugged when we headed towards Desolation Sound, and didn't plug in again until returning 21 days later. With the old fridge, we had to stay within range of a plug-in, as there was no way we could keep up with the draw while on the hook. Neither us or our neighbours could handle the running of our genset for the hours needed to keep our batteries up, so we were constantly in danger of wrecking them with too much discharge. The alternative of charging from the main engine only works if the group we are cruising with all want to move, and the move is far enough to get a decent charge.

Don, none of this matters if your cruising style is dock to dock and you always have a ready shore power supply. In that event, keep your Norcold.
koliver is offline   Reply With Quote
Old 02-29-2012, 04:51 AM   #30
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,515
RE: Understanding my genset alternator

What is the thing that makes a Danfoss compressor better?

Without writing a book , the basic improvement is the units ability to operate slower and slower ,using smaller electric pulses from your batt set.

The fridge folks would love it if owners were knowledgible enough to understand a high eficency modern fridge should run 24/7 at a very minor draw .

A dumb compressor that does not monitor run time , just a thermostat is always a power hog.

From the SSCA cruising board, this comment,

Your Boat Refrigerator's Future

Postby Richard Kollmann » Sun Jun 13, 2010 2:11 pm
The pleasure boat refrigeration industry today is following marine industry down the drain. We have seen refrigerator companies like Grunert, Crosby, Adler Barbour, WAECO acquired by Demitic. Gleaser Bay has stop production of their boat refrigeration products. Northern Lights, a manufacturer of marine generator sets has acquired Ft. Lauderdale-based Rich Beers Marine. What seems to be missing in this new market are the experienced people that provided technical after market support in the past. The technical approach to small boat refrigeration today is the same as when you buy a toaster, if it does not work after a short warranty it is expendable so they advise you to buy a new one. The most resent loss to small boat refrigeration support is the announcement from Rparts.com that they will discontinue operations of Refrigeration Parts Solution Effective June 30, 2010.

If someone tells you to buy new 12 volt refrigeration because compressor will not run do not believe them. If your compressor runs but there is no cooling then solution is difficult and generally requires technical help. If compressor fails to run then anyone with basic technical knowledge can find and correct a failure to run of a Danfoss compressor. If your refrigeration unit is over 10 years old and has a Danfoss BD 2 or BD2.5 or BD3 compressor then it has the older discontinued electronic 4 pin module.
Troubleshooting Danfoss compressors with 4 pin modules will consists of the following steps:

1. All of these compressors have a 4 pin module connector and their modules contain an external fuse. If this fuse is blown there are two reasons why either power wires to module are reversed or module has an internal failure.

2. Check to see that there is actually power at the refrigerator control module.

3. Place jumper wire across thermostat terminals on electronic module, Compressor still does not run go next step.

4. Disconnect black fan wire from electronic module, Compressor runs, replace fan. Compressor still does not run after fan ground wire is disconnected, go to next step.

5. Run correct size and correct polarity jumper wires direct from a fully charged battery in order to bypass all boatās wiring. Volt meter readings are of no value when looking for voltage spikes. Compressor still does not run electronic module needs to be removed and tested on another unit. If there are no other units available to test your module on I will test all 12 volt Danfoss control modules free except BD80 compressor modules. Email me for shipping address and details.

Small 12/24 volt boat refrigeration using Danfoss compressors manufactured after 1996 will have a BD 35 or BD 50 variable speed compressor with a troubleshooting computer chip built into their control module. This circuit makes them easier to find troubled area if compressor fails to run. If your unit does not have this $2 LED install one, as it could save you a lot of money later. Without the LED on these new units troubleshooting will be the same as earlier 4 pin Danfoss BD compressors.

If installed trouble shooting LED will only flash if electronic module sees a compressor problem. In each case problems of compressorās failures to run are identified by Counting number of flashes of LED:
ā¢ No LED flashes would indicate either thermostat is open or no power to module.
ā¢ One LED flash and a 4 second pause indicates a boat wiring electrical resistance problem or low batteries. Because of modules sensitive to milliseconds of a voltage spick they cannot be detected by a voltmeter. Solution is to bypass boatās wiring till problem is located.
ā¢ Two LED flashes indicates fan over current cutout. If fan circuit on these variable speed compressors exceeds Ā½ amp compressor start up will be aborted. This condition can be confirmed by disconnecting Black fan wire at module if fan runs replace fan.
ā¢ Three LED flashes indicate excessive torque is required to start compressor. This is commonly caused by turning compressor off and back on too quickly or too much refrigerant or poor condenser cooling. Most people jump to the conclusion that there is a mechanical rotor lock up inside compressor and this is a mistake on Danfoss BD compressors.
ā¢ Four LED flashes indicate compressor motor not reaching sustained controlling speed above 1,850 rpm quick enough.

If someone has tampered with refrigerant by connecting gauges to a system letting air in or adding too much refrigerant can cause either a Three or Four LED flashing signal. On water cooled Danfoss condenser systems three and four LED signals are common when seawater gets into refrigerant circuit.

If you have sources for refrigeration fair priced parts and technical assistance email them to me and I will list them on my web site. I found a source for 4 pin modules at a fraction of the price currently being asked and have been advised that refrigeration parts outlets like United Refrigeration can special order the newer Danfoss modules or compressors at a fair price.

Richard Kollmann
FF is offline   Reply With Quote
Old 02-29-2012, 06:24 AM   #31
TF Site Team
 
Larry M's Avatar
 
City: JAX, FL
Country: USA
Vessel Name: Hobo
Vessel Model: Krogen 42-120
Join Date: Nov 2008
Posts: 5,725
RE: Understanding my genset alternator

Quote:
The most resent loss to small boat refrigeration support is the announcement from Rparts.com that they will discontinue operations of Refrigeration Parts Solution Effective June 30, 2010.

RParts got back in business last year and have expanded their services.**www.rparts.com

Another good resource is Kollman Marine Refrigeration.****www.kollmann-marine.com

We have a custom refrigerator/freezer*by Sea Freeze, Bellingham, WA that was installed in 2007.* http://www.seafreezeinc.com/* It was expensive but we would do it again.* The 6 cubic foot refer has 4" of insulation with 3.5" in the door, powered by a Danfoss BD35 with it's own compressor area exhaust fan.* The freezer is 2.5 cubic feet with the same insulation.* They share a common wall with 2.5" of insulation.* The freezer is powered by a Danfoss DB50, also with it's own compressor exhaust fan.* The*DB35 and DB50 compressors both use the same electronic module so spare parts are minimal.
Attached Thumbnails
Click image for larger version

Name:	new refer 012copy.jpg
Views:	54
Size:	66.6 KB
ID:	10378   Click image for larger version

Name:	new refer 037copy.jpg
Views:	65
Size:	85.4 KB
ID:	10379  
Larry M is offline   Reply With Quote
Old 03-01-2012, 11:43 AM   #32
Guru
 
timjet's Avatar
 
Join Date: Apr 2009
Posts: 1,905
Understanding my genset alternator

With all this input I decided to do a little research. One, I need to probably redo my battery banks so that all 4 of the AGM batteries are on one bank and then install 2 engine start batteries in parallel on a separate bank. Maybe we can talk about the details on installing this later.

I've come up with 3 options to replace the power used. Cost is an important factor in deciding the best way to do this but not the only one. So without further ado here are the options I've come up with. Recall I use about 150 amps every 12 hours with my current refrig.

Note: Since I need to replace both alternators I am not including this cost, however upgraded alternators are included.

Option A: Replace both alternators, one with a 105 amp unit and the other engine with a 160 amp unit. The 160 amp unit will require some modification to the engine, but sbmar sells a kit to do this. The larger unit will go on the port engine because it is much easier to access. *I will keep the current Norcold refrig. The combined alternator ouput at 1000 rpm should be about 100 AH requiring a 1.5 engine run time every 12 hrs to get the 150 amps used. The cost of this option including 3 hours of mechanic help labor should be about $850. (Does not include the cost of the starboard alternator)

Option B: Replace both alternators with 105 amp units (cost not included). No engine mods necessary. Replace the Norcold refrig with a Isotherm CR219 or similar unit. Amp draw on this unit is about 65 amps per day. Ive upped the stated amp usage because Isotherm rates it at an ambient temp of 70 deg. I live in So FL. The alternators combine at 1000 rpm should produce about 70 amps. Using a refrig draw of 35 amp in 12 hours and other usage at 30 amps total out at 65 amps in 12 hours, requiring an engine run of nearly 1 hour twice a day or run the genny for a little more than 2 hrs. *Total cost is right at $2000, mostly for the refrig with a little for any extra wiring etc.

Option C: Replace both alternators with like units (no cost) and replace my current 30 amp 3 bank battery charger with a Magnum 2000 watt/ 100 amp inverter/charger. Keep the current Norcold. The generator would run about 1.5 hours twice a day to replace the 150 amps every 12 hours. I think the genset *would need to run closer to 2 hours with inefficiencies and such. *An added benefit is the inverter, but it is a modified sine wave. Cost of the charger/inverter is $1120, but estimating additional controllers and wiring could bring the cost closer to $2000. *Since the engines will only produce 70 amps it probably makes sense to just run the genny and not involve the engines. A Xantrex 2000 watt 100 amp pure sine wave charger/inverter is $1600.

Summary: Option A: Cost $850, Engine run 1.5 hrs every 12 hrs. Considerations; Old refrig may need to be replaced at any time. When refrig dies, engine run time reduced to :45 every 12 hrs or genny 2+ hrs.

Option B: Cost $2000, Engine run 1 hr every 12 hrs. Advantage; new refrig and should not need to be replaced ever. Adding one 160 amp alternator reduces engine run time to :45 every 12 hrs or run genny for a little more than 2 hrs per 12 hr charge cycle with the current 30 amp battery charger.

Option C: Cost $2000, Engines dont need to run, but genny runs 2 hrs per 12 hr charging cycling. Considerations; only option that adds an inverter. *In this option if the engines and genset/charger are running at the same time it would reduce the running time on each to less than one hour. Would it make sense to run both at the same time reducing the run on each?

An important consideration in all this is how we use the boat. I dont envision spending several days on the hook without moving the boat. I think perhaps 3 days at most and probably a day or 2 would be the norm. Running the engines with the current alternators would charge the batteries at about 100 to 150 amps per hour depending on how fast we run the boat. An hour or two of running like this will charge the batteries.

Option A of upgrading one alternator is by far the cheapest. When the refrig dies the cost goes to $2850 but that may or may not ever happen.

So what do ya think??

Tim

*


-- Edited by timjet on Thursday 1st of March 2012 12:47:47 PM
timjet is offline   Reply With Quote
Old 03-01-2012, 01:33 PM   #33
Guru
 
Phil Fill's Avatar
 
City: Everett Wa
Country: US
Vessel Name: Eagle
Vessel Model: Roughwater 58 pilot house
Join Date: Oct 2007
Posts: 2,919
RE: Understanding my genset alternator

Run the old refrigeration until it dies.* Take the alternator off the gen and install it on one of the main engines.** Buy several cheap 100 amps battery chargers to multi gang charge the batteries and run the AC gen set for a couple of hour, estimate cost 200 to 500 bucks. *Buy inverter separate if you want/need one later,*estimate cost 700 bucks.

*

*
Phil Fill is offline   Reply With Quote
Old 03-01-2012, 02:10 PM   #34
TF Site Team
 
Larry M's Avatar
 
City: JAX, FL
Country: USA
Vessel Name: Hobo
Vessel Model: Krogen 42-120
Join Date: Nov 2008
Posts: 5,725
RE: Understanding my genset alternator

Tim:* Try plan C but instead of the Magnum 2000 watt inverter with 100 amp charger, go with the Magnum 2500 watt inverter with 125 amp charger.* The cost difference should be less than $250 and you get 20% more charging capability.* Keep*in mind when you run the generator you'll only get about 80-90% of the published charging amps from the charger.* I've never been a fan of using my main diesel to charge batteries at anchor.* Decisions, decisions, decisions...
Larry M is offline   Reply With Quote
Old 03-01-2012, 02:26 PM   #35
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,515
Understanding my genset alternator

Many small (under 10KW ) noisemakers will not power any large amperage battery charger to rated power,

Sure 100A or whatever was advertised might be possible on a 10.8V dead battset , but the power to charge 100A at 14.4 just isn't there.

A good H-D alternator is a different deal, IF it has a 3 stage smart charger.

Check on the existing noisemaker , you might get 2 belts to run a good alt and have minimum run time .

Remember you will be running between 85% SOC on the high side and 50% on the low with wet batts,.

Size your loads and batts to be happy in this 35% range.


-- Edited by FF on Thursday 1st of March 2012 03:28:12 PM
FF is offline   Reply With Quote
Old 03-02-2012, 05:39 AM   #36
Guru
 
timjet's Avatar
 
Join Date: Apr 2009
Posts: 1,905
RE: Understanding my genset alternator

Quote:
Larry M wrote:
Tim:* Try plan C but instead of the Magnum 2000 watt inverter with 100 amp charger, go with the Magnum 2500 watt inverter with 125 amp charger.* The cost difference should be less than $250 and you get 20% more charging capability.* Keep*in mind when you run the generator you'll only get about 80-90% of the published charging amps from the charger.* I've never been a fan of using my main diesel to charge batteries at anchor.* Decisions, decisions, decisions...
*I never thought about running the engines to charge the battery, after all that's what the genset is for. However looking at the cost it can be cheaper to do just that. We did that all the time on the sailboat.

But as you say I'm not real wild about that either. We're going to check out the nose level and vibration with the engines running and sitting on the sun deck. To do that for 2 hours twice a day may just be too much. Good point.
timjet is offline   Reply With Quote
Old 03-02-2012, 07:00 AM   #37
JD
Guru
 
JD's Avatar
 
City: New Bern NC
Country: USA
Vessel Name: Stella Di Mare
Vessel Model: Mainship 34t
Join Date: Apr 2010
Posts: 1,702
Understanding my genset alternator

Timjet,

I'm still having a little problem with a statement that you made on page two. "My twin '98 Cummins diesels are due for a front end alignment, according to the guru's on boat diesel. Meaning everything on the front of the engine that spins, idler pulley, alternator, and supporting stuff should be replaced. ".

I'm not a Cummins tech but statements like that*by mechanics sound like money makers and not*facts.* That being said.* If the guru was Tony Atherns then I might give it some credence.* How may hours are on your engines that they need to have everything replaced on the front end?* And why no matter how many hours?* Are there inherent failures? *My M/B has 150k on the odometer which is about 3,500 hours.*It has a 120 amp alternator on it and*I would not think of replacing everything on the front end of that engine.*There are trucks with Cummins*engines that have twice that many miles and I don't think that they have everything replaced just for drill.

Just been bothering me.

BTW I think you are on to what has to be done and there is no "one only way" to attack your problem.



--


-- Edited by JD on Friday 2nd of March 2012 08:03:15 AM
JD is offline   Reply With Quote
Old 03-02-2012, 08:24 AM   #38
Guru
 
timjet's Avatar
 
Join Date: Apr 2009
Posts: 1,905
RE: Understanding my genset alternator

Quote:
JD wrote:
Timjet,

I'm still having a little problem with a statement that you made on page two. "My twin '98 Cummins diesels are due for a front end alignment, according to the guru's on boat diesel. Meaning everything on the front of the engine that spins, idler pulley, alternator, and supporting stuff should be replaced. ".

I'm not a Cummins tech but statements like that*by mechanics sound like money makers and not*facts.* That being said.* If the guru was Tony Atherns then I might give it some credence.*

BTW I think you are on to what has to be done and there is no "one only way" to attack your problem.



-- Edited by JD on Friday 2nd of March 2012 08:03:15 AM
*JD, that's very perceptive of you to pick up on that. The guru was indeed Tony and I just talked to him yesterday about what needs to be done.

I was incorrect in saying everything needs to be replace. The idler pulley has had a history of problems where the bolt that attaches the pulley to its mount has worn and in some cases has allowed the pulley to come loose. If this happens at high rpm, it can do big damage to the engine. Tony has talked to Cummins about this and they have made some minor changes, but not to Tony's satisfaction. He sells an upgrade kit for these pulleys that costs I believe less than $50. The other issue is the belt tensioner. It is pretty reliable from what I believe Tony said, but based on the age of my engines, '98, he suggests taking it apart, cleaning and re-lube them. The alternator is the other thing he thinks I should replace, primarily because of the bearings. If the alternator freezes up it could cause damage. Tony is a pro-active guy as you probably know and he knows what fails on these engines. I think he's trying to give me an heads up so I can prevent future problems. Besides he has no real skin in the game, but I think I will probably just send the idler pulley and belt tensioner to him and let him refurb them for me. Cost I believe was less than $100 per engine. Pretty cheap insurance.

BD you mention that AGM batteries of which I have 5 will accept a charge at a rate of 100% until they're full, unlike wet cells which charge at 100% until they're 80% full and then the charge rate falls off dramatically. Is this correct?

I agree that there seems to be no one correct way to solve this electrical issue. In talking to my wife see wants to replace the refrig until I told her how much one costs and it still doesn't fix the charging issue.
timjet is offline   Reply With Quote
Old 03-02-2012, 08:31 AM   #39
Guru
 
timjet's Avatar
 
Join Date: Apr 2009
Posts: 1,905
RE: Understanding my genset alternator

Quote:
FF wrote:
Many small (under 10KW ) noisemakers will not power any large amperage battery charger to rated power,

-- Edited by FF on Thursday 1st of March 2012 03:28:12 PM
*Glad you mentioned that. I had thought about that, but didn't really check it out.

If my calculations are correct my 7.5 KW genset should put out 62.5 amps at 120 volts. According to the specs on the 100 amp charger "the Input current at rated output (AC amps)" is 15.

I'm guessing I'm OK as long as I don't run the AC and microwave.
timjet is offline   Reply With Quote
Old 03-02-2012, 09:30 AM   #40
JD
Guru
 
JD's Avatar
 
City: New Bern NC
Country: USA
Vessel Name: Stella Di Mare
Vessel Model: Mainship 34t
Join Date: Apr 2010
Posts: 1,702
RE: Understanding my genset alternator

Quote:
timjet wrote:JD wrote:
Timjet,

I'm still having a little problem with a statement that you made on page two. "My twin '98 Cummins diesels are due for a front end alignment, according to the guru's on boat diesel. Meaning everything on the front of the engine that spins, idler pulley, alternator, and supporting stuff should be replaced. ".

I'm not a Cummins tech but statements like that*by mechanics sound like money makers and not*facts.* That being said.* If the guru was Tony Atherns then I might give it some credence.*

BTW I think you are on to what has to be done and there is no "one only way" to attack your problem.



-- Edited by JD on Friday 2nd of March 2012 08:03:15 AM
*JD, that's very perceptive of you to pick up on that. The guru was indeed Tony and I just talked to him yesterday about what needs to be done.

I was incorrect in saying everything needs to be replace. The idler pulley has had a history of problems where the bolt that attaches the pulley to its mount has worn and in some cases has allowed the pulley to come loose. If this happens at high rpm, it can do big damage to the engine. Tony has talked to Cummins about this and they have made some minor changes, but not to Tony's satisfaction. He sells an upgrade kit for these pulleys that costs I believe less than $50. The other issue is the belt tensioner. It is pretty reliable from what I believe Tony said, but based on the age of my engines, '98, he suggests taking it apart, cleaning and re-lube them. The alternator is the other thing he thinks I should replace, primarily because of the bearings. If the alternator freezes up it could cause damage. Tony is a pro-active guy as you probably know and he knows what fails on these engines. I think he's trying to give me an heads up so I can prevent future problems. Besides he has no real skin in the game, but I think I will probably just send the idler pulley and belt tensioner to him and let him refurb them for me. Cost I believe was less than $100 per engine. Pretty cheap insurance.

BD you mention that AGM batteries of which I have 5 will accept a charge at a rate of 100% until they're full, unlike wet cells which charge at 100% until they're 80% full and then the charge rate falls off dramatically. Is this correct?

I agree that there seems to be no one correct way to solve this electrical issue. In talking to my wife see wants to replace the refrig until I told her how much one costs and it still doesn't fix the charging issue.

Timjet,

*That sounds better and Tony is a person to be trusted from what I can tell.*Getting his beefed up kit is probably a good idea. I like everything he has said but I think I might check on an alternator shop in Tampa and get new bearings put into the ones you have and be done.* Truth be known I'm not sure I would do even*that but if you would feel better that is going to be a hell of a lot less money.* Now if you want to jump up the amperage on the alts that is a different story.

Your battery charging statement is incorrect.* AGM charge or accept 100% of the charge up to*a point near full charge then the voltage needs to be bumped*up*.2 V or something like that to get over the hump and get to a full charge at which time the charger or alt can go to a float.* A wet cell battery can only accept 50% of a charge rate and then it has the same problem at some point as the*AGM*and the regulator needs to increase the voltage a bit*until it is at full charge at which time it goes to a float as well.* So a 400 amp*bank of*AGMs at half charge, ie*200 amps needs four hours + on a 50 amp alt or*two hours+ on a 100 amp alt or one hour+ on a 200 amp alt or half an hour on a 400 amp alt..... Get the picture.* Wet cells can only by nature of their design accept 50% of that available charge so take the previous numbers and double the time of the charge for each alternator.

Here is a good read site for you.* It is about using batteries at your house to be off the grid but the information on the batteries is still good on a boat or what ever.

http://www.windsun.com/Batteries/Bat...ery%20Voltages

I think once you read this a lot of this will become more clear.
__________________

JD is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Help understanding my batteries 7tiger7 General Discussion 14 03-07-2011 11:47 PM
Understanding Engineers Doc Harbor Chat 0 01-07-2011 08:41 AM
Understanding Diesel Fuel marinetrader Power Systems 5 03-28-2010 05:57 AM




All times are GMT -5. The time now is 01:47 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012