Genset / Alternator / Inverter / Charger Questions

[bobox]

Hello,
Just purchased a boat and am just getting my head around the power/charging requirements.
The boat is pretty power intensive and I figure I'm using close to 150AH per day. Mainly the fridge which seems to
be running almost continuously @ 5A (thats another issue again).
There's a 8kva onan which generates 110v and also runs a protech battery charger which outputs 40amp max. To recharge the batteries for a day off the genset takes about 3 to 4 hours.
I figure given diesels need to be loaded up this is bad because its only using maybe 10% of the gensets capacity (I do try and run the watermaker to make use of the load)
I've attached a diagram which the previous owner had done to show the setup.
There are 2 225AH house batteries and 1 225AH starter battery (all gel). There is also a separate starter battery for the genset.
I'm thinking of a few options to improve the situation and am ofcourse looking for the biggest bang for the buck.
I'm looking at getting solar cells which hopefully take some load off the system (400W) and fixing the fridge problem.
With improving the efficency of charging off the genset I could think of only a couple of options on my own.
Option 1 - mount a high capacity 12v alternator on the Onan genset. I've got a 100a balmar. It looks big. Is there any mechanical reason not to mount a big alternator on a genset?
Option 2 - inverter/charger. run off genset to produce 12v charging current (> than 40A I'm getting off the Protech). Not sure what the output of these charges are and whether they can deal with gel batteries. The added advantage is that I could run 110v appliances without running the genset. Something like this

Any advice is appreciated.
Cheers
Robert

[skipmac]

I think large alternators are not recommended for gensets for several reasons. Maybe a mechanical pro will confirm but I think the genset may not handle the side loading of a large alternator and when the full output is needed the alternator could load down the motor.

In any case I would get a much larger battery charger. At least double what you have now.

[Chief Engineer]

Mounting a big altenator on a little genset is a bad idea....people do not realize the power it takes to run one.....

I am absolutely astounded at some of the ****-engineering that some people try.

100 amp alternator on a 1 cylinder yanmar.

Two alternators on a two cylinder.

and the people wonder why the boat can't get out of its own way.

[btrayfors]

The wiring diagram appears to differ markedly from your description. Perhaps changes have been made since the diagram was created.

It's a very good idea to get a larger charger. For a total of 450AH gelled house battery bank, a charger with a 75-100A capacity would be appropriate.

What size is the alternator on the engine? If it's the typical 40-55A model, you might substitute the 100A Balmar, with a smart external regulator like the MC-612 MaxCharge.

Solar panels are a good idea for many cruising boats.

The diagram shows a wind generator. Do you have a working one?

Bill

[matauwhi]

G'day, Bobox, I have been living aboard for 12 years with an 8kw genset. We typically use around 175 AHRs a day, and yes, our fridge/freezer is the big load at around 140 AHRs. We have 3, 260 AHR Lifeline AGM's for our house bank. I eliminated that genset starting battery and just use the house bank to start the genset.

I would just keep the 100 amp Balmar, this is what we have on the genset. My advice would be to purchase at least a 2500 watt inverter/charger, like a Xantrex. The charger is capable of putting out 130 AHRs initially. Keep your 40 amp charger, as a spare, electronics do tend to fail over time.

I normally run the genset one day for around 2.5 hours running the fridge/freezer, charging the batteries and 30 gallons of water with the watermaker. The next day, I run our fridge off the batteries and do not have to run the genset. You should connect your hot water cylinder to the genset coolant if it has a internal coil in it. We also have a LPG hot water heater to take a hot shower with on the day we don't use the genset.

Upgrade your cabin lights that you are routinely using (like for reading) with LED's and yes, a couple of solar panels, help to keep the batteries up. I have a couple square, 40 watt panels, that fit nicely inside a large forward hatch. We just keep them on the deck when we are at anchor and the sun is shinning and can quickly secure them when we go sailing.

Our AGM's are 12 years old and still going strong. If we have to replace them, we will go with AGM's again. Hope that helps. Cheers, Matauwhi

[s/y spindrift]

I suggest these option based on my own refit experience;
1. A significantly larger capacity charger. Ask your electrician for advice but I would suggest not less than 100 amp. Ask your electrician about the option of a combi charger invertor such as manufactured by Mastervolt.
2. Fit two alternators to your engine which would be likely to give you in excess of 200 amp charging. I think you will probably need a smart regulator.Again ask your electrician.
3. LED lights for navigation, mast head and saloon are now good quality and huge power savers.
4. 5 amp hours does not sound to bad for a fridge.

[bobox]

Thanks for all of the responses.
I think a 100A+ charger running off the genset is the way (budget permitting) to go given the mechanical uncertainties of sticking a big alternator on a genset.
Only started living off the hook last week so am learning as I'm going. The learning started with the main motor alternator not working on the motor up here. After a days investigation I worked out it must have been wired incorrectly. The power to the Balmar 612 regulator was coming off the alternator itself rather than a 12v power source (I gather it needs power for the logic circuit). Changed it and it started to work however the 130A alternator only produces 60A according to the BEP meter. Also the west marine isolator, which is rated to only 70A, gets burning hot (probably a fire hazard).
I'm conscience that running the main motor under very little load at anchor is probably not good so thought I'd run the genset. 4 hours to claw back the previous days usage seemed a bit excessive hence the original post.
I dont trust the BEP meter, either its not setup right or I dont understand it. Currenly its reading 12.9v on both starter and house batteries and shows 30% capacity remaining. Its not registering the wind generator which has been going strong all day and has shown some odd readings over the past few days.

Other comments
Matauwhi
- I've been looking at a couple of Xantrex chargers on Ebay.I'm in Aus and they're in the US so the postage will be steep.
- I think the extra starter battery for the genset is overkill but then it must have been done for a reason. One 225Ah gel is used for the main starter battery.
- the hot water is 110v electric but I did notice an unused inlet which could be for engine coolant heat exchange. Will have to find the manual
- I've switched bulbs for warm LEDs. They use about 1/5th of the current but are a little less bright.
- Solar panels seem to be a good investment. I think I can fit at least 400w.

Bill
- I'm creating my own wiring map as I dont trust the diagram after running into a few anomolies eg the regulator had no power. I think it had the 512 balmar previously which only had one power input for sensing rather than the 612 which needs an additional 12v power source.
- the engine has a 130A Balmar. I also have a spare 100A balmar with the old 512 regulator which I was thinking of sticking on the Genset.
-I only got the wind generator working yesterday. The blades were damaged so I re-glassed and balanced them (which was a real pain). I also moved the power output from the isolator (where the previous owner had wired it) and wired it directly to the house battery as per the Airbreeze instruction manual. Not sure if the onboard regulator would work otherwise.

Spindrift
- 100A+ seems to be the go. Apparently the GELs will accept 30% of there capacity.
- Even though I already have a 130A alternator only 60A is being produced according to the meter. Dont know whats going on here. Increasing the rpm didnt work. I have a spare 100A balmar and reg which I guess could be fitted to the motor.
- Got the LEDs everywhere now although I noticed the 36led strip lights were drawing 1.3A which seemed excessive. Also noticed that the LPG solenoid was drawing 1.2A and running hot.
- Today I spent 30min monitoring the fridge.Its now running for 10 minutes every 10 minutes at about 5A so 50% duty cycle. yesterday, unless I'm paranoid it seemed to be running continuously.

Thanks for all the responses to my first question on this forum.
Cheers
Robert

[Pete7]

What size engine are you starting with a 225 amp starter battery? I suspect you could start a small aircraft carrier with that. Why not put that into the house bank and install a smaller battery for the engine and genny?

Pete

[Conch Cruzer]

Here's another idea that you might try.

On my IP40, I had a factory 40 amp charger that I could power from my little genset. Rather than toss it (and my nice sine wave inverter) to get a bigger inverter/charger unit, I just added a second 40 amp charger in parallel. That way, it was cheaper AND if one of the chargers failed, I still had one to use. I saw lots of Xantrex combo units being sent back for repair. When that happens, you have no charger and no inverter.

In your case, Mastervolt and others make some 60 or 80 amp chargers that you could add as a parallel unit to run off of the genset. Keep in mind that charging amperage drops off very quickly after the first few minutes.

[bobox]

Hello Pete, the guy who surveyed the boat made the same comment. The main motor is a Westerbeke 80hp. There already is a separate starter battery for the genset so it wouldnt be too difficult to change. Its says Odyssey PC1500 on it and looks pretty hefty. According to the circuit diagram it charges off the genset battery charger rather than the main engine alternator however there is a switch to start the genset off the house battery instead. Note that the battery selector on the main switch board is set to both (starter/house) so I gather stuff effectively runs off both at the moment.
Could I:
1- put the starter 225AH gel in parrallel to the 2 x 225AH house batteries
2 -connect the main engine starter to the same battery switch the genset is connected to
3 - remove the battery isolator as now there is only one bank.
This would simplify the diagram a bit and do away with the dodgy isolator.
Cheers
Robert

[bobox]

Hello Conch Cruzer,
The parrallel chargers is a good idea. I was thinking about it but thought that the chargers may somehow interfere with each other. I read somewhere for example that you had to turn off the wind generator when running the main engine alternator because the regulator would sense the higher voltage from the wind generator and assume the batteries were in a higher state of charge than they actually were. I thought this principle might apply to other charging devices which are sensing battery voltage to determine there output.
Cheers
Robert

[Pete7]

Robert, thats exactly what I would do. We have a Redflash 1000 (similar technology to the Odyessey) to start our cantankerous old Volvo 2003, and your PC1500 is nearly 3 times the size. Providing there is form of emergency start from the house bank incase it all goes pear shaped you will be fine.

With the other changes that gives you a great big house bank to run an inverter for short mains power requirements rather than starting the genny.

Pete

[Conch Cruzer]

The parallel chargers will work fine. If you have a big bank (over 500 amp-hours) that is at, say, 60% of full charge, a 40 amp charger won't take it up to bulk charging voltage. Paralleling a second charger will raise the intial charging voltage. As the bank gets charged, the two chargers will drop to about 50% of their capacity and on down until they go to "float" voltage. Note that I had two 40 amp chargers and both were three stage chargers (bulk/absorb/float) with wet/gel/agm settings.

[bobox]

After looking whats around for chargers the Iota 90A model looks like the winner. More amps for the dollar than the Xantrex models. An inverter model would have been good but the shipping to Aus was going to be close to $300 given the extra weight.

IOTA 12 VOLT 90 AMP BATTERY CHARGER POWER SUPPLY NEW - eBay (item 320545141581 end time Jul-07-10 18:54:13 PDT)

With the Protech 40A I already have that will give 130A max less what I'm using at the time.

Working out whats involved with combining the 225AH starter battery gel with the 2 house 225s at the moment. It simplifies things alot as 2 battery switches are eliminated and the battery isolator can probably go.
Cheers
Robert

[rourkeh]

I am also in the process of redoing my electrical system and have been buying everything from a new panel to a generator. Due to the large outlay of $$ I have been scouring every available source for the best prices and have found that items on ebay have been among the highest priced available every single time. So IMHO spend a little more time looking and unless you find an item used on ebay in a distress sale you will save lots of money shopping elsewhere. Retailers are in really bad shape due to the current economic meltdown and competition is fierce. Goood luck