Generator charging advice

[DougFisher]

Heading into my second winter in a location that receives little to no sun for the next couple months. Today my Outback controller tells me only 12 amp hours gained from the sun. I'm off grid and will be relying on a 11kw yamaha diesel generator.

I see alot of very usefull info here on solar controller settings and it has been more than helpfull! Thank you all.

I have been running my generator 4 hours a day to replace my roughly 80 to 100 amp hours daily use. I have 8 rolls 6v batteries in series for a 48v bank. The settings I use for generator charging: Absorb = 60v, Float = 54v as per the manufacturer and absorb time 4 hours max.

I've been using a temp correct refractometer to keep my sg in check.

I'm trying to find a better balance between diesel useage and battery longevity. If I only charge to 90% in 2 hours my diesel useage goes way down, but my batteries will sulfate. If I go the full 4 hours on the generator my batteries charge nicely, but I use twice the fuel, it stinks, and is noisy more than I'm comfortable with. The generator is a constant 3500 rpm (I think) with no eco throttle or any way to produce less than 11,000 watts even during the final 10% charging stage. Maybe charging to 90% 6 days a week and up to 100% once a week would be the solution?

Any advice on how to set this up as efficiently as possible would be greatly appreciated! Thanks

[Bala]

Dont float charge on generator just stay with the highest charge rate you can, basically as per the "Max Smoke" method Sunking has posted.

there is a balance between the cost of diesel, the cost of replacing batteries and also a convenience factor of the process of actually getting and fitting new batteries depending on where you live.

Sadly your generator is far from ideal as most generators that size would be revving at half the speed yours is. I have a Lister twin about that size and it revs at half the speed of yours.

For noise i built it a room and silenced it. I can still hear it running but its not annoying.

For exhaust fumes I have put about 10 meters of 100mm steel pipe then another 30meters of 100mm pvc pipe to get the exhaust a lot further away. Rarely get fumes in the house now.

[DougFisher]

Thanks Bala!

I will look for the max smoke method by Sunking. I may have already seen it.. Bulk=Absorb=Float right? I thought maybe that was only for solar? I guess it would be the same so long as I keep an eye on the sg.

The charger never makes it into float. I shut the generator off well before the Absorb timer gets to 4 hours. Totally makes sense to get rid of float I'll do that.

I double checked the generator specs and it's 3600 rpm not 3500 like I said before. I calculated the costs is about $20 for about 14 liters for 4 hours diesel per day to run this noisy thing. I like your idea of the extension exhaust and sound proof room!

I'm thinking a wind generator or thermoelectric wood stove generator. Anyone have any other outside the box electricity generators?? There are no streams here... There is a 15 foot tide change though.. maybe micro hydro from rain tanks!

I could move my pannels into the sun but its 100 yards away or 100 feet up all our house plants are dead from lack of light. Is it even possible with cable run lengths of 100 yards or a 100 foot pole on the roof!

[DougFisher]

I have another question about SG but I'll start another thread for that. Cheers

[Mike90250]

Question & suggestions

? What is ah rating of your bank __________
? How do you get from 120/240VAC of generator, to battery charging ?

I suspect your generator is WAY oversized. I have 48V 800ah bank and a 6hp, 650rpm Lister diesel, charge about 2400w into the batteries via my inverter with a .95PF charger.
I burn a quart an hour and seldom run more than 2 hours a day charging.
Can you consider a new generator in the 3-5 kw class ? Doesn't need to be an inverter generator, which are really expensive, but save a lot of fuel below 3/4 load
I think you can charge up to 90% daily, and just hit 100% 2x a week.
Run the genset in the AM, time the termination for about 11am or whatever is a good average time to let the brightest part of the day contribute useful work
Keep a log, it gives you something to track the batteries with, and after a month, you will really know what's going on with your system

dailyLog_01.jpg

[DougFisher]

Here are the charger specs from my Magnum MS4448 PAE inverter. This is what I charge my 8 x 420 amp hour battery bank with Rolls S-550's. When bulk charging at 60vdc i see about 40amps. I was thinking a smaller generator would be better as well. I didn't pick the generator. Someone else before me decided an oversized generator would be more robust and less maintenance. This house has been through 3 or 4 generators, they get used!

CHARGER SPECIFICATIONS
Continuous output at 25° 60 ADC
Charger efficiency 85%
Power factor > .95 >
Input current at rated output (AC amps) 17.5 AAC per leg at 120/240 VAC split phase

[Bala]

As Mike posted long term you will be better off looking for a better sized slower RPM generator.

It would also be worth running your panel specs through a cable size calculator to see if it cost effective to get you panels in the Sun.

Wind hydro etc can be investigated but form what you have said I dont think they will be an option for you.

[DougFisher]

Thanks Bala. It's good to here that all confirmed. This is what I suspected about the generator size.