Electrical question

[Kevin]

Doing 12 volt and 120. 120 is with a Gen.. Planned to charge the batteries for the 12v system when I run the Gen.
Problem is Battery chargers don't work real well with Gen. power. The only thing I can think of is a power conditioner.
Anyone have any other ideas?
Kevin

[NM_Shooter]

What is the size of your battery array?  Do you know what your peak charging current will be?

I very much like my sunsaver battery charger / conditioner that I have on my camper.  It is only a 6 amp version, as my solar panel is only 53W.  If you get a good charger it will prolong the life of your batteries and keep their capacity high. 

Take a look at this: 

http://www.altersystems.com/catalog/sunsaver-duo-25-amp-two-battery-charge-controller-with-remote-meter-12v-p-1525.html

There must be an A/C input charger similar to this.  If not, get a 120AC to 12V step down transformer, follow it with an appropriately sized bridge rectifier, and plug the outputs from the bridge into the conditioner inputs. 

[MountainDon]

Depends on the generator to some extent. Do you have a generator yet? If not consider getting one of the Inverter type. I use a Yamaha 2800i with an Iota 55 amp charger for my RV battery bank. I also have a small pair of solar panels (2x15 watts) with a simple regulator. Together they work well.

The generator is used to build a good charge in the batteries. The solar keeps the batteries up when things are left unattended for extended periods. They are not large enough to recharge the discharged batteries. No  grid power on site at all.

If you only use a generator to charge the batteries the batteries will suffer if left for periods of time. When the batteries are new they'll keep for a month, two or three, without use. But as they age, or as you abuse them by discharging too deeply, not recharging fully, etc. they will suffer. Then they'll be self discharging more, etc. Been there, done that.

So my questions are (and include Frank's)...
*Size of battery bank; # batteries, volts, capacity?
*Do have the gen already?
*Do you have the charger, how much output?
*Is it a good one that won't overcook the batteries?
*How long will the batteries sit between charges, not being used? Batteries really don't lie that.

I've been doing this for over a year and I can't wait until the cabin is built and I get a proper array of solar panels, etc. so I don't have to worry about keeping the battery charge up. I'm also buying a new set of batteries as the older ones have been abused too much to be good for much. The gen will only be needed for an equalization charge every so often. It will cost, but still only about 12-15% of the cost of getting utility power brought in.

[Kevin]

Batteries are 2 six volt to make 12. 230amps.
My gen is a colemand powermate 6250. fors great. I was
thinking of the Iota. not worried about the the batteries
being left for periods of time.

Also what about trying to run other electronic devices
with the gen. at 120 volts. Ant thoughts?
Kevin

[MountainDon]

Iota has very good customer service in my experience. They answered any questions I had via email. Check their website and ask them about using their charger off a generator feed.

Also what about trying to run other electronic devices
with the gen. at 120 volts. Any thoughts?

Like a microwave?    We've been doing that for years in the RV. Not a problem. Except for the noise and smell (depending on the wind direction). If the gen has a remote electric start, good; if not, add going outside to start and stop it to the downside. Add the increasing cost of fuel to the downside.

In our case the original genset was too noisy to be enjoyable, but it was convenient with remote starting. The Yamaha is much quieter and is also 12-15 feet from the RV, but it doesn't have remote starting. Trade off for the quieter operation. I didn't want to spend what was required for a quiet on board RV genset.

I also run power tools, table saw, portable saws, etc. off the generator. No problems. FYI, the inverter generators throttle down when drawing small loads, throttle up when a larger load is applied.

But things like the TV, stereo, radio, etc. we run off an inverter powered by the batteries. To do any amount of that though you need more than 12 VDC, 230 amp-hours of battery storage, IMO. Don't forget batteries react poorly to being discharged over 50% too much.

In the RV we use 12 VDC FL lights. In the cabin I plan on using CFL's on 120 VAC from the inverter, except for two 12 VDC lights, just in case the inverter acts up. Microwave will run off the (bigger) inverter as well.

Over winter the battery bank can sit there with the solar panels keeping the charge up and the batteries in good condition. I have a neighbor up there who going into his 5^th year like that on the same set of eight 6 volt golf cart batteries.

[NM_Shooter]

If you plan on not using your batteries for a period of time, make sure that you check the fluid level before leaving, and put even a small solar panel on with a charge controller to manage the batteries.  A good controller will be able to fairly rapidly charge the batteries up to full charge, then float charge them to keep them healthy.  You don't need a big panel to keep a float charge on your batteries, even 5W would be fine.

Added benefits of a good charge controller:

1)  New technology used pulse width modulation and voltage transformation.  This means that even when there is very little sun, the controller optimizes the amount of energy available to be able to produce some charge to the battery.

2)  You won't over cook your battery and damage it.

Try not to use your batteries to power 120VAC requirements.  It is inefficient to do this and places a huge strain on the batteries.  Try and get 12V appliances instead (TV, lights, radio, whatever), and use your genset to directly power any 120VAC stuff.  Here's why...

Power is measured in Watts.  Watts are equal to voltage times current (different ways of measuring AC power, but let's not worry about that for this exercise).

If you need 1000W of 120VAC, that is roughly 8.3 Amps (which is a bunch of power).  Using an inverter, that translates into a 1000W battery load of ~83 Amps!  In addition to this, your inverter has losses associated with running the inverter.  I would estimate that an inverter is roughly 85% efficient, and you lose most of that power even at low inverter loads. 

I run two golf cart batteries in series, and even with a family that squanders electricity we have all that we need to run our trailer without loss over a 24 hour period using a Sunsaver6 and a 53W solar panel.  This is probably 6 hours of lights, some water pump, and maybe two cumulative hours of heater blower in a 24 hour period. 

Also.... charging batteries off of a genset is not a great way to keep them conditioned.  That is a great way to get a rapid charge, but due to the high charge current, the batteries tend to heat up and you don't acheive a full charge that way.    Keep in mind that these are not car batteries, but deep cycle batteries, and the charge / discharge characteristics are different.  Deep cycle batteries don't like to charge or discharge fast.

Get good batteries (Sam's club golf cart batts are fine), a good charge controller (not just a standard auto charger), and even a small solar panel.  My last set of batteries were fine when I sold my camper, and they had 7 seasons of use on them.

BTW... keep your batteries in a vented enclosure.

[MountainDon]

One thing I may have lost sight of with my comments is the frequency of use of the property/cabin in question.

We don't work June through early to mid August. We will be using our cabin, once built, probably at least 70% of that time. Also starting this August we'll have three day weekends through to the end of May the next year and then the cycle repeats. We intend to be up there in the mountains as much as possible, especially in the hot desert summer months.

Frank made a point

Try not to use your batteries to power 120VAC requirements

that is quite valid, with some exceptions, IMO.

We don't want to be on the power grid. Actually we don't want to spend the $55K they want for hookup.    So IMO, our type of use warrants installation of a reasonably large (for a small cabin) solar PV panel array (500 watts or so) along with a battery bank configured for 24 VDC with 660 to 880 amp-hours capacity. Such a system has no problem running a powerful inverter, one that can power a standard microwave and other appliances. With one of the highest solar insolation ratings in the country, we have lots of potential for PV power.

It would make no sense at all, it would be very inefficient, to run a fossil fuel generator to charge storage batteries, and then use a large inverter to run the microwave. However, when use warrants investment in sufficient solar equipment the story changes. The Outback Inverter I plan on using is rated at 92% efficiency in the 24 VDC model.

If we were only using the cabin on weekends, and maybe not even every weekend like a lot of folks with recreational property, we're looking at a whole different situation. I apologize if I went off on my own thought track and confused the issue. In that case I'd likely be using the generator a lot more, have fewer batteries and a smaller PV array.

No matter how small a set of batteries you have though, a small solar PV panel with a charge controller will extend your battery life.

[glenn kangiser]

I didn't want to hassle with any 12v so  made mine into my own power company--

24 v inverters  2 4024 Trace inverters stacked to make 240v.  There is a bit of inefficiency but I just added enough panels to overcome it.  We have a bit over 2000w panels and a 1000 watt wind generator.  We have 12 L16 batteries giving us a total of 1125 AH at 24v-- about half safely usable -- oldest batteries are around 4 years I think and doing well.

We pump about 600 gallons of water per day in the summer with a standard 240v pump.  We have 2 freezers 28 cu ft total and a refrigerator, washer and dryer besides standard house needs and 2 computers and wireless - and a printer and occasionally run a welder or shop tools.

Our power is usually always working even when the county is down.

[tc-vt]

Kevin

The following mentions the distorted waveforms of small generators, especially under light load:

http://www.rpc.com.au/pdf/BCH-WoodsTechnical.pdf

Is your generator the Powermate (PM0675700) with the Yamaha engine that Home Depot was selling for $400?  I picked one up and charge my batteries at 80a and 12v through my Prosine.

You should charge at 5 to 10 percent of the amp-hour capacity of your battery, so your generator would be running under a very light load as mentioned in the article above.  They say the wave form is cleaner if you load the generator with a light bulb or similar.

Next time I have the generator running, I'll check the distortion with my clamp meter.  If I am understanding it correctly the distortion I just measured from the inverter on a 1000w load is around 1 percent.


Tom

[Kevin]

Thanks Tom,
Thats a good website.
Kevin