tiny generator to charge gel batteries

[CosmickGold]

In the far Northwest, clouds can hide the sun for months at a time, so I need an alternative to solar for charging my gel batteries.

Is there something like a tiny gasoline generator (100 watts would do) I can let run just for slow charging?

 

[Wabbit]

I have seen a 500w surge 450w continuous generator, but not smaller. They may exist, just haven't seen 'em.

How are you imagining this working? What size battery bank? How long do you plan on running generator daily? So how much power do you plan on using every day and how long each day do you want generator running? What kind of budget are you looking at spending to have power?

Solar can still charge in cloudy weather, just not as much.

 

[Almost There]

How big are your gel batteries?

The generator needs to be powerful enough to run the battery charger that is sized to 'fit' the batteries you need charging. It is counter-productive to use too small a unit because then you're limited in the size of the charger which means that you end up having to run the generator for umpteen hours to get the job done.

 

[CosmickGold]

To answer your questions:
1)  "How big?"  I have four 12V 63Ah MK Gel batteries. They weigh 50 lb each, totaling 200 pounds.
2)  "How long do you plan on running generator daily?"  Since gel batteries want to charge slowly, I need something that can run several hours a day, very quietly and efficiently.
3)  "What kind of budget are you looking at spending?"  As needed.  I don't think a tiny gen or fuel cell would cost over $300.  And what about the fuel cells that can use gasoline or other fuels to chemically produce electric power? I've not heard more about them in years. (Government cover up?)
4)  "Solar can still charge in cloudy weather, just not as much."  Really?  I have two 100W solar panels. Maybe I should get two more because of clouds and be satisfied with it.  Four panels would be 400W in direct sun, but how much wattage would they give under thick clouds?

 

[Wabbit]

Thick clouds? Prob crap all. If your panels are making a shade pattern, maybe 25-50% depending on how much "shade" is showing. That make sense? Is there alot of wind in the area you're at? Wind generator might help.

 

[Wabbit]

How many amps can you charge that bank at safely? 35a?

 

[jimindenver]

When charging batteries that taper the amps a Sportsman 800 will purr all day on a half gallon of gas. The Ryobi 700 is propane so no gas can and MUCH longer run times.

I use to know of some really small inverter generators, like 350 w. The problem was if you went up in altitude you ended up with the ability to run a light bulb. (not to mention that they did not last)

 

[CosmickGold]

How many amps can you charge that bank at safely? 35a?

I found the spec sheet which says:

Charge Voltage @ 77°F (25°C)
    Cycle 13.8 - 14.6 volts
    Float 13.4 - 13.6 volts

So I guess the current changes along with battery-resistance changes.

 

[highdesertranger]

as far as I know you will need to use a battery charger in between the generator and the batteries. the reason for this is, if the generator has a 12v outlet it is unregulated. you could build one using an automotive alternator but that has it own set of problems, which I won't go into here. highdesertranger

 

[CosmickGold]

Thank you all.

I am now satisfied that getting two more 100w panels -- and accepting slow charging -- is the best answer.
More replies are not needed.

Again, I thank each of you for your suggestions and info.

 

[tx2sturgis]

I use to know of some really small inverter generators, like 350 w. The problem was if you went up in altitude you ended up with the ability to run a light bulb. (not to mention that they did not last)

I saw one of those at Quartzfest a couple of years ago...it was purring like a kitten, powering a communications trailer.

BTW Jim, you might want to check out Quartzfest this winter...I'm guessing you might be able to line up a few jobs over there.

https://quartzfest.org/

https://quartzfest.org/previous-quartzfests

 

[XERTYX]

I know you said you're satisfied and further replies arent necessary but I wanted to point out that will prowse did an experiment in which his data seemed to indicate that polycrystalline panels were more efficient in cloudy conditions than monocrystalline panels. There was controversy over the experiment among members as to how accurate the data was and methods used and so forth. But might be worth considering. Especially if this is a stationary array.

 

[XERTYX]

Sorry I looked up the video. I originally posted them incorrectly.

 

[AuricTech]

Given what you said about cloudy conditions, this might be a situation in which amorphous silicon panels (such as the kits Harbor Freight sells) would be a good fit.

 

[jimindenver]

I know you said you're satisfied and further replies arent necessary but I wanted to point out that will prowse did an experiment in which his data seemed to indicate that polycrystalline panels were more efficient in cloudy conditions than monocrystalline panels. There was controversy over the experiment among members as to how accurate the data was and methods used and so forth. But might be worth considering. Especially if this is a stationary array.

I have been reporting about mono vs poly since 2012 and most of it fell on deft ears but some did listen. Poly's produce more amps to the battery in bright light, lose less power in overcast conditions, they even respond to freezing temps better. Most assume that the advertisement...I mean experts know better but they do not run side by side test either. The issue is that it is getting harder to find poly panels anymore.

Here's a kick in the pants for ya. The Voc of a 12v mono panel is above 22v while a 12v poly is a bit above 21v. The thing is that the mono panel produces less amps because volts times amps equals watts. It seems all equal except in a MPPT controller you have to convert the excess volts to watts and there is a loss there, In a PWM system any voltage above the battery's is shed including that extra volt the mono produces. So even a expensive mono panel like the Renogy eclipse that cost over twice that of a Home Depot poly and all you end up with is fewer amps for the money. Isn't advertising great?

 

[jimindenver]

Given what you said about cloudy conditions, this might be a situation in which amorphous silicon panels (such as the kits Harbor Freight sells) would be a good fit.

I use to think this but in knowing people with roofs covered in Uni-solar panels I was able to do some comparisons. They both reported impressive low light numbers that would beat a like wattage poly panel. The thing is that take a roof full of Uni-solars and replace them with polys and you have so many more watts up there that you still get comparative numbers in low light and much, much more power in bright light. It does not work that way with mono's.

My poly's produce 50% (40 amps) in heavy overcast conditions and up to 25% (20 amps) in the rain. I could never get enough Uni-solars up there to run a air conditioner.

 

[XERTYX]

I didnt know you were a fan of polys Jim. It makes sense to me. More surface area seems to be a no brainer that in cloudy conditions it would put out more. Maybe there is more to it than that but that seems like a logical reason.

In that thread where I first saw the video I believe I said a 30 foot wide 100w panel would do even better in low light than a 3 foot wide 100w panel. It seems logical to me.

I'm planning on buying polys myself. Amazon had some last time I looked for 80-88 bucks for 100 watts.

 

[DLTooley]

Running a small generator in the 1000 watt range in the morning and getting the ‘bulk’ of your charging done would work. The solar panels can then finish off the job at the lower charge rate.

A good charge controller will make this more precise.

 

[vangotransit]

I recovered some eFoy fuel cells from a some CCTV trailers, they do not generate much power, take up a bit of room and the methanol fuel is spendy at times. If it wasn't free I would have done so. They start at 3k new, for 80 watts. I have about 4 145 watt units left over... I currently use two and have a spare

 

[jimindenver]

I didnt know you were a fan of polys Jim. It makes sense to me. More surface area seems to be a no brainer that in cloudy conditions it would put out more. Maybe there is more to it than that but that seems like a logical reason.

In that thread where I first saw the video I believe I said a 30 foot wide 100w panel would do even better in low light than a 3 foot wide 100w panel. It seems logical to me.

I'm planning on buying polys myself. Amazon had some last time I looked for 80-88 bucks for 100 watts.

Anymore there isn't always a difference in footprint. A 250 watt poly uses the same frame as a 250 watt mono panel does. You will see it between 290 watts and 320 watts because the poly jumps up to a 77 inch long frame sooner. I think a comparison of those panels would be interesting.

There are other panels to chose from besides just mono, poly and amorphous. There are multi crystalline, multi layer like the Uni-solar but not amorphous and bi facial. Panels like SunPower are in their own league. The 200 watt 12v panels I use in my van designs are bi-facial. Point the bottom at the sun and you will get 125 watts.