Solar + Gas Generator Charging?

billiebob

Well-known member
watts is watts, voltage is voltage and amps is amps, it's all simple math.
no, watts is voltage x amps.... watts do not exist without volume and flow....

But quite right, I have no idea how long a 100amp Renogy battery might last as I boil a litre of water..... I might need a second battery.... I'm just saying I'm feeling confident it'll work for me.

I overland alone. I NEED a coffee in the morning so I NEED to grind some beans, boil some water and french press 16 ounces every morning. Plus I might want an egger on an induction hot plate. I think a 2000Watt Inverter is overkill but the 3000Watt version is $20 more..... same as my choice to buy 160Watts of solar or 320Watts of solar.... $200 vs $240.... simple math.
 
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Peter_n_Margaret

Adventurer
But quite right, I have no idea how long a 100amp Renogy battery might last as I boil a litre of water..... I might need a second battery.... I'm just saying I'm feeling confident it'll work for me.
It is not the storage capacity of of the battery that will be the limiting factor, it is its ability to deliver the power without excessive voltage drop. Voltage drop in lead acid batteries is a limitation of the chemical reaction producing the electricity to keep up with the demand.
In this regard, lithium will perform better as the voltage drop will be lower.

EDIT: Deep cycle LA batteries are characterised by fewer, thicker plates that make them more robust. Cranking batteries have more, thinner plates that allow them to create electricity faster and with less voltage drop, but they won't last as long.
Cheers,
Peter
OKA196 motorhome
 
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billiebob

Well-known member
It is not the storage capacity of of the battery that will be the limiting factor, it is its ability to deliver the power without excessive voltage drop. Voltage drop in lead acid batteries is a limitation of the chemical reaction producing the electricity to keep up with the demand.
In this regard, lithium will perform better as the voltage drop will be lower.
Cheers,
Peter
OKA196 motorhome
thank you..... this is the advise I need...

OIP.qGe46xZiEjv0rPnF1l964AHaDt.jpeg

this drinking thing often leads to a reprimand from the mods but cheers
 

Peter_n_Margaret

Adventurer
Just boiled our kettle for you via the 12V to 240V inverter.
900ml of water from about 15C to boiling took 5 minutes and 20 seconds.
The name plate of the kettle says it is 1,100W.
It was drawing about 104A from the batteries at about 12.3V. That is about 1,280W which is about right allowing for the inverter losses (amps climbs slowly as the voltage drops slowly so the actual power draw stays about the same).
1280W for 5.3minutes is about 113Whrs or about 9 Ahrs out of the 400Ahs of battery.
Cheers,
Peter
OKA196 motorhome
 

Oscar Mike Gulf Yankee

Well-known member
Peter Paul and Margaret are absolutely correct.
@billebob, you can't just drink your way through this and come out with it working like you want.

When you're sober, study the link I gave you. Then add up the wattage requirement of the things you want to run.

When you have that total, I suggest you multiply that by 3 for the total watt hours you need.

It's great if your storage batteries are twice or more than your estimate, but it doesn't need to be, because you can make up for some or dang near all your requirements from the panels. It's a balance you need to find between storage and production of power, if you're in sunny territory more panels than battery might do, if you're in poor weather areas then you'll need to rely on more storage. Regardless, for any good mobile system, you should also use a generator or genset, because there will be times that neither storage nor production will perform 100% of the time. That, or plan on having powerless periods.

And, seriously, you'll be dollars ahead by getting a larg(er) solar generator set up than trying to buy pieces at a time and building a system. OK, if money up front is an issue, buy smaller generators instead of batteries, smaller units can work in a series to build up a more powerful system.

I'd also suggest you pay attention to charging cycles, this indicates the life of the battery or generator, actually that can be more important than the wattage size, seldom do you ever need all the power available but how often you can charge up to provide power becomes more useful. Also, in the same dollar park or nearly the same price, I'd always go with more charging cycles than total watts, example; 1200 watts at 2000 cycles vs. 1500 watts at 900 cycles, the best bang for the buck is the first mentioned at 2000 cyces.

And, selecting panels; mount your panels on your vehicle or camper if you are ok parking in the sun. In the summer, I'd rather park in the shade, save 1500 BTU and put the panels in the sun, which requires portable panels (which cost more) uness you like moving several 30 pound hard panels around by hand and storing them on the move. Give that some thought and you'll probably be glad to pay 50% more per watt.

Work it out, good luck!
 

billiebob

Well-known member
Just boiled our kettle for you via the 12V to 240V inverter.
900ml of water from about 15C to boiling took 5 minutes and 20 seconds.
The name plate of the kettle says it is 1,100W.
It was drawing about 104A from the batteries at about 12.3V. That is about 1,280W which is about right allowing for the inverter losses (amps climbs slowly as the voltage drops slowly so the actual power draw stays about the same).
1280W for 5.3minutes is about 113Whrs or about 9 Ahrs out of the 400Ahs of battery.
Cheers,
Peter
OKA196 motorhome
this is gospel stuff.... I go to any solar store they cannot answer this question.... you guys are gods
 

billiebob

Well-known member
Peter Paul and Margaret are absolutely correct.
@billebob, you can't just drink your way through this and come out with it working like you want.

When you're sober, study the link I gave you. Then add up the wattage requirement of the things you want to run.

When you have that total, I suggest you multiply that by 3 for the total watt hours you need.

It's great if your storage batteries are twice or more than your estimate, but it doesn't need to be, because you can make up for some or dang near all your requirements from the panels. It's a balance you need to find between storage and production of power, if you're in sunny territory more panels than battery might do, if you're in poor weather areas then you'll need to rely on more storage. Regardless, for any good mobile system, you should also use a generator or genset, because there will be times that neither storage nor production will perform 100% of the time. That, or plan on having powerless periods.

And, seriously, you'll be dollars ahead by getting a larg(er) solar generator set up than trying to buy pieces at a time and building a system. OK, if money up front is an issue, buy smaller generators instead of batteries, smaller units can work in a series to build up a more powerful system.

I'd also suggest you pay attention to charging cycles, this indicates the life of the battery or generator, actually that can be more important than the wattage size, seldom do you ever need all the power available but how often you can charge up to provide power becomes more useful. Also, in the same dollar park or nearly the same price, I'd always go with more charging cycles than total watts, example; 1200 watts at 2000 cycles vs. 1500 watts at 900 cycles, the best bang for the buck is the first mentioned at 2000 cyces.

And, selecting panels; mount your panels on your vehicle or camper if you are ok parking in the sun. In the summer, I'd rather park in the shade, save 1500 BTU and put the panels in the sun, which requires portable panels (which cost more) uness you like moving several 30 pound hard panels around by hand and storing them on the move. Give that some thought and you'll probably be glad to pay 50% more per watt.

Work it out, good luck!
you are an abrasive idiot.... sorry I inspire your worst but you need some manners
 

Oscar Mike Gulf Yankee

Well-known member
you are an abrasive idiot.... sorry I inspire your worst but you need some manners
I can agree with abrasive with a sense of obtuse humor, idiot implies stupidity which clearly doesn't apply, perhaps don't give a ******* is more appropriate. After all, you're the one who said I was behind on the bar tab. :rolleyes: :cautious::unsure:o_O:ROFLMAO:
 

billiebob

Well-known member
you'll be dollars ahead by getting a larg(er) solar generator set up than trying to buy pieces at a time and building a system. OK, if money up front is an issue, buy smaller generators instead of batteries, smaller units can work in a series to build up a more powerful system
yep, initially I was looking at 160W with controller but 2 panels, 320W with controller was $40 more. Glad I went that route. It exceeds my expectaions and I will build within the limitations...... Right now I'm pretty content but I am focused on pure electric, no propane period. This will be next springs project. My goal today is mostly boiling a litre of water. The cooking thing might be a pipe dream. But this still works.

DSCN2249.jpg
 

Peter_n_Margaret

Adventurer
Adding panels to an existing solar system is easily done.
There is no problem adding an extra solar controller with the extra panels if the existing one's capacity is reached. They will play happily together. In fact it is a good idea because it provides some redundancy compared with a single large capacity controller.
Just choose good quality MPPT controllers that are fully programmable for the charge parameters in order to treat the batteries as the battery manufacturer intended.
Cheers,
Peter
OKA196 motorhome
 
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67cj5

Man On a Mission
It's all very well blast charging these units in under and hour but that is going to cost you in terms of cycle life, dispite what the companies say in their advertising blurb does not alter the fact that these batteries don't like being hammered.
 

LR Max

Local Oaf
I am going to assume your on board auxiliary electrical system is 12V DC.

Many small generators have a designated 12v DC port. Last I saw the output of these ports could be anywhere between 5-8 amps. Like the Predator 2000 has a 12v 8am socket right there on the front. This would probably be the easiest, cheapest, and less complicated connection to make. Also you could just see how small of a generator you could get away with as you won't really be using the 120v portion of the generator.

I checked and I didn't see a 12V outlet on the modern Hondas, but I vividly remember charging the battery in a rock crawler once with two janky wires out of a 12V outlet on a generator (I forgot what brand the generator was). So it has been done and I have done it with less than ideal setup. I would think with the proper ports and non-exposed wires it would work like a treat.

The other bright side of having a small generator is while its charging your on board electrical system, you could also use the 120v portion to charge a Jackery, camera batteries, laptop batteries, etc.

In reality, the best/easiest solution is to just turn on the engine to your truck. Turn off all electrical...everything inside (no radio, no lights, no AC/heat, etc) and let the engine run at like, 2000rpm or so. That'll provide ~100 amps (if a modern truck) of 12V DC REAL quick. You could run your truck like this for ~20 minutes and your batteries would be at a good charge. Couple this with your solar panels keeping the batteries topped off, you should be good to go. Also with this system you aren't having to carry a generator (something else), a gas can for it (something else), a bunch of extra cables/cords to use it (something else).

2 years ago some guys drove an old 4x4 cross country. They had a Dometic fridge with the Dometic fridge battery. Every 2 days or so they'd stop and use one of those cheapo Harbor freight Sportsmans Gen1000 to recharge the battery (had a wall charger with it). They said it worked really well for that.
 

Peter_n_Margaret

Adventurer
t's all very well blast charging these units in under and hour but that is going to cost you in terms of cycle life,
Not at all.
Irrespective of the capacity of the charge source, the actual charge rate is determined by the voltage offered and the battery internal resistance. If the voltage is appropriate, no excess charge rate will occur.
Take for an example the crank battery. It can be offered 200A from some alternators, but it only accepts a fraction of that due to the relatively low voltage offered.
Many small generators have a designated 12v DC port. Last I saw the output of these ports could be anywhere between 5-8 amps.
Yep. A total waste to run a generator to get 5A of charge. If you MUST run a generator, power a separate battery charger with it that has some decent capacity. But the alternator and solar makes more sense.
Cheers,
Peter
OKA196 motorhome
 

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