Solar vs Generator/alternator or both?

[mikEXpat]

Thanks always for the great advice. I'm learning so much. Here's one I just can't decide on. I've read so much recently about solar, but with the cost of generators coming down, appliances consuming less energy, and fuel prices down, I'm wondering if a small generator might be enough for me.

My rig (or the one I'm thinking about getting) is a van with either a pop-top or fiberglass hi-top.

The Problem
Let's say I will use, on average, 30Ah in the evening from two 100% charged (12.73V) 6V T-105RE batteries in series. That would bring me down to around 12.3V, right? 225*.30=67.5% I've given myself some leeway in case of rain, laziness, or forgetfulness.

The next morning I will:

A) Use my single 200W-ish monocrystalline panel mounted on the roof (sketchy and too heavy, maybe) to slowly charge the two batteries given there is enough sunlight in the Pacific Northwest during the summer. 

B) I take out my Renogy suitcase 100W (50Wx2) and place it in the sun (hopefully) to charge the batteries even more slowly.

C) I start the van and let the van's alternator charge the house batteries to 90% and then use the suitcase to finish charging.

D) I buy a 2000W inverter generator to charge the batteries to 90% and then use the suitcase to finish charging.

E) I buy a 2000W generator, cheap batteries, keep charging them to 90% and just replace the batteries when they don't give me 30Ah of use a day.

Which one of these options:
1. Will be most affordable considering I might sell or lose the van after only a couple years? Hopefully it won't break down and be too costly to fix.
2. Is the easiest to operate and maintain?
3. Is the most dollar-for-dollar energy efficient?

Buying a generator means I have to buy fuel, store it, and maintain the generator. 
Buying solar means I have to purchase more parts and install everything. A generator can be taken out of the van very easily and used for many other things.
Solar is dependent on the sun. I'll be in California but will be spending most of my time in the trees, hopefully. I'm not a sand guy unless it's too cold. RTR is a given.
The solar panel might be too heavy for a hi-top or pop-top. I think is OK, but two would be stretching it.
I'm not too thrilled about pulling out the suitcase and placing it every morning, but then again what else to have to do with my time?

Thanks for taking the time to read this. 
Mike

 

[minimotos95]

30ah off a t105 is 86% state of charge(roughly).voltage is going to vary but that should be in the 12.5-12.6 range.

My typical discharge on my 105 non RE is 15-25ah overnight if I run my laptop maybe up to 35-40ah. Even with a relatively flat mounted 100w panel the basic renogy pwm charge controller has been just floating by 10am everyday usually earlier. It's my understanding that 100w of panel can't supply the juice Trojan batteries need for the bulk charge when dipping below 80%.
Now that I am in a TC not a non-running van I plan to setup for an alternator charge as a backup(basically option C but I plan to add more solar when funds allow). A generator would be nice but it's yet another thing to maintain, up front cost is high for me.
I definitely can't tell you what's right for you because I'm still figuring it out for myself.

 

[Optimistic Paranoid]

Both the Honda and the Yamaha generators have so-called "charging ports"  for 12 volt batteries.  However, they are all limited to 8 amps, which is way too low for our purposes.  You will be running the generator all day at that rate.

If you decide to go the generator route, you also need to buy a battery charger that can use all the power the generator can put out - something in the 40 to 60 amp range.  And it really needs to be one of those "smart" chargers with bulk, absorption, and float settings along with an equalizing setting if you go for flooded batteries.

Something like one of these:

http://www.sterling-power-usa.com/l...Stage Batttery Charger Comparison Article.pdf

Here's a good, big one:

http://www.amazon.com/Xantrex-804-1...60974040&sr=8-5&keywords=xantrex+truecharge+2

 

[highdesertranger]

I can almost guaranty that after running the generator everyday for a couple of months you are going to wish you had solar. highdesertranger

 

[jimindenver]

The first thing I would do is hook the alternator up. you get a advantage while driving, as a main charger or as a back up.

I would wait to see what the roof can handle but if it's that fragile I would go for a pair of Uni-solar strips like the member with the toaster van. They will produce in the lowest light levels where Monocyrstaline will produce the least.

Portables can be a hassle putting them in and out but at least you don't have to gas them up and listen to them. They just sit in the sun while you are in the shade and tracking doubles to output of a mounted system.

2000w inverter generators can be had for $500 or less. along with a decent charger could do the bulk charging in short order. Only charging to 90% will have your batteries in progressive loss of capacity in two weeks.

 

[ZoNiE]

If you are worried about running too low on SOC at night, Run the laptop on it's own battery, then charge it during the day with the solar/genny/alternator when you are driving, or someplace you can plug it in. I don't know about today's Windoze laptops, but my 5 year old macbook pro can go 5+ hrs on a charge. I assume the newer Windoze machines can too?

Take advantage of that computer's battery, and run it to 5-10% charge before you charge it back up and it will last longer.

 

[Almost There]

Whatever method you choose to keep the batteries charged, choose at least 2 and IMO, aim for all three eventually.

Charging only from your alternator means that you have to keep driving even on days you'd rather be doing something else like fishing or reading or just plain sitting around.

Charging only from solar means that you're dependent on mother nature, who as we all know, is a rather fickle friend.

Charging only from a generator means that you're stuck sitting still while it does it's job. Also, if you're going to get a generator, get a quiet one. A loud one will annoy the **** out of your neighbors even at a 1/4 mile on a good day and more importantly, it will bug the hell out of you because you'll have to be there listening to it all the time it's running.

I realize that having all three does cost money but since the aim is to be independent of grid power, it's well worth it, both from the freedom perspective and also from a financial position. You either buy once or you keep paying the electric company.

 

[B and C]

If I were to start from scratch, I would get a latching solenoid connected first.  They are cheap and relatively easy to connect.

Next I would get a 1000 watt quiet generator and a seperate battery charger (I think these will run a good battery charger and are light - see remarks).

Third - add the solar.  

Remarks - I put 200 watts on the roof and have 200 watts of portable panels.  Best of both worlds.  You will find that setting out the generator every time just like the portable solar will get old pretty quick.  At the RTR I left the portable panels out all the time we were there.  Having the portable generator will allow you to charge even on those overcast days without running the van engine.  

Not keeping the vehicle long term?  The solenoid is cheap enough to just leave it with the van along with the batteries = selling point.  The generator and charger easily transportable = goes with you if you will be using it again.  Solar panels and charger could either be sold with the van or taken with you.  A little more effort to take with you but could also be used as a selling point.  If the buyer does not want it, take it with you.

 

[JT646]

Charging only from a generator means that you're stuck sitting still while it does it's job. Also, if you're going to get a generator, get a quiet one. A loud one will annoy the **** out of your neighbors even at a 1/4 mile on a good day and more importantly, it will bug the hell out of you because you'll have to be there listening to it all the time it's running.

Good Advice!  I believe Bob did away with his---by having a good size "house battery" bank and extra solar.   I don't have solar (yet) but I"m usually moving between camp locations every 2-4 days.  This allows me to charge up the two house batteries  by driving (alternator) alone.  IMHO avoid a generator if at all possible.

 

[SternWake]

Not knowing how much sun any panels are likely to get, makes guessing more inaccurate.


I have no facts to back this up, only suspicion, but I think the trojan re and the non RE are the same exact battery, but for the marketing, price, warranty and the green hue of the sticker slapped on the side.

30Ah overnight usage is also a guess?  Ones electrical consumption can vary fairly widely.  My range is 12 to 65Ah, overall average might fall around 30, but perhaps 30 one week, and 45 another, 20 another.

Definitely plan on alternator recharging, but do not plan on just idling to recharge.  It might not be very effective and might kill the alternator prematurely due to excessive heating.  Too many variables.

The trojans are going to be fairly resistant to abuse.  With only 30Ah use each night, you could go 3 nights without any charging in between.  An well wired alternator could get them to 80% in 90mins  to 2 hours of driving, but that 80% to 100% is going to require close to 4 more hours when batteries are healthy and 5 to 6 hours when not so healthy.

100% is determined by a hydrometer, not when an automatic/ smart charging source drops to float voltage.

If you transfer vehicles, bringing your equipment only makes sense if a buyer absolutely does not want it and you cannot find another buyer.  Next vehicle you might likely want to set up a better system with better components and wiring and wiring terminations anyway. 

If you decide that short battery life is acceptable, it could still take quite some time before capacity declines to the point where it affects your ability to enjoy the life.  Spending many hundreds to prolong the life of 250$ worth of batteries might be considered quite foolish.

Hook up the alternator and some portable solar could see a pair or t-105s through the time you need them to provide.

Never forget the batteries are your employees, not the other way around. 
 You can give them minimum wage until they quit.

 

[Almost There]

I have no facts to back this up, only suspicion, but I think the trojan re and the non RE are the same exact battery, but for the marketing, price, warranty and the green hue of the sticker slapped on the side.

Actually, they aren't the same. The RE's weigh 5 lbs more and are .6" taller than the T105s.

I got them because of the warranty and cycle stats. And by shopping around I got them for $30.00 a piece more than I would have paid for T105s. Well worth it to me!

Oh yea, mine had no green hued sticker either...

 

[debit.servus]

Have as many options as you can afford to buy and maintain, in both money AND time cost.

Also, don't obesess about weight to the point where you're buy one model of batteries because they weigh 5 pounds less and pay $30 more for them. The lighter weight versions cost more than the fuel savings from carrying the lighter weight versions.

 

[GotSmart]

Have as many options as you can afford to buy and maintain, in both money AND time cost.

Also, don't obesess about weight to the point where you're buy one model of batteries because they weigh 5 pounds less and pay $30 more for them. The lighter weight versions cost more than the fuel savings from carrying the lighter weight versions.

Reread what was written.  They are heavier, and have better warranty and statistics.  That is why it was worth the extra $30 each.   

It is a better product for $30 more. (At least on paper)

 

[GotSmart]

I have my batteries hooked to the Alternator, with solar.  I do not pull enough power at this time to warrant the expense of a genny.  Free power either way, as I do not run the van just to charge up the house batteries.

 

[SternWake]

Good to know the trojan RE-s are a different product and not just modern marketing gone awry.
As far as 'free energy', GS, each 25 amps the alternator needs to make consumes about 1HP from the engine, so it does affect fuel economy to some degree when feeding a depleted battery bank.

 

[GotSmart]

Good to know the trojan RE-s are a different product and not just modern marketing gone awry.
As far as 'free energy', GS, each 25 amps the alternator needs to make consumes about 1HP from the engine, so it does affect fuel economy to some degree when feeding a depleted battery bank.

When you are going somewhere, and have a lot of unused HP, it is as close to free as it gets.  Certainly a lot less than investing in a generator and fuel to run it.  I did pay for the panels and wires~~~ and so on...

I do understand that nothing is free with the exception of a politician's promise.  (And we all pay for that!) 

 

[sunday1951]

My power need will really only be to power a Dometic CFX 65DZ refrigerator freezer. I understand the basic idea of adding an alternator isolator to charge the AGM battery that will then power the frig but are you saying a battery charger goes between the alternator and the battery?
Can someone please inform me of all the steps/equipment I need to set up to power the frig. I plan to use a Honda generator to charge the battery when not running the van as I plan to camp in trees. I only have the 1997 Ford E150 so far. I still have to get the other items over the next few months. Any help is greatly appreciated. I have never seen a generator in person...only pictures. When I use the generator to charge the battery to charge the frig is there anything that has to go between the battery and the frig? This is very confusing!

 

[Optimistic Paranoid]

OK, take a deep breath.

First of all - assuming the frig you are talking about is a 12 volt frig - then nothing goes between the battery and the frig.

If it is NOT a 12 volt frig, then you would need a suitably sized inverter between the battery and the frig, to change the 12 volts dc to 120 volts ac.

Second, nothing goes between the vehicle's alternator and the house battery except a relay or some other device to keep the engine battery from also being discharged by the frig when the engine isn't running.

Third, when charging the battery with a generator, you will want to plug a battery charger into the 120 volt ac of the generator and let THAT charge the house battery.  While most of these generators have a so called battery charging port that outputs 12 volts dc, they are restricted to only 8 amps.  This is only a small fraction of the power available.  I believe they do this so that people don't overcharge their batteries and destroy them.

If we are talking a bout a 1,000 watt generator, 8 amps times 12 volts is 96 watts.  You could run the generator all day and possibly not completely recharge a deeply discharged battery at that rate.  Whereas 1,000 watts of ac should easily power a 30 or 40 amp battery charger that will recharge the battery in much less running time.

Hope that makes things clearer.

 

[GotSmart]

OK, take a deep breath.

First of all - assuming the frig you are talking about is a 12 volt frig - then nothing goes between the battery and the frig.

If it is NOT a 12 volt frig, then you would need a suitably sized inverter between the battery and the frig, to change the 12 volts dc to 120 volts ac.

Second, nothing goes between the vehicle's alternator and the house battery except a relay or some other device to keep the engine battery from also being discharged by the frig when the engine isn't running.

Third, when charging the battery with a generator, you will want to plug a battery charger into the 120 volt ac of the generator and let THAT charge the house battery.  While most of these generators have a so called battery charging port that outputs 12 volts dc, they are restricted to only 8 amps.  This is only a small fraction of the power available.  I believe they do this so that people don't overcharge their batteries and destroy them.

If we are talking a bout a 1,000 watt generator, 8 amps times 12 volts is 96 watts.  You could run the generator all day and possibly not completely recharge a deeply discharged battery at that rate.  Whereas 1,000 watts of ac should easily power a 30 or 40 amp battery charger that will recharge the battery in much less running time.

Hope that makes things clearer.

There MUST be a fuse between critical parts for system safety.

 

[29chico]

It is not just that the 8 amp 12v charging feature that most generators have is wildly inefficient, the DC output is  pretty dirty current usually.  Dirty current is not good for long term battery health.  Using a generator with a good quality charger that is sized to take full output of the genny and have a high enough output of amps to quickly bulk charge the battery bank and then hold it at absorption long enough to fully charge it is a much better plan.

I have spoken with a Trojan tech and they usually suggest that their flooded deep cycle batteries have a max charge rate of 13% of the amp hour capacity of the battey bank.  They said that if you really know what you are doing: temp comp, battery bank kept cool & so on a 20% max charge rate is OK.