A real solar generator

[29chico]

How does a 945w solar array feeding a 102 amp hour group 31 Northstar AGM battery sound?  Works great for me.   The battery is bulk charged fast on cloudy mornings.  On sunny mornings if you are not watching closely you will miss the bulk charge.

The only things being powered overnight besides my two Engel fridges is a small amount of LED lighting use and sometimes a bit of car audio in my cargo trailer. 

I just don't get the folks who say a 100w panel for a 100amp hour battery.  A few cloudy days and the battery is damaged unless the user is really on top of minimizing the load.

 

[John61CT]

You have **tons** of free excess power available there.

Once batt is 90% full, start making ice or heating water or something.

What do you drive has that much room on top?

 

[willprowse]

Holy cow. Yeah tons of potential power. Would be great if you could put it to work.

And yeah what do you drive?

I have never heard of someone using that large of an array for that size of a battery. What is the charge rate of that battery? Hopefully you are not heating up the battery too much when you charge it quickly after a deep discharge.

 

[kllcbosmetris]

How does a 945w solar array feeding a 102 amp hour group 31 Northstar AGM battery sound?  Works great for me.   The battery is bulk charged fast on cloudy mornings.  On sunny mornings if you are not watching closely you will miss the bulk charge.

The only things being powered overnight besides my two Engel fridges is a small amount of LED lighting use and sometimes a bit of car audio in my cargo trailer. 

I just don't get the folks who say a 100w panel for a 100amp hour battery.  A few cloudy days and the battery is damaged unless the user is really on top of minimizing the load.

945w? In 300w+ increments? How many panels? What kind of square footage? On the roof?

 

[ZoNiE]

3x 315W panels are about 5ft by 3.5 ft. probably a cargo trailer, large TT, or toy hauler...

 

[29chico]

3x 315W panels are about 5ft by 3.5 ft. probably a cargo trailer, large TT, or toy hauler...

You got it.  6x10 cargo trailer.  The 3 LG 315w panels in their rack cover the entire roof.

 

[29chico]

Holy cow. Yeah tons of potential power. Would be great if you could put it to work.

And yeah what do you drive?

I have never heard of someone using that large of an array for that size of a battery. What is the charge rate of that battery? Hopefully you are not heating up the battery too much when you charge it quickly after a deep discharge.

I do put the power to work during the day.  6x10 cargo trailer/man cave.

The Northstar battery has no inrush current limit as it is a pure lead high performance AGM.  Yes, if it was a flooded battery of the same capacity, heating and damage would probably happen.

 

[jimindenver]

29chico uses the system much as I do by running things directly off of the output of the panels without the battery knowing it. 975w is enough to run my little A/C, cook top, water heater, etc.

What about those 75w panels?

 

[John61CT]

Actually all lead chemistries are self-limiting, won't accept more than they can handle.

Long as the wiring is robust, even a 400A source is just current available, not "pushed", it's the bank resistance controls actual flow rate.

Even a little 35A lead FLA, no problem

 

[frater secessus]

I just don't get the folks who say a 100w panel for a 100amp hour battery.  A few cloudy days and the battery is damaged unless the user is really on top of minimizing the load.

Pretty sure that's a minimum recommendation.  It'd be fine if there was some other form of charging helping out (alternator, shore, genny).  I recall sternwake recommending 2:1 or 3:1 for folks that cycle the batteries and charge by solar alone.  

I agree about the need to dramatically reduce loads in those conditions.  Probably a good thing for us non-powerplant folks to think about before it's needed.

What controller are you running?  Any pics of your setup?

 

[John61CT]

> 2:1 or 3:1

Depends on latitude, weather, usage patterns, no one rule fits all.

Having a little genny gives lots more flexibility.

Or LFP, no need to ever get to 100%.

With lead, user needs to be able to view endAmps to confirm 100% Full, adjust usage as needed or of course add panels.

Or accept short bank lifespan.

 

[willprowse]

Actually all lead chemistries are self-limiting, won't accept more than they can handle.

Long as the wiring is robust, even a 400A source is just current available, not "pushed", it's the bank resistance controls actual flow rate.

Even a little 35A lead FLA, no problem

I have always wondered about this. Why do so many battery manufacturers have a "safe" charging rate in amps? Many solar application batteries will have a "maximum charge rate". Is there any reason for this? 

I remember when I was a kid working at my dads mechanic shop, I was always told not to speed charge the batteries too much or else they will degrade. 

That is pretty interesting. That means that one could easily over panel their system without worry. WHich means they could build a very lightweight system for specific applications. Such as powering an electric bicycle with solar panels on a trailer. Have a tiny 7 amp hour sealed lead acid hooked to 200 watts of solar. Of course one would have to be very careful to not discharge the battery too far. But man, that would be awesome. Super lightweight and cheap, and would provide a great amount of continous electricity when the sun is out.

 

[jimindenver]

The first time I heard the 1-1 rule of thumb was because it was what was needed to equalize at a certain temp. I can tell you that I would never suggest any less than 2-1 unless you use less than the output of the daily solar haul or have a back up means of charging. I have only once used my little generator to charge up the house bank but it is making the rounds here doing morning bulk charging so that peoples 1 to 1 solar can finish the job. (hopefully)

Lifelines are rated for a ridiculous charge rate, so much so that I can not practically charge my bank at its limit even with shore power. The 80 amps that my solar puts out is as much as a tickle to the 675 Ah bank. It works because I have full control over the voltages, absorption time and equalization. Morningstar controllers are great for that be it a custom profile for my Lifelines or the neighbors LiPo's.

 

[29chico]

29chico uses the system much as I do by running things directly off of the output of the panels without the battery knowing it. 975w is enough to run my little A/C, cook top, water heater, etc.

What about those 75w panels?

Jim: 

After much thought I decided that I have enough weight up high on the trailer now.  So adding the extra wings onto the existing array seems not such a good idea. 

I'm thinking about putting a single 160w or so panel in front of the roof tent on the van.  With a charge controller that will charge two batteries, a smallish AGM dedicated to the Engel fridge in the van and also to keep the starting battery topped off.  Doing so would simplify my life by eliminating the daytime charging of the battery in the trailer that is used to power the Engel in the van at night.   Thoughts?

 

[John61CT]

> Why do so many battery manufacturers have a "safe" charging rate in amps?

My theory is in the US lawyers stopping people from burning things down, even professional DC sparkies often don't do properly robust wiring.

Soon as you get past 100A rates IMO all charge sources should have dedicated sensing wires for both volts and temp compensation, which should include derating current if the batt gets hot.

But so many people buy on price, so awyers have to assume cheap Chinese cr^p.

> I remember when I was a kid working at my dads mechanic shop, I was always told not to speed charge the batteries too much or else they will degrade. 

Old-school garage chargers are still sold with no smarts at all. At the other end too-smart garbagegets in he way.

House bank usage wants good quality chargers, often at high amps cost more than the bank, Sterling, Promariner. But they last longer than your vehicle will and give a good bank longer ifetime.

> Have a tiny 7 amp hour sealed lead acid hooked to 200 watts of solar.

Sure but any EV use wants LFP if not NMC or LiPo for fast charging, no need too keep full, higher density, faster discharge.

 

[29chico]

Pretty sure that's a minimum recommendation.  It'd be fine if there was some other form of charging helping out (alternator, shore, genny).  I recall sternwake recommending 2:1 or 3:1 for folks that cycle the batteries and charge by solar alone.  

I agree about the need to dramatically reduce loads in those conditions.  Probably a good thing for us non-powerplant folks to think about before it's needed.

What controller are you running?  Any pics of your setup?

The controller is a Morningstar tristar MPPT 60.  The inverter is a Magnum MSH3012 "hybrid" with load support to allow one to start tools with large starting loads by dipping into the battery bank for a moment.  To run heavy loads all day, my 2000w peak Yamaha  generator comes into play.  Options are good.

No good pics at the moment.

 

[John61CT]

> Lifelines are rated for a ridiculous charge rate, so much so that I can not practically charge my bank at its limit even with shore power. The 80 amps that my solar puts out is as much as a tickle to the 675 Ah bank.

Yes minimum charge rate for good longevity for those is spec'd @.4c, so ~300A for that size bank.

Would be an expensive shore charger, maybe two 180A Sterlings in parallel.

But wouldn't be hard to rig a little say 10HP engine to drive an alt that size, big reco Leece Neville or surplus "CEN" (C.E Niehoff & Co), not that expensive.

Hear great things about EcoTech also.

Just in case you ever want to boondock deep in the forest

 

[John61CT]

> 2000w peak Yamaha

Would drive what a 80-100A charger?

 

[Almost There]

Probably not even with 2000 W genie.

I need 2000 W to run my 50 amp charger.

 

[John61CT]

I forget they rate peak not continuous.

But some have reported eu1000i can run 40+A?

Of course they may be on banks not actually pulling that much. . .

So confirms, it's OK to try for higher, but always use a charger that can derate as needed.

Also useful on mains circuits that can get overloaded.