Solar Nightmare

SO..... Where to begin, I have about 200-300 GOOD 18650 batteries from laptop packs all above 2AH rating. I have 2-100 W, 1-150 W, 3-15W and a 75W solar panels, 480 watt total, currently have a 30amp 12 volt charge controller for LA batteries, they died over winter, sulfated POS boat anchors. I want 12 volt DC so the first question is do I go 3s for more amp hours or 4s for more voltage, 3s is 11.? nominal and 4 would be 12-14 volt. I am using this for a RV trailer year round 365 days a year. No AC available unless I run generator which is very expensive. I have about 10 Amp max draw which includes 1 propane fridge which only needs 12 volt for the safety seleniod and some led lights that may take up too 1 amp per hour that I run about 6-7 hrs a day. I would love to get wind but can do that at a later date.

I guess what I am asking is charge controller? for solar lithium ion and should I go 3 or 4 in series?

I have about 4-6 hrs sun in summer and 2-3 winter depending on weather, this last winter I had maybe 1.5-2 hrs/day sun 3-4 days out of the week. So I would need at least 3-5 days reserve. I have no clue what my total wattage use is, I've tried to figure it out but no access to a DC meter or any idea how to even use one. BTW I'm in Canada so hard to get real equipment here with all the stupid border regulation crap. My panels are rated at 12-18 volt normal but can go past 20 volt.

BTW please don't throw numbers at me, I can't juggle and have no clue what most of them mean, I barely know enough to figure out the solar system without cross wiring it.

Future add on's would be a inst-hot water tank (igniter and safety valve) wind generator-new charge controller, and possibly a well pump (max 20 ft lift) very high water table here. Please ask if you need more info and Please use simple terms, a picture tells me more then a whole book of words if that helps.

Its a bit tricky to combine all those panels. You cannot just hook all those up. im guessing they are diff voltages and such. If so you can get issues. But enough about that. If you add up exactly what panels you have perhaps someone here can help you make sure you utilize the panel the best you can!
If all would be same voltages you could paralell them but perhaps not recomended.


If you go 4s you get voltages between 13.6-16.8. That will be to high for most inverters (If we talk about Li-Ion 18650 chems that have nominal of 3.7v)
3s is better for 3.7v nominal.
And that's the most common in laptop packs. If its LiFe cells 4s works but for normal 3s is the way to go.


Are you only using DC equipment hooked up to this setup?

http://www.ebay.com/itm/LCD-DC-Comb...nt-KWh-Watt-Car-Battery-Monitor-/252795007261
Something like this will help you calculate what you need. Hook it up between your battery and all your appliances and let it go for some days.




I hope i didnt throw you to much numbers if so just shout at me and I or someone else break it down for ya.

For hooking all those different types of panels together, I'd look into micro-invertors. that would make each panel output the same Hz/Volts and then use a single input to convert back. Plus they would give you the added data availability to know what each panel is doing and you'd see a failing unit (either physically, electrically, or just plain dirty).

If you expect to get morelaptop batteries then you might want to run them at higher max voltage up to 4.3 this will reduce their life drastically , but you can put 3 packs in series ... putting 4 packs in series will give along life because you run at below 3.9...

Sounds like your panels are 21V open circuit ... if they are put them all in series they'll be fine , if not sure tell us what the sticker on the back says ...

The best advice anyone will give you is forget all about wind ... it's a gimmick... lots of trouble , high price , and very little power. Just get more panels ...second hand are fine , you still get 75% power when they're 25 years old

All panels are 12 volt coleman currently using the 1-150 and 2-100 hooked for 12 volt 350 watts. Yes I remember that meter from when I made a 120 volt dc charger out of an old resiostat. Perfect solution, ok so I'll go with 3 series and 3 packs each 3.7 nominal for as much AH as I can get so I don't drain packs lower then the recommended 3.0 volt. Next would be a Canadian available SOLAR 12 volt in and 4.2 OR 12 volt out charge controller? for lipo batteries. Or should I charge the packs individually at 4.1 volt dc? It should ave a low voltage cut off and high voltage cutoff I presume? I can get the racks fuse wire and bus bars easy enough. I'd prefer something thats just turn a screw and slip the wire in for a charge controller. ALSO battery monitor system (BMS) or not? wouldn't the charge controller do the same thing as long as it has a balance function? Sorry lots of questions but I want to make sure I know I'm on the right track and don't have my info wrong.

A lot of the PWM controllers work fine for lithium as long as yo can adjust parameters ie. High low voltage.
Im using one of the small blue ones (digital with 2 x usb) model CY3024.
I agree 3s all the way.
I recently built a 3s 20p pack. Ideal for12 volt
All the best with it all

Depending on where you live wind can work for ya. Where i live its dead end. I have less than 3m/s in avg... You need atleast 6m/s or higher for it to work good. Its all depends on what you want to pay

I'm in basically the same situation but a lot further south, in a trailer with no grid connection, depending on a generator, a few solar panels and an inverter with some random crappy lead acid at 12V until I can get a powerwall built. The only real difference is that I spent years building and riding ebikes with salvaged laptop cells so I have a bit of a handle on the technology.

One little trick I've found that saves fuel is to do only bulk charging off my generator and do it in the early morning and then let the panels do the lower amp part of the charge cycle when they get sun. That keeps my generator running closer to full power where it's most efficient. Most generators get even more inefficient at light loads unless you have an inverter generator. In fact I try to do everything that requires the generator to be running (microwave, induction cooktop, heavy power tools, charging drill batteries etc..) while bulk charging because I don't want to run the generator any other times.

A charge controller and a BMS are two different things, the charge controller will cut off the charging current at a certain voltage but generally has no balancing functions. With a decent size 3 cell powerwall manual balancing shouldn't be that much of an issue since sheer randomness should ensure the packs are reasonably well matched as to capacity and internal resistance so they shouldn't get out of balance quickly. If I were going to run with no BMS then I would put an overvolt/undervolt alarm on each pack in your powerwall.

Elmo said:

<snip>.... The only real difference is that I spent years building and riding ebikes with salvaged laptop cells so I have a bit of a handle on the technology.....COOL <snip>


<snip> ...manual balancing shouldn't be that much of an issue since sheer randomness should ensure the packs are reasonably well matched ..... YUP ...<snip>

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I am in a similar situation myself. I live off grid in a trailer (caravan) making do with an ad hoc system. I mostly use gas for everything but computers lights, i have a small washing machine and a rice cooker. It is time to upgrade so I am looking at the option. Elmo you sound like I was 30 years ago. Pulling old valve wirelesses together and building stuff.

I am trying to figger out the viability of using second hand batteries. Maybe I am thinking too much like and engineer where I should be thinking like a womble.

I have had a bit to do with UPS Ni CADs and I love them. You can flog them hard.

LEAD ACID are fragile.

Hadn't heard of Wombles before, yep thinking like Womble, our societies are burying themselves in rubbish, people are making entire houses of cast off water bottles filled with dirt and that sort of thing.

Nicads are why I avoid commercial battery holders, I ruined a lot of them with nicads, overheat the steel springs with too much current and they lose their tension at which point throwing them in the rubbish is the only option.

Korishan said:

For hooking all those different types of panels together, I'd look into micro-invertors. that would make each panel output the same Hz/Volts and then use a single input to convert back. Plus they would give you the added data availability to know what each panel is doing and you'd see a failing unit (either physically, electrically, or just plain dirty).

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for the price of the 4 micro inverters he needs, he could buy 500 watts of new matching panels, which is more than he has now.

Hrmm, I didn't realize they were still highly expensive

Could always make one with a Nano, and other parts to make the syncing correct

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Power optimizer

[size=small]From Wikipedia, the free encyclopedia[/size]

https://en.wikipedia.org/wiki/Power_optimizer#mw-headhttps://en.wikipedia.org/wiki/Power_optimizer#p-search
Apower optimizeris aDC to DC convertertechnology developed to maximize the energy harvest from solarphotovoltaicorwind turbinesystems. They do this by individually tuning the performance of the panel or wind turbine throughmaximum power point tracking, and optionally tuning the output to match the performance of thestring inverter. Power optimizers are especially useful when the performance of the power generating components in a distributed system will vary widely, such as due to differences in equipment, shading of light or wind, or being installed facing different directions or widely separated locations.
Power optimizers for solar applications, can be similar tomicroinverters, in that both systems attempt to isolate individual panels in order to improve overall system performance. Asmart moduleis a power optimizer integrated into a solar module. A microinverter essentially combines a power optimizer with a small inverter in a single case that is used on every panel, while the power optimizer leaves the inverter in a separate box and uses only one inverter for the entire array.

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Could try the power optimizer route. It is cheaper, by almost 1/2 the cost. Just a thought. :idea:

OK figured I show you people what I have so you have a better idea of what I have and want to do, I want 12 volt dc with as many amp hours as I can get, I have all coleman1-150 watt 12 volt and 2-100 watt 12 volt solar panels hooked in series for 12 volt dc 350 watts going into a cheap coleman 12 volt 30 amp charge controller, I know I will have to replace this with the lithium battery pack. My current power requirements are........Lights- http://unvlt.com/pdf/specsheets/M10CC8xxD32N2S.pdf currently using a step up from 12 volt to around 18 volt dc, the switch is before the step up so that it doesn't draw phantom load when the lights are not on. The fridge is....... https://www.manualslib.com/products/Norcold-663-653402.html and from what I gather uses maybe a total of 10 amps per day, I have it set as low as possible and still keep milk fresh. The step up boosters are...... https://www.amazon.ca/Voltage-Regul...coding=UTF8&psc=1&refRID=G6XBC1GGFAEXK50F7XJZ and I have lights and step up wired so no phantom loads, the fridge is another matter. Water pump....http://www.campingworld.com/shopping/item/flojet-quiet-quad-ii-water-pump/9372 currently not hooked up. I do have an instahot water tank camp model but no clue what the power requirements are yet.

So I'll go 3s40p as I have 126 18650's that are good. Now doI need a solar charge controller to charge them and a bms?
Not even sure if a BMS is required or not thats why I ask, IF I gothttps://hobbyking.com/en_us/imax-b6-50w-5a-charger-discharger-1-6-cells-genuine.html/?___store=en_us could I regulate the input to 12 volt and charge the packs at 4.1 volt dc or do I get a solar charge controller for lithium ion and charge all the packs at 12 volt? 3 packs of 3.9-4.1 volt=12 volt approx either charge them as a whole or each pack separately? I'm thinking at 12 volt with monitors on each pack. The question then becomes what charger do I need that not only has a low and high cut off but no float function as well?

I will be replacing the lights very soon with a cheaper solution I found at the dollar storehttp://www.promierproducts.com/Promier-COB-LED-Cordless-Light-Switch_p_95.html I figure I can take it apart and put them in a case, tried one on a 18650 and it works and only uses 1.5 watts power. Other then those is only the laptop 50-150 watt which I would like to have at least 8 hr of use per day.


Please try and keep all answers simple, I'm not an idiot but I do have a dumbies book shelf

OFF TOPIC

Elmo said:

Hadn't heard of Wombles before, yep thinking like Womble, our societies are burying themselves in rubbish, people are making entire houses .... <snip>

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When I was in Vietnam it blew my mind how so many folks could live so frugally and yet be happy clean and prosperous. Waste of space particularly. They are using some primative technologies. I was surprised to see so few solar panels. Most particular with transport people do not travel a long distance to work. They live and work from thier residences. Mostly young office workers motor scooter to work. To us in Australia when we think "out in the county" we mean several hundred kilometers. In VN they may be talking 10 ks. It is an eye opener.

Clever thinking on the lights...

A lot of it depends on your ability to keep an eye on the system, cheap does not equal install and forget.

You have somewhere around 600 watt hours of energy storage available if you wish your cells to last 5Wh X 120 cells = 600, multiply the amps times the volts times how many hours something is on and that gives you the watt hours, so 12V x 3A x 3h = 108Wh

Add all your watt hours from everything you need to power during the time your panels aren't producing energy and then divide that into 600 and that will tell you how long you can power your stuff after a full charge.

Forget the iMax, it doesn't have the power to charge your cells at anywhere near the maximum they can accept or your panels can put out. If you are going to go the hobby charger route then the iCharger 206B would be about a minimum choice and a 306B would be better. That sort of solution is going to take a lot of hands on management, it will be a daily chore to turn on the charger and keep an eye on it. The iCharger solution will balance your cells and might even take your solar panel output without any controller, it's good to 28V on the input side which should be higher the the open circuit voltage of your panels.

I wouldn't get rid of your lead acid, I'd keep them and put the smaller panels with your existing controller set to keep them charged up. That simplifies connecting the big panels to a different controller for the lithium somewhat and also gives you an emergency reserve of stored power or perhaps you can connect them to one of your minor loads like lights. Even if you only have 150Wh in the LA it's still a significant fraction of your lithium pack.

In full sun your panels will put out more than your lithium should accept so that's when to use your more energy hungry things.

@ Elmo, TY I think I know what you mean but could anyone maybe make a system design diagram so I could visually see what the system should look like?

I'll see what I can find locally for a charger to get me started making the pack, then upgrade as I start to install it.

Q. would it be better to make 3s40p x 3 or 3s20p x 6 so that I have redundancy packs in case something happens to a cell?

Felineman, I'm going through the same decision process you are, limited funds, some random existing equipment bought on the cheap often for other purposes and a burning desire to keep the generator off as much as possible. A lot of what I say is going to be thinking out loud, I'm not an expert by any means but I'm a strong generalist with a fairly deep background in electronics and I'm not afraid to think outside the box. That being said, go read the disclaimer at the top of the site...

If you have a PWM controller that will connect your big panels to the LA battery already you might want to stick with that, then you could use an iCharger running from that + your solar to charge your lithium to the optimal voltage. The nice thing about the iCharger is it works either way, it will discharge one battery by charging another at a fairly high efficiency and you can set the limits independently 3.9V - 4.3V for the lithium, it's also a pretty good balancer for large amp hour packs up to 6s. When I was flying I had friends with them and they were always bragging, I already had a charger that worked and still works so I never owned one but I've heard all about them.

That's probably the simplest option with the least wiring, your current setup with the solar and lead acid >> two wires to the iCharger >> iCharger>> two charge wires + 4 balance wires for 3s to the lithium>> lithium cells. Then you can pump energy back and forth between the two systems as needed. It would need a fair amount of manual intervention to keep running optimally but it would allow the easiest combination of lead acid and lithium together. Basically the LA would be a "flywheel" for the solar charging the lithium and would absorb any overage or make up underage. Also the iCharger arrangement would take care of charging the lithium from the generator, just charge the LA from the generator and the iCharger will take care of the lithium.

You're in a tricky situation and it's difficult to know what's the best option for you, I haven't even figured the best option for myself is yet.

Ya I know what you mean, just picked up a cheap onyx 225, no discharge but will charge and balance. Doing some tests on those new lights I'm thinking about using, figure I can get 2-3 hours per 18650 2.250 AH from a 4.1 vdc charge. I'll continue to play around and hopefully find something that will work for what I have, just can't afford the solar charger that I need, maybe a cheap deep cycle to regulate the 12 volt for the lipo charger would work, just have to make sure that I don't over charge the lipo pack.

Make up about seven more of those alligator clips and you'll be set to start charging your cells for testing, charging in parallel with hobby charger works fine but they seem to have a tendency to want to overcharge a big single cell (which is what the charger "sees") so if the CV voltage can be changed on that turn it down to start.

The discharge on hobby chargers is worthless for most of them, not worth considering unless you have years to spend testing. It's good you avoided buying one for that. I have an iMax B8, it's like a super B6 with more amps and more cells and still charges but the discharge burned out looooong ago when I was still flying e-RC.

Depending on how much time and attention you are able to devote to testing your cells it can be real low tech. All you really need is some way to measure elapsed time, your DC volt meter and a 12V 1156 tail light bulb each with one of your alligator clip arrangements for however many cells you want to do at once. But you are going to have to keep an eye on it, once cells fall off the charge curve they plummet and it's not good for them to run them dead, the bulb starts getting dim fast and you'll know it's time to disconnect the bulb and record the interval and put the cell aside for leak testing. Basically it's an amp hour per hour with an 1156 bulb across a lithium cell. If the cell keeps above 2.9V (remember your volt meter) for 90 minutes that's 1.5 hours so your cell is 1.5 amp hours or 1500 milliamp hours. Those numbers aren't precise but they will all have the same small error for all of your cells so you'll know which are stronger and which weaker and a good idea of how strong they in absolute terms.

If you start several at the same time all you should have to do is record the starting time, watch the bulbs and record the elapsed time and the voltage every now and then. It will be obvious if any are getting much lower than the others, the bulb for that cell will be dimmer so until under 3V you only need to glance at them to tell if any is weaker. I used 2.8V for a cutoff but I had a computer there ready to cut it at a moment's notice, doing it my absent minded self I'd go for 2.9V to give me a cushion. Hopefully they will all last a couple of hours or more so you won't have much to do for most of that time.

Don't expect to get 2 amp hours regularly out of a cell you measure at 2 amp hours, more like 1.5 amp hours, be conservative in how you use them and they will last, abuse them and you'll be looking for more before long.

Charging the lead acid battery on solar and then charging the LiPo from the LA also gives you a buffer. Sunshine isn't constant. The LA buffer provides a more constant power supply for charging the LiPo. When the panels are in the sun, the solar power is available. Clouds decreasing the available solar power isn't a problem, since the bufferis there.

You might even want to power your loads from LA when the sun is shining to take advantage of the available power without floating the LiPo, though there are opposing opinions about floating lithium cells.

Rigging the charged Lithiumcellsto float the LA when the sun goes downwould be ideal, but I'll have to find a trick for that.

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Of course, a switch to transfer your loads from LA to Lithium after the sun goes down would also work.

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3s120p (simplified for calculation) with 2ah cells gives you 240Ah. If your budget is 80% of capacity, it brings it down to 192Ah. At 0.2C, with 0.66 derating (fudging it) and 4 hours of sunshine, you have 1920.20.664x4.13=178.9W of solar panels. Right? If the LA is kept at full charge, 200W might be enough for you. Put the 2 100W panels in series with an MPPT charge controller, and it gets more power out of the panels and an edge in the winter.

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24V and MPPT also helps when hot panels drop the voltage too much due to the temperaturecoefficient.

Also, it's important to have a remote temperature sensor (RTS)on the LA for temperature compensation.

Charging LiPo is NOT temperature compensated .