BMS as solar panel charge controller ?

My ebike charging station has been on hold due to a lack of electronics at what I considered reasonable prices, and refusal to go the high loss route. I want to charge my packs with an 82V cutoff using solar power. For a portable solution it makes no sense to charge a 12V pack to run an inverter with a charger plugged into that.

Now that I've sourced some small 12V solar panels I can finally get up above pack voltage, and I was going to try running a cheap low charger using DC directly from the panels. Then it dawned on me, why not run the solar output directly to a BMS. As long as the open circuit voltage from the panels is higher (significantly higher looking at cell output graphs) than pack voltage, then I think it should work well and charge and balance my pack in the process with an appropriate cutoff, as well as no issues cycling on and off when panel output drops off due to clouds.

FWIW, in the interest of safety I'll do this with used A123 M1's that could use regular balancing anyway.

Panels, diodes, BMS, battery pack is it. I'm guessing that the max voltage of these 12V panels maxes out at 16-18V, so I plan on 7 in series and add parallel strings to increase current, limited by the area of panel I want to go for, though I'd want to stay well below the BMS's charge limits.

John

Any holes in the plan.

you can design it so that when the BMS shuts off the charging above 3.9V/cell then there is a path for the current to flow around the BMS and into some other storage device. and have a device capable of switching off the charging altogether when the pack has fully charged all the cells. you might be able to hack up the BMS design that richard and gary put together and use the low value resistors to get maximum shunt current bypass so the pack would balance fastest. they have the all shunts active signal line.

dnmun said:

you can design it so that when the BMS shuts off the charging above 3.9V/cell then there is a path for the current to flow around the BMS and into some other storage device. and have a device capable of switching off the charging altogether when the pack has fully charged all the cells. you might be able to hack up the BMS design that richard and gary put together and use the low value resistors to get maximum shunt current bypass so the pack would balance fastest. they have the all shunts active signal line.

Click to expand...

I wouldn't want to go that high per cell, and hacking BMS designs is definitely outside my comfort zone, but a switch to go to my other ebike packs when my daily rider is full is within reach. Eventually all my other packs could be paralleled and run most of the house, but that's down the road once I have sufficient solar panel. Right now I want to focus on a simple and cheap portable ebike solar charging rig. There are some out there, but thin film stuff approaches or exceeds $10/watt.

What's been killing me is the 0.5V output of the 6"x6" cells Harold and I got. I just haven't figured out a way to turn them into a reasonably portable rig without big losses in stepping up the voltage and an expensive charge controller for my higher than typical battery voltage. Now I just have to find the right combination of price per watt and panel efficiency in those 12V solar trickle chargers, and combine them into a useful output that folds up with maybe a string or 2 exposed while riding and double or triple or more easily faced to the sun when stopped.

Our dry season is coming soon, so my interest is high now that I think I've got realistic cell/panel solutions.

John

Regarding efficiency losses of charging a 12v battery and then running a inverter from that. lets say your loosing 30% with the low cost of PV's wouldn't it be easier to just add 30% more PV. Perhaps not using led acid as your 12v buffer pack. A high output 12v pack from a123 could work and can be easily charged from a programmable regulator.

I know you want to keep it portable and efficient.

My thinking is once your low capacity buffer pack is charged and running at float voltage lets say conservative 3.5v cell any drain on the pack from the inverter will be provided by the PV trying to maintain float voltage (up to the output limit of the PV). I see this everyday with my off grid house PV system. My 63kw pack is on float by 9am and any load after that is coming more or less directly from the PV.On a nice day I can usually maintain loads directly from PV up to 2600w before the battery drops out of float and back to the point were the battery is providing some of the load.

on a smaller scale ..

A small 12v 10ah a123 pack and a small inverter powering your mains charger the small pack would be just acting as a filter-buffer and you would be running directly from PV anyhow . it would be like a UPS it runs through the battery's but they stay on float and its really running from the charger that takes the load. Though this solution works best with good solid pv output (sunny day) as the load (inverter-charger) has to be less than PV output at any given time. Within reason as the 10ah pack could handle small dips due to clouds but would fall over on a overcast day. this is were your direct charging solution works best as charge output is self regulated to what ever the pv production is rather than a constant load with the AC solution.

The best solution i can think of is a high voltage programmable PV regulator. Like you say regulators that can handle over 48v are expensive . I run a mid nite solar classic 150 that can charge up to 72v and they do have a 200 and 250 that can charge up to 120v. Full control over all your settings so charging lithium isn't a issue but there is a catch at $600 - $700 at a discount its a serious regulator that i can justify as it charges a 63kw house bank at 90A.

I guess the BMS could act as a simple regulator just remember to factor in very cold conditions can spike voltages high as long as that wasn't a issue.

Kurt

I've been trying to figure out charging scenarios with solar myself. I'm not an electrical enngineer, my degree is in chemical engineering, but as quoted elswhere "nothing gets invented until someone changes disciplines" gives me courage to post.

Here's what I come up with. Use a 9 cell or so pv panel. The 6X6 cells would give about 32 watts usable. Charge through the balance taps. Using counter circuits, allow current to flow to 1s"x"p lithium cells until they comes up .1 volt or so, step to the next cell, take that up to the same voltage, cycle to the next cell etc, when all cells are up .1 volt repeat cycle. As I said though, I only have enough electronics knowledge to be almost dangerous.

A 9 cell panel would be much easier to assemble than a standard 36 cell panel. They would be about 20" square. 7-8 amps. The arrays could be parralleled for higher current. This is not an off the shelf solution, though, but if there is anyplace that could make this happen ES is it.

Any holes? No, except "add on" that external power drain, whether it be a regulator fired electric fan or an oil heater, just something that will drain off the extra power produced after the battery bank's float, while the sun is still shining.The solution may be a simple voltage regulation, closed when the power's flowing, open when it's not, open when it's dark. That way, you don't have to baby sit the connection.
You said portable. So design the whole big mess to charge and power something else, regardless.
Maybe a mill wheel. Stone grind masa.
Somebody pumped water back uphill and caught it in a reservoir.
The only hole could be:
Everybody wants portable. It goes without saying the most economical unit is the one that hasn't moved off the cement pad for seventy years.
Also unclegrumpknee hit on the portable solution, thinking you could bite off smaller chunks of the work and do a smaller load more times during the day. THAT could make your rig extremely portable if it could multitask all day long.
But don't forget about the mill wheel, either. There's a lot of juice to use after the battery's float.

HAROX,

Maybe that's the part I'm missing. Can I not just turn off the panel's electrical connection? Do they overheat or something if not allowed to put out juice? If I have to provide some load at all times, then I may just go with no electronics at all other than a diode and I'll be the charge controller just like I'm the BMS for my bikes. Typically I wouldn't carry enough panel in a backpack to fully charge anyway, so the solar charger would be more of an opportunity charger anyway.

Regarding portable, this isn't about the economics, just to be able to silently put out charge current at pack voltage somewhere away from an electric socket. That concrete slab at home won't do any good in a clearing in the jungle, or at the beach, or on top of a mountain.

John

There's normally no problem with just turning off a PV panels electrical connection, even when it's running at full power. The panel will run a little warmer, as it will be absorbing an additional 15% or so of heat energy that would have been taken away as electrical power, but this won't have a big effect.

The crude and easy way to limit charge from PV is to use a shunt regulator to stop the panel voltage exceeding the maximum voltage you're after. It's a bit wasteful and the shunt regulator will get hot when working, but its the way many solar battery charge systems have been built for many years. The shunt regulator could be designed to mimic an ordinary CC/CV charger easily enough.

I'm making the final edit now.
Hey John, you lucky devil, in Costa Rica sipping ice tea (while I'm frizzin my butt off in Denver). This "opportunity charging" from a solar panel has me a bit stymied, so I'll just point out another possible hole.
analogy here:
(When I learned to shoot rifles, I had to learn how to use the scope, sights and notches (whatever) to get the targeted results. Now if I had a tripod, once I got the sights it would be cake... just pull the trigger and hit the bull's eye.)

Questioning your prospect, and the fact being, your bike is a super-wattage-sucker, a SWS as it were I wonder (depending on how efficient your solar array really is, whether you might wait til the cows come home, for (that much) super power to be produced. It's the old "something for nothing" argument, sort of like my "regen" argument.
"well if I pedal this 1000 ft pound force really fast, will I fire up a battery?"

I'm convinced regen is doomed to stay on the road down to hell.

Even though the sun is a much bigger target, it's still a target, and you have to be able to do what you have to do to get the energy (the target). I'm understanding you only want to use the energy for replenishing batteries on the bike, however once again, stand there, for seven hours, holding a panel, up towards the sky.

A special versatile portable anchoring device helps with location, or at least, for no other reason than economy ... there's just too much other stuff to do with one's time :lol:

Amberwolf suggested using folding aluminum cots for some of his frame designs.
http://endless-sphere.com/forums/viewtopic.php?f=3&t=46183


I HOPE I've not shot your idea in the foot. Your idea has dangling question marks.
I should know. I have stuff dangling that begs to be finished.

I know why I feel this way now, as I see it:

It doesn't matter how one generates power.
One must figure out how to get the stuff away from mother nature . I literally have to pin her down to wring super energy from her

and the sun is just one part of her big buxom bounty. Hydro, wind, gas fired, geothermal, all have "tricks" and solar (I believe, proove differnt) solar is the same.

"You might think you're coaxing the juice out of the sky, and two to one, you'll fry trying"

Location makes solar energy (or it doesn't), water flows downhill, heat rises, and the wind comes from who-knows where? You don't stand in the wind propeller. You don't stand in the thermal stack. You don't stand near the end chute. You don't stand and fry in the sun.

An array needs location, and an "attitude" concerning the sun.That's the brass tacks that hold it together. I wish it weren't so. The battery pack is just too damn big for the size of the array. The opportunity charging isn't a fully covered charge, like you could get off a light pole.
Location is just so important for PV generation.

I know about "100 watt-super-solar-powered-squid-shaped vehicles that could traverse the Sahara while they roast the rider like a Christmas turkey. Not my idea of a Sunday ride in the park.

A great location for an array would be a daisy field (in my mind), because nobody tramples in the daisies, because they only grow "this high", because they love sun just like me, and because they make the solar arrays look very pretty. :lol: seriously :|

If you knew somebody who lived on the hill, and you could install an off grid charging base there with part of your panels, and if you knew someone who lived twenty clicks away from the hill, and you could install a charging base with them, then you could go there and back, and they could get a bike and come see you as well.

I know it's not about economy, your plan. However, the time for action is in the future, and right now probably, there's somebody just twenty clicks away from you who wants an E bike, and who'd be trusted to take care of your solar electric exchange, and power up their bike. or their wagon, or grinding wheel, or ceramics dryer, or dehumifier. They might even have a field of daisies to plant it in, some place that won't be in the way any more than it already is.

Location Location. Costa Rica, you lucky devil.
Well...enough rambling for a lifetime...

To solve,
Basically, would you agree? A mixed source application (RecVehicle) using renewable sources plus ICE generated plus household standard current uses a "manager" in mediation with a battery bank? That's a BMS acting as a charge controller?
If BMS controls the distribution of the pooled power, it required a pooled constant source to do its job over time, i.e. for the duration of the opportunity. That's the way it's designed, and considered as a battery manager.
The key is in the constant, consistent duty, over time. Right?
Gotta have a constant pool to draw from, to go fast, or to charge back up, or to just turn on the radio!
So how big is your pool? Is it 84 volt plus? Is it a 4.4KW type of arrangement?
It would seem you would need "the pool" filled to think about tapping in.
The pooled energy available for charging a battery has to be greater, something like 110%, than the energy that going to be needed and used. Then when the solar contribution come along, it product becomes part of the pooled energy, which is being managed and stored in a battery (pack).

I can listen to a crystal radio.
Are you talking super power? multi watts per second? Then you'd need a pool. Right? You'd need something that acted at least like standard current for the duration of the opportunity.
I've been wrong so many times, not including the past! HA. Please tell me I'm thinking right for once. before I go electrocute myself.

Regardless, John's Original Posting has/had an objective...(to get enough power from the sun with the footprint of his bike, basically, to go another mile or ten. or two. or twenty)
I'm just somebody who has a strong affinity for the numbers on ES. The math. It takes this affinity to make the affinity become infinity.
John your objective I believe is attainable. Sorry to be so negative sounding about going to hell with regen, and frying by the panels. When I hear regen, I think human power plus one, and my ass is tired.
Somebody. Point out where this is already done. I know the numbers can be extrapolated from any simulation. If I had a pencil and a rule of thumb...

Watts per second out, consumed, on the road, replenished over time, takes how much focused watts per second in? And then, how big the pool to facilitate this happening?

These web links are worth checking.
http://gigaom.com/cleantech/tesla-unveils-free-solar-powered-car-charging-stations-for-model-s-owners/

http://physics.ucsd.edu/do-the-math/2011/11/a-solar-powered-car/

http://now.msn.com/elf-velomobile-is-a-solar-powered-vehicle-thats-half-bicycle-half-car

This one is just funny.
http://now.msn.com/surgeon-rides-kids-bike-to-work-after-getting-stuck-in-traffic

One 6 x 6 solar cell - 4 watts / .5 V = 8 amps ($2.99 ea)
To charge to 72V, should have at least 75V, so we need 150 cells. ($450)
75V x 8A = 600 watts
15 x 10 cell array = 90" x 60" or 7.5 feet x 5 feet.

This sounds like it would work great to me...

-Warren.

Recumbents.com,
I do have about 130 6x6 cells, but those will be for home 12V system, and aren't enough to directly charge my bikes without stepping up the voltage. The modules in route are 12V nominal 5W panels, so nice and small and each series string of 6 or 7 is enough to handle my bike packs. I plan to make them modular, so I can expand what I carry.

Harox,
While I'm running my main ebike at a marginally adequate 15kw peak right now, the part you're missing is that's just in spurts a few seconds in duration on each launch. With the higher efficiency hubbie I'm running now my consumption averages only 50wh/mi and only 500-1000wh/day most days. That makes a direct solar charging proposition much more realistic.

There's also my cargo bike that gets used less frequently and for short trips. It's a low slung long wheelbase ebike with a kickstand that has it leaning to the side pretty well. With our quite dependable morning sun and low energy needs of that bike, it's pretty reasonable that I can keep it parked to get hours of good morning sun at a good panel angle and never have to plug that bike in for a charge with a small enough array that it's permanently affixed on the side of the bike. If I can do that through a BMS, then that bike becomes the ultimate in convenience ebike, ie just turn the key on and go, and just remember to park at the proper angle.

For my high power bike, my 6A charger only has to run an hour or 2 a day to keep that pack ready, so 2 or 3A from an ebike solar charging array is probably good enough at the house without even worrying about changing panel angle and stuff. I don't want to make it a permanent thing. eg When we go to the beach it would be nice to have a portable rig to provide some shade, provide power for a stereo, as well as charge a bike or two. Everyone loves going for low tide ebike rides, so at the beach is one place we commonly run short on juice and have to ration our riding. With a trail ebike and a portable modular solar charger getting far from people and having juice while camping is a reality.

Then there's the idea that's been nagging at me, a highly efficient recumbent with a tailbox and maybe a sunshade too covered in solar cells. While it won't offer enough charge power while riding for continuous riding, all it takes is planned stopping times. A couple of hour stop at midday for a long lunch with the tailbox folded out flat for a full power charge along with some time morning and afternoon with the panels folded to good sun angles would be all it takes. At 25-30mph for 2 hours in the morning and 2 in the afternoon, 100-120 mile days on solar power alone would be easy and leave plenty of time to see the sights at each stop.

John

In case you haven't noticed, I've parked here, on a compelling premise.
Universal answers, what you're doing John. BTW I know you're one of the down home geniuses at ES. So thanks for replying to my head-aches. Prove this out correctly, on your issues, everyone will know it, and probably know it right, and know it right in other sets of circumstance.

John in CR said:

Recumbents.com,
I do have about 130 6x6 cells, but those will be for home 12V system, and aren't enough to directly charge my bikes without stepping up the voltage. The modules in route are 12V nominal 5W panels, so nice and small and each series string of 6 or 7 is enough to handle my bike packs. I plan to make them modular, so I can expand what I carry.John

Click to expand...

stepping up, for the porta-charger is possible.

John in CR said:

When we go to the beach it would be nice to have a portable rig to provide some shade, provide power for a stereo, as well as charge a bike or two. With a trail ebike and a portable modular solar charger getting far from people and having juice while camping is a reality.

Click to expand...

1)shade no prob 2)stereo no prob 3) charge a bike-solve portable part

John in CR said:

Then there's the idea that's been nagging at me, a highly efficient recumbent . While it won't offer enough charge power while riding for continuous riding, all it takes is planned stopping times.
John

Click to expand...

John believe most portable panels will power on the fly to move any vehicle "at a weak speed", so right there, you'd have to park that "tea sipper" to charge, so you're right there. You have changed YOU to fit the idea, riding a weaker version, a trimmed down clone. That's okay for your perspective to become the brute active force in the equation.

Question: Is charging a battery similar to making a pot of steamy fluffy rice? Or a pot of pinto beans? Yes or no> I think yes b/c you start rice on a rolling boil. Once it comes back up to a rolling boil, you reduce the heat,or even shut the heat completely off, and the rice becomes good, plump.
Excuse the analogy, but hold on to it as well. With rice, if you burn it you have to start over. If you don't get the rolling boil, you have to eat crunchy rice- tomorrow, not today.
I believe battery charging is a LOT like rice cooking. You need the head of energy to start, and the tapered charge to the cutoff. Otherwise you risk 'throwing out the rice/battery"

That's why I insist ANY charger/BMS must have a pool of energy to work from, to get the desired results. The pool must come from somewhere, so why not make it come FROM a charged bank of battery cells, to supply the charging sequence on a depleted battery? More stuff, more weight but in this case, possibly more consistency. Make the charged bank to use on the ebikes as a motive battery, knowing you can use it as the "pool" as well. Realize, we are talking about using TWO battery banks, one to pool, and one to charge into. Make sense?

And thanks again for unveiling this entire premise. It's closer than before, and I'm not talking about perpetual generation either. Just remember, if people could do it easily, like hanging fruit, it would be consumed already.
This is finding the fuel, above the treeline, in order to run the ravine.

HAROX said:

Just remember, if people could do it easily, like hanging fruit, it would be consumed already.

Click to expand...

You give them too much credit. Putting scooter hubbies on ebikes was a ridiculously simple route to high power, yet they continue to resist it, while I've been riding ebikes that I almost never ride at WOT and climb mountains with heavier loads without a single heat related failure. 12V systems are simple, cheap, and readily available, but the only readily available portable panels are low power thin film solar, which is crazy expensive and low in efficiency so you need lots of area. For some reason panel makers don't consider it a solar panel unless it has a glass front, and weight tosses that right out the window. Sure there are some marine use panels, but prices go even crazier.

Subsequent to starting the thread I found out that the BMS's only cut at the cell level, and I don't really trust them to shunt off useful charging power. An ES member helped with a very low parts count panel cutoff solution, so it looks like I'm going to be good to go.

John

John in CR said:

You give them too much credit.John

Click to expand...

Whoops, the people I refer to are the ones OUTSIDE this forum, call them average joe.

John in CR said:

Subsequent to starting the thread I found out that the BMS's only cut at the cell level, and I don't really trust them to shunt off useful charging power. An ES member helped with a very low parts count panel cutoff solution, so it looks like I'm going to be good to go.
John

Click to expand...

Need say no more, except I do not understand "parts count panel cutoff solution", a PCPCS. Is that like a "sherlock style five percent solution"? ,a SS5%S

Yeehaa! Christmas came early. While I was near the end of the previous post the Fedex man came delivering 2 boxes. One full of an assortment of LED lights mostly for auto and marine use (without the marine pricetag hehehe), and the other with 50 raw 18V solar panels. They're much more than I expected, since I thought I was getting something closer to raw cells. I need to verify the construction to find out if the front surface is weather resistant, because while not glass it is smooth and flat. The back is supported by what seems to be a rigid fiberglass sheet. Except for 2 small strips of exposed metal on the back for the pos and neg connections, these seem to be ready to go weather resistant 18V nominal 5W panels only 2.3mm X 135mm X 330mm, so compact, and lightweight at less than 150g each.

I'll get the construction details and some pics along with output measurements asap, but so far I'm one extremely happy camper. This is about as low hanging as good cheap fruit can get.

John

HAROX said:

Need say no more, except I do not understand "parts count panel cutoff solution", a PCPCS. Is that like a "sherlock style five percent solution"? ,a SS5%S

Click to expand...

Low parts count solution to switch off charging....A handful of cheap small parts, resistors, diodes, a voltage regulator and a transistor...ie something cheap, easy even for me, and small. That way I can put one of these charge cutoff boards at the end of each series string of panels. Then I can connect as few or as many together in parallel as I want to meet the needs of the situation. Also, I can stagger the cutoff voltages resulting in essentially a CC/CV solar charger that has extremely low losses from panel output to what goes into my battery, over 90%. Every other solution I looked at was bulky and lossy, and expensive for a reliable 82V cutoff.

John

You know I went back and checked your postings and you have only just started on this venture. You've never really talked about this... until just about November 1st. So I have to say this is a genius at work type of situation. I'm just watching it happen, right now, and though I don't know all the numbers yet, I know John's got the numbers almost down to the last nickel.
Sorry John I gotta say it once again b/c it feels good.
Like I said, This is finding the fuel, above the treeline, in order to run the ravine.
subscribed, in a heartbeat

Thanks Harox, but don't use those kinds of words. My head's often bigger than it deserves to be. I'm just a 98th percentile guy with common sense to match...over flowing with so many ideas that they impede follow through. I try to select the best to work on, and for me easiest is a big part "best". Living down here has really stimulated my outside the box thinking, since for DIY here you not only have to look outside the box, but around the corner too. The exact item I want is rarely available and since I'm not big on patience I find things to repurpose instead of ordering online.

To me every ebiker dreams of solar charging their batteries except those who live in typically overcast locations and Dogman. He lives in the desert, so you'd think he'd lead the way on solar, but he's anti-solar....I think jaded by solar scams targeting desert dwellers for years.

Precious few have tried solar panels with their ebikes, I think because common panels are so bulky and heavy for the amount of power they generate. While you can look at the cars for solar challenge races and see that continuous running under solar power isn't practical, our ebikes spend most of the time parked. That means we just need a fold out solution that's thin, light, and rigid enough to make a portable solution.

Unlike a home solar installation a solar charger for an ebike isn't about the economics vs charging from a wall plug. It's about freedom, and since utility co's are also The Man, the idea of being completely off his leash for transportation puts a smile on my face. Too bad thin film solar still hasn't come around, otherwise we'd just be able to wrap our bikes in the stuff, and carry a tube with a big ass panel rolled up inside to use when parked. A backpack with a solar panel sewn on to charge a cell phone just doesn't do it for me. Except as an emergency communication device I don't even like the damn things.

I've thought about and discussed this topic on ES for a few years, typically when someone wants to build an ebike for cross country trips. Now I think I've got the cells/panels to easily pull off what I talked about in those topics.

John

PS- Since I'm not going to use a BMS, I'll start a new topic about these cells. I did get a response about the specs and need to edit a previous post, but all the details will be in the new topic along with pics and testing. Wouldn't you know, just like when the wind dies as soon as you launch a wind turbine, I get a box of solar panels and wake up to a very unusual morning...overcast and "pelo de gato". That's cat hair rain, more like a mist than actual rain.

John in CR said:

Thanks Harox, but don't use those kinds of words. My head's often bigger than it deserves to be.

Click to expand...

OK i won't use the G word and you let me talk in 3. Common sense make sense, and it comes by about a third at a time. You build your system to a rule of thumb, to a standard. There's no kinky stuff in this system. It's a standard, internationally. It's already easy fruit to make jelly out of. Talking twelve here as in 12V.
1got a problem with too much power generation? throw the bed sheet on it. done.
5 need a buffer, a jumper, a UPS type thing? Yeah, it's a box as well, and all the stuff in it is small parts too. so end of "standards" subject here.
12V is the rule in 3rd world, know mean?

John That BMS-less circuit is good, too. I know it is.
You wrote...over flowing with so many ideas that they impede follow through"
Do you use a balloon drawing to focus everything together?
I string qualifiers, "who what where why when how" and run them through my IF THEN speculations, and sometimes that breaks down the obstacles. You probably do. It's outer box thinking. Your panels are
in a transient stage of production. I would have missed that. Good thinking.
A mind numbing circle, chasing the sun. The exposure, daily, is finite.
I say, if you can get 2/3rds of a can stored in a day, what say you have after six days? Four cans.
Do you have to babysit the connection, or has it been potty trained so to speak?
Are the cans portable? Make it easy to use the can, too.
All that and more could be part of it.


BTW since I have things to say, I'll confine here, b/c I already butted in over here, John, and you've been gracious, and i don't take up much room here.

not pushing any buttons; not safe at any speed

The power from a panel is .75A in this case. That's all I see, the flow, no different from seeing the flow at the bottom of the Hoover Dam. I still see it.
When the sun is shining where the panel is tilted towards it, the sun causes some voltage to occur, in this case.
Both are examples of a power becoming something dynamic, small or large. It can grow into being more, if the power is not used, and once thrown out to the ground it is dissipated.
Your job seems to be to get something from up there, to run through this, and be stored thusly in that, so it can be dissipated at a later time, for some duration and at some amplitude with some frequency.
easier said than done, and it's not going to happen until the idea runs the gauntlet of proof. Thank your stars it's a simple approach.
I think you want every last ampere you can get, and a suitable gang of batteries to jockey it through.If all I see is .75A, then, that's what it is. It could be more, and you'd get different results.
Just remembering, the first part of any charge is the steep part. Then follows the plateau. Then the float. Then the discharge. If you can discharge the float amount to suit your needs, okay. If you have to run it back down, okay. Just be ready soon after, to run back up again, to pump back up again, to charge back up again.
Using a high amperage steep burst to charge is like boiling water. Then comes the grains of rice. Then it levels out and sometime later, you got rice pudding. That's what you want anyway, a great charge. Anything less than a great charge will abuse an otherwise great battery pack. I really think you will get great results if you adopt such a system. The race guys might be right.

When the thread started I was hoping that the BMS controlled the charger. It still might work, but I don't have BMS's on any bikes to try. Fechter is great, so I'm sure it will work....gotta get some parts to find out. In the meantime, I'm doing baby sitting, a few panel adjustments to maximize the charge, and the fiddling with them helps me get a good grasp on the issues to hopefully end up with something slick and safe for the structure of the portable rig. Lethal voltage requires a different level of care than a 12V system.

The kids ebike with a small pack was at about 40% DOD, so it was done at noon. Then I put mine back on the charger. It will be full tomorrow if I use my cargo bike in the am. I gotta get busy on figuring out the structure and get all my modules into service. If I'm lucky I won't have to plug in until dry season ends in April/May.

No drawings or notes to organize and prioritize. That would end up as another pile on the desk. I just keep everything in RAM for instant access to analyze and improve. I float some on the forum in case someone wants to take it and run with it, or for feedback, or to solicit help in areas I'm weak.

I'm not dropping the portable thing, but I have lots of cans including nearly 10kwh just idle. I run a standardized voltage that works for both lipo and lifepo4, so where I'm headed is one big can at the house. I've got the space to keep it separate from the dwelling...no fire risk despite risk of fire. I want to connect all ebike packs to the big central can, and right now I'm trying to resolve how to connect a partially depleted pack directly to the can for charging....all cans kept at the same voltage, so no conversion losses. I think I can get charging losses below 10% that way too. There will be some loss, since I have to somehow slow down the current flow during charging. A variable faucet on that charge connection would be nice for those rare occasions I want a quick charge.

Then I do a main solar panel for the house, most likely with tracking, to keep the big can charged. Almost immediately I can cover my transportation energy and add some lighting for the house using LEDs I got from my new LED manufacturer contact. Then as I add solar capacity I can switch the household needs over to the solar system. We don't have or need air conditioning or heat, so the electric bill is only $100/mo. This wouldn't be something to save money, just for satisfaction.

John

HAROX said:

The power from a panel is .75A in this case. That's all I see, the flow, no different from seeing the flow at the bottom of the Hoover Dam. I still see it.
When the sun is shining where the panel is tilted towards it, the sun causes some voltage to occur, in this case.
Both are examples of a power becoming something dynamic, small or large. It can grow into being more, if the power is not used, and once thrown out to the ground it is dissipated.
Your job seems to be to get something from up there, to run through this, and be stored thusly in that, so it can be dissipated at a later time, for some duration and at some amplitude with some frequency.
easier said than done, and it's not going to happen until the idea runs the gauntlet of proof. Thank your stars it's a simple approach.
I think you want every last ampere you can get, and a suitable gang of batteries to jockey it through.If all I see is .75A, then, that's what it is. It could be more, and you'd get different results.
Just remembering, the first part of any charge is the steep part. Then follows the plateau. Then the float. Then the discharge. If you can discharge the float amount to suit your needs, okay. If you have to run it back down, okay. Just be ready soon after, to run back up again, to pump back up again, to charge back up again.
Using a high amperage steep burst to charge is like boiling water. Then comes the grains of rice. Then it levels out and sometime later, you got rice pudding. That's what you want anyway, a great charge. Anything less than a great charge will abuse an otherwise great battery pack. I really think you will get great results if you adopt such a system. The race guys might be right.

Click to expand...

The .75A is just the first 3 strings. I have modules for 10 strings, and will have more on the way before the Chinese new year. I've got 500W of 6x6 raw cells and some of the supplies to build them out. I need to horse trade those away in favor of a less labor intensive solution. Unless I can talk/pay them into some interest in building them out. I can't get to the voltage I require though, so I'd need even more....Harold, let's make a deal.

The voltage of these new modules ended up perfect for 5s to match my packs. Once the pack got to 80V, current started tapering off. Someone's looking over me on this, because I couldn't have asked for a better match. ie No wasted panel area and with the simple rig I get max power.

John