Solar Panel to charge a 52v 13.5 ah battery pack?

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TannerL22   1 µW

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Solar Panel to charge a 52v 13.5 ah battery pack?

Post by TannerL22 » Jul 08 2016 2:07pm

I'm looking to buy a solar panel to charge an ebike battery pack with. I don't want to build my own and was looking more for something like a Goal Zero type deal. I just don't know what specs I need to be able to use it on said battery. Thanks for help

titusmc   100 W

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by titusmc » Jul 14 2016 12:58pm

I've been experimenting with charging my own 52V 20Ah pack using 2 50W flexible panels by HQST in series (https://www.amazon.com/HQST-Monocrystal ... words=hqst) through a 900W Boost Converter (https://www.amazon.com/gp/product/B01E3 ... UTF8&psc=1). It seems to work very well.

Basically, the panels in series output about 36V, which needs to be stepped up to 58.8V by the boost converter. Then you just set the current limit to whatever the panel/battery can handle - with such small panels you're basically just setting the current limit so the panel isn't saturated because the battery can take far more current than the panel will be able to produce. If you were charging with a larger solar array or had a much smaller battery, then you would limit the current to what the battery can handle.

I've found that a sheet music stand makes an excellent mount for these flexible solar panels.

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by titusmc » Jul 15 2016 7:06am

FWIW -

Last night I used that 900W boost converter to charge a 14S (58.8V full) pack from a 10S (42V full) pack and had a power meter on the input and output.

Ignore the "energy" number - the meters weren't connected the same duration. What's important to me here is the efficiency.

268.4W out/288.1W in means that the converter is ~93% efficient (at 5A). To me, that seems rather impressive.
boost.JPG
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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by titusmc » Jul 20 2016 7:10am

The meters I used are these: https://www.amazon.com/gp/product/B017F ... UTF8&psc=1

I also can recommend the "800W MPPT Boost converter" on eBay. It does appear to continuously vary the current limit to achieve more power in low light - I don't know how to prove that it is actually an MPPT algorithm, though.

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by titusmc » Jul 30 2016 3:58pm

Just thought people might be interested in this MPPT Solar Boost Charge Controller on eBay (http://www.ebay.com/itm/LCD-MPPT-Solar- ... SwZ8ZW9OVV).

Image

I just received mine in the mail today and while it isn't sunny enough outside to play with my solar panels, I decided to hook it up to a 36V (10S) battery I have and use it to charge my 52V (14S) battery. I have done this many times with normal boost converters. To my surprise, however, I noticed that with this "MPPT Charge Controller" the output current drops (in CC mode) as the input battery voltage (what it believes to be a solar panel) slowly falls. A normal boost converter with no MPPT algorithm would not do this. This makes me optimistic that the device actually does implement MPPT.

I'm interested in what others think of this as a way to "prove" an MPPT device.

As soon as I get some good sun I'll of course try it with real solar panels.

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by memy » Aug 15 2016 7:46pm

Hi titusmc how did you go with this MPPT?

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by titusmc » Aug 16 2016 12:59pm

memy wrote:Hi titusmc how did you go with this MPPT?
I have had an excellent experience with this MPPT charger so far. I actually was pleased enough that I bought a second one. The best info regarding it I have found is a 3-part review on Julian Illet's YT channel (https://www.youtube.com/watch?v=mM6JTquNSZU). Part 3 is especially helpful in getting the settings right.

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by memy » Aug 18 2016 12:22am

titusmc wrote:
memy wrote:Hi titusmc how did you go with this MPPT?
I have had an excellent experience with this MPPT charger so far. I actually was pleased enough that I bought a second one. The best info regarding it I have found is a 3-part review on Julian Illet's YT channel (https://www.youtube.com/watch?v=mM6JTquNSZU). Part 3 is especially helpful in getting the settings right.
Thanks, Found that after I posted question. :) , think I have seen Julian before reviewing some fake MPPT's.
So I ordered one. :D
Hope it does well with 2X250W panels in parallel, boosting the Optimum power voltage of 30volts to 55 volts.
Happy days if they are reliable.

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by titusmc » Aug 18 2016 6:10am

memy wrote:Hope it does well with 2X250W panels in parallel, boosting the Optimum power voltage of 30volts to 55 volts.
Happy days if they are reliable.
I have used it with 2 100W panels in series boosting from 36-ish volts to 58.8V and it does a great job (I have seen it push 172W into the battery from that setup in perfect sun!). I'm getting another 100W panel soon 8) .

Make sure you set it up like in Julian's video to remember the settings, otherwise it will get screwed up when a cloud passes over.

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by titusmc » Aug 21 2016 9:55am

It's worth noting that although this converter is rated at 10A, that is 10A max on the input, not output. So, if you are charging a 58.8V battery from 12V panels, you can only pull 120W maximum from the panels. I believe the top line voltage setting for the panels is what determines this, but I haven't verified.

Yesterday I had 300W of 12V panels in parallel hooked up and could only pull 1.85A at 58.8V (in absolutely perfect sun), which was confusing me at the time. This morning, I realized...

12V*10A = 120 W input
58.8V*1.85A = 108.8 W output
108.8 W / 120 W = 91 % efficient

So, I'm hoping if I put 2 x 150 W in series (I have 2 100W and 2 50 W panels), I'll be able to pull much more current to the battery...

24V*10A = 240 W input
240*0.91/58.8 = 3.71A output at 58.8V

Now, the only complication here that I'm aware of is that a 12V panel actually has a maximum power point around 17-18V and not 12V. So, hopefully if the top line is set to 17V, the output current possible will be even higher.

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by memy » Aug 30 2016 9:18pm

Input limited to 10amps is a bit sad :(
If you tell the unit that your solar panel runs best at 17 v it should get a better power transfer.
Though series is a better plot, it won't need to work as hard at boosting.

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by Cephalotus » Sep 18 2016 9:35am

Buy this Genasun Boost MPP charger:

http://genasun.com/all-products/solar-c ... ontroller/

They are costly but excellent.

The money you pay for them can be easily saved on PV panels. Just buy a high quality and cheap standard panal at around 300W for rooftop installation. It will be much cheaper and also much better than any Goal Zero setup I know...

The MPT-7210A "charger" mentioned above is NOT a good solar charger. It has a horrible(!) MPP tracking and especially in cloudy conditions often refuses to charge at all (not because low input, but because it will not start MPP tracking). It's ok to charge one battery from another battery (with lower voltage) though but this is not what you want...

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by craneplaneguy » Sep 22 2016 10:40am

Cephalotus wrote:Buy this Genasun Boost MPP charger:

http://genasun.com/all-products/solar-c ... ontroller/

They are costly but excellent.

The money you pay for them can be easily saved on PV panels. Just buy a high quality and cheap standard panal at around 300W for rooftop installation. It will be much cheaper and also much better than any Goal Zero setup I know...

The MPT-7210A "charger" mentioned above is NOT a good solar charger. It has a horrible(!) MPP tracking and especially in cloudy conditions often refuses to charge at all (not because low input, but because it will not start MPP tracking). It's ok to charge one battery from another battery (with lower voltage) though but this is not what you want...
Exactly. And you'll have that high quality panel for the rest of your life. Locally, I'm selling 280 watt REC (brand) panels for $260.00 for one, $500.00 for two! That is so cheap, MUCH cheaper then I could BUY them just a few short years ago, it's a no brainer for me. Unless you really need the flexible ones, get a "real" solar panel. Going just a bit further, get a few of them, grid tie your home, and you're done! Now you can, in effect, solar charge your bike while fully realizing a long term payback on your investment for DECADES. Plus a tax credit if applicable! To me, there is nothing sadder then a solar panel sitting inside, not working, and being wired to a battery system with the charge controller is NOT working. In the 28 years I was off grid, I shudder to think of all the power I wasted, when
the charge controllers for my PV and wind systems were floating. Now, for the last 9 years, all my power is saved in the grid and/or used, none wasted. Rant over :shock:

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by memy » Sep 25 2016 3:31am


Exactly. And you'll have that high quality panel for the rest of your life. Locally, I'm selling 280 watt REC (brand) panels for $260.00 for one, $500.00 for two! That is so cheap, MUCH cheaper then I could BUY them just a few short years ago, it's a no brainer for me. Unless you really need the flexible ones, get a "real" solar panel. Going just a bit further, get a few of them, grid tie your home, and you're done! Now you can, in effect, solar charge your bike while fully realizing a long term payback on your investment for DECADES. Plus a tax credit if applicable! To me, there is nothing sadder then a solar panel sitting inside, not working, and being wired to a battery system with the charge controller is NOT working. In the 28 years I was off grid, I shudder to think of all the power I wasted, when
the charge controllers for my PV and wind systems were floating. Now, for the last 9 years, all my power is saved in the grid and/or used, none wasted. Rant over :shock:
Horses for courses. In my case I elaborated here https://endless-sphere.com/forums/viewt ... 2#p1214531

Confirmed the 7210 seems to be limited to 10amps in.
The 7210 set at 31volt input and 48volt output hooked up to 2X250W pannels (parallel) full sun. The 7210 lets the panel voltage drift up at about 300W going into the battery.
So max I have seen is about 320W on this setup, with the panels running at 33V rather than 30.4 volts where max power is meant to happen..
Have seen the 7210 have issues with shading (cloud) causing it to load down the panel voltage, hunt a bit and then give up. It then disconnects pause's and then starts ramping up the load on the panels again.

RE $260 for 280watt panels.. Just finished installing 4X250W panels on two sections of north facing roof, no more roof space left. ($160 AUD a panel new. Though I had to add some bypass diodes to the panels)
1.5Kw tied and now another 1000W that will probably be tied. (The 1500W just about covers the A/C in summer).

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by craneplaneguy » Sep 26 2016 7:32am

Got it memy, a whole different deal for your situation. Too bad they have such restrictive regs down there. Idaho Power, for now anyway, is amazingly easy to get along with, I'm spoiled! Off grid is your case makes perfect sense.

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by Syonyk » Sep 26 2016 10:30am

titusmc wrote:I'm interested in what others think of this as a way to "prove" an MPPT device.
Monitor input current/voltage and output current/voltage. If they don't match, it's MPPT, or at least some sort of converter.

The other type of charge controller is a PWM controller, which literally just connects the battery to the panels (or not). You'll see ~the same voltage on the input and output side (perhaps a slight voltage drop over the switch), and identical current.
Battery packs, Sunkko Welders, and more. http://syonyk.blogspot.com/

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by titusmc » Sep 27 2016 7:17am

Syonyk wrote:Monitor input current/voltage and output current/voltage. If they don't match, it's MPPT, or at least some sort of converter.
It's clear that it's doing a DC-DC conversion, but whether or not it is actually tracking the maximum power point is more difficult to prove.

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by Syonyk » Sep 27 2016 10:55am

Ah, true. I thought you were concerned about it being a PWM unit labeled as MPPT (which I believe exist).
Battery packs, Sunkko Welders, and more. http://syonyk.blogspot.com/

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by fcbrants » Jul 12 2017 1:01pm

Marissa Muller worked with Sunpower (IMO, one the best PV manufacturers out there & I sold solar for SolarCity, then for Sunpower) to set up a solar system, which included Genasun chargers, that helped her cross the country on an eBike:

https://www.marissamuller.com/rig/

Works for me...

I'm working with a member of the Genasun sales team to custom configure their GVB-8 Boost controller for my 52 V pack.

It's a new 52V 17 ah pack from Luna, configured 14S5P, and I believe the cell specs are close to the standard:

Nominal voltage: 3.6 V
Discharge end voltage: 2.5 V
Charging voltage: 4.20 +/- 0.05 V
Standard charging current: 1.25 A

I'm still fairly new to all of this, but if I only wanted to take the pack to 80% using this charger, then should I ask them to configure it to 47 V, as follows?:

Charge Voltage = 4.2 V * 14S = 58.8 V * 80% Desired State of Charge = 47.04 V

Is that correct? That seems pretty low.

I gave it a little thought & realized that it wouldn't make sense to order a $250.00 non-configurable solar charger to put out anything less than 100%, so I ordered two chargers set for 58.8 volts.

Is that that the correct charge voltage?

Thanks!!

Franko
Cephalotus wrote:Buy this Genasun Boost MPP charger:

http://genasun.com/all-products/solar-c ... ontroller/

They are costly but excellent.

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by Hillhater » Jul 12 2017 8:35pm

47.04v on a 14s pack is a DEAD pack at 3.3 v per cell !.... So obviously that is no good.
An 80% capacity charge on that pack would be at approx 56v (4.0v per cell) and a good safe charge level for long life.
58.8v will give a 100% charge at 4.2v per cell, but is not recommended for maximum cell life or storage periods.
But Its fine for a daily charge just before use to maximise range etc.
This forum owes its existence to Justin of ebikes.ca

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by fcbrants » Jul 12 2017 8:44pm

Thanks Hillhater, I appreciate the info, and thanks for the reminder that "This forum owes its existence to Justin of ebikes.ca" It looks like he's carrying some parts that I need.

Would you mind sharing how you calculate these numbers?

Thanks!!

Franko
Hillhater wrote:47.04v on a 14s pack is a DEAD pack at 3.3 v per cell !.... So obviously that is no good.
An 80% capacity charge on that pack would be at approx 56v (4.0v per cell) and a good safe charge level for long life.
58.8v will give a 100% charge at 4.2v per cell, but is not recommended for maximum cell life or storage periods.
But Its fine for a daily charge just before use to maximise range etc.

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by Hillhater » Jul 12 2017 9:44pm

Sure !
Remember battery capacity is measured in Amphours not volts
As you stated the cell voltage range is 2.5-4.2v with a nominal of 3.6v.....but capacity is not linear with voltage, with most of the capacity available between 3.0 and 4.1 volts ( see some of the "capacity mapping" threads for detail)
So at 47 volts the pack (3.3 volts per cell x 14 series = 47v) is close to empty capacity wise.
But a 14 series cell pack at 4 volts each, will give a pack voltage of 56 volts ...likely 85-90% full capacity depending on the exact cell type.
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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by amberwolf » Jul 13 2017 1:02am

fcbrants wrote:Charge Voltage = 4.2 V * 14S = 58.8 V * 80% Desired State of Charge = 47.04 V
Needs an extra step; it's not 80% of the total voltage, it's 80% of the difference in voltage between full and empty.

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by fcbrants » Jul 13 2017 2:40am

Thank you both for the info!!

Franko
Hillhater wrote:Sure !
Remember battery capacity is measured in Amphours not volts
As you stated the cell voltage range is 2.5-4.2v with a nominal of 3.6v.....but capacity is not linear with voltage, with most of the capacity available between 3.0 and 4.1 volts ( see some of the "capacity mapping" threads for detail)
So at 47 volts the pack (3.3 volts per cell x 14 series = 47v) is close to empty capacity wise.
But a 14 series cell pack at 4 volts each, will give a pack voltage of 56 volts ...likely 85-90% full capacity depending on the exact cell type.
amberwolf wrote:
fcbrants wrote:Charge Voltage = 4.2 V * 14S = 58.8 V * 80% Desired State of Charge = 47.04 V
Needs an extra step; it's not 80% of the total voltage, it's 80% of the difference in voltage between full and empty.

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Re: Solar Panel to charge a 52v 13.5 ah battery pack?

Post by amberwolf » Jul 13 2017 3:11am

BTW, to be more specific, to get the rough charger end voltage for 80% of the voltage of the battery, it's 80% of the difference in voltage between empty and full, added to the empty voltage.


However--if you want actual 80% of charge state, you have to know which cells are in the pack, then look at the actual cell specification sheet, which has a voltage-vs-state-of-charge chart. Then find 80% on that particular chart, and multiply by the number of series cells. Then use that for the charger's final voltage.


Just keep in mind that if you don't at least periodically charge to the full voltage, the BMS probably won't balance the cells. It won't matter if they're really good cells that are well-matched and used well within their specifications and not run down too far; if they stay balanced there's no worries. (but it would require manual checks to find that out).

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