charge controller recommendation request

mscir

My neighbor recently bought an *Ecoworthy 120W solar panel w/charger kit from Amazon to power a **Lithium Power Station that can be used to run a laptop or charge phones or other devices over usb. Her battery charges completely from being nearly dead in 4 or 5 hours on AC power, but in direct sunlight it only charges about 75% after a full day's exposure to the sun (in California with long, clear days). Also she said the charge rate indicator used to read at the highest level but now even in direct sunlight with the solar panels cleaned and soldered wire joints everywhere it never gets above half. She wants to replace the charge controller. I suggested she return the unit but since the wiring is altered (from alligator clips to soldered connections) the warranty is void.

I'd be appreciative hearing any comments on these points:

- a source for a high power resistor I can connect to the output of each panel to measure the power output, each panel is listed at 60W.
- a procedure to test the charge controller
- are these controllers worth repairing if I find that it is defective? 
- recommended robust replacements if the controller is found to be bad.

*ECO-WORTHY 120 Watt 12Volt Off Grid Monocrystalline Portable Foldable Solar Panel Suitcase with Charge Controller
https://www.amazon.com/ECO-WORTHY-Monocrystalline-Portable-Foldable-Controller/dp/B01M4NH9ES?pldnSite=1

**SUAOKI Portable Power Station, 150Wh Camping Generator Lithium Power Supply with Dual 110V AC Outlet, 4 DC Ports, 4 USB Ports, LED Flashlights
https://www.amazon.com/Portable-Station-Generator-Flashlights-Emergency/dp/B076PR4TBZ?pldnSite=1

Thanks,
Mike

mcgivor

To test the panels current output short the leads whilst under full sun and measure the current, a suitable meter  will be required such as a DC clamp on ammeter.

The unit has an on board MPPT charge controller which converts the source power, AC adapter, car battery or solar panel, if the AC adapter works then the controller works.

Probably not worth repairing, they are a disposable type applience.

Since the internal MPPT and BMS would be designed to work with each other modification with another charge controller is something I would not recommend, lithium batteries require very precise charging to prevent damage, not knowing what the BMS requirements are would further complicate matters.

The description says it takes around 8 hours of solar to fully charge, most locations get much less, usually 4 to 5 hours, so it may need a second day to reach full capacity, without loads between or during charging.

mscir

mcgivor said:

<snip>
"The unit has an on board MPPT charge controller which converts the source power, AC adapter, car battery or solar panel, if the AC adapter works then the controller works."

Are you referring to the charge controller on the Lithium Ion battery device? I apologize for not being clear, it is the charge controller on the solar panels that I wanted to test. There doesn't appear to be an AC adapter on the solar panel charge controller.

Thank you for your reply,
Mike

mcgivor

mscir said:

mcgivor said:

<snip>
"The unit has an on board MPPT charge controller which converts the source power, AC adapter, car battery or solar panel, if the AC adapter works then the controller works."

Are you referring to the charge controller on the Lithium Ion battery device? I apologize for not being clear, it is the charge controller on the solar panels that I wanted to test. There doesn't appear to be an AC adapter on the solar panel charge controller.

Thank you for your reply,
Mike

Tha Ecoworthy setup would need a lead acid battery itself to work, it needs power from the battery to operate and reference a 12V nominal.
How do you have it connected? 

mscir

Are you saying the Ecoworthy is not a good choice to charge the camp generator LIon battery?  The camp generator specs literally say "3 Ways of Recharge- Recharge from the sun by connecting a compatible solar panel (charging time depends on the output of solar panel)"
 https://www.amazon.com/Portable-Station-Generator-Flashlights-Emergency/dp/B076PR4TBZ?pldnSite=1

Estragon

It looks to me like the lithium thing is designed to be connected directly to a 12v nominal (~18vmp) panel, not through a charge controller designed to charge a nominal 12v battery.  From the description, it's hard for me to tell exactly what the lithium thing is doing, but that it has mc4 connectors implies connection directly to pv, not through a charge controller.

If I'm understanding this right, you essentially have 2 charge controllers in series (1 with the suitcase thing, and another in the lithium thing).  I don't know if that could damage something, but it could certainly mess with battery charging.

If the lithium thing is designed to be hooked up to the solar panels directly, I'd try doing that and see what happens.

If the 12v suitcase controller is seeing ~5v at boot, it may not be in a happy place.

littleharbor2

Depends on a couple things. What do you connect the battery and solar panel with? The solar panel shown has alligator clips. What do you connect them to? Does the battery come with a solar panel connector?  
What is the voltage requirement and limits for the battery? There isn't much info in the link here. Sounds like you might be better off buying the optional solar panel from the battery maker.

mcgivor

This link describes in more detail the input requirements https://www.suaoki.com/products/portable-power-station-s270 PV input 30W minimum 13-22V. The Ecoworthy panels would work but the controller would have to be removed from the circuit, 

mscir

I'll see if the owner will let me bypass the solar panel charge controller and connect the panels directly to the battery. I'll post back any results, thanks to everyone who replied so far, this makes good sense.

mscir

Taking another look at the hardware, something I should have done at the start (apologies for wasting everyone's time) each of the two solar panels puts out a max of 3.12A and operating in parallel the max current coming from both is 6.24A, while the input to the battery pack says 2A max, I think the panels were supplying too much current and it was doing a (charge - overheat - shutdown) - (charge - overheat - shutdown) loop. The battery doc's do say it has some sort of protection built in.

I disconnected one of the solar panels, then blocked off portions of some of the cells with black construction paper to lower the output current, just by experimentation we got the charge indicator on the battery pack to flash exactly the way it does when it's charging from the 120VAC adapter. My reason for doing that was that the banks of solar cells are wired in series, so limiting the current coming through one or more of them will limit the current coming from the whole panel, and since I don't have an ammeter, getting the charge indicator to act similarly to the way it acts on the AC charger seemed like a good first step for proof of concept.  I guessed that there are two banks of series cells so I blocked off parts of one group of cells on each one to try to limit the current through each set of cells. The owner is bright and understands the series current concept, so she'll take construction paper and tape with her on her camping trips to adjust the charge rate.

My question now is - is it advisable build a 1.8A current limiter to go on the output of the solar panel so we can stop messing around with blocking off parts of the solar cells? (1.8A so I'm not at the max spec'd 2A input current).

mscir

I looked at the hardware again, the owner  had more time for me, and found that the two solar panels each have a 3.12A max output, so in parallel that's 6.24A. The batter pack they're charging says 2A max for the solar or ac adapter input.

When hooked up to ac power the adapter charge rate indicator acts normally, when hooked up to the solar cells the charge indicator appears to go into a charge - turn off - charge - turn off kind of loop.

I guessed that we were overdriving the batter charge controller so I disconnected one solar panel, and blocked off sections of solar cells on the connected single panel to reduce the current. By trial and error I could replicat the battery charge indicator behavior.

I blocked off cells because if I understand it correclty, some solar panels have cells or banks of cells wired in series, so limiting the current in one section will limit the currnet of the whole panel. This appears to be the case based on the batter charge indicator behavior.

My questions now are
- is it possible that the battery charger could be overdriven by 6.24A 30V?
- is it time to build a 1.8A current limiter so we don't have to use construction paper?

If the current limiter sounds good, does anyone have suggestions of where I can find plans for one, schematic, parts list?

mcgivor

Something to ponder, buy a small panel ~30W and use for the lithium pack.
Buy a 12V deep cycle battery ~ 45ah and use with the Ecoworthy, that way both devices are working as designed and two sources of power would be available, the latter being of greater capacity.

mscir

mcgivor said:

Something to ponder, buy a small panel ~30W and use for the lithium pack.
Buy a 12V deep cycle battery ~ 45ah and use with the Ecoworthy, that way both devices are working as designed and two sources of power would be available, the latter being of greater capacity.

Yes, that is a great idea, it's up to the owner. Thank you.

mscir

Blocking off sections of the solar cells allowed the battery to charge normally. That seems to indicate that both the single and the pair of solar panel(s) had been providing more power than the LI battery device charge controller could handle. The owner doesn't want to purchase any more batteries or panels at this time, she is interested in a circuit that would limit the power going to the LI battery device. I'm not sure what to build if I want to limit the power going to the battery pack to 40W from the solar panel, do I need to build/buy a charge controller or is there simpler current or voltage limiter approach I could use?

mike95490

A post-it-note on the panel.    If that's been working, I'd keep on.   Eventually the panel bypass diode may die, and then you can buy the right size panel.

Tecnodave

Another approach would be to turn the panel so the sun hits it at an angle, reducing the light on the panel, or possibly using a sheet of common window glass as a light filter. Window glass contains iron and does not transmit light as good as solar glass or water white glass. By filtering light the diodes will not be stressed. Looking at the edge of the glass, if it's green it's window glass. Picture frame glass is water white so as to not distort images. Maybe even thin plastic. Mounting the panel vertical will reduce output, less area exposed to the sun. A 

mscir

I recommended she experiment orienting the panel at oblique angles. Also a semi-transparent fabric or plastic sheet might be really effective, and it would be light and non-breakable.

What do you think of something like this to cover part or all of the panel as needed?

12"X48" Light Black Headlight Fog Light Taillight Tint Viny Film Sheet Sticker
https://www.ebay.com/itm/12-X48-Light-Black-Headlight-Fog-Light-Taillight-Tint-Viny-Film-Sheet-Sticker/360764909679

Thank you for your suggestions.