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Golf Cart Solar Trickle Charger - Failed Experiment ***NOW WITH SUCCESS***

ryankenn

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Aug 2, 2022
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Well maybe failed is a bit much, but highly ineffective definitely in the November sun here in Kingston, ON. This is a 36V cart and we use it from May-Oct at our trailer so its used Fri/Sat/Sun at most, and that drops it about 20%. The plan was to get a system that could trickle in 1A all week and it would be full again the next weekend. We have to pay a small fee every year to have the cart on site for charging so this was to remove that.

I used (4) what were AliExpress advertised 20W panels in series, and a generic controller that could handle 12/24/36/or 48V batteries. The panels output 18V, and I assumed I need more voltage so they could work. I tested and in series they put out 71.8V. Hooked up and on the direct sun I did see the controller putting in 37.8V and about 300mA for a few hours, but far less than I thought I would have gotten.

Don't know if its the sun at this time of year, or that the 20W is an inflated value for these panels but it seems like I need more panel. The issue is I have limited roof space. I have a spare CSP-260 that would fit, but its open cct voltage is 39V and I don't know if that, through this controller is high enough to successfully charge the batteries. During the charge the controller wants to put 41.4V into the batteries.

Does anyone make a small footprint 100W panel (or similar) lightweight or flexible panel that has the larger output voltage of a bigger panel? If I could get two panels 32x32 or something that had a higher output I could fit them up there.

Thoughts?

IMG_8322.jpgIMG_8323.jpg
 
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put out 71.8V. Hooked up and on the direct sun I did see the controller putting in 37.8V and about 300mA for a few hours,
37.8V x .3A = 11.3W

I thought those style of SCCs had a limit of 50V max input. 71.8V didn't let the magic smoke out so must be ok for more, ??
 
The ad and the label on it state 100VDC max voltage. I just checked and the panels are advertised as 30W, so obviously that's inflated. Maybe in the stronger summer sun they may work, just these days here the sun is low and only strong about 4 hours (when I saw 300ma).
 
Another solar golf cart...
 
Well maybe failed is a bit much, but highly ineffective definitely in the November sun here in Kingston, ON. This is a 36V cart and we use it from May-Oct at our trailer so its used Fri/Sat/Sun at most, and that drops it about 20%. The plan was to get a system that could trickle in 1A all week and it would be full again the next weekend. We have to pay a small fee every year to have the cart on site for charging so this was to remove that.

I used (4) what were AliExpress advertised 20W panels in series, and a generic controller that could handle 12/24/36/or 48V batteries. The panels output 18V, and I assumed I need more voltage so they could work. I tested and in series they put out 71.8V. Hooked up and on the direct sun I did see the controller putting in 37.8V and about 300mA for a few hours, but far less than I thought I would have gotten.

Don't know if its the sun at this time of year, or that the 20W is an inflated value for these panels but it seems like I need more panel. The issue is I have limited roof space. I have a spare CSP-260 that would fit, but its open cct voltage is 39V and I don't know if that, through this controller is high enough to successfully charge the batteries. During the charge the controller wants to put 41.4V into the batteries.

Does anyone make a small footprint 100W panel (or similar) lightweight or flexible panel that has the larger output voltage of a bigger panel? If I could get two panels 32x32 or something that had a higher output I could fit them up there.

Thoughts?

View attachment 122161View attachment 122162
Is that a PWM controller?
You might get better results with an MPPT SCC.

Also, flexible panels are much less efficient than glass rigid panels.
 
I may try that first. I just wish a 50W smaller panel could be had with standard MC4. All the ones I find are like these, they have a module with 5V usb outs which are stealing from my output.
 
I also just discovered Boost Controllers are a thing. Guess I should have read up on that first because that's what I need. I could get two flexible 100W panels at 12V and that would charge the 36V pack. Whoops. Lucky I only paid $16CAD for that PWM controller. I think I will get the boost controller as it gives me way more choice of what I can buy for the roof.
 
I also just discovered Boost Controllers are a thing.
Happen to have a link to this?

I could get two flexible 100W panels at 12V and that would charge the 36V pack.
Aren't there higher voltage 100W panels?
"12V panel" is a marketing term for a ~18Vmp solar panel.
If you got "24V panels", 2 of those in series (sum the voltages) should produce a high enough voltage for PWM or MPPT SCCs to charge a 36V battery.

36V batteries are a bit of a rarity in the solar world as far as i've seen.
 
You might want to try disconnecting one of the 3 panels and see if you get more output with only 3 in series. PWM controllers do a decent job of charging if the panels are matched to the voltage of the batteries. My guess is in fall and winter you should see slightly less than half rated output from the panels in “full” sun with a MPPT controller but when you operate the panels way outside of their max power point their output could be 1/4 or less than rated output in the same conditions. Thus with a pwm controller you might possibly get much more output from 3 panels than 4.
 
I will try that. I retained the connectors they came with so its easy enough to bypass one.
 
Well with 4 weeks of the season at our campground under my belt its time to call the updated design a big success. I bought a single Dokio 100W panel off Amazon for $100 CAD (https://www.amazon.ca/dp/B074DZNN8T?psc=1&ref=ppx_yo2ov_dt_b_product_details) and a Boost charge controller from Ali Express for $36CAD.

With this setup the boost charger takes the 18V and gives up to 42V to charge my 36V cart. Under optimal conditions I see 9A from the panel. It has had no issue keeping the cart topped up. We drive it Friday/Sat/Sun, and it will drop about 3 or 4 bars on the display (10 segment) and through the week when we return its full again.

Total cost with XT60 connectors and wires, maybe $200CAD to never plug it in. I love it.

IMG_0020.jpgIMG_0021.jpg
 
I have done two more carts at our trailer parks, both 48V and it seems to work just as well. One used my panel, one used a Canadian Tire Noma branded 100W panel, both seem to work fine. I think this setup is a really good option for part time cart use at seasonal parks. Means never having to plug in again.
 
Well with 4 weeks of the season at our campground under my belt its time to call the updated design a big success. I bought a single Dokio 100W panel off Amazon for $100 CAD (https://www.amazon.ca/dp/B074DZNN8T?psc=1&ref=ppx_yo2ov_dt_b_product_details) and a Boost charge controller from Ali Express for $36CAD.

With this setup the boost charger takes the 18V and gives up to 42V to charge my 36V cart. Under optimal conditions I see 9A from the panel. It has had no issue keeping the cart topped up. We drive it Friday/Sat/Sun, and it will drop about 3 or 4 bars on the display (10 segment) and through the week when we return its full again.

Total cost with XT60 connectors and wires, maybe $200CAD to never plug it in. I love it.

View attachment 151435View attachment 151437
9 amps from a 100w panel, that doesn't sound correct. The optimal amperage for this specific panel is around 5 amps.
I would check again...
 
Yeah its these Chinesiam Boost controllers. I have now installed 4 of these at our park, and the data they show is oddly presented. Its shows "B", battery voltage, which is accurate, "P" which they describe as solar panel power, but is actually solar panel voltage, and "C" which is described as charge current, but that number means nothing. It goes up and down but I took my clamp meter today and sure enough the panels are giving the full 5.5A at full sun, but the charge current the clamp sees is about 2.8A to the batteries, which is right. I don't know, but the only way to get close to the number its displaying is if you add the solar current (5.5) and the charge current (2.8), maybe thats what the display is showing.

Overall, still very happy with this setup. All I could wish for is a panel 5-6" wider, and 12" longer with a 150-200W output to speed it up.
 
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