Golf Cart Preliminary Test with Four HQST 12V 100W Solar Panels

[Delmar]

Laughably unscientific test only as a learning experience, and ensuring the panels work before installing. Was a nice 85F south Texas day with a decent breeze, should provide some panel cooling. Panels were new out of the box, very first time exposed to sunlight.

Connected the four panels in series. Was chicken to test short circuit amps, open circuit voltage at start of test measured 73V. I have a SCC however for the preliminary test I did not connect. Had old nasty jumper cables to connect the panels direct to the battery. Not the best of connections but it worked.



Batteries are six @ 8V Trojan FLA that came with the cart, unknown age or condition. Do not have a hydrometer as I plan to replace with Nissan Leaf when they die. So far are doing very well for my usage. Prior to testing drove the cart around the neighborhood to discharge the battery. Resting voltage at start of test 49.95V.



The first hour I forgot to zero my clamp meter (duh!) so the early amp readings were artificially low. I constantly adjusted the panels to maximize the charge amps. Last reading is resting voltage 51.67V. I then connected my wall charger and it showed +80% full and only charged for a few minutes before going into float.

Had a self-imposed cutoff at 58V but the batteries never reached that level. Still am debating whether to install the SCC as the cart is stored under cover, and only will charge when under load (either driving or powering my UPSverter). Will use a 10A breaker to switch off for safety.

Was extremely surprised and happy to see the panels charged the batteries in three hours. Still am scratching my head over the 3PM spike in battery voltage. Any thought or insights would be appreciated.

 

[MisterSandals]

I have a SCC
...
Still am debating whether to install the SCC

I've said this before... its never a good idea to hook panels directly to a battery.
Why would you not use an SCC that you already have?

Regarding the 3pm spike: did you check individual cell voltages? If one of the batteries has diminished capacity, it could have a rapid voltage increase, especially at extremes of the battery's voltage range.

Are you going to mount any panels on the roof of the cart? I was expecting your OP to head that way.

 

[Delmar]

Thanks for the insights. Responses:

SCC: My plan is to repeat the test next weekend using the SCC and compare results. Objective is to learn solar, and that includes learning the hard way. I have no problem trashing the old FLA battery set as a learning experience. It appears the panels do not have enough capacity to overcharge the battery, but have way more power than I first expected.

3PM spike: Next week will record the voltage of each 8V battery but cannot access each cell. When one battery is unusable will replace the set with Leaf.

Still designing a tilting roof mount for the panels. However reinforcing the uprights to withstand side-side shaking while driving is a challenge.

Also plan to purchase a 2nd set of four panels for use during extended grid-down, and cloudy days after a hurricane. Will tie to the cart during UPSverter usage. Want enough capacity to run my fridge for multiple days.

 

[Silentpower]

Hi, to know the condition of your trojans, which are high end batteries, when you are in a position to charge them properly, do a capacity test. It would be a shame to trash batteries like those as a learning experiment.
Ask away if you have any questions, I have experience with lead acid traction batteries, I used to have a job looking after milk floats here in the UK. ??

 

[waktaylor]

so when i learned to drive i drove straight for a fence post to make sure i understood the brakes. i didn't use the brakes, but instead smashed the fence post so i could use my brakes on the next car. hard way wins every time.

Are you mounting these to the golf cart? We are adding a few panels to my friend's electric john boat. Shade for Sunny day on the lake and extra range.

 

[JoeHam]

C’mon man, take two minutes to hook up the SCC already.

 

[Delmar]

Yall need to calm down a bit. Please consider:

• The solar panels are undersized for the battery capacity.
• The cart is mobile and can easily moved out of the sun, and is always stored under cover.
• I will connect the SCC and duplicate the test for comparing results. Objective is to test if the SCC measurably reduces the panel output.
• The SCC will be permanently mounted onto the cart and connected for normal driving usage.
• If indeed I measure the SCC reduces the panel output, I will only bypass during extended grid-down while running my UPSverter.

I would never intentionally trash the FLA batteries. During the above test I took readings every 10 minutes, and when the voltage approached my self-imposed 58V cutoff was continually monitored. I was ready to pull the plug. After disconnecting the resting voltage was only 51.67V. The FLA batteries are a learning experience so I don’t do anything dumb(er) with the future Leaf replacements.

The cart tilt-mount is almost complete and I will post an update soon.

 

[waktaylor]

I was just messing around. Looking forward to seeing more.

The cart tilt-mount is almost complete and I will post an update soon.

 

[Roger S]

How will the normal AC charger be connected? I am going to do much the same to my 36 volt cart. Unfortunately the solar alone will not provide the complete power needs and I will still need to charge the cart with the battery charger. I don't know too much about the solar charge controller, will it be damaged by charging the cart with the normal AC charger?

 

[MisterSandals]

I am going to do much the same to my 36 volt cart.

If you start your own thread, add info about your equipment and goals, we'll be able to help you out without hijacking this thread (i know you're mostly doing the same but we're on the edge).

 

[Delmar]

I have a Delta-Q 18A charger that came with the cart. Supposedly there are 10 charge profiles so can change for the lithium batteries. Neither will be connected at the same time.

 

[Red Squirrel]

Wait,did you seriously connect the panels straight to the battery? This is very dangerous. There is no voltage control that way and you risk overcharging and damaging the batteries without having to closely monitor it. You are also not achieving maximum power point that way. You need a proper MPPT charge controller to regulate the voltage to proper charge, but also to harvest power from the panel at the right "point" as to get the most watts. You can't just connect solar panels straight to a load.

Panels on the roof of a golf cart is not a crazy idea though, would provide shade too while driving or hanging around the cart and probably provide a decent amount of charge for the batteries as under typical use a golf cart is not really driving non stop.

 

[Roger S]

If you start your own thread, add info about your equipment and goals, we'll be able to help you out without hijacking this thread (i know you're mostly doing the same but we're on th

If you start your own thread, add info about your equipment and goals, we'll be able to help you out without hijacking this thread (i know you're mostly doing the same but we're on the edge).

Sorry, I tried that the other day, the advise I got did not really pertain to my question. Sorry I rained on you Parade!! Don't Worry wont happen again! I'm outta here!

 

[Delmar]

Sneak peek of the tilt-mount installation so far. Will post an update when the wiring of the panels and SCC is complete.

 

[waktaylor]

Wayne Szalinski may want to race you

 

[namesgolden]

I'm looking for a electric golf cart to do something similar to this. ordered this mppt BOOST converter to play around with til I find one.

 

[Delmar]

I am officially ready for Cristobal. The MakeSkyBlue SCC was about as dummy proof as you can get, just fastened to the underside of the roof and terminated the wires. It is voltage sensing and preconfigured for FLA and AGM batteries. Did not have to configure a single parameter.

The MakeSkyBlue has a cooling fan that only turned on during initial bootup. Observed the highest amp reading of 6.5A from the 400W of panels.

 

[Delmar]

your batteries were full I take it?

Not sure, my family was over on Saturday so the cart had unusually heavy usage. I had minimal time to observe but did see the SCC go into absorption mode once. Can't recall if it went into float mode, but will monitor more closely today.

...when it produces 400 of 400, the fan will be on a lot.

The SCC is rated for 40A and I doubt the panels will generate over 7A. Then again the fan is programmed to go on at 113F and in hot August won't take much to hit that temp.

 

[Delmar]

Way different than PWM or other mppt chargers I tried. Very fast tracking

I watched a couple of your YouTube videos and saw you have experience with MakeSkyBlue. Their manual is sorely lacking, the only downside of the SCC.

What does this screen indicate? Panels were producing 59V at 4.8A which equals 0.28kw. Or is 1.7 actually kWHours generated since I installed the system?

 

[Delmar]

Cart has not used the wall charger since Friday overnight. Heavy usage on Saturday, and without any usage today by 12:30pm already went into absorption mode. Impressive. The Acc screen now displays 2.1 so assume is 2.1 kW hours generated in 1.5 days.

I now have three forms of 48V charging available (wall charger, UPSverter and solar panels). Debating getting a new battery pack for the cart and keeping the good used set for stationary UPSverter usage. Look for my future breaker panel mod posting in Danger Zone!