Solar charger for 4 6v golf cart batteries LONG TERM?

[DiskDoctr]

After a few years of medical hiatus, moving camper to a semi-permanent spot on our property. Looking for reasonable setup to keep our 4x 6v golf cart batteries topped up.

Usage will be 1-3 days about 3-4 times per month. We will have a generator available if we take it.

Topping off batteries after we leave or if we are away for a month or two is the goal.

It is on top of high hill in SW Pennsylvania, so looking at solar.

Don't want to get the wrong "trickle charger" that kills the batteries prematurely. Also don't want to be required to stay extra (few hours?) to run generator after a stay, or require a "service trip" just to charge up batteries.

We would run off generator and/or 2k inverter from batteries during out stay, likely run coffee maker, microwave, etc in am and eve, which also runs our 4 stage charger.

Winter usage as well, so propane fridge and RV furnace that uses the energy gobbling fan. Likely an internet link and remote camera setup for security will run 24/7

2005 Cougar 33BHS

Thanks in advance.

[valhalla360]

Do an energy audit.
- Each device will have a watt rating (possibly amps @ volt rating which can get you to watts.
- Estimate how long each device will run.
- Multiply watts * hours (amp * volt * hours alternatively) to get to watt-hr.
- This is your consumption per day.
- Assuming 50% of the battery bank is usable for lead-acid batteries, so multiply the amp-hr * 12v * 0.5 to get usable watt-hr.

So by dividing usable watt-hr by daily watt-hr consumption, you have an idea of how long the battery bank (by itself) will last.
- If it's 3 or more days, you can charge while in storage which means a much smaller solar array. Or it can be much more convenient to run the generator once per trip.
- If it's below 2 days, you are looking at replacing the consumed power daily.

Solar: A good rule of thumb is for every watt of solar panel rating, you will get around 4w-hr of daily output (assuming clear view of the sun). So a 100w panel should generate somewhere around 400w-hr per day.
- If your daily consumption is 600w-hr, you need around 150w of panels, though I would round up to 200w. That way, if there is less than ideal conditions or you missed a bit of consumption, you are still covered.
- If you do have 3 days worth of battery storage and will rarely have less than 3 days between trips, you can divide the amount you need to replace after a trip by 3 and then make the same calculation...ie: if you are down 1200w after a trip, you need to replace 400w-hr per day, so a 100w panel should have you topped up before the next trip.

This is much better than randomly picking a solar panel size because it worked for someone else.

[DiskDoctr]

Thanks again 😉

[time2roll]

Polarity and sequence of connections is critical. I don't know Renogy except to read the manual and see what features each has. Watch the shipping cost on the large panels. Make certain the controller max input voltage is 120% of the expected panel Voc spec. Otherwise yes mostly mount, plug and play.

[DiskDoctr]

I found 2pc of 320 watt each 24v Renogy panels for $623 and
Renogy MPPT 60a controller for $305 or $439. Is the Renogy REGO worth the extra money?

Other than that just wiring and mechanical/mounting, right?

Thanks.

[DiskDoctr]

Thanks. I am going to look into a setup for 300w plus. Probably have to get a little at a time but might be a good idea to plan to run most things without the generator, too 😉

[Boon_Docker]

time2roll wrote:
For the effort I recommend looking at 200 to 600 watts mounted on the roof. Large home panels are best value and require an MPPT controller. May never start the generator again.

X2

[CarnationSailor]

I use the following 30-watt Renogy panel when my 5th wheel is in storage during our 5-month off season. Keeps our 4 6-volt batteries topped up.:

https://smile.amazon.com/Renogy-12-Volt-monocrystalline-Solar-Panel/dp/B07MZL3PSD/ref=sr_1_2?a=aps&crid=2ZOCD6UDMJSHI&keywords=renogy+30w&qid=1667764454&sprefix=renogy+30&sr=8-2&ufe=app_do%3Aamzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840

And I use this charge controller with it:

https://smile.amazon.com/dp/B004Q820UK/ref=redir_mobile_desktop?_encoding=UTF8&aaxitk=87975b49f0613849f129e63777bfaf4e&content-id=amzn1.sym.53aae2ac-0129-49a5-9c09-6530a9e11786%3Aamzn1.sym.53aae2ac-0129-49a5-9c09-6530a9e11786&hsa_cr_id=5773970610501&pd_rd_plhdr=t&pd_rd_r=b4298c85-1ad1-4321-8b70-5b0c037dd929&pd_rd_w=q9tZZ&pd_rd_wg=snbqr&qid=1667764695&ref_=sbx_be_s_sparkle_mcd_asin_0_img&sr=1-1-a094db1c-5033-42c6-82a2-587d01f975e8

It should do the job for the extended periods you mentioned; however, you may need a larger panel to bring the batteries to full charge between outings. This will depend upon how low the charge goes during usage and how many days you have before the next usage.

Good luck

[time2roll]

For the effort I recommend looking at 200 to 600 watts mounted on the roof. Large home panels are best value and require an MPPT controller. May never start the generator again.

[DiskDoctr]

Thanks for the info.

To clarify, I am not looking to run off the batteries, just finish topping off whatever we don't charge with the generator, and to keep them properly charged unattended.

Does that help?

[Matt_Colie]

Well Doc,

The only real thing to consider is how much you want to spend.

The problem is that the 1~3 Days 3~4 times a month looks a lot like continues to the house bank. If the 3 days comes right after the other 3 days, that is really tough for the sun to make up.

Were I in your place, I would start with as much PV on the roof as you can justify. Then shop the market for charge controllers. Those will be your not-so-secret weapon here. There are two basic types: Maximum Power Point Tracking (MPPT) and the industry-standard Pulse Width Modulation (PWM).

All of these are better than they were when I was working this market. If I was to try to recommend, the model would be obsolete by now. There are many that will do a good job of changing without damaging the bank.

Matt