New to RV and Solar - could use some guidance

[lennon_68]

So any votes on how I should proceed?

1. Keep the cheap PWM controller and both panels. Accept that I'm limited to 133W and spend more on copper for the wire runs (and more fuses I believe). Downsize to a 300W or 200W inverter.

2. Keep the cheap PWM controller and 1 panel. Downsize to a 300W or 200W inverter.

3. jflorey2 recommended the Victron 100V 20A controller. Can I get away with their 75W/15A with both panels (had it in my cart yesterday for $80)? If so maybe this is a route worth considering? Downsize to a 300W or 200W inverter.

4. Is there some other option that I should be looking at instead

5. (added later...) The amount of solar in my budget isn't worthwhile. Spend the money on a bigger battery bank and keep the 600W inverter (or even scrap that plan too). Charge the batteries by alternator or generator and call it a day.

[jflorey2]

So any votes on how I should proceed?3. jflorey2 recommended the Victron 100V 20A controller. Can I get away with their 75W/15A with both panels (had it in my cart yesterday for $80)?

Do the math here. Voc for the Grape panels is 22 volts. 22 volts * 2 in series * 1.25 for temperature variation = 55 volts so you should be OK with a 75V controller.

5. (added later...) The amount of solar in my budget isn't worthwhile. Spend the money on a bigger battery bank and keep the 600W inverter (or even scrap that plan too). Charge the batteries by alternator or generator and call it a day.

Not a bad option. The solar will make a good battery maintainer, even if it can't keep up with your energy needs.

[Sunking]

Thanks for the input! I did some digging and found that my battery is a Super Start 27DCM which I found information on in this thread suggesting it was 99Ah::

Stay away from that forum, they are making things up and do not know what they are talking about.

The battery in question is a hybrid Marin Cranking Battery. Note it only list Cold Cranking Amps, Marine Cranking Amps, and Reserve Capacity. The only useful number to get an idea of what Amp Hour Capacity is the RC specification of 165 minutes.

RC or Reserve Capacity is a measure of how many minutes the battery can supply 25 amps until discharged to 10.5 volts. So the first conversion is minutes to hours and 165 minutes / 60 minutes = 2.75 hours. So 25 amps x 2.75 Hours = 68.75 AH. I have clue how they came up with 99 AH other than just made it up.

Another conversion formula is RC x .4167 = AH, and 165 x .4167 = 68.7555 AH. Same as above.

As for me I am lazy, do not have the time to use calculators, so I do math in my head. Quick and painless formula. AH = RC / 2.4. so 165 / 2.4 = 68.75 AH. I make more money by not working so long and can move on to another job to make money. That is how I knew in 1 second the other forum is full of poop. I did not have to spend and waste any time calculating anything. Collect my check and move on to next job.

[Suprasoup]

Since you have the battery isolator: (I would look into upgrading to a quality one like Blue Seas ACR models. Get a larger battery.

As Sunking pointed out using 225AH golf cart batteries would allow you to retain your 600w inverter. 2 x 6v golf cart batteries are a worthwhile upgrade from a single group 27 battery. Most times just upgrading the battery is all most rv owners need to satisfy their energy requirements while out boondocking.

[lennon_68]

Thanks guys. A quick search shows that although you can buy golf cart batteries online you're much better off buying them locally as shipping is a real killer. Any recommendations on what batteries to look for or what kind of stores might carry the batteries I want locally? I see some recommendation for Trojan T-105 but I also see lots of other Trojan batteries with high Ah.

[SunEagle]

Thanks guys. A quick search shows that although you can buy golf cart batteries online you're much better off buying them locally as shipping is a real killer. Any recommendations on what batteries to look for or what kind of stores might carry the batteries I want locally? I see some recommendation for Trojan T-105 but I also see lots of other Trojan batteries with high Ah.

I have 2 x 6V 230AH Interstate batteries in my RV. They can be found at most automotive part places.

[Suprasoup]

Places that service golf carts. They go through batteries by the pallet. Never hurts to ask if you can purchase a couple. As far as brands, Trojan, US Battery and Crown i have had good experiences with.

[lennon_68]

Thanks again! Looks like if nothing else there's a place within an hour drive that services golf carts and has US Battery options for pretty reasonable. I do really appreciate the help. I realize all the questions I'm asking are easy and the math is easy but for someone like me that has no frame of reference it's a lot to take in and sort out.

If I do upgrade my battery bank is there any reason to keep the solar stuff I bought or am I best off to just try to return/sell it? I don't see myself dropping the coin to step up to a 400W solar array.

[Sunking]

Trojan and US Battery make the best.

[Guest]

We bought our first motorhome last summer - kind of an impulse buy off a family member that was going to trade it in - a class c 1994 Conquest 102. A friend from work was telling me that they have one and it has a solar setup on it which is really nice. A couple weeks ago I saw a good deal on some solar panels and started researching what all we would have to buy to add solar to an RV. I think I did OK on my research and purchasing... Ended up with this stuff:

2 x Grape Solar 100-Watt Poly solar panel from Home Depot (5.56 amp)
Allpowers 20A Solar Charge Controller (PWM) from Amazon
2 sets of Z-Bracket for solar panel roof mounting from Amazon
5 pair of Renogy MC4 male/female cable connectors from Amazon
10-pack of ATC in-line fuse holders + 30 amp fuses + 40 amp fuses from Amazon
Power TechON 600W pure sine wave inverter from Amazon

During my research and purchasing our motorhome was parked at our family's house for the winter. After picking up the motorhome and poking around I realized that although I figured out what to buy I actually have no idea how to actually hook it up to my RV...

Thank you for sharing! The same to you, most of us are green hand.