My Solar Install

[Night Sailor]

I decided to pull the trigger on two new AGM batteries a few hours ago. I'll have them on Thursday.

My uncle talked me into it over the last few days. I was going to buy just one battery. I was shocked he was so firm and enthusiastic about pushing for the extra capacity.

I debating dual full size 8D batteries a while back, and decided against the huge 165 lbs weight penalty. That was too much for me, given that my current battery seemed to be doing ok at the time. I liked the idea of the huge capacity though.

I was leaning towards one slim battery and a weight savings of 46 lbs. It is hard to argue with a significant weight reduction. Uncle Tom liked the idea of two batteries and a whopping 400 amp hours of capacity. I liked the modest weight increase of 73 lbs with two batteries. Although, I'm concerned the lighter weight might impact battery longevity. The fact that I can fit two of these 200 amp-hour Master Volt batteries in the same space as my current 8D battery is very nice. Space is always at a premium in campers and boats. This is the future. Higher energy densities.

Second, four and a half days consecutive days of overcast conditions helped me make the purchase decision. Yesterday was overcast, and today is very dark and this continues on until Monday. I'll be down about 30 amp hours or more today and that trend is likely to continue with inadequate reserve. I may go one more day without short power to see how my current battery holds up.

Last, my electric blanket arrived today and was the third factor in my decision to purchase two batteries. If I want to be able to warm my bed and take the chill out of the cab-over bed area, my coldest spot, I'll need both increased charging and battery capacity. I am hoping this will work out. I'll have to test it out and see. The device lists the power demand as 180 watts on high which is bigger than I expected.

Some numbers. I am hoping a 3 setting, will be about 54 watts (5 amps) and comfortable drawing 40 amp-hours over the course of a night. That would put my energy budget at 100 amp-hours and should be easily recoverable on a sunny day. I'd recover most of that on an overcast day, an estimated 80 amp-hours, putting me down about 20 amp-hours. I could tolerate quite a few overcast days and be able to recover from this in one to two days of clear skies.

Cold days are the clear days, so the two extra solar panels I'm in the process of installing, and deep capacity will set me up well for extended dry camping in any conditions . I can use the deep capacity on extended overcast days and the electric blanket freely on those clear very cold days and nights when I can expect a maximal recharge the following day.

I've read the rule of thumb for matching solar panels and batteries is you should have an amp-hour of capacity for every watt of solar power. That may work for people who live out west in generally clear conditions. Here in the northeast, we need more solar power than amp-hour capacity to replace what we lose on overcast conditions. I'll have 1.5 watts production per amp-hour.

In any event, that level of charging and capacity will allow me to do the sort of winter camping I want to do; I'll be able to tolerate extended overcast conditions and not worry about discharging my batteries even with heavy furnace or electric blanket use. New batteries will, for the first time, allow me to accurately set my LinkPRO battery monitor's capacity. Finally, I be discharging typically 25%, which should prolong the longevity of these batteries.

[MCDenny]

Sounds like a good choice. Once the batteries are in and paid for you will never regret having "too much" capacity.

[Night Sailor]

I am surprised that my present battery is holding up so well. I'm going to repurpose it for my ham radio station as emergency backup power. I can still get more than 70 amp hours out of it.

[Night Sailor]

Last two panels installed. I have a few minor thing to wrap it up. Four more bolts, some cable ties, and a bit more Dicor. It was late in the day. Tomorrow will give me a peak at the production. Tonight I'm off shore power and running my battery down to see how it charges tomorrow.

ATTACH]69461[/ATTACH]

[Night Sailor]

9 am at 9 am on am overcast day so far.

[tmaken2157]

Hi all, I took the jump recently and started my small solar system. I have a 100 watt panel going to a 35 amp schneider charge controller going to a fuse to the stock casita battery. I also got a meter to measure usage and charging info. Perhaps it's really obvious and I am missing it but my questions are.

is it ok to just leave the battery hooked up to the trailers charge converter and run the 12 volt items, lights fan ect.

Does the trailers charge converter draw current off the battery?

Thank you

Mak

[Night Sailor]

Originally Posted by tmaken2157

Hi all, I took the jump recently and started my small solar system. I have a 100 watt panel going to a 35 amp schneider charge controller going to a fuse to the stock casita battery. I also got a meter to measure usage and charging info. Perhaps it's really obvious and I am missing it but my questions are.

is it ok to just leave the battery hooked up to the trailers charge converter and run the 12 volt items, lights fan ect.

Does the trailers charge converter draw current off the battery?

Thank you

Mak

What are you using to meter usage?

The trailers converter converts AC shore power to DC and also will charge your batteries. No current is drawn off the battery. Current is drawn off by the loads--lights, water pump, etc. If you are plugged into shore power you will be using power from either your solar or your converter or perhaps both.

You can leave them both hooked up. If you don't have any shore power, you may want to switch off your loads during the day so the solar panels can charge batteries and recover as much power as possible.

[tmaken2157]

Thanks for the reply, the monitor is a Victron Bmv-600s. The trailer charge control is a parallax 7345. Looks like its a single stage fry your battery type unit that should be modified into a three stage. A 200 dollar upgrade. before I do that may I pick your brain a bit.

I have a PMW solar charge controller (xantrex c35)

When hooked to shore power The trailer parallax will send 13.8V to the battery if it needs it or not.

Is it possible to disconnect solar panel input to the Xantrex, route the parallax output back to the solar charger and charge the battery properly when hooked to shore power.

Thanks for your posts, there is a lot of over simplifications of solar out there and its nice to see the real deal.

Mak





BMV-600S series - Victron Energy

[multi-task]

Originally Posted by tmaken2157

Is it possible to disconnect solar panel input to the Xantrex, route the parallax output back to the solar charger and charge the battery properly when hooked to shore power.

Your parallax is designed to be connected to a battery, your charge controller is designed to receive input from a solar panel. They aren't designed to work together and usually your controller manual will have warnings against doing so. Connecting them should result in the controller showing a fault/error but it might also damage the controller.

[tmaken2157]

THank you Multi-task, Your answer is certainly safe enough however, I am not entirely convinced. The power converter is designed to output 13.8 volts to the battery continuously. The charge controller can accept that voltage easily, perhaps you might want a "gizmo" in line to keep spikes out that might cause damage.

So I was interested in what an elctrical engineer might think of something like that.

[multi-task]

Originally Posted by tmaken2157

THank you Multi-task, Your answer is certainly safe enough however, I am not entirely convinced. The power converter is designed to output 13.8 volts to the battery continuously. The charge controller can accept that voltage easily, perhaps you might want a "gizmo" in line to keep spikes out that might cause damage.

So I was interested in what an elctrical engineer might think of something like that.

When your converter is connected to your solar charge controller it's not under any load, it also won't read the battery voltage as it's not available from the pv input on the charge controller. This should mean that it's providing 0 amps so it won't accomplish what you're expecting.

[tmaken2157]

OK so much for that option.

I don't know enough to argue, I do know enough to say thanks for your input.

Do you folks have a schematic for a simple solar hook up I could use for a Casita?

Its been a long winter and we are chompin at the bit to get out of dodge for a while

[blodn1]

This diagram pretty much shows everything you could do so you can pick out the pieces of your system and see how they're connected.

[David Tilston]

Your missing the inverter.

[blodn1]

Inverter is after the DC fuse panel. I just pasted this from another site 'cause I thought it would help a little:-)

[Carol H]

Originally Posted by tmaken2157

OK so much for that option.

I don't know enough to argue, I do know enough to say thanks for your input.

Do you folks have a schematic for a simple solar hook up I could use for a Casita?

Its been a long winter and we are chompin at the bit to get out of dodge for a while

Simplest schematic is to mount the controller someplace dry close to the battery - some put them inside the trailer some put them outside in a water tight box by the battery and connect it to the battery -leave it connected all the time. Then decide if you want to permanently mount your panel or leave it loose so you can easily move around the campsite and just unclip it from the controller and store it in the trailer when traveling. Doesnt get much simpler than that and has worked well for me for several years.

[MCDenny]

Your charger connects to the battery. The solar controller connects to the battery. Note the battery negative goes to the battery side of the shunt. All other negative wires connect to the other side of the shunt.

[blodn1]

Denny's correct. The charger would be connected to the battery. The diagram was from a Charge Wizard installation - apparently a different animal.

[tmaken2157]

Sounds like it should be a pice of cake and a bunch of wire

Sent from my SCH-I405 using Tapatalk 2

[Night Sailor]

My panels recharged my -87.2 AH deficit sometime after noon today. It was more than that, because it was charging with 8.6 Amps when I checked about 8:11 this morning and had recovered 65 AH at 1246, when I switched on the fridge which draws 28 Amps, thinking I'd have to turn if off in a few hours. I just checked at about 3PM to find my batteries showing fully charged and 7.4 Amps going into the batteries (they were not really fully charged), for a net production of about 35.4 Amps or 5.9 Amps per panel average. It has been clear and cool today. I'm happy to keep my fridge running on electric. I just wish it was an Engel and I could run it 100% on solar power.