Insufficient Solar Setup?! Input Appreciated

[B350]

Unfortunately, it seems I've put the cart before the horse meaning I fear I have a solar setup installed on my camper van that is not sufficient for the size of battery bank.

Here's what I have:
-2x Eclipse 100W monocrystal panels in series
-20 Amp Commander MPPT solar charge controller
-MT-50 Tracer Meter
-2x Lifeline 4D AGM 210 Ah batteries in parallel (12V, 420Ah)

After living in the van for 10 weeks now I realize that the batteries never reach full charge due to the fact that the solar output is not sufficient for a battery bank with 420 Ah. The average charge the system will achieve is about 12.7V. So, never do the batteries reach a full state of charge.

2 question for your imaginative input:

1. How could I add to the existing solar setup to achieve the charge needed for this battery bank? Space is the biggest constraint being there is only an additional 42”x15” area to work with behind the other 2 panels. And the controller is a max of 20A.

2. Would I be better off downsizing to just one 210Ah battery? The existing setup should sufficiently charge just one correct?

Any help and insight is appreciated. The van will be home for another year so having a properly working solar and battery setup is pretty important. My apologies for being a bit ignorant on the subject and obviously not doing the thorough homework I should have in the first place.

Thank you!


https://www.instagram.com/schmutzandhonig/

 

[calicamper]

The controller may be dropping to float charge too early? Just thinking. Be sure to check with a hand held meter. There could easily be power drains that bring down the displayed voltage. My batteries will often show 13v right after being disconnected from the charge source and taper off to a mid to high 12v reading over a short time with no load on them.

 

[john61ct]

It's not that your bank is too big.

Your usage per day needs to be less than 90% of what your solar puts into the bank.

Get more solar (double+), or use dino juice to get the bank to 75-85% before the solar ramps up in the morning. Alt from driving or a small genny.

 

[calicamper]

Also consider Solar generation can drop by 50% or more as we go into the winter months. Here at my house in Central CA by the 2nd week of Nov I see nearly half the solar gen that I see in July.

 

[jonyjoe101]

keep the float setting at 14.4 volts, also verify what the voltage is at the battery and what the controller is reading. If you have any voltage drop, the controller will stop bulk charging too early and go into float. On my system I have a 1/2 volt difference. The battery reads 14 volts but the controller reads 14.4 volts (and thinks my battery is fully charged). I had to raise the bulk to 15 volts to get the battery to read 14.4 volts. The higher you raise it the quicker it will charge.

With such large battery bank you should never be at less then 14.4 volts when on solar, you run out of sunlight before you can fully charge your battery.

If your battery only reads 12.7 volts when on solar it means it has never been fully charged and solar is just trickle charging it which will eventually charge it after several weeks if you don't use the battery while it's charging. Example my 110 ah lifepo4 if I take it down all the way, it will take my 240 watt solar panel/mppt controller at least 3 days to get it up 100 percent and thats if I got good sunlight. My panel maxes out at 12 amps output when the sun is overhead.

I recommend you get a coulomb meter and connect it to the battery, this will help you when you finally fully charge it, it will keep count of all amps going in/out of battery. You program your battery bank size 420 amps, and say you use 40 amps, then the next day you know you have to put at least 40 amps back. You won''t have to rely on battery voltage to know the battery condition or if it got fully charge. In the picture it shows my 110 ah battery, I used 15 amps, I know the next day I have to put 15 amps back in, and the meter will count back up to 110 ah. It will also help you find all your power hungry devices, everytime you turn something on, it shows amps being used on the display.

TK15 High Precision LiFePO/Lithium/Lead Acid Battery Tester Coulomb Counter 50A

 

[B350]

Unfortunately, doubling the amount of solar is not possible from an economic and space standpoint.

As far as I understand, an AGM battery charges quite slow. That said, just idling the van will give a short charge peak with very little actual charging done to the battery. For a full charge from an alternator a van would have to be driven for anywhere from 4 to 8 hrs.
I can attest to this seeing a short charge spike into the 13V range after idling or even a short 1 or so hour drive. The battery voltage then falls back off to the 12.7V range.
And that is with a larger than stock alternator rated at 135A and 14.5V. I then also have the Blue Sea 7622 automatic charging relay which combines the van and house battery anytime 13V is sensed for 90 seconds and disconnects the two when voltage drops below 12.75 for 30 seconds.
Would a larger alternator yet be any better?

The lack of overhead sun at this time of year is something I thought about but never thought would make such a considerable difference. So maybe that is playing a more significant role in the equation than anything else?

 

[B350]

Thanks jonnyjoe101

Before we left Minnesota in August the charge state was always around 14+V. But, that was with good overhead sun in June and July. A couple of weeks of cold coupled with almost no sunlight fir the solar panels lead to the present state. It seems that with the dwindling overhead sun getting these batteries fully charged again with daily use will be nearly impossible.

I do have the float charge parameter on for the controller set at 14.2V. I guess the problem is still not being able to put back into the batteries what was used...

I'll definitely have to check the actuall battery voltage compared to what the controller reads and see what the difference may be.

 

[Herbie]

Unfortunately, it seems I've put the cart before the horse meaning I fear I have a solar setup installed on my camper van that is not sufficient for the size of battery bank.

Here's what I have:
-2x Eclipse 100W monocrystal panels in series

Why series?

Going in series to raise the solar voltage can be good if you have a very long transmit length between the panels and the solar controller, but generally I'd think you would want more current. If you have even the slightest amount of shading on even one part of one panel, a series installation is really going to hurt your output.

Just because you have an MPPT controller, doesn't mean you need the higher input voltage. Renology has some thoughts on the subject here.

 

[dwh]

If you have even the slightest amount of shading on even one part of one panel, a series installation is really going to hurt your output.

I hashed that out thoroughly here:

http://forum.expeditionportal.com/threads/176160-Roof-solar-panels-go-2-50w-or-100w

Turns out, series is generally better for shade toletance.

Just because you have an MPPT controller, doesn't mean you need the higher input voltage. Renology has some thoughts on the subject here.

That quicky article makes a few assumptions that would apply in some situations, but would not apply in other situations.

 

[john61ct]

No dino juice source is worth running to charge to 100%, cheaper to just buy new batts every year.

But a little genny or al running two hours in the morning up to 85%, followed by the low-amp solar day for the long tail, will work well.

A proper alt setup to get decent charge from even high idling would be expensive, for some vehicles impossible.

Better to get a big DCDC "batt to batt" charger like Sterling, $4-700.

Or carry a genny.

 

[rayra]

The biggest difference you could make is making your panels erectable so they can be positioned face-on to the sun, particularly heading into winter in MN. Your latitude is ~45deg. Flat mounts aren't going to cut it, as you seem to be discovering.
It would take very little hardware to alter your panel mountings. A few bolts and wingnuts, a couple bars or rods, then you could unbolt whichever side of the panel is opposite of the sun and raise the panel and insert the brace that's sized to produce the proper panel angle. Take 5mins any time you are parked long enough to make it worthwhile.

 

[Darwin]

If you don't have the funds to remedy the situation then your only option is to remove one of the batteries. I have been full time off and on for 2 years now and removing a battery just so it can get fully charged is not an option I would even think about considering. I would probably work more hours and come up with the cash to fix the issue before I ever removed a battery, but I am fortuante enough that my job compensates me well for what I do and have the ability to work overtime if I choose.

Edit to add:
I see you are heading to south america, I am not sure if you have a fridge or not or plans for a fans, but I can tell you from experience, your issue will only get worse for a couple of reasons. If you have a fridge it will run a lot more in Mexico and Central America because of the heat and humidity, the heat will be so bad that you will also likely want to run fans so as not to suffer as much, all of these things will mean you will be using more battery amps with less imput from solar, the next issue is it will be hot as balls in the direct sun on the van so you will want to park in the shade, or you might have no choice depending on location to have to park in the shade, only making the problem worse. Under dense jungle canopy not much sun can get through. My suggestion would be to fix this all before you leave so that you suffer less, even if it means delaying your trip.

Good luck!

 

[DLTooley]

The general rule of thumb is one watt solar per ah of battery. But if you are only discharging, on average, to 75% then your bank will be healthier. Starting from fully charged and returning there is crucial. AGMs have specific charging requirements including different absorption float needs. I’d spend time learning that. I use a portable panel to supplement my main and it makes sure I get to 100% semi regularly. Ring at 90% for a few days isn’t harmful.

 

[B350]

Splitting batteries to alternately charge and discharge one at a time just doesn’t sound appealing considering the extra switches and wiring to make it a convenient setup. And ditching one seems like a step backwards so I’ll definitely stick to the dual battery setup with 420Ah.

Angling the panels makes a lot sense. Getting up to the roof would be a bit of a hassle but, I think I could make something work for at least 2 of what will be 4 panels.

What I’m thinking is to ditch the Yakima box in favor of something much smaller and then add 2 100W Renogy Eclipse panels, still in series. This way I can stick with the same 12awg wire that came with the original installation kit, and go to the 40A Renogy Commander MPPT charge controller. I would then go with bigger 8 or 6awg wire rather than the current 10awg from the charge controller to the battery bus.
Thoughts or ideas on that verdict?

So, I may have everything shipped to Sacramento in mid November or just go to Renogy in Ontario, CA late Nov/early Dec.

Thanks for all the great info and input! Much appreciated.

 

[Nomad1]

The biggest difference you could make is making your panels erectable so they can be positioned face-on to the sun, particularly heading into winter in MN. Your latitude is ~45deg. Flat mounts aren't going to cut it, as you seem to be discovering.
It would take very little hardware to alter your panel mountings. A few bolts and wingnuts, a couple bars or rods, then you could unbolt whichever side of the panel is opposite of the sun and raise the panel and insert the brace that's sized to produce the proper panel angle. Take 5mins any time you are parked long enough to make it worthwhile.

Totally correct he is only getting 50% out of them solar panels I know went through the same thing with my setup I took them off the roof and store them inside when I get to camp I set them upright directed at the sun and move them every so often if I am around everyone that camps with me knows and helps out aiming them towards the sun during the day seems I supply everyone else with power to recharge their gear I don't mind at all as I now have more than enough power now... I have 130 watts and just over 500ah of batteries... before this I was thinking of getting another 100 watt panel but saved myself a few bucks by just taking them off the roof...