Seven days camping off the grid, batteries slowly winding down.

Whenarewethere · Guru

RE: Seven days camping off the grid, batteries slowly winding down.

iana · Guru

Changing the voltage is a major job, I will have to remove the charger and change internal jumpers. Yes I know about disconnecting the solar panels first, then the battery before working on the unit. The system is wired in series, it was in parallel, and I was advised to change it to series. It could be changed to a series/parallel system, but that would mean the installation of the fourth panel on the roof.
Looking at our van, and other vans in the park, they are all going to get shadows in the morning at low sun angles, no matter which way the van is orientated. These shadows are from the roof vents and air-conditioner.
To eliminate the shadows would require a complete re-think of present systems, such as means to put them at an angle, its not going to happen.
Perhaps the best solution would be to buy a couple of flexible panels, and with the awning part the way out and angled, attach them so they sit on the awning. Windy conditions may be a factor here.

I'll be doing a service on the van soon, and one job will be to take out the batteries, i shall look to see what voltage info they have on them, don't have high hopes there though.

Whenarewethere · Guru

Your controller should take 4 panels in series. Stick a fourth panel in or 2 smaller panels totalling the same amps if you can't fit 1 large panel. At least you would have an increase of 33% input or 25% more overall.

Craig1 · Guru

The " Kings Brand"(4wd super centre) fold up panel has a great report form a mate of mine, if that is any help, and not too badly priced

Jaahn · Guru

iana wrote:
Changing the voltage is a major job, I will have to remove the charger and change internal jumpers. Yes I know about disconnecting the solar panels first, then the battery before working on the unit. The system is wired in series, it was in parallel, and I was advised to change it to series. It could be changed to a series/parallel system, but that would mean the installation of the fourth panel on the roof.
Looking at our van, and other vans in the park, they are all going to get shadows in the morning at low sun angles, no matter which way the van is orientated. These shadows are from the roof vents and air-conditioner.
To eliminate the shadows would require a complete re-think of present systems, such as means to put them at an angle, its not going to happen.
Perhaps the best solution would be to buy a couple of flexible panels, and with the awning part the way out and angled, attach them so they sit on the awning. Windy conditions may be a factor here.

I'll be doing a service on the van soon, and one job will be to take out the batteries, i shall look to see what voltage info they have on them, don't have high hopes there though.

Hi Ian smile

No free lunches are there hmm I would be looking more closely at what you have and measuring the individual outputs and the shadows at different time of the day. Not easy to do ! How much would you need to lift the panels up to get clear of some shading. confuse

But your solution of the flexible panels raises the question of how to wire them into your system. You will need diodes and check that the current panels are also so fitted. Some flexible panel have failed using them in parallel. But at the least the output voltage should match that from the other three !!

Jaahn

PS Ian I went for a walk and things spring into my mind aww I was wondering if your panels have by-pass diodes fitted. These are fitted to help stop the problem of panel shading and other problems. The diode for each panel lets the string current bypass the shaded panel and the others can still make current. If there are no bypass diodes the whole string is blocked and produces very little.

The diodes are a dollar or two each and simple to fit somewhere, in the terminal box or even at the wire connections if that is the only place available.

https://www.electronics-tutorials.ws/diode/bypass-diodes.html

-- Edited by Jaahn on Saturday 25th of July 2020 05:56:56 PM

iana · Guru

Just found the battery spec's. Remco Deep-Cycle AGM batteries. RM12-120DC (12v 120 AH/20hr). Voltage reg. Standby 13.6-13.8, Cyclic use 14.4-14.7. Fitted 20/11/18.

I have wired the system so that I can just plug in a panel so that its in series with the system via Anderson plugs.

When the system was wired in parallel, I fitted by-pass diodes to each panel, with supply of these diodes from Tony, and one other former member. But being on the road, and not sure if the same circuitry applied when wiring the panels in series applied, I think two panels had them removed, I just didn't have the room, or the resources to do the extra engineering while stuck in a caravan park. I can revisit that when I eventually get back to our base.

Dick0 · Guru

Peter_n_Margaret wrote:
Any panel with shade will produce almost nothing. If that panel is in series with others they will all produce about nothing.
Having panels in parallel will mean that only the panel with shade will stop producing.
Cheers,
Peter

Yes, agree. smile

4 x 200w panels in Parallel feeding 2 x 150ah Agm's through MMPT controller.

Whether it's full sun or light cloud my batteries fully charge 3-5 hours.

(cheapest panels, controller and batteries from Ebay performing splendidly for several years).

biggrin

Jaahn · Guru

iana wrote:
Just found the battery spec's. Remco Deep-Cycle AGM batteries. RM12-120DC (12v 120 AH/20hr). Voltage reg. Standby 13.6-13.8, Cyclic use 14.4-14.7. Fitted 20/11/18.

I have wired the system so that I can just plug in a panel so that its in series with the system via Anderson plugs.

When the system was wired in parallel, I fitted by-pass diodes to each panel, with supply of these diodes from Tony, and one other former member. But being on the road, and not sure if the same circuitry applied when wiring the panels in series applied, I think two panels had them removed, I just didn't have the room, or the resources to do the extra engineering while stuck in a caravan park. I can revisit that when I eventually get back to our base.

Well Ian I believe you have a couple of things to check and change to improve your present system. Up the voltage to 14.5V, and fit the by-pass diodes to all three panels.

I would still say put the panels in parallel.

Jaahn

swamp · Senior Member

Hi
Wire the panels in parallel.
Reposition the worst shade panel effected roof panel. The higher the shade source the further away the panel needs to be ,horizontal clearance 300mm minimum .
True 200 watt portable with own reg wired straight to battery .

I run 400watts wired in parallel to mppt regulator no problems with volts/amps . At best performance I get 27-29 amps when batterries are flat, greater than 30%.

iana · Guru

OK job one done, upped the voltage to 14.6v, will see if there is a change by tomorrow at the end of the day. This morning the fridge was complaining, low voltage. At the end of todays travel, the battery voltage (disconnected) was 12.81v, which off my chart is about 75% charge.

swamp · Senior Member

Hi
Generally there are
AGM voltage chart and Lead acid flooded charts.
The agm is considered 50% at 12.oo --12.05 volts

Batt /solar test . Have battery at 50% discharged
At 12.00 noon with a flat battery what is the charging amperage ie max performance .
Then measure every hour from 7.00am till 5pm to work out a charge profile
The results would be interesting

iana · Guru

The next few days will see if we have an improvement after changing the voltage. have been cheating and holed up at a caravan park on 240v. An interesting test I read, covering each solar panel with a blanket to see if one or another panel will take down the system.
Giving thought to means of tilting the panels, and or wiring the system up as a series/parallel, two panels of 150W for each side.

iana · Guru

The next few days will see if we have an improvement after changing the voltage. have been cheating and holed up at a caravan park on 240v. An interesting test I read, covering each solar panel with a blanket to see if one or another panel will take down the system.
Giving thought to means of tilting the panels, and or wiring the system up as a series/parallel, two panels of 150W for each side.

Yep I have 14.6v

-- Edited by iana on Friday 31st of July 2020 02:50:33 PM

gdayjr · Senior Member

Jaahn wrote:
Noelpolar wrote:
iana wrote:
Yes the panels are clean, shadows yes, cant help that, unless I remove the air-con and the skylights. The panels are wired in series, so while the wiring is a good size, wiring in series overcomes any voltage drop. During the summer we got over 30 amps coming in, but the passed few days only got a max of 17 amps.
I think that a portable 200 watt panel would help, so I can position it to follow the sun.
I was up in the flinders a few weeks ago.... 20 amps was common.... maybe high 20's occasionally is all I got out of my 800w.... and mostly only for the few hours when the sun was up a bit..... say 10:30 to 2pm ish..... long shadows this time of year etc.
Hi
Let me say clearly that if you want to go free camping for a while you need to put in as much power every day as you use. You cannot go long on the batteries alone. So if they are getting lower each day you do not have enough charging. Perhaps the posters here already know that but others reading here may need this spelling out.
Soooo how to do that ! There are suggestion made here, all standard things for solar. MORE solar, check the solar has no shading, that it is working as well as it should, get portable panels to chase the sun better, cut back on usage, LED lights, etc. In winter down south the sun is lower and the days shorter so care will be needed to select your sites.
Then what alternative charging do you have. The first should be your engine alternator, the best charger you have. Dumb alternators will supply a high constant voltage at a high rate, so rig that up with good wiring and perhaps that is all you need. Smart alternators will need a dc-dc charger that is bigger than most people buy, to cut the run time to a reasonable short time. EG if 20 Amps it will take 6 hrs to put in 120Ahr. At 40 amps it will take 3 hrs to do that. Basic maths.
A generator is the other means of charging. But if you have a 240V AC generator then you also need a big DC charger to get the power in to the battery in a reasonable time. So do the maths there too just like above. A small charger that charges over night is not big enough. I have a 12Vdc generator/charger that does 50Amps. I must admit that I never take it but it is an expensive but lighter option(aussie made too)
Jaahn
PS http://www.christieengineering.com.au/products/12-volt-55-amp/

-- Edited by Jaahn on Wednesday 22nd of July 2020 10:35:47 AM

The days are shorter? how so, i thought they all had 24 hrs in them, no matter where you are?

Whenarewethere · Guru

The days are actually getting shorter!

https://weather.com/news/news/2021-01-07-earth-rotation-speeding-up-record-setting-short-days#:~:text=Now%2C%20the%20world%27s%20official%20timekeepers%20are%20considering%20subtracting,a%20rotation%201.0516%20milliseconds%20faster%20than%2086%2C400%20seconds.