Solar charging while driving

Solar is pretty new to us. Didn't have it on our previous travel palace, the Odyssey CT. Now being caravan owners, we have a full solar set up:

3 x 130 W Kyocera panels, charging 3 x 120 AH AGMs via a 40 Amp Plasmatronics controller. The panels are mounted flat on the van roof.

The question is, is there any reduction is charging efficiency from the panels while driving. For the sake of the answer, leave aside any effect of occasional shade while driving.

I have the vehicle and van set up for charging from the alternator via Anderson plug, but since we also have two AGMs mounted in the vehicle (1 x 120 AH and 1 x 90 AH). Further, I carry a 100AH AGM for the boat (used both for starting and for electric motor). I have set up so that I can charge the boat battery from the alternator when driving if necessary, by connecting in parrallel with the 120 AH in the canopy.

If I have them all connected, that is 6 x AGMs, totalling 670 AH, all connected to the alternator!!!! I'm figuring that if for some reason (camping for a couple of days in the rain), the batteries are run down a bit, that is far too much to connect to the alternator.

My proposition is that in that circumstance, I would leave the vehicle to van Anderson plug disconnected. The two (or possibly three) AGMs in the vehicle would charge from the alternator and the three in the van would charge from solar.

Hence my question, would the van batteries charge from solar as effectively am I likely to lose?

Norm C

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Reply By: Member - Norm C (QLD) - Saturday, Jan 17, 2009 at 16:45

Saturday, Jan 17, 2009 at 16:45
UGH! Buggered up last sentence. Should read:

Would the van batteries charge as efficiently as when camped. If not, how much efficiency am I likely to lose?

Norm C
AnswerID: 344794

Follow Up By: Member - Tony B (Malanda FNQ) - Saturday, Jan 17, 2009 at 16:51

Saturday, Jan 17, 2009 at 16:51
Norm - You will need a bigger truck to tow your batteries :-). Cheers Tony
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Follow Up By: dublediff - Saturday, Jan 17, 2009 at 22:57

Saturday, Jan 17, 2009 at 22:57
You should plug into the Victorian power grid, the excess power you provide will run the State houses of parliament, supplemented of course by the methane that emanates from the chambers.....
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Reply By: Witi Repartee - Saturday, Jan 17, 2009 at 17:25

Saturday, Jan 17, 2009 at 17:25
If you need that much power, have you considered a (longish)
extension lead?
AnswerID: 344798

Follow Up By: robertbruce - Saturday, Jan 17, 2009 at 17:58

Saturday, Jan 17, 2009 at 17:58
Maybe another two panels would keep some ballast for the fridge...or a sun-tracker

have you isolated the fridge batteries so that only it uses them?

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Reply By: Gone Bush (WA) - Saturday, Jan 17, 2009 at 18:06

Saturday, Jan 17, 2009 at 18:06
G'day Norm,

when we were bringing our Trakkiie home to WA from Victoria 2 years ago I broke my Anderson plug quite early in the journey. We kept on travelling for another four weeks using only the solar panels (2 of them) and infrequent visits to caravan parks.

Not once did the batteries look like losing charge and, as a matter of fact, even now I purposely leave the Anderson plug disconnected simply because, on sunny days, I don't think it is required.

So, to answer your question, based on my limited experience, your solar panels will be doing a very good job while driving.

cheers
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Follow Up By: Gone Bush (WA) - Saturday, Jan 17, 2009 at 18:08

Saturday, Jan 17, 2009 at 18:08
And I have never, so far, cranked up my generator in anger. So there's another 2 grand I could have saved.

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Reply By: Member - Vince B (NSW) - Saturday, Jan 17, 2009 at 18:23

Saturday, Jan 17, 2009 at 18:23
Hi Norm.
We have friends in a motor home who have been on the road for 14 mths.They have 2 x 130 units fitted & have had no problems at all while driving.
Cheers.
Vince.
AnswerID: 344809

Follow Up By: Gone Bush (WA) - Saturday, Jan 17, 2009 at 18:34

Saturday, Jan 17, 2009 at 18:34
Vince,

I believe that in a motorhome the batteries would be receiving a charge from the engine while driving, that's why they haven't experienced any problems.

In a van the van's batteries are only charged from the solar panels, or the vehicle via an Anderson Plug, or a generator while parked, or 240v input in a caravan park.

While driving, the choice is Anderson Plug or solar panels.

cheers



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Reply By: Neil & Pauline - Saturday, Jan 17, 2009 at 18:34

Saturday, Jan 17, 2009 at 18:34
Norm
If you travel less than the speed of light then the sun light should keep up with you.
I am not a scientist but it sounds a good theory as we have travelled for 3 years without the car charging and had no problems. Was no different when we were driving or parked.

Neil
AnswerID: 344811

Reply By: Peter_n_Margaret - Saturday, Jan 17, 2009 at 20:25

Saturday, Jan 17, 2009 at 20:25
All other things being equal, the solar panels will charge BETTER while driving than while stationary, because they will be cooler due to the air circulation.

Cheers,
PeterOKA196 Motorhome
AnswerID: 344819

Reply By: Dave B (NSW) - Saturday, Jan 17, 2009 at 20:26

Saturday, Jan 17, 2009 at 20:26
Norm, I don't think we would have a solar car race from Darwin to Adelaide if the panels didn't charge the batteries while driving along.

Dave
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Follow Up By: Gone Bush (WA) - Saturday, Jan 17, 2009 at 23:29

Saturday, Jan 17, 2009 at 23:29
Dave, that's just too sensible.....
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Reply By: Nomadic Navara - Saturday, Jan 17, 2009 at 22:52

Saturday, Jan 17, 2009 at 22:52
Sun light travels a a tad bit faster than your van does. It is only the portable ones you pack away that don't work whilst moving.

However, solar charging on the move will be reduced when you attempt to charge your batteries from the tow vehicles alternator without employing a voltage booster. A solar panel will charge a battery with 14.2 - 14.6V (depending on battery type setting.) A motor vehicle alternator has temperature compensation built into it. When the motor compartment heats the alternator output voltage is reduced, so that the warm battery under the bonnet battery does not get overcharged. The system voltage is reduced to a level below 14V. As a consequence, a cold battery that is remote from the motor compartment will not receive much of a charge.

When you connect your tugs electrical system to the system in your van, the tug's system will control the maximum voltage of the whole system. As this voltage is less than the solar systems maximum charging voltage your van's battery will receive less charge than if you leave the solar panel to charge it.

If you have a current meter in the solar input leg of your regulator it will indicate roughly the same current whether you have the tug connected or not. As your van's battery is not receiving as much current with the tug connected you will find the difference current is going bank into the tug's electrical system. If you don't believe me then put a current meter in the line and check this.

PeterD
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AnswerID: 344838

Follow Up By: RV Powerstream P/L - Sunday, Jan 18, 2009 at 09:00

Sunday, Jan 18, 2009 at 09:00
Peter
Not all alternators have early temp control to reduce the charge voltage but I know the Prados,Disco 3 and Range Rover Sport do.

Some that do cut back to 13.3V but the Sterling smart DC to DC 12V charger has been adapted for that drop and can still boost to the battery type voltage and give multi stage charging to the aux batteries so that driving can give you full batteries from the fuel you are using anyway .

The combination of a Smart charger and solar gives you the best efficiency overall regardless of battery type.

Ian





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Follow Up By: RV Powerstream P/L - Sunday, Jan 18, 2009 at 09:11

Sunday, Jan 18, 2009 at 09:11
I missed the Rodeo and I should have remembered that as someone that I believe Norm C knows that is an excellent DC man on the Gold Coast uses the combination of Sterling Smart Charger and solar on his Rodeo.
Ian
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Reply By: Member - Norm C (QLD) - Saturday, Jan 17, 2009 at 23:29

Saturday, Jan 17, 2009 at 23:29
Thanks guys. I got the response I expected, including the comments on amount of battery power I carry. Just thought I'd check. My batteries are, in part, a matter of history. I have them, so might as well use them.

I have had the two in the vehicle, plus the one for the boat for a 3 or 4 years as they were part of my previous Hilux / CT set up and the van came with the 3 AGMs.

But they are all handy. We have a large two door fridge /freezer in the van, plus I have 2 x 40 litre Engel fridges in the ute which are often both on freeze. Kathryn insists on carrying her sewing machine (runs via inverter) plus two laptops, etc etc.

Kathryn says she can never have too much material or thread. I say I can never have too many batteries or fishing lures.

Norm C
AnswerID: 344850

Follow Up By: jdwynn (Adelaide) - Sunday, Jan 18, 2009 at 00:06

Sunday, Jan 18, 2009 at 00:06
Amazing set up Norm.

I'd be interested in your reflections about changing from the camper trailer to the off-road van set up. Have you written about that?

cheers
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Follow Up By: Member Brian (Gold Coast) - Sunday, Jan 18, 2009 at 08:25

Sunday, Jan 18, 2009 at 08:25
Norm C Posted: "Kathryn says she can never have too much material or thread. I say I can never have too many batteries or fishing lures."


ROTFL!!!!!!!!

We must come and see you before you head off Norm.

Cheers

Brian
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