Solar or car charging?

Submitted: Thursday, Dec 04, 2014 at 21:20
ThreadID: 110339 Views:1923 Replies:3 FollowUps:3
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G,Day fellow members, 2 questions for you knowledgeable auto elec types out there.---When I'm driving with my van hooked up and my 12 pin plug connected, what charges the van batteries,---the car alternator, or the solar panel on the vans roof ?----does one cancel out the other?
Question 2...when camped, and by bad luck the vans in the shade, can my portable panels (regulated) charge the van as per a running car if I fit a 12 pin plug of them to the van,- just the same as if it was the car plug?...........Look forward to some answers on this....Regards...Sapper D
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Reply By: HKB Electronics - Thursday, Dec 04, 2014 at 22:29

Thursday, Dec 04, 2014 at 22:29
Hi Sapper D,

Can you supply a bit more information, in the van do you have a DCDC charger for charging the van batteries or are the van batteries charged directly by the car?

If you have a DCDC charger are the solar panels also connected to it or do they have their own regulator that is connected to the batteries?

Can you supply the brands and model types?

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Follow Up By: Sapper D - Friday, Dec 05, 2014 at 13:27

Friday, Dec 05, 2014 at 13:27
As far as I know it's the normal Caravan solar set up,--fixed panel on roof, wired to the batteries through a C-Tek regulated charger.---the 12 pin of the car is the same as every other vehicle, and charges while running-----my query is -which one charges the batteries on the road----solar from the sun,--or power from the alternator?---If I didn't have solar, the cars alternator would do the job,--if my car wasn't plugged in for some reason, the solar panel would do the job,---which one cancels out while travelling?
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Follow Up By: Rimsky C - Friday, Dec 05, 2014 at 13:50

Friday, Dec 05, 2014 at 13:50
Alternator is usually wired directly to the Starter Battery, depends on whether you are using dual battery, the solar panel could probably wire to an auxiliary battery or to main battery through the c-tek charger.

It would be good to know the model number of the charger, as it maybe the type that support isolation and solar panel. AFAIK, solar panel product variable voltage under different condition and angel so usually if you are fitted properly through a installer they will not wire it directly to the battery but through a controller. Either a PWM one (cheap) or MPPT one (expensive but more efficient). Thanks.
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Follow Up By: HKB Electronics - Friday, Dec 05, 2014 at 15:52

Friday, Dec 05, 2014 at 15:52
If your van is fitted with a Ctek 250S Dual the alternator has priority.

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Reply By: Member - Alan H (QLD) - Friday, Dec 05, 2014 at 07:48

Friday, Dec 05, 2014 at 07:48
It is all a question of what setup you have??

In my case I have 4 panels charging 4 batteries with no connection to the tow vehicle.

I always avoid shade (scared of branch fall and mess made by birds) and try to camp in the open. Van is well insulated. Unfortunately it is hard when I have to use a van park as they seem to be obsessed with shady sites and usually shaded by unsafe trees.

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Reply By: Sand Man (SA) - Friday, Dec 05, 2014 at 18:57

Friday, Dec 05, 2014 at 18:57
In almost all cases, the source with the highest current input will take preference.

A normal vehicle alternator is capable of putting in something like 60-80 amps, if there is no other controller in the circuit.
If a solar panel is also connected to the battery bank, it would be putting in something like 3-6 amps, depending on the wattage rating of the panel.

When you add a smart "dual" controller, such as the Ctek D250S Dual, the controller recognises which is the higher input and uses that source. Obviously with the high current input available from an alternator, that would be the better source. The D250S then restricts the charge current into the battery bank it is connected to a maximum of 20 amps, (the max. rating of the controller, but this is still much greater than the 5 amps available from a 120 watt solar panel array. Only when the vehicle alternator has been switched off, would the controller select the alternative solar port circuit, if connected.

If I understand your second question correctly, yes, you could connect the solar panel input to the van's charge cable circuit, assuming there is no other controller in the van, which would then confuse each other. You can only have one solar controller in the circuit, whether it is mounted on the back of the portable solar panels, or connected to the battery end of the circuit.

I have a D250S Dual dc-dc charger installed in my van, which uses the alternator input while travelling. When I wish to connect my portable solar panels to the D250S when stationary, I use a second "uncontrolled" circuit from the panels and plug this into the solar panel port on the charger/controller.
Basically, I am bypassing the on-board controller mounted on the panels and relying on the Ctek to control the charging process.
When I connect the solar panel to another battery, (such as the auxiliary one in the vehicle) I use the original circuit controlled by the solar panel's built-in controller.

Note: the 12 pin plug you are referring to, only uses two pins for the charging circuit. So identifying the two pins required, you can make up an adapter cable to connect the solar panel plug to a 12 pin plug fitted to the van's "charge" cable and the solar panel will happily supply its charging current and voltage, into the van's battery bank.

Many van/vehicle installations use a 7 pin plug for normal connection between the van and the vehicle and a second two wire circuit for battery charging, usually utilising Anderson connectors.

I'm diagonally parked in a parallel Universe!

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