Solar w/ dual battery and Projecta DBC100

MrPoopypants

Well-Known Member
I'm not sure whether you mean 'portable solar panels' to use when you are stationery/camping or a 'fixed vehicle mounted solar panel' and trying to use that to boost your charging when travelling?
From my experience you'll have no problems, if using portable solar panels to charge the aux battery when camping.
If thinking about a vehicle mounted solar panel and trying to use it in tandem with the vehicle alternator charging to fast track/boost charging of the aux battery, my thoughts are, "why bother?" If you have adequate size wiring from the vehicle battery to the aux battery, adding solar to the mix whilst driving is a waste of effort/resources (the vehicle alternator charges adequately/fast).
If a vehicle mounted solar panel (e.g. on the roof rack), I'd do it with an on/off switch incorporated. So switch to 'solar on' when stationery/vehicle engine off, to add solar charge to the batteries; switch it to 'solar off' when driving and let the vehicle alternator do the charging.
Check this link out, which may add some useful information
http://www.home12volt.com.au/upload...s_and_the_alternatives_-_vehicle_charging.pdf
Cheers,
A.D.
Thanks for that file Colly. It helped me fill in some gaps regarding use of a continuous solenoid. Has been working well. Cheers G.
 

silkwood

Well-Known Member
Marco, I have a simple VSR connecting my main to my two Aux batteries. I also have a 120W panel on the roof connected (via controller) to the Aux batteries. In addition I have a portable 120w panel for low sun conditions. Works fine. Batteries are now 8 years old (keeping all body parts crossed they survive until my next trip next month).

No need for a dc-dc, in fact, you may benefit from not having one. I'm absolutely no expert (not even a good amateur) on this but listening to and reading of those who are, coupled with my data results and the longevity and reliability of my battery system, I'm confident I'm on the right track.

Cheers,
Mark
 

MarcoNSW

New Member
Went straight to the manufacturer and got the answer I was looking for.
FYI - a dcdc charger is NOT necessary

Screenshot_20191021-093742_Outlook.jpg
 

tommyb

New Member
Piggybacking on this thread,

Seems fine in my eyes but just double checking, I have a DCDC charger from my main to my AUX battery. If I run an MMPT solar charge controller to the main battery and plug in portable panels while stationary and the vehicle is off, will this cause any issues? Idea is to have it charge both the main battery and the aux going through the DCDC charger?

Cheers!
 

Swaggie

Moderator
Piggybacking on this thread,

Seems fine in my eyes but just double checking, I have a DCDC charger from my main to my AUX battery. If I run an MMPT solar charge controller to the main battery and plug in portable panels while stationary and the vehicle is off, will this cause any issues? Idea is to have it charge both the main battery and the aux going through the DCDC charger?

Cheers!

If you think about it, what’s the difference between the charge from an alternator and charge from solar panels sure theres a big difference in amps but the same principal applies.
Depending on your model it may even have the solar option build in With a mppt controller.

Maybe someone can correct me in my way of thinking but that’s how I see it.
 

tommyb

New Member
If you think about it, what’s the difference between the charge from an alternator and charge from solar panels sure theres a big difference in amps but the same principal applies.
Depending on your model it may even have the solar option build in With a mppt controller.

Maybe someone can correct me in my way of thinking but that’s how I see it.

That was my thinking too, just making sure I'm not missing something obvious.
And nah the charger doesn't have a solar option. But even if it did it wouldnt charge the main anyway? Cheers!
 

Swaggie

Moderator
That was my thinking too, just making sure I'm not missing something obvious.
And nah the charger doesn't have a solar option. But even if it did it wouldnt charge the main anyway? Cheers!

Yeah all kool mate better to be safe than sorry,arrrgh depending on the unit it should take care of both batteries connected to solar, mine does....
 

silkwood

Well-Known Member
If you think about it, what’s the difference between the charge from an alternator and charge from solar panels sure theres a big difference in amps but the same principal applies.
Depending on your model it may even have the solar option build in With a mppt controller.

Maybe someone can correct me in my way of thinking but that’s how I see it.


Does your dc-dc not turn off with the vehicle? If so, how will it charge the aux battery(ies)? More common to have the solar charging the aux batteries, some vsr's and some dc-dc allow emergency linking of the aux and main for jumping. Your dc-dc almost certainly omits initial charging to the aux battery until the alternator has brought the main up to charge. What dc-dc?

Cheers, Mark
 

Swaggie

Moderator
Does your dc-dc not turn off with the vehicle? If so, how will it charge the aux battery(ies)? More common to have the solar charging the aux batteries, some vsr's and some dc-dc allow emergency linking of the aux and main for jumping. Your dc-dc almost certainly omits initial charging to the aux battery until the alternator has brought the main up to charge. What dc-dc?

Cheers, Mark

Hi Mark
As mentioned earlier it’s not a dct-dc charger , it’s the TJM IBS system, it’s Swiss.
 

tommyb

New Member
Does your dc-dc not turn off with the vehicle? If so, how will it charge the aux battery(ies)? More common to have the solar charging the aux batteries, some vsr's and some dc-dc allow emergency linking of the aux and main for jumping. Your dc-dc almost certainly omits initial charging to the aux battery until the alternator has brought the main up to charge. What dc-dc?

Cheers, Mark

Hi Mark,

The DC-DC turns off when the input voltage drops below a certain voltage (Alternator no longer providing power). My thought is that if the MMPT is put before the DC-DC, it will detect the charge voltage and begin charging the AUX again, while charging the main?

Cheers
 

Swaggie

Moderator
Hi Mark,

The DC-DC turns off when the input voltage drops below a certain voltage (Alternator no longer providing power). My thought is that if the MMPT is put before the DC-DC, it will detect the charge voltage and begin charging the AUX again, while charging the main?

Cheers

I wouldn’t be putting any solar charger before the dc/dc charger so I believe you could be correct. Different story if it was in the hardware but it isn’t...
I’d be putting it after it even on the auxiliary.

You could of course send an email to Projecta .
 

silkwood

Well-Known Member
Answering a different post, not the OP... I think you're getting confused between posts...

Cheers,
Mark

Just noticed, the confusion was mine, I meant to answer tommyb, not yourself. Apologies.

Is the suggestion that placing the solar input between the house battery and the dc-dc will allow the solar to continue charging both the main and aux batteries via the dc-dc, even with the ignition off? I hadn't heard of that.

Cheers,
Mark
 

tommyb

New Member
Just noticed, the confusion was mine, I meant to answer tommyb, not yourself. Apologies.

Is the suggestion that placing the solar input between the house battery and the dc-dc will allow the solar to continue charging both the main and aux batteries via the dc-dc, even with the ignition off? I hadn't heard of that.

Cheers,
Mark

That was the basic idea yes, to connect the solar charger to the main battery and then that should also trigger the DC-DC to charge as well? As long as the voltage is above the DC-DC unit's trigger voltage
 
My Intervolt battery isolator has a function to join the batteries to allow charging from a solar panel. It automatically joins them if the main battery is below a certain voltage and the aux battery is above a certain voltage, ie. receiving charge from a solar panel.
 
Top