DC to DC Charger and Solar

[Tikka7mm08]

Hi - fitted a Powertech DC-DC charger with the solar connected to it. Previously the solar went through the MPPT into the main battery. Am I right that the solar only chargers the aux battery? The solar was great at keeping the main battery topped before the DC-DC but now it sits in the 12.3-12.5v range. Wondering if I just disconnect the solar off the aux and run it though the MPPT to the battery again - I only have a 50a/h battery for the air compressor and fridge I might purchase later. No extended stays anywhere without motor running for long periods.

[drivesafe]

Hi Tikka and the only battery that will be charged when a DC/DC device is being used as a solar regulator, the the battery connected to the output side of the DC/DC device.

There are a few DC/DC devices that will trickle charge the cranking battery from the solar input, but this will only occur when the auxiliary battery is fully charged, and I am pretty sure Powertech devices do not have this feature.


Is your vehicle sitting unused for long periods of time between uses?

[Tikka7mm08]

Thanks for that...yes the 90 is usually a Sunday car. And it has an OBD2 on it but nothing else that should be pulling power. I found with the solar direct the starting battery was over 13v easily (13.6v from memory) and it made a difference when starting.

[Robmacca]

What initiates the Powertech DC-DC charger to start charging? Is it an increase in Volts when engine is started or is there a ignition wire that triggers the Powertech DC-DC charger to start charging the Aux Battery?



Hi - fitted a Powertech DC-DC charger with the solar connected to it. Previously the solar went through the MPPT into the main battery. Am I right that the solar only chargers the aux battery? The solar was great at keeping the main battery topped before the DC-DC but now it sits in the 12.3-12.5v range. Wondering if I just disconnect the solar off the aux and run it though the MPPT to the battery again - I only have a 50a/h battery for the air compressor and fridge I might purchase later. No extended stays anywhere without motor running for long periods.

[Tombie]

What initiates the Powertech DC-DC charger to start charging? Is it an increase in Volts when engine is started or is there a ignition wire that triggers the Powertech DC-DC charger to start charging the Aux Battery?

It’s a very basic unit…
Needs 13v to trigger on. So engine running as practice.

However, if a solar input was put on main battery, then every time the main battery exceeded 13v at terminals the charger will kick in, and start charging / drawing down on the main battery pretty hard. Could result in a flat main battery quite easily.

[Robmacca]

It’s a very basic unit…
Needs 13v to trigger on. So engine running as practice.

However, if a solar input was put on main battery, then every time the main battery exceeded 13v at terminals the charger will kick in, and start charging / drawing down on the main battery pretty hard. Could result in a flat main battery quite easily.

Yeah, that's why I asked the question... If it was ignition operated, then it would be easier...

[drivesafe]

It’s a very basic unit…
Needs 13v to trigger on. So engine running as practice.

However, if a solar input was put on main battery, then every time the main battery exceeded 13v at terminals the charger will kick in, and start charging / drawing down on the main battery pretty hard. Could result in a flat main battery quite easily.
Good point, as they do not have an ignition sense, they are a bit of a problem.

Tikka, being that you have a 90, a simple Ignition activated relay would be a far better set up than a DC/DC device.

This would allow the solar to keep your cranking battery maintained, and would allow for very fast recharging of your auxiliary battery when your motor is running, something the DC/DC device can not do.

[Tikka7mm08]

Just my luck.

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[Tikka7mm08]

Tikka, being that you have a 90, a simple Ignition activated relay would be a far better set up than a DC/DC device.



Can you suggest one by brand so I can look up and reference?

[drivesafe]

Can you suggest one by brand so I can look up and reference?
Hi again Tikka, I was suggesting a simple high current capacity relay, wired to your ignition circuit. This could also be controlled with as simple as a switch that you turn on and off as you need it.

Or you could use one of my Traxide isolators and the setup would be fully automated. This would also allow you to connect your solar panel to either battery and the Traxide isolator would connect both batteries together while the solar panel is active.

Both of these setups would recharge your batteries far quicker than any DC/DC device could.

Because you have a 90, the Traxide setup would allow you to use a lithium auxiliary battery in the future, with out the need for any modifications to your setup.

Using a Traxide isolator with a lithium auxiliary battery would give you a setup that would better look after both batteries even when your 90 is not used for many weeks at a time.

[Tikka7mm08]

Ok - have sent an inquiry for the DT90.

[drivesafe]

Ok - have sent an inquiry for the DT90.

E-mail quote send and thanks for your enquiry.

[Tins]

X2 on the Traxide. Great device and Tim’s after sales support is second to none.

[prelude]

FYI. For those that come across this topic at a later stage: a DC-DC charger with this function (trickle charge main battery from solar) is the CTEK DS250S or SE.

-P

[Tombie]

FYI. For those that come across this topic at a later stage: a DC-DC charger with this function (trickle charge main battery from solar) is the CTEK DS250S or SE.

-P

If its intended use is Lithium it needs to be the SE version.
And to charge the starter requires the Smartpass also.

They’re a terrible system IMO

[prelude]

True, I stand corrected you do need both yes. The 250 is the dc-dc charger with mppt solar input and the smartpass is effectively a large passthrough relay, only powered by mosfets instead of physical contacts. When the smartpass detects the battery voltage of the starter to be lower than the aux battery it will trickle charge the starter battery. It can also be a start help if the main battery is flat, automatically connected the aux to the main for some seconds at a max of 350A (which is usually enough).

Also for lithium you do need the SE to have a lithium profile indeed (I own that type and have used it on gel, agm and lithium not flooded)

Funny, I have used the system for quite some time and I rate it. Why do you feel it is a bad system?

-P

[Tombie]

Poor algorithm for Lithium, requires bus bars to link, not a tidy install. And I find all previously owned Cteks unreliable.

I now run Victron for most of my charge needs and a stand alone MPPT for my primary solar.

[Tikka7mm08]

Put the traxide kit in today. Very nice kit too thanks Tim.

Wired my solar back into the cranking battery via MPPT but it looks like I managed to fry the panel as it is not producing enough voltage to switch the icon on for it. Tested with multimeter and very minimal charge. Bugger.

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[AK83]

Put the traxide kit in today. Very nice kit too thanks Tim.

Wired my solar back into the cranking battery via MPPT but it looks like I managed to fry the panel as it is not producing enough voltage to switch the icon on for it. ....

Obvious first step is to triple check the connections to the panel. This will do it every time.

Happens to me regularly, where I have a single (say) 100w panel on the roof of the shed, which runs into a Victron controller, which charges a few batteries I've collected over the years.

Panel nor wiring ever get manhandled, but every now and then I get the low/no input and the Victron is on the blink!
Took me a while to work it out first time it happened, and no obvious disconnected cables, but pushed the connectors together to make sure, and as sure as the sun comes back the next day, Victron not on the blink any more.

Panel was a hand-me-down, and works fine(for me), and it has a mix of both MC4 connections and Anderson coming down into the shed, with another Anderson at the Victron too.

So just check the connections again to be sure.

[Tikka7mm08]

Yep will give it a go. Read on the net you can fry the panel if it is in the sun before the mppt and battery are connected.

[AK83]

Yep will give it a go. Read on the net you can fry the panel if it is in the sun before the mppt and battery are connected.

I got no idea how accurate this info will be, but my experience is, I had my panel on the roof for well over a year before I connected it to a controller to charge the batteries.
Got around to start setting it up, then basically got lazy, and only had a cheapo PWM controller and two 200ah batteries. Couldn't find the ideal(ie. long term) spot to mount the cheapo controller, etc ... so got forgotten .. and then lazy.

Finally remembered, a year or so later, to get myself the controller(in my case Victron) and some cables and connectors and so forth and connected it all up.
Panel is cheapo, but still can give me up to 100W in ideal conditions.

[W&KO]

Yep will give it a go. Read on the net you can fry the panel if it is in the sun before the mppt and battery are connected.

Some panel manufacturers include a warning…

I’m saying that I’ve forgotten to cover the panel when connecting / disconnecting and haven’t experienced any issues.

[Tikka7mm08]

Checked cables and the wire box connector glued on the flexible panel had broken off. So often the simplest thing isn't it... bought a Rydge Ryder 160W panel today.

[Tikka7mm08]

New 160W panel mounted on Rhino Rack. I kept the 30A controller as better than the 15A one that came with the panel.

Traxide going well too with the wee remote.

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