Camper Battery Charging

[paulyg]

I have a 6 b&s cable with an Anderson plug on the draw bar of my camper going to a Ctek 250s Dual dc to dc charger, which then goes to my 2 100ah battery's in my camper.
I plugged my 250 watt solar panel to this Anderson plug, after I bypassed the mppt controller, But I don't think it charges as quickly as it does using the panels own controller.
I would like to use the panels own controller and connect directly to the battery's, But I don't really want to run another lead and Anderson plug.
Can i do this? perhaps through a relay and switch between the different inputs?

[the evil twin]

Uuummm... something is odd in your post.
Do you have the Anderson Plug connected to the "Alternator In" or the "Solar In" of the D250S?

also...

What is the brand/model/part # of the Solar Controller?

[paulyg]

Thanks evil, the lead is normally connected to the Alternator In terminal when connected to the Troll.
I had been camping for a few days, so i moved the lead over to the solar input terminal, so i could use the solar panel to charge the battery's.
I don't now what brand the Solar Controller is, it came with the panel.

[mudski]

Thanks evil, the lead is normally connected to the Alternator In terminal when connected to the Troll.
I had been camping for a few days, so i moved the lead over to the solar input terminal, so i could use the solar panel to charge the battery's.
I don't now what brand the Solar Controller is, it came with the panel.
Why do you want to use the panels controller? The ctek will work more efficient than the panels controller. Plus you should need to move the lead over to the solar input. Have one lead always connected to the solar input, for you panels, and the other input from the car.

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[BigRAWesty]

Pretty sure there is no need to change from alternator to solar.. that's so you you can simply have 2 sources plugged in at once and the unit will pick the best source.
If you have it on the alternator but unplug car and plug in solar then that's the only source so it'll select that input.
The charger on the pannel more than likely isn't an mppt charger. So that's probably why it seems quicker.
I'd say bypass the pannel mppt and go the ctek..
But don't bother changing alternater to solar. Just leave it on whatever pin and plug in whatever the charge device..

[the evil twin]

Sweet... that makes sense now.

OK, the Ctek is a pretty good Solar Controller and should have functioned quite well with the panels connected to it.
Certainly it should have equal or close to the same performance as the Panel Controller all things being equal.

To do what you are thinking would be reasonably easy and indeed there are a few different ways.
The object is to bypass the Ctek so simplest one... Get a Changeover Relay (5 pin) rated to at least 40 amps and a mounting socket

Remove the Camper Battery +ve from the Ctek and connect it to Relay pin 30 (common)
- also note there will be two wires on this terminal when you finish
Connect the Ctek Service Battery +ve to Relay Pin 87A (normally closed)
- this means the Ctek will charge the Service battery as normal if the bypass switch is "OFF"
Connect Relay Pin 85 to Ctek -ve or Camper Battery -ve or earth if the camper is earthed)
- switching wire so light gauge is fine
Connect a wire of 12 AWG or heavier from Ctek Alternator Battery +ve to Relay Pin 87 (normally open)
- this is the wire that will carry the Solar Panel charging current bypassing the Ctek when the switch is "ON"
Connect a switching wire from Relay Pin 30 via a switch to Relay Pin 86 (relay coil +ve)
- this is the wire that will energise the relay when the switch is thrown thus bypassing the Ctek

I would put a 25 amp fuse in the 12 AWG "bypass" wire just in case you forget and hook up the vehicle with the bypass energised

[mudski]

A lot of work just to save adding an extra lead i reckon. I'd just run two sets of leads together in the one sheath, or convolute tubing and have two anderson plugs and just have them marked as Solar and car.
less that could go wrong....

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[the evil twin]

Mudski and westy replied while I was dicking around but as per my post I agree with them that the Ctek should be goodo as a Solar Controller.

You will need to connect the panels to the Solar input tho because that is where the MPPT Controller lives and it is not on the Alt terminal

If you want to use 1 Anderson plug for both Alt and Solar via the Ctek controller then...
Remove the Alt +ve from the Ctek and connect it to Relay pin 30 (common)
- also note there will be two wires on this terminal when you finish
Connect the Ctek Alt +ve to Relay Pin 87A (normally closed)
- this means the Ctek will see the Vehicle Alt as normal if the bypass switch is "OFF"
Connect Relay Pin 85 to Ctek -ve or Camper Battery -ve or earth if the camper is earthed)
- switching wire so light gauge is fine
Connect a wire of 12 AWG or heavier from Ctek Solar +ve to Relay Pin 87 (normally open)
- this is the wire that will carry the Solar Panel current to the Ctek when the switch is "ON"
Connect a switching wire from Relay Pin 30 via a switch to Relay Pin 86 (relay coil +ve)
- this is the wire that will energise the relay when the switch is thrown thus moving the Ctek input from "Alt +ve" (pin 87A) to "Solar +ve" (pin 87)

Don't balls it up tho or you may blow the Solar

Me?... I agree with Mudski and I would just have two 50 amp Andersons or 75 Amp powerpoles and use the Ctek as manuf designed it

[paulyg]

Strange thing is when i have the solar panel going through its mppt controller and connected to the Trolls 2nd battery i could see up to 13.6 volts on the volt gauge i have on the second battery.
When i had the panel connected to the ctek in the camper with out going through the panels controller, the highest voltage i saw was 12.9.
Maybe the panel voltage without the controller goes to high for the ctek, the ctek max voltage is 22 volts and the panel max voltage without the controller is 21.99.

[the evil twin]

Strange thing is when i have the solar panel going through its mppt controller and connected to the Trolls 2nd battery i could see up to 13.6 volts on the volt gauge i have on the second battery.
When i had the panel connected to the ctek in the camper with out going through the panels controller, the highest voltage i saw was 12.9.
Maybe the panel voltage without the controller goes to high for the ctek, the ctek max voltage is 22 volts and the panel max voltage without the controller is 21.99.

Uummmm... if I read that right you had a reading on one battery (in the Trol) 13.6 and a reading on another larger battery bank (in the Camper) 12.9... yeah?

I would suggest all that means is that the Camper Battery Bank (which is way bigger than the Patrol so will load up more) was at a slightly lower SOC than the Aux Battery in the Trol
IE everything is working as it should and you mistakenly compared apples to oranges (I could be wrong tho)

To be sure I would use the same voltmeter for both tests and hook the panels via the Ctek to the Camper Bankand check the reading and then the panels via the Controller to the Camper Bank and check the reading again

[mudski]

Dont quote me Paul but the ctek works on lower volts but higher amps. I think thats correct???? Maybe why your seeing a lower voltage. ..

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[the evil twin]

Nah, thats the DC/DC conversion happening on the Alt +ve input.
IE the Ctek will take a voltage too low for efficient charging due to losses (say 12.5) and raise it to 13.8 at the cost of amperage

The Solar is opposite
IE it will take a voltage that is too high for efficient charging (17 volts) and use it to make more amperage at 13.8

[mudski]

Nah, thats the DC/DC conversion happening on the Alt +ve input.
IE the Ctek will take a voltage too low for efficient charging due to losses (say 12.5) and raise it to 13.8 at the cost of amperage

The Solar is opposite
IE it will take a voltage that is too high for efficient charging (17 volts) and use it to make more amperage at 13.8
Yeah i thought about that after i posted...

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[Cuppa]

Hi Paul,
Just read this thread. I too suspect that ET is correct.

I don’t believe there should be any need for a relay set up, & the Ctek should do a way better job than any cheapie reg stuck on the back of a panel. I have a relay set up with my Redarc BCDC, but this is only because the Redarc requires this for ‘auto’ switching between fixed solar panels & alternator. (Ignition controlled). I believe as Mudski has said that the Ctek automatically chooses the best source itself (different to the Redarc).

As per ET’s post (post #10) I reckon all is probably working as it should be. You could roughly check this by measuring the voltage of the Patrol’s aux battery & the camper battery bank after each has ‘rested’ for 20 to 30 minutes (i.e. ignition off & nothing running off the aux or camper batteries). I think you will find the camper batteries at a lower voltage than the Patrol’s aux battery, confirming what ET has suggested. You can check solar operation by then connecting the solar panel to the solar in terminals on the Ctek (still with nothing running off the camper batteries) you should observe a slow rise in camper battery voltage until they reach float voltage. Of course there will be less amps available than via the alternator so the charge rate will be lower & take longer.

I note that you said (in post #3) “I had been camping for a few days, so i moved the lead over to the solar input terminal, so i could use the solar panel to charge the battery’s."
If I’ve understood this correctly, you had used the camper batteries for a few days with no charge before connecting the solar to give them a charge. It is most likely that this is an unreasonable expectation of the solar panel. The best way to utilise the panel’s charging ability would be to connect the panel as soon as you can after arriving at camp, that way it will assist in keeping the level of charge as high as possible from the outset. Of course it you take out more than you put in to the batteries, they will still discharge, but by having the solar connected from the outset this will help to slow that discharge rate.

Also if when you measured the voltage on the camper batteries you had anything in the camper using power this too would show a lower voltage. (Eg. if a fridge was running voltage would be lower, with it switched/cycled off battery voltage would rise again after a short time (the reason for checking ‘rested’ batteries).

The reason the voltage would have been higher in the Patrol’s aux battery is that the Ctek also acts as a battery isolator, so any loads in the camper would not be drawing from the aux.

I reckon two leads/two anderson plugs is a better solution than a relay set up, but if running the additional lead is impractical an alternative would be a manual switch somewhere close to the Ctek to change between alternator & solar. A three position switch (On/Off/On) will suffice.

[paulyg]

Hi Ian, I should have made post 3 a bit clearer, I did connect the solar panels to the Ctek as soon as we got to camp.
Thank you to everyone who replied, as usual lots of good advice,