Solar charge controller feed by truck alternator

This is what I was thinking. It may cost a little more but it's less components and less space is taken up.

From my research and talking to people who have had both PWM and MPPT charge controllers the MPPT is by far the best option. This is especially true for those that like to roam in the mountains and areas that do not have wide open full sun during the day .

 

to each their own. My pwm controller does fine in the mountains. Some people just like to spend money.

 

You can run up to 3 100W(5.5ADC) modules with any (input limited to) 22VDC charge controller (ie D250S). You run them in parallel.

 

Just run 10AWG for your PV wiring.

 

Good choice my man. I'm two years with the Ctek setup/ 180 days backcountry. Set it and forget it. It's never let me down.

 

Good to know. For some reason I thought the CTEK could only handle 1. That adds a LOT of capacity to the controller.

 

Yeah. In the D250S manual they state in a bol d print "Warning! Max 23V input. Do not connect two solar panels in series".

 

Thought that I'd bump this.

So I found a bad connection in my setup. I have a 6awg run from the starting battery to a trolling motor plug in the bed to feed my D250S via ALT input. I was seeing a huge voltage drop when the Ctek tried to draw via that wiring run.
Bypassed the run by supplying 13.5v/20adc from my Ctek 25000 battery charger by means of the supply setting. And all worked fine.
Pulled my trolling motor apart. And low&behold. About 2" of my neg wire was cooked. And I mean the tinning was evaporated! I'm going to go with Chinese manufacturing for the failure here.

Which got me thinking (since I now have access to AC power the first time in 3-1/2 months) about experimenting with my Morningstar SK12 12a PWM charge controller. To see why it didn't get my second battery charged to 14v in the past via ALT input. Or if the problem was my wiring flaw.

First I got my starting battery to 12.3.



It's a crappy Sears Diehard 31m with four years on it. After a year old it never held a full charge. Whatever that's worth...

I attached my Ctek 25000 to my Anderson type plug input for the Morningstar CC. The Morningstar turns on when it sees at least 11v. The Ctek has a supply setting feature which is around 13.5v @ 20A which im using to simulate an alternator feed.


Then I just monitored the input vlt and current at the CC and the battery vlt.













Seeing how much power the input of CC is using after 6 hours:



And battery voltage:



So after six hours, the CC is still on the bulk stage and never got to regulation/float. Battery never got over 13.6 (which is around the battery charger's supply vlt setting). Even with up to 20a of readily accessable amperage, the CC is only pulling 1.5 to 1.6 amps. And the battery isn't charging fully. So I guess that's why the Morningstar fed with the ALT never seemed to work well. 18v of solar gets the battery at 14.4 with the Morningstar no problem.

The Ctek D250s on the other hand was able to charge a similar sized Ah battery via the 13.5/20A (with an ARB fridge pulling 6A) from 12.3 to 14.4 in four & a half hours.

So if anyone is looking to adapt a solar- specific CC to use Alt input to charge their second battery they may want to install a dc vlt boosting upconvertor if they're seeing results like I am.

Or. Go the D250s route. My battery always seems to be happy.
(Resting voltage after 72 hours)