Newbie needs help replacing PWM with MPPT controller

[jsmith8918]

Hello, all. Total newbie here. I have a camper trailer with some leftovers of my friend's former solar system including 2 (unknown brand) 100W panels, 1 (@100Ah?) Sun Cycle 12V Lithium Iron Phosphate Battery Model GP-LiFePO4, Magnum Energy MagnaSine MS-E Series Pure Sine Wave Inverter/Charger 2000W 12V 100A model MS2012, Magnum Energy ME-RC (remote control?), Nature Power Solar Panel 28-Amp PWM Charge Controller 60028 UPC 839290006054. All of these items have been installed on our camper trailer for about two years now, but I've never learned how to actually use them. I started watching Prowse's YouTube videos (excellent!) and read the "Made Easy" book (also excellent)! From one of the videos, I became convinced that I should probably replace my current PWM controller with an MPPT. I bought from Amazon the "MPPT Solar Charge Controller 40A Max.PV 100V Negative Grounded Tracer 4210AN + Remote Meter MT50+Temp Sensor Cable for Gel Sealed Flooded Lithium Solar Battery Charging" which is a controller and "remote meter." But after comparing wiring diagrams in the "Made Easy" book with the literature that came in the MPPT package, I can't find any diagram that looks exactly right for my system (mostly because of the apparently oversize Inverter/Charger). I'm normally a tinkerer and usually don't hesitate to just start hooking wires up and seeing if stuff works, but I'm now hesitant to do that after reading Prowse's cautions about possibly frying components by such haphazard experimentation. So I'm hoping someone might be able to help direct me through this solar wiring minefield with maybe a wiring diagram (either commercial or hand-drawn is fine with me, or even a photocopy of one from the "Made Easy!" book with appropriate hand-drawn modifications). And though my goal is to replace the existing PWM with the new MPPT, I also don't know whether I should use the MT50 in place of the ME-RC (or if those even do the same job). Finally, my MPPT package arrived from Amazon with damage in the form of a dented mounting flange on one corner, and though I can straighten it out with pliers, does that maybe suggest it was thrown around hard enough to damage internal components (maybe necessitating a return / exchange). Thank you in advance for any help and / or suggestions. Kind regards.

 

[camelCase]

A picture is worth a thousand words. If you could draw a diagram of how your system is configured it would be a lot easier to give advice.

 

[MisterSandals]

Nature Power Solar Panel 28-Amp PWM Charge Controller 60028

This is probably at least as good for what you are doing as the MPPT that you bought.

Why do you suspect your existing PWM SCC is not working?

I'm not a big fan of PWM (i have several PWM and MPPT) but for the 2 little panels, its probably putting everything the panels are producing into the batteries. I'd check to see if its broken before you go about fixing it...

 

[jsmith8918]

A picture is worth a thousand words. If you could draw a diagram of how your system is configured it would be a lot easier to give advice.

This first photo is from the owner's manual from the Inverter/Charger. It is the closest representation from that manual to the way things appear to be currently wired up in my camper trailer.

 

[jsmith8918]

A picture is worth a thousand words. If you could draw a diagram of how your system is configured it would be a lot easier to give advice.

This second photo is from the owner's manual for the MPPT. What I find confusing about this diagram is that I'm not sure whether that unlabeled suitcase-looking device is supposed to represent an Inverter/Charger, and there's no MT-50 or ME-RC. Also, my existing cables from my battery to my Inverter/Charger are huge, and would in no way come anywhere near to fitting into those shown terminals of the MPPT as shown in this image.

 

[jsmith8918]

A picture is worth a thousand words. If you could draw a diagram of how your system is configured it would be a lot easier to give advice.

This third photo is from Prowse's "Mobile Solar Power Made Easy!" book.

 

[jsmith8918]

This is probably at least as good for what you are doing as the MPPT that you bought.

Why do you suspect your existing PWM SCC is not working?

I'm not a big fan of PWM (i have several PWM and MPPT) but for the 2 little panels, its probably putting everything the panels are producing into the batteries. I'd check to see if its broken before you go about fixing it...

I bought the MPPT for two main reasons: (1) my battery is LiFePO4 and my understanding was that this particular MPPT is made to work with that kind of battery while my existing PWM is supposed to be a poor substitute for LiFePO4, and, (2) I'd like to eventually bump up to a second identical LiFePO4 battery along with two more solar panels, and I think this MPPT is supposed to be better for that combination than the existing PWM. But I readily admit to being new to all of this, and am open to the advice of more knowledgeable folks than myself, so if I should just leave well enough alone with my PWM, I'm not opposed to returning this MPPT and putting the money toward a second battery.

If I do end up using the MPPT, I think the third photo seems closest to providing the schematic that I need to follow, but I'm not sure if I would then need to use the MT-50 that came with the MPPT in place of the current ME-RC that came with the Inverter/Charger, or whether they are not direct replacements for one another and I would therefore install both. Hmmm.

Thanks for any input. Keep it coming.

 

[MisterSandals]

I bought the MPPT for two main reasons: (1) my battery is LiFePO4 and my understanding was that this particular MPPT is made to work with that kind of battery while my existing PWM is supposed to be a poor substitute for LiFePO4,

Do you know what your preferred charge profile will look like? How high will you charge, float and how long will your absorb be? Do either of these SCCs do that?

 

[Wakintx]

Actually other than the y question of changing out the charge controllers the how should be simple. There should be wires coming from the solar panels they go into the PV input on the new charge controller after removing them from the old charge controller.

There should be wires for the battery probably Mark battery out or something similar on the old charge controller that either go to the battery or a bus bar or some terminals on the Magnum I've looked at Magnums before but I don't own one and I don't have them memorized that you would remove from the old charge controller and hook them to the new charge controller.

And then if there's any other wire such as a battery temperature sensor on the old charge controller although most pwm controllers are pretty cheap and don't necessarily have one you would need to connect that to your new charge controller. If it connects.

All this should be done with the batteries disconnected and sure power disconnected.

Any remote monitoring display unit if it is hooked to the charge controller is most likely not going to work. If it is strictly connected to the Magnum inverter to monitor it it would remain but your new mppt if it comes with a interface display screen that is used to program it or monitor it that will be what you connect.

Once you look and see what wires are connected to your existing charge controller and the answer should be fairly obvious. As long as your new charge controller handles more or the same amps as your old charge controller handles the voltage that you are using most likely 12 volts it's pretty much a and easy swap

Since it's a pwm charge controller the settings on your new mppt should be able to be configured to optimize your battery.

Optimizing the solar panels is a whole nother story also. Your title was how do I change out my charge controller and it's simple pretty much to do