Reliable Budget MPPT controller req'd

[Don 130]

Greeting all, I got a 40watt solar charger from Ebay a few months ago to keep a breakaway battery charged up. The controller has failed so I want a recommendation for a reliable budget MPPT controller to run the panel through. I got Victron one for my camper trailer battery but the budget doesn't stretch that far for the cheapie little panel. There are quite a few MPPT controllers advertised on Ebay etc, but I'm after a recommendation based on experience. Thanks.
Don.

[p38arover]

I've often wondered if the MPPT controllers on ebay are really PWM. They seem too cheap to be MPPT.

I built an MPPT controller a while back (Jaycar kit from Silicon Chip design I picked up at 75% off) but haven't got around to doing a comparison with the PWM controller on my camping solar panels.

The camping panels I have comprise two that unfold. I'm thinking of connecting the PWM to one half and the MPPT to the other. They will receive the same level of sunlight as they will be side by side and I can can record the voltage and current with a 4 channel digital recorder (I wondered for years about a use for it. :) )

One day. :)

[loanrangie]

Most of the cheapies are PWM Ron even though labeled as MPPT.

[DiscoMick]

For a 40watt panel a cheapie PWM should work fine, from my experience, with little to gain from going to a more expensive MPPT.
It will probably be rated to 15A and a 40 watt panel is unlikely to ever make more than half that anyway, so no problems. I've never seen more than about 10A from a 160watt panel.

[p38arover]

I've never seen more than about 10A from a 160watt panel.

I've never seen more than 7.5A from the alleged 160 watt panels that I have. I think one might need to take the panel specs with a grain of salt.

[PhilipA]

I bought a supposed MPPT 15 amp on ebay for $25 as I was concerned my 12 amp Good quality MPPT would be too light for my new 240Watt (ha ha ) panel.

It gave a good output but about 1 amp less than my good MPPT.
Regards PhilipA

[W&KO]

I bought a supposed MPPT 15 amp on ebay for $25 as I was concerned my 12 amp Good quality MPPT would be too light for my new 240Watt (ha ha ) panel.

It gave a good output but about 1 amp less than my good MPPT.
Regards PhilipA

If my number are correct a 15amp controller is on the small side, I’d probably get a 20amp controller

I use the following to size a controller

240w x .85 (85% efficiency) = 204w

204w / 12v (although some say you should use 13v) = 17amp on a good day.

Do we ever get perfect conditions and angle to the sun, not sure.

[Ferret]

I've never seen more than 7.5A from the alleged 160 watt panels that I have. I think one might need to take the panel specs with a grain of salt.

That and the fact panel output is rated at constant temperature (25C I think) and incident radiation equal to levels you might achieve at midday on the equator both of which aren't achieved locally.

[Gav 110]

I've never seen more than 7.5A from the alleged 160 watt panels that I have. I think one might need to take the panel specs with a grain of salt.

This thread is going to turn into the AULRO great solar debate
Here is what I remember from years ago, it may not be 100% but like I said it’s what I remember from years ago


Solar panels specs are rated to a standard test condition
And there are so many variables
If I recall it’s 1000 watts per metre square at 25 degrees Celsius
If your panel isn’t facing the sun directly you won’t be receiving full solar irradiance
In summer, If your in Tasmania you will only get at most about 800 watts per metre square
If In FNQ you will get 1200 watts per metre square
But your panel is going to be more than 25 degrees and in tassie your panel will be less than 25
So you could end up with about the same power produced
Then there’s dirt
If you clean your panels expect 5-10% better output
Until they get dirty again
How old are your panels, the cells deteriorate

I’ve got 1520 watts of panels at the farm house on an inverter with 94% efficiency

I’ve seen 2110 watts of output on a cool
Spring afternoon after cleaning them

Anyways back to the original post
For what you are trying to do Don try this little sucker from Jaycar

Miniature 12V 3A PWM Solar Charge Controller | Jaycar Electronics (https://www.jaycar.com.au/miniature-12v-3a-pwm-solar-charge-controller/p/MP3762)

I’ve had a few running for a couple of years on electric fences
Compact and reliable

Gav

[DiscoMick]

I've never seen more than 7.5A from the alleged 160 watt panels that I have. I think one might need to take the panel specs with a grain of salt.I once, for an experiment on a stinking hot day about midday in FNQ last December, connected both a set of 160 watt folding panels plus a 200 watt flexible blanket facing the sun, through a single 15A PWM controller, with a meter attached in line to double-check the reading, just to see how high the combination would go.
It peaked at 12.7A.
So I don't think a 40watt panel is going to cause any problems, even without any controller at all.

[prelude]

So far as I can tell, a PWM for such small power applications would do nearly as well as a MPPT. In fact, if it is only the maintain a battery: it might be beneficial to just hook it up directly. The losses any charge controller produce are almost similar to the "inefficiency" of a direct connection. Do not forget to check if it has a diode in there of course.

I tried my (small) 5 watt test panels with and without mppt controller and without was more efficient in the end.

Cheers,
-P

[Homestar]

Cheap and MPPT don’t generally go together. As mentioned by Loanrangie, cheap fleabay MPPT units are actually PWM units, which IMO would be fine for your application - I have a couple running some low use/power stuff and they are absolutely fine. I use Victron units in my van and new project as I run top shelf equipment in them, and have higher power demands so getting the most out of my solar matters there.

[Don 130]

Thanks everyone. I'll get this one (Miniature 12V 3A PWM Solar Charge Controller | Jaycar Electronics) as suggested by Gav110. It seems that sort of thing will do the job, and his experience with them is just what I was after. There's a Jaycar shop just over the gorge from here.
I opened the case of the little controller and checked the voltage before and after it. Before was 22.6volts and after the controller 2.4volts in bright (June) sunlight. I thought the output voltage should be about 12 volts, is that correct?
Don.

[Gav 110]

Thanks everyone. I'll get this one (Miniature 12V 3A PWM Solar Charge Controller | Jaycar Electronics) as suggested by Gav110. It seems that sort of thing will do the job, and his experience with them is just what I was after. There's a Jaycar shop just over the gorge from here.
I opened the case of the little controller and checked the voltage before and after it. Before was 22.6volts and after the controller 2.4volts in bright (June) sunlight. I thought the output voltage should be about 12 volts, is that correct?
Don.

Try connecting to a battery
The smarts know when to bring the power on
It senses the battery voltage and starts it’s cycle when required
[emoji481][emoji481]
If you were to not use a controller (as disco mick suggests) on a small battery (as in a break safe) it would be alright for a day or so if there was no other load then the voltage would creep up and wullah cooked battery ☹️

[Don 130]

Try connecting to a battery
The smarts know when to bring the power on
It senses the battery voltage and starts it’s cycle when required
[emoji481][emoji481]
If you were to not use a controller (as disco mick suggests) on a small battery (as in a break safe) it would be alright for a day or so if there was no other load then the voltage would creep up and wullah cooked battery ☹️

I need the thing to be properly controlled it's fitted to a horse float that's only used occasionally, and is stored on a farm. Obviously the breakaway system needs to work when the float is on the road. I had the new panel hooked up to the battery and it was charging ok. Wired it up here at Arcadia. The float was sent away, then some weeks later the battery started going down, (I also fitted a bluetooth battery monitor) so I'm pretty sure the original controller is shot, hence the inquiry.
Don.

[DiscoMick]

Yeah, use a controller to be safe.

[Gav 110]

I need the thing to be properly controlled it's fitted to a horse float that's only used occasionally, and is stored on a farm. Obviously the breakaway system needs to work when the float is on the road. I had the new panel hooked up to the battery and it was charging ok. Wired it up here at Arcadia. The float was sent away, then some weeks later the battery started going down, (I also fitted a bluetooth battery monitor) so I'm pretty sure the original controller is shot, hence the inquiry.
Don.

When you hook it up to the battery the input voltage will drop down to 17-18 volts
Output should be 13-15 volts depending on what state of charge the battery is at
Check it around lunchtime after being hooked up the day before and you should see 13.5 volts (give or take 0.2 volts)
A calibrated meter is always best but as long as you see higher voltage in the beginning and it stabilise down to a lower voltage you should be good

[Grahame Roberts]

Greeting all, I got a 40watt solar charger from Ebay a few months ago to keep a breakaway battery charged up. The controller has failed so I want a recommendation for a reliable budget MPPT controller to run the panel through. I got Victron one for my camper trailer battery but the budget doesn't stretch that far for the cheapie little panel. There are quite a few MPPT controllers advertised on Ebay etc, but I'm after a recommendation based on experience. Thanks.
Don.

12V/24V 100Amp MPPT Solar Panel Charge Controller Battery Regulator LCD Dual USB | eBay (https://www.ebay.com.au/itm/12V-24V-100Amp-MPPT-Solar-Panel-Charge-Controller-Battery-Regulator-LCD-Dual-USB-/163926234672?var&hash=item0&_uhb=1)

[Tombie]

I once, for an experiment on a stinking hot day about midday in FNQ last December, connected both a set of 160 watt folding panels plus a 200 watt flexible blanket facing the sun, through a single 15A PWM controller, with a meter attached in line to double-check the reading, just to see how high the combination would go.
It peaked at 12.7A.
So I don't think a 40watt panel is going to cause any problems, even without any controller at all.

Please STOP!

If you dont know or understand the topic then please realise its ok to not post anything.
40w unregulated will certainly start to cook that battery if left unchecked.

As for linking your 160w and 200w panels. Did you go Parallel or Series? Both methods will have different outcomes.

[DiscoMick]

Did you miss the bit where I said to use a controller?
My example was only to show a 40 watt panel was unlikely to overload a 15A controller.

[Odysseyman]

Greeting all, I got a 40watt solar charger from Ebay a few months ago to keep a breakaway battery charged up. The controller has failed so I want a recommendation for a reliable budget MPPT controller to run the panel through. I got Victron one for my camper trailer battery but the budget doesn't stretch that far for the cheapie little panel. There are quite a few MPPT controllers advertised on Ebay etc, but I'm after a recommendation based on experience. Thanks.
Don.

If the controller is mounted on the panel it could be that heat has caused its failure. It’s much better if any controller is mounted away from heat, particularly well away from the solar panel. I use a Victron for the flexible panel I use for topping up the car batteries.

Have you considered hard wiring the breakaway battery to the camper power supply? Doing so would require a fair bit of research as apparently can be quite complex (and well beyond my understanding).

cheers

David

[Tombie]

Did you miss the bit where I said to use a controller?
My example was only to show a 40 watt panel was unlikely to overload a 15A controller.

Your singular post at the time stated “I dont think it would be a problem without a controller at all.” Nothing about overloading a controller.

Remember people don’t always read further on, and it was only later you posted “use a controller”

Keep that in mind.

[modman]

Wow.......
So much uninformed content.........
I’d suggest people just google the differences between pwm and mmpt.....
You need to understand panel voltage and the benefits of an mmpt...
If you buy the cheapest possible equipment you will see failures......
Nothing wrong with that, just don’t expect different.
Jaycar are usually 12 months behind eBay IMHO.....
Classic Tombie👍
I love the velvet sledgehammer 😂😂😂😂

[p38arover]

Wow.......
So much uninformed content.........
I’d suggest people I’d suggest people just google the differences between pwm and mmpt.....

Or perhaps MPPT. :)

[DiscoMick]

Your singular post at the time stated “I dont think it would be a problem without a controller at all.” Nothing about overloading a controller.

Remember people don’t always read further on, and it was only later you posted “use a controller”

Keep that in mind.I was talking about the size of the panel and controller, not about if a permanent controller was needed.

[Don 130]

My knowledge of how this things work is clearly lacking. On the suggestion of Gav 110, I connected the panel/controller to a battery and found that the output reading of the controller shot up to 13-15volts. So the controller is not stuffed, but that means I've got a different problem. I tapped into the wiring coming from the towing vehicle to input the power from the solar panel/controller. There is a circuit board in the breakaway battery housing through which the input power flows, so perhaps that circuit is stopping the feed from the panel. My knowledge of these things is well depleted by this time. Would that happen or not?
The float is 6 hrs away from me, so it's a decent trip to replace the panel, I'd like to try and sort the problem before returning to it. In the meantime I've suggested the battery is removed and kept charged on a separate charger.
I also wonder if I connect the panel/controller output directly to the battery terminals would be a better option.That way the circuit in the breakaway box would be bypassed....wouldn't it?

Don.

[Gav 110]

Yes I would connect straight the battery as you don’t know what the other electrical circuits are doing even though they are supposed to regulate the charge from the vehicle

Maybe your original controller is putting out a higher voltage than it should?
Is it going into float mode?

Without a calibrated meter, it’s hard to get proper readings

As mentioned when you buy something cheap don’t expect the world

The controllers Jaycar sell are at least of half decent quality for the price from my experience
My controllers (exactly the same as Jaycar sell) I bought off eBay three or four years ago (for a third of the price), I checked the voltage when I installed them
All units are on the original batteries and doing what they should (giving the animals a zap when needed)

My advise (take it with a shot of your best hooch as required)

Get a new controller ($15 ain’t gunna break the bank)
Mount it somewhere away from the panel (as mentioned by Oddiseyman)
Check your meter (against at least one other (poor mans calibration))
Take a packed lunch (maybe even a swag and dinner) and a new battery
Hook directly to battery and test
Leave it for a couple (beers or hours)
Retest and hope for the best[emoji12]

[Don 130]

Thanks for your help with this Gav, when you say calibrated meter, I have a digital multi meter (https://www.jaycar.com.au/cat-iii-multimeter-with-temperature/p/QM1323?gclid=EAIaIQobChMIuJG3pNP56QIV2DUrCh24mwTqE AQYAyABEgJGovD_BwE) does that count?
As for getting it to float stage,I didn't get it hooked up first thing and the sun went down by the time I got back to it. I'll give it another go over the weekend and watch carefully. A trip to Jaycar is also on the list.
Thanks again.
Don.

[Gav 110]

As i have found, just test the same battery with a couple of meters at the same time and see if there the same
I’ve sent multimeters in for calibration only to find they were out when I got them back

[ozscott]

For maximum output best to mount the the controller close to the battery. You see eBay panels where the controller is mounted on the frame of the panel.

Cheers

[DiscoMick]

Yes, put the controller as close to the battery as possible, to minimise voltage drop.