Reliable Budget MPPT controller req'd

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

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.

Thanks everyone. I'll get this one 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.

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Originally Posted by Don 130

Thanks everyone. I'll get this one 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.

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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 ☹️

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Originally Posted by Gav 110

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 ☹️

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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.

Yeah, use a controller to be safe.

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Originally Posted by Don 130

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.

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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

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Originally Posted by 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.

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12V/24V 100Amp MPPT Solar Panel Charge Controller Battery Regulator LCD Dual USB | eBay

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Originally Posted by DiscoMick

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.

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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.

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.