MPPT charge controller recommendations

Ljohnsaw · July 11, 2023, 08:50:30 PM

I'm planning on putting some little (10W) solar panels on my equipment to keep the batteries topped off. I picked up three of them pretty cheap. It has some unknown controller that I don't trust enough to use. I learned my lesson on those knock offs boiling a battery dry. I have a bigger MPPT type controller on my camper and it works great but I don't need anything near that size or cost for the tractor and SkyTrak. Amazon is having "Prime Day" and there are a few smaller MPPT controllers.

SUNYIMA 60A MPPT Solar Charge Controller with LCD Display Dual USB Multiple Load Control Modes,New Mppt Technical Maximum Charging Current (60A) for $25, normal price

10A MPPT Solar Charge Controller, Bateria Power Solar Intelligent 10 Amp 12 Volt Solar Regulator with LCD Display and LED Indicate Light Designed for 12V Gel AGM Lithium LiFePO4 for $31.19 from $38.99 (water proof!)

Allto Solar Intelligent 10A MPPT Solar Charge Controller,10 Amp 12 Volt Solar Panel Regulator with Digital LCD Display + Temp Sensor + Charging Level for 12 Volt Wet Gel AGM Lithium for $33.71 from $39.99

I know nothing of these brands and have review ratings from 4 to 4.3 stars. The panels I have have a short circuit amp rating of a whopping 0.31A. If I bought higher ratings, I could use it elsewhere down the road, but am I sacrificing something on these small panels? Also, do I need to disconnect when I want to run my equipment? Ideally, I'd like to keep it connected so I don't forget to reconnect at the end of the work period.

Southside · July 11, 2023, 10:20:31 PM

Wasn't half an hour ago I told my wife we needed a solar charger for the excavator after I spent an hour trying to jump it and ended up pulling the dead batteries so I am interested in hearing this too.

mudfarmer · July 12, 2023, 08:47:52 AM

There are more qualified folks to answer but no you don't need to disconnect when the engine is running, the controller will just see that the battery is at higher voltage (fully charged) and will stop trying to charge it.

I think those are all "no name" brands, but so is basically everything else in the world today, get the waterproof one and spray it with a hose, I'll buy some if it doesn't go bad ;D

Joe Hillmann · July 13, 2023, 07:53:34 PM

For a 10 watt panel I would go with a cheap $5 pwm controller.

MPPT is way overkill for 10 watts and may actually draw more power that it puts into your battery.

I have makeskyblue charge controllers if they draw 2 watts at idle that is 48 watthours per day. Your 10 watt panel probably will put out closer to 7 watts for 6 hours per day. Thatis 42 watthours per day. For a loss of 6 watthours per day. Of course the controller MAY use less than 2 watts and you may get more than 6 hours of sun. But that 7 watt output is only with the panel pointing directly at the sun in cold weather. So cloudy days, parked in a sheaf or panel not aimed directly at the sun and you will get nothing.

A PWM draws no power when the sun isnt shining.

Joe Hillmann · July 13, 2023, 08:01:58 PM

I dont think a single one of those controllers you linked to are MPPT.

They are PWM with screens being sold to people who dont know the difference. Many, many manufacturers outright lie and claim there PWM controllers are MPPT. If a controller is MPPT it will weigh several pounds and be close to $100 for the cheapest Chinese knock offs.

Southside · July 13, 2023, 10:21:49 PM

Any chance someone can translate this into redneck? ;D

newoodguy78 · July 13, 2023, 10:24:37 PM

:D :D

mudfarmer · July 14, 2023, 10:36:21 AM

redneck translation:

Ya asked me which one o those outboards to buy, just get ya a cheap trolling motor instead. Those are just all trolling motors anyhow but theys chargin ya more and callin it an outboard.

47sawdust · July 21, 2023, 09:13:59 PM

I had very good luck with Windy Nation. They sell small to large solar packages.Answer questions quickly and ship even faster.

Ljohnsaw · July 22, 2023, 01:54:45 AM

Nice site! I just ordered a pair of water proof 10 amp PWM controllers with express shipping for less than $50.

peakbagger · July 22, 2023, 05:47:13 AM

I have always been a fan of Morningstar charge controllers. Barring a direct lightning strike, they run forever. I also like that they have built in Low Voltage disconnect on many models. They have sold lots of them over the years and they pop up on ebay used.

mudfarmer · July 22, 2023, 11:16:35 AM

morningstar tristar mppt60s have been rock solid for a decade here

maple flats · September 20, 2023, 08:52:53 PM

I have 2 large solar charge controllers, and have good luck with them, but I also have a 50 watt panel and over the years I've gone thru 2 different cc's they don't seem to be very well made and fail far too soon. I had one (an MPPT, name unknown) that worked for about 3 years, then it failed. It was just being used to maintain the battery on a diesel tractor that often sat 3-4 months at a time. I had another, (also MPPT, name unknown) that I used to maintain the battery on my excavator, which sometimes sat idle for up to 7-8 months, that CC failed in the 7 months it sat , when I needed the excavator, the battery was dead.
In both cases the CC's were rated to be moisture proof, and when I connected them they were each sending a proper amp flow to the batteries. One failed before 7 months, another failed between 2 and 3 years. I can't recommend a brand that is any good.
Now, if you want a CC for a bigger Solar array, I like Outback, Tristar and Xantrex in 60A, and 80A MPPT sizes in 12,24 and 48V models. While I never tried one of their 12V models, their 24 and 48V units were very dependable. The one I had that failed ran in the $80-$120 range each. The big ones I have were about $550-$800 each. Likely more now, but until this last 3 yrs of Covid fueled inflation it seemed all things solar was coming down every year.

maple flats · September 20, 2023, 09:09:20 PM

I just looked up some solar charge controllers and the prices, it appears at least on the larger sizes the prices have still dropped more, however on 12V units I won't makeany suggestions which is better or worse.

maple flats · September 22, 2023, 09:38:51 AM

Just keep in mind, a 10watt panel at full sun, if 12V will only put out 1.2A, in partial or not aimed at the sun 100% it will be less, you don't need a 10A controller, a cheap PWM will suffice. PWM stands for pulse width modulation, it sends a pulse thru the battery and the pulse varies according to how well charged the battery is. Ideal for a 10 watt panel would be 2A up to maybe a 5A PWM, 2 or 3A preferably

Sod saw · September 24, 2023, 08:13:48 PM

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Many of the 12 volt charge controllers manufacturers state that the charge controllers should not have the solar panel connected with the battery disconnected.

In other words you must connect the battery first then the panel. If you disconnect (even by accident) the battery, the charge controller could be damaged (yes, first hand knowledge).

I suspect that these inexpensive ($100 [+ -] range) all use the same circuitry inside of the box. With different displays and manufactures labels .

I now work very hard to be sure that the battery is always connected to the circuit. Some of mine have been connected for a few years, others are not as old.

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