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vanholladyke avatar image
vanholladyke asked

My solar MPPT shows no evidence of charging the battery?

Before I start; I apologise for being a complete moron when it comes to electrics. I must have missed that physics class at schooled. I’ve got an MPPT 75/15 with a 150w solar panel and a 110ah battery, all brand new and installed by the company who converted my van. The only real load I have had on the leisure battery is the thermo electric coolbox, which is dc load Input rated at 3, 91 A. Admittedly, the ambient temp has reached 35 degrees C daily last couple of days, so the coolbox has been grafting. However, the leisure battery died last night whilst showing around 13.5V on the app. No power to the coolbox, not even enough to turn on the lights. Now I accept that my solar isn’t big enough to power that fridge forever, especially in this heat, however the app not showing any evidence of the solar yielding any power confuses me. Surely it was grafting to keep the battery charged all day?

Ive checked the fuses, all good.
any help, guidance or layman explanations are hugely appreciated!


regards,

Jim

MPPT SmartSolar
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4 Answers
Justin Cook avatar image
Justin Cook answered ·

Hi @VanHollaDyke,

Start by checking the wiring from your controller to battery; the history shows a lower minimum battery voltage every day than is actually possible, so this is strongly indicative that you have either a bad connection, a bad breaker or fuse, or something connected incorrectly... now it's just a matter of tracking down what exactly that is.

If you have a bad connection or a half-blown fuse (which can and does happen) or perhaps a bad/knockoff breaker then the controller won't be able to pass any current through to the battery... and you don't want it to, either, since passing current through a bad connection is an invitation to disaster.

Run through your controller-to-battery wiring, checking every single crimp, fuse, breaker (make sure that they're recognized-brand breakers or fuses like LittelFuse, Zeeman, or Bussman), connection, and etc and I'm confident you'll find the source of the problem.

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dgnevans avatar image
dgnevans answered ·

Also check to make sure you have Charge enabled on the mppt.

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vanholladyke avatar image
vanholladyke answered ·

Thank you both for your answers. @Justin Cook - Bay Marine Supply USA In particular for your detailed response. I’ve just got back home and managed to check out the full circuit. I can’t find any loose/dodgy/blown/disconnected bits. It all seems connected securely and no errors on the LEDs or the app. I’m completely stumped. I would be tempted to say that it is just working very efficiently, but the history in the app tells me otherwise.

Could I be missing something? I notice on the front of the setup I have a fuse box with three blade fuses in, and LEDs that indicate when the fuse is blown (evidential when the fuse is removed). Fuses 1 and 2 indicate the red light when I remove the fuse, but fuse 3 doesn’t show the red light when I remove it. Could this be an indication of something not set up correctly? I can’t work out exactly what these fuses are for mine. Stumped!

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klim8skeptic avatar image klim8skeptic ♦ commented ·

Have you checked the fuse in the bottom of the Mppt??

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Alexandra avatar image Alexandra ♦ commented ·

@VanHollaDyke

Are you able to check the polarity if the pv cables?

The most common mistake is they are the wrong way round.

Has the unit worked at all?

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vanholladyke avatar image vanholladyke Alexandra ♦ commented ·

I haven’t seen it working at all. My history on the app says not. I’ve only had it about a month and no readings at all, until now I have just removed The fuse on the bottom and waggled a few wires to check they are connected and I’ve noticed the following on the app. Is this sign of it working? It’s not a sunny day...

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marekp avatar image marekp vanholladyke commented ·

I heard that you need minimum 5V more from panels than the battery voltage for charging to start.

https://www.youtube.com/watch?v=EVAvRs32TiE

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vanholladyke avatar image vanholladyke marekp commented ·

Very cloudy day unfortunately. I’ve put a demand onto the battery with lighting and night heater. I’ve now got fluctuating around the following image. This is certainly more activity than I have ever had before on the screen. Is this a good indication it is functioning?

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ vanholladyke commented ·

Did you replaced the fuse or did you use the old one?

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vanholladyke avatar image vanholladyke Matthias Lange - DE ♦ commented ·

Just removed it, checked it, looked intact so put it back in. Wiggled a couple of wires on the controller to ensure they were connected firmly and it seemed to start doing stuff!?

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ vanholladyke commented ·

"Just removed it, checked it, looked intact so put it back in. Wiggled a couple of wires on the controller to ensure they were connected firmly and it seemed to start doing stuff!?"

Than you maybe had a bad connection.
Getting 0V at the battery everyday is mostly a indication for a blown fuse or a bad connection somewhere between the MPPT and the battery.

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marekp avatar image marekp vanholladyke commented ·

For a cloudy day this 11W from 150W panel looks reasonable.

Do you have, in your system, something that would disconnect the load from battery when battery voltage drops to 10.5V?

When I see battery voltages of 0.01 and 2.27V I suspect that you do not have it.

If those voltages are correctly measured, you are slowly killing your battery.

Is your load connected to the load output of MPPT or directly to the battery?

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vanholladyke avatar image vanholladyke marekp commented ·

There is nothing wired into the load connection points on the MPPT so I assume it is directly into the battery?

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marekp avatar image marekp vanholladyke commented ·

Is is bad.

If your load is not connected through load output of this MPPT, this charger will not disconnect the load when battery voltage drops to 10.5V.

If you keep discharging this battery below 10.5V soon this battery will die.

I do not thing there is anything wrong with this MPPT.

Your setup is not optimal.

You have only 1 PV panel and for that reason MPPT will start charging battery only at almost full sun or when the battery is deeply discharged.

If you can, add second PV panel in series with the first.

This way MPPT will start charging your battery even in cloudy day.

Connect you load to MPPT load output to save your battery.

If you cannot connect your load to MPPT load output you can buy external battery saver device.


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Matthias Lange - DE avatar image Matthias Lange - DE ♦ marekp commented ·

"You have only 1 PV panel and for that reason MPPT will start charging battery only at almost full sun or when the battery is deeply discharged."

The screenshot of the History shows more than 20V every day (even today with not much sun as VanHollaDyke wrote). That's more than enough to start charging even if the battery it not "deeply discharged".

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marekp avatar image marekp Matthias Lange - DE ♦ commented ·

It is possible that you are right, but those voltages are max values and we do not know what was the battery state/voltage at that moment.

Battery could have been fully charged by the second source of charging (alternator) and no charging from PV was needed so it was not happening.

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vanholladyke avatar image vanholladyke vanholladyke commented ·

Success??!

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marekp avatar image marekp vanholladyke commented ·

Success will be when your battery voltage stops going below 10.5V.

Do you have second source of charging this battery?

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vanholladyke avatar image vanholladyke marekp commented ·

It’s on a split charger so charges when the engine runs. I have the bridge between pins 2 and 3 as per the 75 diagram in the image so should disconnect when low voltage?

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marekp avatar image marekp vanholladyke commented ·

It will disconnect only if the load is connected to load output of the MPPT.

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vanholladyke avatar image vanholladyke marekp commented ·

Ok, thanks. I find those results very strange though as the battery shows such a low minimum, even on days where there hasn’t been any demand on the battery at all?

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marekp avatar image marekp vanholladyke commented ·

In that case, there could be also a bad connection between MPPT and the battery.

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vanholladyke avatar image
vanholladyke answered ·

I think the situation may have been resolved. The readings have been how I would expect them to be, for the last few days since checking all connections are good. Thank you all for your responses



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