woodsy avatar image

batteries not fully charging from solar

I have a stand alone system with a multiplus controller. I have 12 x 220 a/h batterieswired as 3 banks of 48v. When the sun is out the bstteries charge up very quickly but they never achieve absorbsion level. In fact the only way i can get them up near that level is to shut one string down. Occaisionally i fire up my 2kva gen set and charge batteries up to float level. I have tried reducing the charging amps but it still does it. The voltage rises rapidly up to around 59v then the system shuts down for 5 mins or so

charging battery
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Hi Woodsy, and welcome! Unfortunately you'll need to give us more info, and indeed even clarification on what you have. Eg. the "multiplus" isn't a solar cc. Just a coupla observations:

Substantial batt capacity, and will need a fair bit of solar. And if you're entering winter, tis a bad time anyway.

2kVA genset is quite small, presumably you have to limit it's demand.

"59V" is too high for a charge V for a typical 48V batt bank, so I'm thinking you're looking at Panel V. If that's so, and it's actually risen to that when charge A is reduced, then it's possible your panels are wired suboptimally,

But I'm guessing. Please describe your system in more detail, even if it's not all Victron. We'd love to help, but give us more to work with..

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JohnC avatar image

Okaay. With grid in the equation and the length of your 2x panel strings, it seems you may have both dc and coupled systems. So it's likely going to be quite complex to diagnose, and frankly, beyond practical to do remotely. You really need a trained Victron tech to look over your system and set it up correctly.

I looked up your supplier to see, but perhaps they're not?? Lookee here, there's plenty near Brisbane, some with names well known in Oz:

Appreciate your frankness re your skill levels, but I reckon you're right about there being something wrong. Grab a local, and when you do, ask for their *top* Victron man.. :)

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Thanks john. I am not in Brisbane but in Boorowa which is approx 50ks west of Yass. Today i put extra load on the system by running an air con on heating cycle. I turned half the panels off and the batteries achieved absorbtion level?

Yeh, something's wrong to have to do that. Appreciate the distances you face, but maybe someone closer can help.

And if anyone else on this Community can help, please do.

This is my set up! I have a 5kw inverter fed by 16 250w REC panels. This provides all the 240v power we need during the day no worries. I also have 6 x 12v Bosch panels putting out around 78v and fedd into the victron charge controller. Along with the victron multiplus. The problem seems to be that the inverter is producing a heap of power and somehow causing it to stop feeding 240v into the power circuits and the multiplus supplies the power from the batteries? The batteries rarely achieve absobtion level from solar input. Because it keeps shutting down for 5 mins or so each time the batteries dont get a chance to fully charge?

Should the 6 bosch panels be rewired so they are putting out say 24v (3 x2 ) i have had a solar tech have a look at it and he thinks the inverter should be configured differently. I have 12 220 a/h gel batteries but each morning the level is very low at first. The only thing on during the night is the fridge? Can anyone offer some advice?


BMV is wired up wrong.

The charge controller (?) seems to be wired to the battery side of the BMV. Will put SOC out of whack.

Good spot Klim. I also note a BT dongle for the mppt, a dial likely for the BMV, and a blue wire from the Multi (MK3 adaptor?). So there's a fair array of comms, but what this system is crying out for is a GX box to bring it all together. Like with full integration of the comms, and the features therein like ESS to take charge.

It's a good system, even the ac inverter is likely a rebadged SMA, so should work fine.

Just my opinion, but I think it needs 'finishing off', and with some www available to a GX, a global event. Configurable remotely by any-ole Vicron expert from anywhere in the world. VRM graphs icing on the cake..

Yes the inverter is an SMA and yes 240v side of things works perfectly

The blue wire connects to a dongle which in turn connects to my laptop and gives me access to all the settings

Can you explain more re "BMV is wired up wrong"

What is bmv? How should it be wired

What is GX box?

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As much as i dislike argueing with experts the terminals on the charge controller are clearly marked and connected correctly???

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@woodsy As others mentioned, the MPPT is wired to to wrong end of the shunt and must be moved from the red position to the black. No connections should be made at the battery end of the shunt. BMV is your battery monitor. Venus GX device is handy indeed, but would unlikely have helped finding a basic wiring issues like this ;) I'd personally not change the configuration of the solar panels unless you have shading issues. Also, higher voltage lowers current and means thinner cables can be used and ensures the solar start working earlier and longer.

Wow what a difference that made to the bmv readings. I changed the cable over and ran my gen set for a short time untill the charge controller showed float! At the same time the light on the ulti plus went to absorbtion ! The only problem is the voltage is showing as just over 59v ? Way to high?

Did you look at the video i put on youtube? With all panels on it is still doing it

59V is too high. Default settings in the Multi for Pb's are likely around 57.6V Abs and 55.2V Float. Subject to temp compensation, and may well rise a little above 58V if it's cold and you have a temp detector, which you'll likely find bolted to a batt terminal with a thin wire running to the Multi. That should be there, your Multi would have come with one in the box.

Check first to see the dc mppt isn't contributing, it should show 0W @ 59V. Then head into the Multi's charging section and see if you can reduce it. With multiple batt strings, even a little lower than the defaults would be ok, you can't hurt anything going a little lower.

Be sure of your V's. Multiple sources should match pretty closely, and a multimeter even to be the judge. You must fix this, that many batts will be expensive to replace.

Glad to hear. Without a wiring diagram or more details it would be difficult. Do you have a model no for the Schuko?

My suspicions are: 1. the Schuko is overloaded either not meeting the design specification per solar input 2. The multiplus draws to much from it as I assume the multiplus charges the battery bank from it? 3. The battery profile is incorrectly set up on the multiplus.

Things get rather complex nd I think the installers may have to come and optimise the system correctly and ensure min and max values etc are also taken into account. It is a complex science and not just plug and play.

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woodsy avatar image

Thanks for that. I am not a tech head so i have trouble with some of the terminology used. My system was designed and built by Uni Ind in Brisbane and is a very good set up. I have 16 200w panels in two strings and 6 more sep panels which constantly trickle charge I believe these are connected to the grid side of the system. I have a victron charge controller and a 5000 as well as a 500w inverter all connected to 12 x 220a/h batteries in 3 banks of 4 (48v). The main prob i have is that when it is bright and sunny the inverter keeps shutting down as the batteries seem to be charging too fast. (The 240v does not shut down just the charging side) i have found that if i shut down half the panels then it holds and almost fully charges the batteries but they never achieve absobtion level just under. The victron battery gauge shows 100% but still bulk charging.

The charge rate shown when i hook up my lap top is 15amps. I have tried dropping that to 5amps but still the same. The gen set i have puts out very clean power and does the job of charging ok so long as we dont put any big load on the system

I just seems to me that the batteries should reach float level before anything shuts down?

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