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woodsy asked

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

battery charging
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JohnC avatar image JohnC ♦ commented ·

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 answered ·

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: https://www.victronenergy.com/where-to-buy

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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woodsy avatar image woodsy commented ·

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?


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JohnC avatar image JohnC ♦ woodsy commented ·

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.

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woodsy avatar image woodsy JohnC ♦ commented ·

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?

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klim8skeptic avatar image klim8skeptic ♦ woodsy commented ·

Hi,

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.

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ejrossouw avatar image ejrossouw woodsy commented ·

@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.

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woodsy avatar image
woodsy answered ·

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 multi.plus 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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