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Old 02-11-2018, 00:33   #1
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Solar charge and consumption

Hello , I was making some tests yesterday and I notice something strange , I started with full charger batteries on float charge state , the charger was supporting the batteries with 13.8 bolt , I added a load of 1 amp on the batteries and the charger state changed to this on the photo .

So the question is why the charger provides 4 times more amps than the amps.being consumed ?
Where the extra amps are going ?
There is no significant voltage drop.
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Old 02-11-2018, 03:29   #2
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Re: Solar charge and consumption

Forgetting the load for now,

whatever the current flow (amps) into the bank at a given lower voltage,

when the voltage gets raised, the amps will increase.
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Old 02-11-2018, 03:35   #3
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Re: Solar charge and consumption

How many amps is the load you're talking about?

How are you determining whether or not your bank is at 100% Full?

You cannot rely on the charger to determine that, certainly will not get there from default settings OOTB.

It is your job to adjust its settings until it gets there before dropping to Float, default will do so way too early.

What do you have Absorb V set to now? Minimum Absorb Hold Time?

Have you got an ammeter or battery monitor?
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Old 02-11-2018, 03:47   #4
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Re: Solar charge and consumption

I do have an ammeter that's how I count consumption, the absorption time is set to 6 hours , and suppose to change automatically .
The batteries have been charging from solar without discharge a week now , measuring the voltage the fact that they are staying mostly at float makes me think that they are full.
The bank is 200 ah .

The question is why when I draw one amp the charger provide 4 and if the batteries really need that charge or the charger is confused

Absorption voltage is 14.5
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Old 02-11-2018, 04:39   #5
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Re: Solar charge and consumption

One of the drawbacks of the Victron controllers is that in some circumstances they can enter float when the batteries are a long way from full.

To compensate for this, the controller will drop back to bulk if the battery voltage drops below the float voltage. This very aggressive return to bulk charge is quite different to how the charge algorithm on most solar controllers is designed to function.

The Victron controllers will often return to bulk several times before the batteries are full. They have a unique very short (about 15 mins) absorption time after this return to bulk, and then the cycle repeats.


The algorithms used for most solar controllers make more of an effort to ensure the batteries are full before dropping to float. As the battery is very likely to be full at the end of the absorption phase, they are therefore much more reluctant to drop back to bulk. There needs to be evidence that the battery has been discharged (in the form of a low battery voltage) before they then initiate another bulk/absorption cycle. This cycle will be much longer than the short Victron cycle.

An analogy may be baking a cake. The Victron keeps removing the cake from the oven to see if it’s ready. If it’s not cooked it goes back into the oven for a short time before it’s tested again. A conventional controller could be compared to the technique of leaving the cake in the oven for a couple of hours on the assumption it will be cooked correctly in this time.

So if the settings are correct, you can be somewhat confident that when a conventional solar controller drops to float then the battery is full (or to be more technically correct, it was an appropriate point to drop to float voltage), but with a Victron controller the battery will often be a long way from full when the controller drops to float. The Victron controller is designed to work this way and will give the batteries another charge before checking again.

In your case the small load has caused the voltage to drop below the float voltage and the Victron controller has returned to a bulk charge state. If the load was 1A then 3.5A is being used to charge the batteries. As the voltage of 13.43v is a long way from the bulk voltage, the Victron controller would have allowed far more current at this point if the solar panels were capable of delivering this.
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Old 02-11-2018, 04:57   #6
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Re: Solar charge and consumption

If they were really Full at the start of the 1A load, I can't see how the charge voltage would be so low.

Full is when trailing amps **at Absorb V** tapers to an amp or two. If that doesn't happen, while testing just set Float V = Absorb V until it does.

Is the bank in good shape?

Did that load run for a long time? Perhaps during non-solar hours?




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Originally Posted by gmakhs View Post
I do have an ammeter that's how I count consumption, the absorption time is set to 6 hours , and suppose to change automatically .
The batteries have been charging from solar without discharge a week now , measuring the voltage the fact that they are staying mostly at float makes me think that they are full.
The bank is 200 ah .

The question is why when I draw one amp the charger provide 4 and if the batteries really need that charge or the charger is confused

Absorption voltage is 14.5
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