Battery voltage drop!

[Leakylunar]

Quick question to determine new battery needed.
Since solar has been installed I can now see voltage of my battery via victron app seems fine during the day
come to get in the van in the morning it’s steadily dropping today it was 11.73!

 

[Diabalo]

The Max showing 13.xx is just a float charge it should show 14.xx for bulk charge if thats whats needed by the battery, do you have any loads on the battery's? Also to get a better breakdown click on the share symbol and email yourself the Bluesolar history, it's a CSV file so will open in excel. You will get a lot more information, like times of charge regimes, bulk, absorption and float. It may help to see what's going wrong.

 

[Bobby-gg]

I'd say you've got something switched on pulling quite a load, pulling your battery down overnight

Have you got the model with the low voltage battery protect?

 

[Raul]

I would say that controller is not set properly. It stays at float, replaces 200 to 300wh per day so is cycled or self discharge is huge, and the batt protect is irrelevant ,unless the load is from the controller load terminals.
Sitting at that voltages for days on end, is bound that some plates are sulphated already.

 

[Leakylunar]

Don’t really know how to set controller as there’s no settings for lead acid type! Rang Tanya batteries who gave me rough.
There’s nothing turned on in n the van as the panel is showing no current being drawn when I turn panel on it only shows 0.1amps being drawn.

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[Raul]

For cycling use start with13.8v float, 14.4v absorb. The consumption is not shown on your panel very accurately, but a small draw is present if 0.1a displays. That’s about 1,5w, not allot. But it needs to be replaced. Set the controller and see if you get to 14,4v, if not, additional charging is needed as the solar is not enough for your batt.

 

[Leakylunar]

I connect EHU once a month for 24-36 hrs but have been told it will only charge to around 80%!
I’ll check my settings when I get back to the van , if I recall the voltage has never reached 14v

 

[Leakylunar]

I also wrongly assumed that if solar is producing 21v there would be at least 14v going to battery clearly I know nothing!

 

[DBK]

I suspect your battery has had it. The voltages under 12 are probably occurring at night when there is no solar input. When daylight comes the voltage goes up but this is misleading as the battery isn't taking in any charge, which is why the battery voltage collapses at night.

To confirm you could take the battery out and give it a good charge, then disconnect the charger and leave to stand for an hour or so. Then measure the voltage, if it is anything less than say 12.5 then it's new battery time I'm afraid.

 

[Leakylunar]

Yes I’ll take battery out and charge it over night and check, I’ve been holding back on buying a new battery while weather improves.
On the app you can see voltage dropping once engine has been turned off, it just keeps dropping!

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[DBK]

Yes I’ll take battery out and charge it over night and check, I’ve been holding back on buying a new battery while weather improves.
On the app you can see voltage dropping once engine has been turned off, it just keeps dropping!

Sounds terminal. . Make sure the battery is somewhere with good ventilation as it might gas on charge if it's faulty. Safety goggles probably wise too.

 

[Leakylunar]

Think I’ll get new battery ordered today,

 

[Leakylunar]

Lucas battery ordered, just emailed myself that file,
It never goes into float stage, so because battery is never reaches 14.4v it never fully charges?
Even though 20-21v going in from solar I am now confused ?‍

 

[DBK]

Lucas battery ordered, just emailed myself that file, View attachment 367702
It never goes into float stage, so because battery is never reaches 14.4v it never fully charges?
Even though 20-21v going in from solar I am now confused ?‍

The controller, if it's an MPPT type, which yours is, converts the 20v from the panel to the lower charging current and increases the amps at the same time.

If the battery has failed it is likely the voltage couldn't reach 14.4v as it may have one or more cells which are virtual short-circuits.

 

[Leakylunar]

So when I replace with a new battery I should see higher voltages?

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[DBK]

So when I replace with a new battery I should see higher voltages?

You will if the sun is shining and the battery needs charging, otherwise it will probably keep the voltage around 13.8.

 

[Leakylunar]

Thanks, still all gobbledygook to me?

 

[DBK]

Thanks, still all gobbledygook to me?

It is to me too!

 

[Raul]

Lucas battery ordered, just emailed myself that file, View attachment 367702
It never goes into float stage, so because battery is never reaches 14.4v it never fully charges?
Even though 20-21v going in from solar I am now confused ?‍

You need voltage AND amps to make power. One without the other is meaningless. Amps are influenced by the brightness the panel is exposed to. Voltage is easy to produce and it will have good voltage even in dull weather but no amps, which equates to little or no power.
That’s why you are confused. Your controller is trying to make some power by converting some of the voltage into amps, hence your harvest is 200 to 300 wh per day, indicates that is very little power available at that time.

 

[Leakylunar]

Yes I can see amps on the app and it’s very rarely above 3amps and assuming I have a 120a/h battery it would take ages to charge up if it’s gone flat.
So assuming the new battery will get topped up easily ??

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[Leakylunar]

Well new battery fitted(12.58v)
Old battery now on charge and will check voltage drop after 48hr
Thanks once again for all the help.

 

[pappajohn]

During the day you are seeing solar charge voltage.
During the evening you are seeing true battery voltage.
Your battery is KNACKERED!

 

[DBK]

Well new battery fitted(12.58v)
Old battery now on charge and will check voltage drop after 48hr
Thanks once again for all the help.

12.58v suggests the new battery is close to fully charged, which is a good sign.

As I suggested earlier, be careful charging the old and possibly faulty battery. Do it somewhere well ventilated and overnight should be ample. If it's faulty it could start gassing which is potentially dangerous. Turn off the charger at the mains plug and don't disconnect the crocodile clips for say a quarter of an hour just in case there is hydrogen in the air.

 

[Leakylunar]

??

 

[autorouter]

120Ah at 12 volts is 120 x 12 = 1440 watt-hours. If it's discharged to 50% then it needs 50% of that to fully charge it again, that's 720Wh.

Your photo shows the solar controller has produced 400Wh, and that's presumably a winter day, so in the summer it will probably produce enough to replace the 720Wh.

Even a relatively high drain of for example 200mA (0.2A) is 4.8 amp-hours over 24 hours, and that's about 60 watt-hours. The solar panels should be able to cover that even on the dullest days.

You need to keep an eye on the battery voltage, measured when it is dark to avoid confusion with the solar controller voltage. If there is a battery drain issue you don't want to be ruining your new battery.

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[Leakylunar]

Yes I’ll check voltage over next couple of weeks before I go to work(it’s dark at 5:30)
Every days a school day ?