Connection of 24v plates on 12v battery

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marcus82
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Connection of 24v plates on 12v battery




by marcus82 » 08/01/20, 16:54

Good morning all.
I power my house with solar only. the devices that I use with the solar work in 12v and are composed of bulbs, Telé, 2 brewers. The installation was made in July 2017 with 2 panels of 250w 24volt connected in parallel and 2 gel batteries of 200ah 12v connected in parallel too. the batteries deliver 12 volts which directly power my equipment. I use a Pwm 30A charge regulator. the batteries have worked very satisfactorily for 2 years. currently the problem i have is that my batteries are giving up the ghost. As soon as the sun goes down, the discharge is very fast. I want to renew my battery park but I'm afraid that they do not hold, especially since a technician made me understand that my batteries dropped quickly because I use 24v plates for batteries from 12v. He advised me to replace my palques with 12v before renewing my batteries. I wish to have your opinions on the use of 24v plates for 12v batteries. Could this be the cause of the premature death of my batteries? Thank you for your reactions and advice.
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dede2002
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Re: connection of 24v plates on 12v battery




by dede2002 » 08/01/20, 17:09

Hello,

We will need more details, but from what I understand you operate in 12V, and your panels although they are in 24V operate in 12V, because the PWM regulator limits the useful voltage of the panels to that of batteries. By using an MPPT regulator you would have a lot more charging power.

Then, your batteries are perhaps insufficient for your consumption? The problem with batteries in parallel is that if one battery is defective it drains the other ... (there are also problems with batteries in series, when one is defective, but it's easier to detect).
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marcus82
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Re: connection of 24v plates on 12v battery




by marcus82 » 08/01/20, 17:33

Good evening, thank you for the reaction. Yes, I work in 12v only. I have a 12v / 24v regulator. it seems that this is what allows you to connect 24v plates on 12v batteries.
"My baterries are insufficient for my consumption"? the first two years, generally, at sunset at sunset, my regulator indicated a voltage of my battery of 13,2V. after use, when I woke up, I still had a voltage of 12,7V. So, I do not believe that my consumption was above the capacities of the batteries. I would like to renew my batteries but I first want to be sure that my 24v plates are not responsible for the death of my batteries.
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dede2002
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Re: connection of 24v plates on 12v battery




by dede2002 » 08/01/20, 17:50

Hello,

No I do not think that the 24V plates are directly responsible, since the regulator controls, and that it switches automatically to 12V, but it is a funny idea to have designed the system like that ...

500W in 12V is a little over 40A, you would need an MPPT regulator powerful enough to be able to exploit the maximum power of your panels.

For your batteries, you should test them separately to see which one has dropped. It may be the fault of no luck, but what is certain is that the power of your panels has been exploited only half!
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marcus82
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Re: connection of 24v plates on 12v battery




by marcus82 » 09/01/20, 09:11

Dede thank you again for your reaction. "No I do not think that the 24V panels are directly responsible, since the regulator is the one that controls, and that it automatically puts itself in 12V" But is it that the fact that it is of the panels of 24v, the current output by these do not "burned" my batteries? I remember that in the meantime before the batteries let go, during periods of very strong sunshine, one of the batteries seemed to "boil". I'm afraid to renew my batteries and fall back into the same situation.
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dede2002
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Re: connection of 24v plates on 12v battery




by dede2002 » 09/01/20, 10:07

And what was the battery voltage when a battery seemed to be boiling? Did all the elements seem to boil?

It is common when one element is short-circuited, the battery still requires current at the absorption voltage, and the other elements are overcharged, it heats up, and also it drains the other battery connected in parallel when it no longer charges.

Ask anyway for an MPPT regulator. In the meantime try to disconnect the battery which seemed to be boiling.
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marcus82
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Re: connection of 24v plates on 12v battery




by marcus82 » 09/01/20, 11:23

Hello,
- generally when it boiled, the voltage was at most around 14,4V on the regulator and the charge was stopped. I speak of bubbling because when we pricked our ears we heard a slight noise from the batery and we saw bubbles of liquid coming out slightly.
- will the MPPT regulator not be too strong considering that I only have 500w of power for the panels and 200ah for the batteries? I thought the MPPT was for large installations.
- How to avoid that in my installation, a battery in bad condition kills the other. would it be necessary to consider putting two regulators, ie one regulator per battery and per panel (1 regulator 30A + 1 panel of 250w + 1 battery 200ah)?
thanks again
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dede2002
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Re: connection of 24v plates on 12v battery




by dede2002 » 09/01/20, 12:30

It is clear that if a battery boils under 14v it is because it is defective. Why I do not know...

it cannot be due to an overload since the regulator cuts above 14.4V, perhaps too deep discharges. (or no luck, since you wrote that the voltage did not drop below 12.7V)

With an MPPT you would have more charging power, to fully recharge your batteries every day. With your system you have much less than 500W of charging power (Amperage of your panels under 13V, see the power curve and calculation ...)

Already try with a single battery to see. Then, to control, install an ammeter on each battery and observe.

Your idea of ​​separating the two batteries is a bit complicated, because they should also be separated for use ...
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marcus82
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Re: connection of 24v plates on 12v battery




by marcus82 » 09/01/20, 12:51

Thank you very much for all your reactions.
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Re: Connection of 24v plates on 12v battery




by plasmanu » 10/01/20, 03:34

On my parents' motorhome a few years ago I installed this same pwm regulator 12V / 24V 30A, but only for a 12V 90W panel.
And now the battery is dead, parked under a canopy in the shade.
However I explained well to remove a canalite to put one in plexiglass or at worst not at all
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