How to charge my batteries with 24Volts and use them in 12 volts

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SEIRMIC
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How to charge my batteries with 24Volts and use them in 12 volts




by SEIRMIC » 13/06/18, 14:04

How to charge my batteries with 24Volts and use them in 12 volts
Hello

I live in a slum in West Africa in Burkina Faso in the capital Ouagadougou.

I have a problem that I can not solve I ask for your point of view.

I have a solar panel 24 Volts, which I used with with digital controller on two batteries 12V 40 Ah. The connection was in parallel, for use in 12 volt (I take directly to the batteries, connect the screen TV 19, lamp 5w x 3, radio, decoder) and other uses in 220V (there I use a converter, just to power the electrical outlets). The charge was so fast that in less than two hours at sunrise the batteries were full. I noticed that my batteries are dead in less 5 less use because the night I have more autonomy, the television goes out in less than one hour or two hours ....... .. but some lamps always work except the one programmed on the regulator in automatic ignition. In one sentence; a tension drops quickly.

Now I'm going to buy two 12 Volts 100 AH batteries and do a series mount with the 24 volts panel. For my batteries to last I intend to connect them in series. My concern is:
How could I use 12 volts?
-Is possible to use the terminals of one battery to power the equipment in 12 volts and the terminals of the other batteries for equipment in 220V using the converter?


- Is this how my batteries last? view that photovoltaics is from 24 Volts ++

Thank you in advance

cordially
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Re: How to charge my batteries with 24Volts and use them in 12 volts




by izentrop » 13/06/18, 14:49

Hello,
Would the characteristics of the charger and panels be needed?
Normally for a lead-acid battery to last, it must be charged with a current not exceeding 1 / 10 and capacity (4 A in your case). 1 / 20 is even better.
The load must be stopped when the voltage reaches 14 V, 28 V for series batteries, then hold 13.8 v with a maintenance current.
The discharge should be monitored and stopped before deep discharge, usually at 11,8 V, but it depends on the type of battery and the discharge current.

It is also necessary that the 2 batteries have an equivalent discharge rate, otherwise the battery remained more charged will morfler when the other has not completed its charge.

With 250 W from PV, about 10 A under 24 V, it would take at least 200 Ah / 24 v or 2 100 batteries Ah / 12 v;)
Is it possible to use the terminals of one battery to power equipment in 12 volts and the terminals of the other batteries for equipment in 220V using the converter?
Yes, as long as you know the state of discharge of each battery and the easiest way is to recharge them independently or to have 2 chargers 12 V
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Re: How to charge my batteries with 24Volts and use them in 12 volts




by SEIRMIC » 13/06/18, 15:00

izentrop wrote:Hello,
Would the characteristics of the charger and panels be needed?
Normally for a lead-acid battery to last, it must be charged with a current not exceeding 1 / 10 and capacity (4 A in your case). 1 / 20 is even better.
The load must be stopped when the voltage reaches 14 V, 28 V for series batteries, then hold 13.8 v with a maintenance current.



With 250 W from PV, about 10 A under 24 V, it would take at least 200 Ah / 24 v or 2 100 batteries Ah / 12 v;)




good morning dear friend

Thank you for your answer
, the charge controller is 10A, it takes 12V / 24volt ..

the panel is 250W. 24Volts.

"The 2 batteries must also have an equivalent discharge rate, otherwise the battery that has remained more charged will languish when the other has not completed its charge."

in this case it is risky to use a battery for 220v and another for 12Volt with the connection of the two batteries in series.


In the end what do you advise me please? to do the assembly in series or in parallel? The charge controller flashes as soon as the charge is full. I would really like both of my 12v 100Ah batteries to last a long time until I can get some really good, expensive drums.


Thank you for your good understanding
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Re: How to charge my batteries with 24Volts and use them in 12 volts




by izentrop » 13/06/18, 15:35

Ben I already said everything since I had guessed your characteristics.

1 / 4 capacity, charging current is too high

Unloaded independently does not pose a problem, you just have to reload them independently as I explained.
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Re: How to charge my batteries with 24Volts and use them in 12 volts




by chatelot16 » 13/06/18, 20:58

when you load 2 battery 12v in series to make 24v you should never consume other than 24v

if you use the 12v battery separately it will never be charged correctly once set and loaded 24v ... 12v battery the most unloaded will not be fully charged and suffers from lack of charge ... the battery 12v the least unloaded will suffer from overcharging ... and the 2 battery will be dead soon

if the 2 12v battery are used separately, 2 charger 12v indepandant

if you prefer to use a charger 24v that you already have on 2 battery 12v new, it is necessary a converter 24v 12v to have 12v by connecting on the 2 battery

but for me the 24v is a trap to c ... it takes 2 identical battery, good for nothing to the first problem

so it is better to have 2 load controller 12v to load 2 battery 12v indepandante, and it works even with 2 12v battery of different size or state ... it loads all the 12v battery that we want and we use as we want
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Re: How to charge my batteries with 24Volts and use them in 12 volts




by dede2002 » 15/06/18, 13:21

24V it still has the advantage of having less losses in the cables that come from the solar panels.

By plugging two discharge regulators (wind type), one on each battery, one can charge in 24V and if one battery is charged before the other the charging current will be dissipated in one consumer while the other will finish charging.

It is of course necessary to monitor the voltage of each battery at the discharge to avoid unloading one too deeply.
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Re: How to charge my batteries with 24Volts and use them in 12 volts




by Gaston » 15/06/18, 14:30

There are regulators (Victron actually very good, but quite expensive) that can connect an 12V battery (or 12V batteries in parallel) on a panel 24 or 48V or more.

Otherwise, you have to plug in and use batteries in series.
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Re: How to charge my batteries with 24Volts and use them in 12 volts




by izentrop » 15/06/18, 17:42

Victron, it takes money. Apparently it is not the sun that is missing there.
You just have to adapt the batteries to the PV as I explained and 12 chargers V / 10 A PWM, we find less than 5 € on the net.
The whole thing is to charge less than 1 / 10 the capacity of the batteries, since that was the main problem of our friend.
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Re: How to charge my batteries with 24Volts and use them in 12 volts




by chatelot16 » 15/06/18, 21:50

the 24v allows a performance improvement explainable in theory, but not practical as long as there is no meter on the sun

battery wear is the most expensive point of a solar installation, and not to massacre the 24v battery must absolutely leave the 2 new battery always in series and never connect anything on a single battery

if you need 12v on a single battery, you need 2 regulator to charge indepandament the 2 battery

you can connect 2 regulator on the same panel ... each regulator takes the current it wants and leaves for the other regulator: the only risk is that if a regulator takes all its battery will be full first and the other battery will be full later when the first regulator will no longer take power ... but it will work without killing battery

with several regulator 12v it can even work with several 12v battery of different capacity
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Re: How to charge my batteries with 24Volts and use them in 12 volts




by dede2002 » 17/06/18, 12:08

In the statement of the problem, we initially have a panel of 24V.
And the fact that there is no counter on the sun does not change the fact that at night, there is no sun.
So to use this panel it is necessary to use two batteries in series, unless you have a regulator mppt that converts the voltage to 12V, but in this case it will double the nominal amperage of the regulator relative to that of the panel.
The essential thing is monitor battery voltage, both the load and the discharge, to avoid damaging them, I have the same installation at home, with a regulator 24V and two dissipative regulators that engage 14.4V and trigger to 13.5V (homemade) to avoid overcharging a battery, so I can put any battery, and monitor the status of each battery.
To use 12V, the important thing is to balance the consumers to make the best use of both batteries.
Put several 12V batteries. in parallel is not a good idea, unless they are separated by diodes, because if one element is defective the other batteries will be discharged in it.
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