Recharge 12V battery on 13.8V? (beginner)

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Recharge 12V battery on 13.8V? (beginner)




by preliator » 26/03/23, 13:51

Hello everybody

I have a battery of a walkie talkie which is initially charged on a box which takes in mains input (230V) and comes out from 12V in 0.5A. I'm looking for a way to get rid of this bulky box to recharge it.

Could, theoretically, I directly connect this kind of battery to 13.8V or should I not exceed ~12.5V maximum?

Goods.
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Re: Charge 12V battery on 13.8V? (beginner)




by izentrop » 26/03/23, 14:23

Hello,
This is the end-of-charge voltage of a lead-acid battery. Depends on battery type and usage, see datasheet. It is also necessary to limit the charging current according to the capacity of the battery.

Small battery on car charger might not like : Cry:

12.5 V is the voltage at the terminals of a charged battery, disconnected from the charger, after a period of rest.
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Re: Charge 12V battery on 13.8V? (beginner)




by Christophe » 26/03/23, 14:56

It depends on the regulation inside and the type of battery. You know him ? Surely there are indications on the label.

Normally no worries because if it's lithium there is an internal charge regulator...
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Re: Charge 12V battery on 13.8V? (beginner)




by preliator » 26/03/23, 15:04

Thank you for your answers.

It seems to me that the battery already has a regulator, it is indeed lithium and I saw on the doc (the battery in question -> https://www.passion-radio.fr/talkie-yae ... -1324.html).

As a safety measure, I was thinking of soldering a small voltage regulator on the charging wire to be sure not to exceed 12.5V maximum.
On the other hand, I don't know how to be sure that the intensity of the current is not too high for this small battery. The base base delivers 0.5A, but what if I plug the battery into a car cigarette lighter for example...?
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Re: Charge 12V battery on 13.8V? (beginner)




by Christophe » 26/03/23, 15:17

The lithim is not 12V because it must be a factor of 4,2 or 3,6...so the battery is clamped if 3 or 4 elements...if there are only 2 or 3 elements then the internal regulator lower the 12V.

You can use 13.8 in both cases...but why 2?
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Re: Charge 12V battery on 13.8V? (beginner)




by preliator » 26/03/23, 15:28

Super good news :)

I have a small autonomous solar installation of which I have adjusted the MPPT so that it delivers a voltage of max 13.8V to my lead batteries which then recharge my portable devices via 5V/12V adapters.
According to my research, 13.8V is the voltage not to exceed to charge most of my 12V devices (12V fridge, 12V radios, cigarette lighter sockets, etc).

13.8V is also a default voltage setting found on one of my lab power supplies.
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Re: Charge 12V battery on 13.8V? (beginner)




by Christophe » 26/03/23, 15:30

Ok
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