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Old 06-07-2017, 02:39 AM   #1 (permalink)
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Battery Charger in My Car

First of all, thanks very much for reading my post.I want to make a car battery charge after I saw an article introducing something about it. Well, I would like to ask some help.

As the essay showing, This car battery charger circuit can be used to charge 12V and 6V batteries. If it is used a transformer that can deliver 4A to 5A at a voltage between 12.6V and 16V then we can get rid of the switch for 6V or 12V batteries. The schamatic is given below.

It aslo gave some maintenance tip about car battery.
The car battery charging current is automatically limited to 4.2A. If there is a 600mV voltage on R1 (4A thru it), then the T1 transistor starts to conduct. Excessive charging current is avoided because the current value on T3ís base is limited. The difference between applied load current (at T4ís collector) and real voltage of the battery is balanced thru T4ís collector-emitter junction.
The datasheet of 2N3055
The power input of 2N3055 is the product of load current and voltage difference already mentioned. When charging 6V car battery this power reaches a maximum of 40W. The rectifier diodes must be able to deliver 4A at 40V. T4 2N3055 must be mounted on a good heatsink in order to dissipate the heat.
However, I canít understand what byx21-40 is?
1) Is it like a diode rectifier ??
2).and what is 21-40 means like between 21-40 or just itís datasheet code (because i hardly found it on google)
3).and if itís being sold just as it is and what if I didnít find it in the market ?

Sorry for all the questions but Iím a mechanical engineer and electronics is a hobby for me so Iím not professional.
Thank you again,
Best regards,

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