Recharger to charge the car battery

>>21816043 several pieces can also be connected in parallel increasing the current

Such cases are also described. As well as other LMs.
Only the Polish seller I could not find

If this is a charger for recharging a car battery, thank you. In an Ursus tractor it would still work, but in a minor car a voltage above 16.0V can seriously damage the electronics. It's not about the average voltage or the effective voltage, it's about the maximum voltage the rectifier gives. Voltage pulsations cause voltage peaks to destroy transils in surge protection circuits. These peaks will be greater the weaker the battery is in condition.
Here in the design, the increase in current is achieved by switching the winding taps, well thank you and I have a request to the author to remove the last word from the topic title: "in the car"
And so to summarise: a very simple rectifier circuit with heaps of bits and bobs.

Quite apart from the Author's reluctance to draw a general diagram, even if only by hand on a piece of paper+smartphone photo. That way, a glance would be enough to see what the author had in mind. And the discussion about stimulating/exercising grey cells - there are hundreds if not thousands of other, in my opinion more interesting ways. I have already mentioned the priceless satisfaction.

Let me ask you straight out: why do it at all? What are the clear benefits of this? The savings?
I am asking from the point of view of an ordinary user who garages the car under a cloud, uses it little to moderately, sometimes stops 1-2 weeks, usually short distances around town. He does not care too much about the battery, 1-2 times a year he tries to take it out and charge it with a charger, if he wants to and does not forget . For emergency starting in case of a big "W" he has a powerbank "jump-starter".
And which replaces the battery on average circa once every 5 years. The cost of a new 50Ah is approx. 300PLN. 60£ per year in my case, as I mentioned (I repeat myself) HERE , and confirmation of my views HERE . Even if I were to magically extend the life of the battery to - I don't know - 8 years, annual cost: 37.50. I would certainly feel the saving in my wallet very much...
And even if I had a garage - for recharging during an extended stop, wouldn't the aforementioned 5-dollar charger from Lidl, or some similar, perhaps slightly more expensive, less marketable charger, suffice? I'm not mentioning the lack of BT control or other miracles on a stick. And the danger to the car's electronics, as mentioned by my colleague @Mastertech above - here even the market Lidl "crap" seems much safer to me, its casing too.

Mastertech wrote:

If this is a charger for recharging a car battery, thank you. In an Ursus tractor it would still pass, but in a minor car a voltage above 16.0V can seriously damage the electronics. It's not about the average voltage or the effective voltage, it's about the maximum voltage the rectifier gives. Voltage pulsations cause voltage peaks to destroy transils in surge protection circuits. These peaks will be greater the weaker the condition of the battery.

This is the point, that I have added a circuit to a very simple rectifier circuit, which measures the peak voltage that the rectifier gives, and if it exceeds the set value (default 14.6 V), the automatic charger stops charging.

Mastertech wrote:

This in the design the increase in current is done by switching the taps of the windings, well I thank you and I have a request to the author to remove the last word from the topic title: "in the car"

What is the problem with switching windings?
I just happened to have such a transformer, I did the winding switching as a test, but this can easily be dispensed with, just adjust the thresholds so that the conditions never occur.

Stanley_P wrote:

Leaving aside the Author's reluctance to draw the overall schematic,

It's exactly the opposite: I have such a huge amount of willingness that despite discouragement on your part (that it's not worth it, why it's even worth it, etc.) I drew that part of the schematic anyway, but you didn't even notice.

Stanley_P wrote:

what is it even for? What are the clear benefits of this? The cost savings?
I ask from the point of view of the ordinary user

In order not to be afraid of overcharging the battery / destroying the electronics in the car with uncontrolled voltage peaks from a primitive transformer rectifier.
So that the battery is improved when the car is driven for short distances.
To make one last start and drive to the shop for a new battery when the old one dies.
Can the 'ordinary user' achieve the same thing by throwing the old charger on the scrapheap and buying some charger at the market? Perhaps; I don't care.
On the other hand, I am keen to know what this charger is doing wrong, why it is endangering the car's installation and what is wrong with switching windings

Sam Sung wrote:

while I am keen to find out what this rectifier is doing wrong, why it is endangering the car's installation and what is wrong with switching windings

The point is that this rectifier does not do anything, there is no regulation, neither of current nor voltage (apart from this additional tap, only that with such a solution the increase in current will depend on the number of windings of the transformer, which is fixed and cannot be regulated). All in all, the only thing you can control are these two relays, which you can use to step down the current or switch off charging completely. You measure a lot of things here, but you do not regulate anything, the whole art consists in precise winding of the transformer, only that it will be a good solution for a specific battery, with a specific capacity and condition.
As for the relays themselves, the first mistake is to control them directly from the processor and the second mistake is that the coil should be on 12V so as not to interfere with the processor power supply. Although this part of the schematic is not very clear, I assume that you are controlling correctly, i.e. one of the relays, the toggle one, is used to increase the current and the other, the normally closed one, works in protection and disconnects the trafo when the voltage is exceeded.

And the biggest disadvantage is the lack of a CV phase, because in the CC mode it charges to the maximum voltage and stops, while it should continue to charge for a few hours at a constant voltage until the charging current drops below, say, 1A (just to give you an example, because this is not the place for PhDs on how high the final charging current should be)

Mastertech wrote:

Sam Sung wrote:

but I would like to know what this rectifier does wrong, why it endangers the installation in the car and what is wrong with switching the windings

The point is that this rectifier does not do anything, there is no regulation, neither of current nor voltage (apart from this additional tap, only that with such a solution the increase in current will depend on the number of windings of the transformer, which is constant and cannot be regulated). All in all, the only thing you can control are these two relays, which you can use to step down the current or switch off charging completely. You measure a lot of things here, but you do not regulate anything, the whole art is in the precise winding of the transformer, only that this will be a good solution for a specific battery, with a specific capacity and condition.

Fact, the charging current depends on the matching of the transformer to the battery and its condition. E.g. in the first video you can see that the peak voltage was 13.92 V, in the pit 12.96 V, peak current ~5.68 A, in the pit 0.

Mastertech wrote:

As for the relays themselves, error one is controlling them directly from the CPU and error two is the coil should be on 12V to not interfere with the CPU supply. Although this part of the schematic is not very clear

I must specify that I did not draw there the the schematic of the HL-525 relay module that I used, which you can see in the pictures. The outputs from the processor marked RELAY1 and RELAY2 are actually connected to the IN1 and IN2 inputs, where they go to the PC817C optocouplers. That is, the relays are not controlled directly from the processor. And there could be a problem with powering such at 12 V, as there is only 8.5 V at the 7805 input.

Mastertech wrote:

Well, the biggest disadvantage is the lack of a CV phase, because in the CC mode it charges to the maximum voltage and stops, while it should continue to charge for a few hours at a constant voltage until the charging current drops below, say, 1A (just for the sake of example, because this is not the place for PhDs on how much the final charging current should be)

In fact, there is no CC or CV phase here, but the current drops as the voltage increases (e.g. at the beginning of the charge it was over 6.5V). at the start of charging it was over 6.5 A at peak, after 10 minutes it dropped to these 5.7 A).
That is, in summary: the battery will not fully charge, but it will recharge without exceeding the set peak voltage of, say, 14.6 V for more than 0.1 s. So is the name "Recharger for recharging a car battery" correct after all?

@Sam Sung interesting design .
At least it's not supermarket ready made.

Sam Sung wrote:

In fact, there is no CC or CV phase here, only the current decreases as the voltage increases (e.g. at the beginning of the charge it was over 6.5 A at peak, after 10 minutes it dropped to this 5.7 A).
That is, in summary: the battery will not fully charge, but it will recharge without exceeding the set peak voltage of, say, 14.6 V for more than 0.1 s. So is the name "Recharger for recharging a car battery" correct after all?

Mate, maintaining a voltage of 13.6(8)V, for 72h or more, will certainly cause a charge, even of those unfortunate "calcium ac'a Ca-Ca"
So plugging in such a "charger" (yes, even the market ones that hold 13.6V standby), at the weekend, or e.g. on a Saturday morning, will still do the battery good.
I know what you mean (16.2V../~C.C. 1.5A), but in a typical recharging operation, when you drive to the market and back and are short of power, there is no need to pack 16.2V , especially if you leave the charger on for 48h every other weekend

p.s. So if it keeps 13.6 after reaching 14.7, not so bad, and the soft can always be improved

Well, that's it - it's for recharging to make up the shortfall.
This voltage is given to a standby voltage of 13.8V.
The charging current is, of course, dependent on the resistance of the battery, i.e. it falls when the voltage is raised.
When I charge a 70Ah EFB in 13.8V standby mode (or standby set to 13.8V), the current drops quickly to 0.1A from 2-3A. The charge will enter little because the current is small, but it sustains and does not allow degradation.

sq3evp wrote:

(does stand-by set to a hard 13.8V) from 2-3A drops quickly to 0.1A. The charge will enter little because the current is small, but it sustains and does not allow degradation.

The ac doesn't draw current because it's charged, a battery discharged even 10% and at 13.8V will draw 0.5-1A and the sustain current with a fully charged battery drops to as low as 70mA (I tested once on a 50Ah...), it will just start to slowly "flotation"

I don't know how long you measured, because I measured up to 24 hours max, of which the electronics probably took something.

>>21816043
Hello ! With this lack of supervision during charging I would be very careful . About 30 years ago returning from the cemetery in the evening I saw a
light in the kitchen . I rang and in a moment my door was opened by my nephew who lived at the other end of town .
After talking for a while I heard the glass on the first floor clink . I told my nephew about it. He said that I thought it was him because there was no one there. Later I heard such a sound from the door next to the entrance to the house . I ran outside but there was no one there . I smelled smoke . I ran upstairs and there was a fire in the kitchen cupboard with a charger from which
i ran downstairs to get water and my nephew, when we came back 2 cupboards had already fallen off the wall along with the plates, the curtains were on fire and the glass in the windows was already cracked. If it hadn't been for the fact that my nephew was at home
if not for the fact that my nephew had been at home and opened the door, the fire could have ended tragically.
Another case in a similar period . I was on my way home from work on Friday and walked past 11 garages in the street. In front of an open
garage there was a taxi driver with a small camera. He was showing the plasterer how the camera worked, filming the Polonez. On Saturday
I was coming back from an unsuccessful trip because I couldn't get things done . Walking across the street past the garages I saw this taxi driver running scared and shouting in a choked voice . I ran across the street and
i saw a car burning in front . A guy with a charger on his hand was trying to push a heavy
mZ motorbike with his other hand. I brought it outside . And then we pulled out the Polonez . We extinguished with water . I have seen a few more cases of fires while charging hence my warning .

I have an automatic charger, but I also keep an eye on it nonetheless. It's just an appliance and can always fail.
That's why I always think about an additional safety device that monitors the voltage and disconnects the rectifier if it exceeds the permitted voltage.