how i know whether my car battery is full charging??

Thread Starter

hcchuar

Joined Nov 8, 2008
23
i'm using below circuit to charge my car battery,how i know wherter my car battery if full charging?because i do not know how to confirm it

another problem is my schokkey diode is getting hot after a min for charging?anyone know how to solve this problem??My input is 16V to 18V, 2.++A
 

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Thread Starter

hcchuar

Joined Nov 8, 2008
23
ic..................so just i need to switch off the charger first than only can measured the voltage right? Between the charging progress, is it the voltage i measured on the battery is the charging voltage?not the battery voltage?

do u know what way to make my shokkey diode to avoid heating?
 

leftyretro

Joined Nov 25, 2008
394
ic..................so just i need to switch off the charger first than only can measured the voltage right? Between the charging progress, is it the voltage i measured on the battery is the charging voltage?not the battery voltage?

do u know what way to make my shokkey diode to avoid heating?
Yes, switch off charger, wait a while for battery to cool and settle, some suggest waiting 2-3 hours, then the measured battery voltage will reflect it's state of charge. Here is a link with a lot of information on charging lead acid batteries:

http://www.batteryuniversity.com/partone-13.htm

How hot is the diode getting? Can you touch it for more then a few seconds? Is it the type of diode case that can be bolted to a metal heat sink?

Lefty
 

Thread Starter

hcchuar

Joined Nov 8, 2008
23
thanks for ur link,is there got any method to know whether my battery is charging full while the charging system is in progress? so that i can switch off my solar panel........to avoid spoil the car battery, the car battery i'm using is distilled car battery (12V33Ah)

my shokkey diode is SB560, data sheet as below
http://www.datasheetcatalog.org/datasheet/wte/SB520-T3.pdf

i'm using DC power supply to simulate the circuit first before i'm trying on solar panel, i'm try on 15V,2.2A, after 30 seconds, the shokkey diode will be getting hot and hot, after few minutes, the level of hot is even cannot touch the diode by hand,is there my circuit wrong or wat? my transistor (2N3055) still cool without heatsink
 

Thread Starter

hcchuar

Joined Nov 8, 2008
23
my shokkey diode without any metal or heatsink? is there got any heatsink for diode?
 

Thread Starter

hcchuar

Joined Nov 8, 2008
23
then do u have any good suggestion? because this circuit is too simple,i do not know whether can be working well or not ..........how do u think this circuit is terrible?
 

Thread Starter

hcchuar

Joined Nov 8, 2008
23
do u have any good suggestion on this?because this circuit is too simple,i do not know whether can be working well or not,how do u think this circuit is terrible?
 

flat5

Joined Nov 13, 2008
403
I'll wait till others respond. I'm not an expert.

Edit: 4 hours later.
I don't know what the internal resistance of the solar panel is but shorting out the panel to control the voltage does not seem elegant.
 
Last edited:

Audioguru

Joined Dec 20, 2007
11,251
You must not use a regulated power supply to power the simple circuit because then the shunt voltage regulator won't work and the voltage and current will be too high.
Then guess what happens to the Schottky diode and the battery?

A solar panel is a current source and it is normal to shunt it to drop its voltage when the sun is very bright. I have a 12V solar panel that produces 18V with a low load current.

The transistor should be hot and need a heatsink so I don't think it is working.
 

SgtWookie

Joined Jul 17, 2007
22,201
Are you certain that you have installed the Schottky diode with the cathode towards the battery's positive terminal? There is a ring around the diode on the cathode's end.

Audioguru's correct - you need a current-regulated supply instead of a voltage-regulated supply to test your circuit.
 

floomdoggle

Joined Sep 1, 2008
217
What you are looking for is a dump load circuit. An automatic electronic circuit that will stop your charger charging when it has been fully charged. But will continue to use the charging power. Your circuit will shut down at full charge, but will have a problem with the continued power input. That is where a dump load comes in. When your battery is fully charged, your circuit has nowhere to get rid of the excess power, except to block the incoming power.
Not a good thing.
Dan
 

leftyretro

Joined Nov 25, 2008
394
What you are looking for is a dump load circuit. An automatic electronic circuit that will stop your charger charging when it has been fully charged. But will continue to use the charging power. Your circuit will shut down at full charge, but will have a problem with the continued power input. That is where a dump load comes in. When your battery is fully charged, your circuit has nowhere to get rid of the excess power, except to block the incoming power.
Not a good thing.
Dan
" but will have a problem with the continued power input. That is where a dump load comes in." "your circuit has nowhere to get rid of the excess power, except to block the incoming power"


Load dumping is only a problem needing a solution with mechanical power generators like wind generators or hydro generators. A solar panel does not have to 'dump' it's load if there is no current being drawn from it, so load dump does not apply or needed for solar cell applications. If you leave a solar cell out in the sun, but have nothing connected to it do you think that you need to have a load dump installed?

Lefty


Lefty
 

Thread Starter

hcchuar

Joined Nov 8, 2008
23
Are you certain that you have installed the Schottky diode with the cathode towards the battery's positive terminal? There is a ring around the diode on the cathode's end.

Audioguru's correct - you need a current-regulated supply instead of a voltage-regulated supply to test your circuit.


yes...........the schottky diode with cathode towards teh battery's positive terminal
 

Thread Starter

hcchuar

Joined Nov 8, 2008
23
You should probably search the web for more proven designs and learn about all the tradeoffs and features. Here is a great document that goes into a lot of analysis and alternates and has a very nice final design on page 53 of the PDF doc.

http://www.designthatmatters.org/k2/pubs/BatteryChargerReport6.pdf


Lefty

Thanks for the link,but i have some confusing on that, LM350 is the variable voltage regulator, so i need adding few component so set the output voltage? is 14.5V? or this circuit already include all component? i'm not quick understand about it




Based on the documentation, trasistor 2N3393 is use for LM117, do u think that LM350 also using the same transistor?
 

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floomdoggle

Joined Sep 1, 2008
217
Lefty.
The OP, among other things in his (her) circuit needs is regulating. Part of any charging circuit, mechanical or solar needs a way to stop. The dump load is part of that circuit.
Dan
 

Audioguru

Joined Dec 20, 2007
11,251
Your new circuit has a lousy old 741 opamp with its input voltages too high. The circuit probably used an obsolete opamp that worked fine with its inputs near its positive supply voltage. A newer TL081 opamp will work.
 
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