No - leave all connections open.
Allan
allanhurst:
No - leave all connections open.Allan
I have just meaured it.7,27 Volt... Sorry, but it says:
"Transistor T1 and Zener diode ZD act as a cut off switch when the battery is full."
Am I not "losing" something here?
So I remove the transistor and connect the battery on the circuit?
Yep - and chuck the zener as well. They provide a (poorly designed) current limit - but your little solar panel won't provide nearly enough current to need this, and the LM317 has it's own internal current limit anyway.
The LM317 limits the voltage to a safe value for the battery. 6.8-7.2 is a reasonable range for a nominal 6v lead acid type.
Allan
6.8-7.2volt?
This could be a small sealed lead/acid battery, not a flooded cell type that you can top up.
A small/sealed/gell 6volt battery doesn't tolerate more than 6.75volt continuous (13.5 for a 12volt type).
Leo..
My car has an alternator running at 14.4V and the battery never needs topping up.
Allan
Don't know what types of sealed batteries are used in cars.
They could have a buildin recombination system, dunno.
The voltage regulator in a car could also have a timer.
Fast-charge (14.4volt) for a certain time, and then float to 13.8volt.
The boat I lived on had had an intelligent charger like that.
All I know is that small/sealed/gell doesn't like to be fast-charged.
And that more than 13.5volt (for a 12volt battery) will kill them faster.
Leo..
Hi Alex5678,
So you have a 6v 4ah battery and two 6V, 3.5Watt, ~560mA solar panels.
I would like you to do the following for us.
Measure the battery voltage after you leave it sit unconnected for an hour.
Put the pannels where you are going to use them and measure the voltage across each pannel while they are not connected to anything. Eg. Panel 1 = ?? Volts, Panel 2 = ?? Volts.
The 3.5 watts will only be achieved at the panels Maximum Power Point (MPP) which you will not reach if unless you have much more sophisticated circuitry.
So you will most likley never achieve the 560mA, probably more like half or less.
So if you hook a panel to your battery, the battery will drag the pannel down to its level and the current will go down with tue voltage. For the sake of this dissusion lets say its 300mA, now at 300mA it will take 4Ah ÷ 0.3A = 13.33 hours to charge the battery, add another hour or two for the fact that the battery needs 1.1 times the input for every amp (4.4amps) and its going to be around 15 hours of full sunlight to charge the battery if you do not use it.
After this the battery will keep charging (not at the 300mA, as that will drop off) untill it reaches the maximum voltage of the panel (as you will have noted above when you measure the panel) where it will begin to gas and go from a square battery to a round one!
IT HAPPENS PEOPLE, IT HAS TO ME! Was quiet a shock to see it all chubby and rocking on the shelf (and a bit scary knowing i had to disconnect it).
All you need to know about the battery is right there in your photo.
Maximum amperage, 1.2amps (note the INITIAL current as if you charge it at 1.2A for very long it will have a meltdown)
Cyclic means you are charging and discharging it regularly and not leaving it on the charger for more than 24 to 48 hours.
Standby means you are leaving it on the charger almost permanently.
Perhaps if you told us what you will be doing with the battery we can give you some better ideas on how to set it up?
First lets see if the panels can generate enough voltage by them selves to charge the battery before we go adding losses from a regulator circuit.
More to think about.
-What are you running off the battery?
-What current will it draw?
-Will the panel provide enough current to run it and charge the battery?
-Will this device run continuously? If so will the panel have enough charge to run the device and charge the battery to full?
Eg. Your device draws 150mA and your panel charges 300mA in full sun so (150mA × 24 hours = 3600mA) but your panel only gives you charge for 6 hours a day (In Full Sun) so (300mA × 6 hours = 1800mA). Meaning you hage 3600mA of your 4000mA battery gone in the first day and then the sunn charges 1800mA back in. You loose 1800mA.
Day 2 and the battery is dead.
-Will what you are running off it be able to take the voltage of the pannel charging the battery?
This is all a rough draft, dont take the figures stated as gospel.
Daz
@Daz1712:Thank you a lot, I will try it as soon as I can...
Something I wanted to ask iss this: Since the output of the charger circuit is 5,45Volt, so it will charge the battery when the battery goes under 5,45Volt right? So, it will charge it up to 5,45 Volt? After the battery I have connected a DC-DC step down/up converter with a fixed output: 5V/1A. Won't it work even if the battery is charged up to 5,45 Volt?
No, if you let the battery drop to 5.45 volts on a regular basis, the battery will sulphate and this will make the battery unusable.
The battery needs at least 6.8V just to keep it trickle charged and needs to be cycled up to 7.45 V regularily to keep it fully charged.
A SLA battery is able to be discharged down to around 40% without damaging the battery.
This means your 4ah battery really only has 2.4ah of power until it hits 6 volts, this is where you should stop.
To use the full 4ah you will have to discharge it to around 5.2 to 5.3 volts (notice this is close to your voltage!).
Have a look here going down to the bit marked "HYDROMETER" (ignore the rest for now)
battery voltage verses state of charge
Note the voltage of the 6volt battery for 25% (6.03v) and for 0% (5.95v).
So what that means is your 4ah battery will have no charge in it.
Look at the solar panel voltage with out load first and forget the regulator circuit for now if its actually a 6v panel it should go to around 9 volts in full sunlight.
Assume for now that there is something wrong somewhere, so we will break it down and check all the parts.
Eg. A flat battery in your car does not mean the alternator is not charging or the battery is dead, it could mean you left the lights on.
Without knowing what voltage your panel is puting out, the rest is based on assumptions.
Daz.
Ps. Try to take a reading from the panel where you are using it now and in full sunlight if its not already in it. Artificial lights will not allow the panel to reach its full potential. I say this because after trying to diagnose anothers fault they finaly mentioned they were in a room and had not actually taken the unit outside to test it,
"Cause it was not working properly yet!"
Daz1712:
A SLA battery is able to be discharged down to around 40% without damaging the battery.
This means your 4ah battery really only has 2.4ah of power until it hits 6 volts, this is where you should stop.To use the full 4ah you will have to discharge it to around 5.2 to 5.3 volts (notice this is close to your voltage!).
Have a look here going down to the bit marked "HYDROMETER" (ignore the rest for now)
battery voltage verses state of chargeNote the voltage of the 6volt battery for 25% (6.03v) and for 0% (5.95v).
So what that means is your 4ah battery will have no charge in it.Look at the solar panel voltage with out load first and forget the regulator circuit for now if its actually a 6v panel it should go to around 9 volts in full sunlight.
Assume for now that there is something wrong somewhere, so we will break it down and check all the parts.
Eg. A flat battery in your car does not mean the alternator is not charging or the battery is dead, it could mean you left the lights on.Without knowing what voltage your panel is puting out, the rest is based on assumptions.
Daz.
Ps. Try to take a reading from the panel where you are using it now and in full sunlight if its not already in it. Artificial lights will not allow the panel to reach its full potential. I say this because after trying to diagnose anothers fault they finaly mentioned they were in a room and had not actually taken the unit outside to test it,
"Cause it was not working properly yet!"
Ok, I will do the tests today and I will post here...
I have been trying many days to make it work...
As a secondary option (in case everything goes bad again) I think of connecting supply from the "wall". I wanted to ask is there any circuit that when I connect the construction to the power supply, automatically disconnects from the battery and switches to the power supply?
Wawa:
The TL431 needs to work at ~7.3volt for a "6volt battery + schottky diode" drop.I calculate that the the 20k pot + 39k resistor should be about 19.2k total.
That could be 15k fixed resistor and a 10k pot, or, for finer adjustment, an 18k fixed resistor and a 2.5k pot.The 22ohm resistor can be a short (all the power is dumped in the transistor),
or lowered to 10ohm (most of the power is dumped in the resistor).
The 10ohm resistor should be a 5watt (or 10watt) cement power resistor.Transistor can be any PNP power darlington.
Leo..
I have simulated the circuit with 12Volt input and I get 12V output... I doubt if the circuit here:
is corect since the + output and the - output is common in both PV input and battery output....
Solar panel is indeed connected directly to the battery (via a diode).
But a solar panel is not a voltage source, it's a current source.
You can short circuit a solar panel.
That's what the circuit sort off does.
It acts as a brake when voltage of the panel rises above charging voltage of the battery.
Leo..
Is there any reliable circuit that takes 12 Volt and charges 6V Sealed Lead Acid battery? In google I cannot find something... I will try again though...
Thanks
Also since in this circuit
where I get output around 5,45V - 5,60V, can't I use another type of battery to charge it? Instead of Sealed Lead Acid?
"I get output around 5,45V - 5,60V"
How, where. On the panel, on the battery.
As said, that circuit is inefficient in low light levels.
It uses power, and it has a high dropout voltage.
It should work though if your panel outputs at least 9volt.
Leo..
Wawa:
"I get output around 5,45V - 5,60V"How, where. On the panel, on the battery.
As said, that circuit is inefficient in low light levels.
It uses power, and it has a high dropout voltage.
It should work though if your panel outputs at least 9volt.
Leo..
With ~11Volts on the input (solar panel), I get around 5,45Volt on the output (in the place where the battery goes -> when I haven't connect the battery) and 5,60 Volt (in the place where the battery goes -> when I have connected the battery)
Are you sure the zener is 6.8volt.
Calculated voltage produced by the LM317 on the output should be about 7.5volt with the trimpot set to max (1k) and without the zener/transistor circuit.
But the zener/transistor could take that down.
Leo..