Batteries

[Qiaozhi]

Hi,
Max please explain again:
I just bought this 12V 1,4Ah battery it's lead acid type!
I have this stupid ac/dc adapter that have scale for voltages.On back side its labeled that its giving 400 mA MAX.Is this mean that when the scale is set for max voltage its give 400 mA then.?

Can I try with this AC/DC adapter because I cant understand this scheme that you give me/I am Nob you now/.Again with some resistor?
The AC/DC adapter should be put in 12v range right?Or
Sorry again for the stupid questions but I wanna finish this finaly!
Thanks

p.s.If you give me some advices I will try to build this circuit but what are AC1;AC2;where should be batteries be conected?

Hi tiktak,

The simple answer to your lead-acid cell charging problems is this:
A maximum charge rate (current) must not exceed 0.25 of the battery rated capacity. e.g. 4Ah battery max charge rate = 1A
Or - in your case, the 1.4Ah battery charge rate should not exceed 350mA.

The easiest solution is to buy a constant voltage sealed lead-acid battery charger. They're not very expensive.

[Fred]

Yes, that would be the right thing to do, but in that case if the battery is not too low, you could just charge it directly, as the voltage difference is not that big and all the 400ma will never go thru.NEVER let your battery go to a low voltage,if its gel it may never take charge again.
Fred.

[Max]

Hi,
Max please explain again:
I just bought this 12V 1,4Ah battery it's lead acid type!
I have this stupid ac/dc adapter that have scale for voltages.On back side its labeled that its giving 400 mA MAX.Is this mean that when the scale is set for max voltage its give 400 mA then.?

Can I try with this AC/DC adapter because I cant understand this scheme that you give me/I am Nob you now/.Again with some resistor?
The AC/DC adapter should be put in 12v range right?Or
Sorry again for the stupid questions but I wanna finish this finaly!
Thanks

p.s.If you give me some advices I will try to build this circuit but what are AC1;AC2;where should be batteries be conected?

Hi tiktak,
Fred is right about constant voltage charge of that batteries without limiter...WHEN THEY ARE ABOUT ALREADY CHARGED.

The fact you need a bought charger or a circuit like the one I posted is related to situations where you have the battery discharged ... so when you connect supply to it you'll get a very high current due to the fact that reactions required for charging will provide a strong current flow inside the cells.

That would be the worse situation if you don't use a real commercial charger or a limiter: your current will be out of control... rising more that 0.25C and then producing H2 bubbles inside the battery case... till pressure will reach some bar and automatic valve will open and free H2 in the environment... but often the pressure rise is so violent that case can break and battery will be permanentely damaged.

That's why I strongly suggest you buy one good and cheap 12v charger for lead-acid (but good for gel-type or other small backup type batt.) or build a charger like in circuit that do some limitation of current.

Best regards,
Max

[tiktak]

Hi

Hi,
Max.
Thanks for your adviceS!!
I conected this lead acid battery to TGS/just to see and compare how battery voltage drops.It were just like I bought it without charging.The voltage were 11.83./But I noticed that it drop very fast.Even faster than 700 ah NI-MH.Buy the way I were using aweys not nulled coil and noticed that when bad nulled machine consume around 45-even more mA!When nulled around 35-37mA.So maybe thats why they drop so fast?!!
And last time when I have charged one of the 700 ah batterie it drop almost good I have played 2 or 3 hours and the voltage droped a litlle bit faster but not as before/when reach 12,35v/.
When I charge this one I have measure the A from the first circuit that you give me/I just desolder afther the point where ADJ and Vout of LM317T connect afther 20ohm resistor afcourse and if my memory dont make me triks it were about 20 mA.Shouldn't it be 70 mA?Is this AC/DC adapter that make me crazy?Should I try to charge with only AC/DC adapter and for example 10 ohm resistor only?And for how long should I cherge with this configuration?


I will look for charger for 1,4 aH lead-acid battery,but my money have gone for now so I am in bad position.And seaching for simple solution!The charger that they try to sell me coast 45 euro!!!Isn't this too much?Can I charge with this AC/DC adapter and some resistor again?For how long should be charged this lead-acid type batteries?
THANKS

[tiktak]

Hi

Hi,
Max.
Thanks for your adviceS!!
I conected this lead acid battery to TGS/just to see and compare how battery voltage drops.It were just like I bought it without charging.The voltage were 11.83./But I noticed that it drop very fast.Even faster than 700 ah NI-MH.Buy the way I were using aweys not nulled coil and noticed that when bad nulled machine consume around 45-even more mA!When nulled around 35-37mA.So maybe thats why they drop so fast?!!
And last time when I have charged one of the 700 ah batterie it drop almost good I have played 2 or 3 hours and the voltage droped a litlle bit faster but not as before/when reach 12,35v/.
When I charge this one I have measure the A from the first circuit that you give me/I just desolder afther the point where ADJ and Vout of LM317T connect afther 20ohm resistor afcourse and if my memory dont make me triks it were about 20 mA.Shouldn't it be 70 mA?Is this AC/DC adapter that make me crazy?Should I try to charge with only AC/DC adapter and for example 10 ohm resistor only?And for how long should I cherge with this configuration?


I will look for charger for 1,4 aH lead-acid battery,but my money have gone for now so I am in bad position.And seaching for simple solution!The charger that they try to sell me coast 45 euro!!!Isn't this too much?Can I charge with this AC/DC adapter and some resistor again?For how long should be charged this lead-acid type batteries?
THANKS

[tiktak]

Hi

Hi tiktak,

The simple answer to your lead-acid cell charging problems is this:
A maximum charge rate (current) must not exceed 0.25 of the battery rated capacity. e.g. 4Ah battery max charge rate = 1A
Or - in your case, the 1.4Ah battery charge rate should not exceed 350mA.

The easiest solution is to buy a constant voltage sealed lead-acid battery charger. They're not very expensive.

Hi,
For how long should I charge?
Thanks

[Max]

Hi,
For how long should I charge?
Thanks

Hi,
if the battery voltage isn't too low (so not too discharged) you can charge just using a stable voltage of 12.7Volts.

Current will drop very fast and battery will charge in few time... some hours...at 12.7V you can also leave battery connected to supply... but you need at least voltage regulation... and can't put something more than 13.7V there cause otherwise you'll damage it.

BUT THAT IS POSSIBLE WHEN BATTERY VOLTAGE IS MAX ABOUT -10% of full charged battery... so maximum untill 11.5V, and not under that.

If you try to charge a battery that have voltage of less you'll maybe damage it without a proper current limiter. Current rise will be too fast and higher and H2 bubbles will make pressure inside the container.

As security devices you could use a fuse (e.g. 500mA) in series with supply ; you could use a diode instead if use e.g. 13.5V regulated voltage... that way diode will open circuit when battery will reach about 12.8V during charge.

Be careful, check initial current with multimeter... it must be always under 0.5C from start (for 1.4Ah not more than 0.7A at start).

Best regards,
Max

[tiktak]

Hi

Hi,
Max.
I have looked again and this AC/DC adaptor is actualy 300mA MAX OUTPUT!!!
So its look like I have to conect directly to lead-acid battery right?
And put in 12V?The only thing that bordars me is that when I measure the voltage from AC/DC adaptor when its in 12 V range the multimeter shows 15.60-15,70 sometimes 16 V.
What do you think?
I think that in AC/DC adaptor there is some kind of voltage regulator and I try to put another?
Please advice me.Should I try to charge 12V 1,4 Ah conected directly to AC/DC adaptor?If I put it in 12V for how long should I charge?
Thanks man I think that finaly will be ready soon!
I am not scared from snow,but what do you think If I clear from snow spot that I now that is good and try detect in frosen ground?Will there be many fals signals?Or I will be able to detect?
Thanks

p.s.AC/DC adaptor is LLA300D

[Fred]

If i were you , i would just connnect the adaptor to the battery, just to be sure check temperature of battery and adaptor for the first hour, and dont worry more.
Of course it is not the academic way to do it, but in practice you will have good resuts.And we all do this but dont want to tell
Those adaptors are not regulated,this is why you get 16V, there is capacitors inside that charges when there is no load.
go for it!
Fred.

[Qiaozhi]

If you're worried about excessive charging current with a 16V supply, then simply put a 20 ohm resistor in the line. This will limit the charging current to the maximum allowable 350mA, even when the battery voltage has dropped to 9V.
However, you are still better off to get one of these ->
http://www.maplin.co.uk/Module.aspx?...arger&doy=7m11
The LED starts to flash when the battery is fully charged, and there is no danger of overcharging.

[tiktak]

Hi

If i were you , i would just connnect the adaptor to the battery, just to be sure check temperature of battery and adaptor for the first hour, and dont worry more.
Of course it is not the academic way to do it, but in practice you will have good resuts.And we all do this but dont want to tell
Those adaptors are not regulated,this is why you get 16V, there is capacitors inside that charges when there is no load.
go for it!
Fred.

Hi,
What do you think for how wong should I charge with this AC/DC adaptor only?
Thanks

[Fred]

It depends of how deeply discharged is your battery, but a few hours should be OK : connect your ammeter and check how many mA it takes, then you should easily calculate of how many hours you need.Keep in mind charge rate will decrease with time,its not linear,and at the first minutes it will be much more .dont take this in your calculations.
regards,
Fred.

[Fred]

BTW, its not good o use battery from factory, first thing to do is to fully charge it.
regards,
Fred.

[tiktak]

Hi

Hi,
How should I understand this 1-2 hours;3-4hours???
I am stupid and used this new battery.Damn...............
Hope that haven't damaged it much?
Thanks

[tiktak]

Hi,

Hi,
fred
for how long should I charge?Now the battery shows 11.04V?
How can I calculate?
Thanks