Battery 12Volt

[ericgibbs]

hi,
Maplins have a range of SLA chargers.


**broken link removed**

 

[chemelec]

Not sure if your referring to be, BUT:

Sealed Lead acid batteries get charged at a Constant Voltage.

Nicads and NiMh batteries (AAA) get charged at a Constant Current.

Gary

u talk a lot but got know sol.
as far i know from AAA bat recommends, dats charge it with same v and 1/10 of the current. but u all are far away from there

though i also know nothing about it...

 

[watzmann]

please check these link ,i have found a charger and the supplier can send it to me with a good shipping cost.

before ordering it i decided to post you the link and you tell me if it's a good one or not.

my battery is 12 Volt 7AH.....i know it may take much time to charge but tell me if i did a bad selection.

https://www.master-instruments.com.au/products/57804/BFJ012.html

 

[ericgibbs]

please check these link ,i have found a charger and the supplier can send it to me with a good shipping cost.

before ordering it i decided to post you the link and you tell me if it's a good one or not.

my battery is 12 Volt 7AH.....i know it may take much time to charge but tell me if i did a bad selection.

https://www.master-instruments.com.au/products/57804/BFJ012.html

hi,
I don't see any price?.
The specification looks OK.

As you say, a 0.75Amp charge rate, so at 100% energy/charge conversion a 'flat' 7AHr battery would take about 9 hours to recharge, BUT usually the conversion efficiency is about 60%... so it will take about 16 hours to fully recharge.

 

[mvs sarma]

you might have had a charger already in the equipment for which you purchased this battery.

you may set up any power supply above 15 volts, that is capable to deliver the required load.
Use a LM317 ina constant current mode set for the rate of charge as prescribed by the battery manufacturer , then you may maintain the charging hours manually.
Mean time you have to watch if the battery is overheated where you can controll the current as per makers specs.

 

[ericgibbs]

you might have had a charger already in the equipment for which you purchased this battery.

you may set up any power supply above 15 volts, that is capable to deliver the required load.
Use a LM317 ina constant current mode set for the rate of charge as prescribed by the battery manufacturer , then you may maintain the charging hours manually.
Mean time you have to watch if the battery is overheated where you can controll the current as per makers specs.

Morning Sarma,
Its a SLA sealed lead acid, constant voltage charger.

If you charge over 14.8/15v you will damage the battery.

 

[mvs sarma]

Morning Sarma,
Its a SLA sealed lead acid, constant voltage charger.

If you charge over 14.8/15v you will damage the battery.

Sorry Agreed
he can regulate 15V to 13.8 and charge the battery.
https://www.electro-tech-online.com/custompdfs/2007/10/slabatts.pdf

As per One supplier,datasheet link as above, we can charge at constant voltage and current upto some hours and there after tapper it for the good health of the battery.

This is what i have been doing

 

[watzmann]

so you mean i can build my charger by adjusting the current to 14.5 using the LM317 ...... i looked at the datasheet it has a constant currant 1.5A

but are you sure that this will not damage my battery?

secondly , how can i know that my battery is fully charged ? ......
i know that i have to check the battery voltage but should be the voltage equal 13 or just 12 ?

 

[watzmann]

something else i need to know : i'll connect the Vin of the LM317 to a power supply output 40 Voltage and 0.9A

in this case will the LM317 be able to supply at the Vout 1.5A as they tell in the datasheet ?

 

[chemelec]

I Would put 40 Volts into an LM317, Especially Not to get out 900mA or more.
It Will OVERHEAT.

I Would suggest Maybe 16 to 18 Volts input and set the output to 14.6 Volts.
The LM317 will also need a GOOD Heatsink.

And When you have it operating as a Constant Voltage Source, it is NOT a 1.5 Amp Constant current Output.

The Current Draw will be determined by the Charge on the Battery and your DC Supply.
If your battery is Low and your DC Source allows too much current, The LM317 will drive at the Full 1.5 amps.
When it gets too HOT, it will Shut down. NOT A GOOD SITUATION.

Typically it will take 12 Hours to Fully charge the battery, No Matter WHAT you do.

On a Dead or low Battery, the Charge rate will be high, But as the Battery Charges up, the Charge Current goes down.
The Final charge rate is in the LOW Milli-Amps.

It appears you have Very Little Electronic Knowledge.

** You might consider Emailing me your phone number and I could Explain all this better to you. I can call most countries for free.

Gary
********************************************

something else i need to know : i'll connect the Vin of the LM317 to a power supply output 40 Voltage and 0.9A

in this case will the LM317 be able to supply at the Vout 1.5A as they tell in the datasheet ?

watzmann so you mean i can build my charger by adjusting the current to 14.5 using the LM317 ...... i looked at the datasheet it has a constant currant 1.5A

but are you sure that this will not damage my battery?

secondly , how can i know that my battery is fully charged ? ......
i know that i have to check the battery voltage but should be the voltage equal 13 or just 12 ?

 

[watzmann]

thank you for this nice post, but you forgot to tell me how to know that my battery is fully charged.

sure i'll use AVO meter , but how much is the fully charged voltage of the battery.

as for my electronics knoweldge....i'm a mechatronics engineer so i'm not specialised in just electronics.

but i'm trying nowadays to improve this knowleledge and i think i'm going rapidly.

 

[watzmann]

look at this link , i like this circuit and i think it well designed

**broken link removed**

 

[chemelec]

Sorry I Didn't notice that you lived in Egypt.
And I Can't call you there. Egypt is one of a few countries I can't call for free.

Your Battery will be Fully Charge When it reaches 14.6 Volts.

As to this Circuit Below, Yes it Will Work OK, But DO NOT put in More than 18 Volts. Contrary to what he says about 40 Volts, It will Cause you Problems.

Take care.....Gary

look at this link , i like this circuit and i think it well designed

**broken link removed**

 

[watzmann]

o.k , i'll follow up this instructions.....thank you

 

[mneary]

Your Battery will be Fully Charge When it reaches 14.6 Volts.

But be sure to disconnect it. Floating at 14.6 will dry it out prematurely. When it reaches full charge (14.6), you can reduce it to 13.4-13.6 and leave it floating.

 

[watzmann]

and how to reduce it again to 13.6 after reaching 14.6 ....... do you mean using the LM317 circuit

 

[ericgibbs]

and how to reduce it again to 13.6 after reaching 14.6 ....... do you mean using the LM317 circuit

Look at this forum link, you need something like this,, a comparator.

https://www.electro-tech-online.com/threads/battery-charger-with-auto-shut-off-feature.30970/

 

[mvs sarma]

I feel it can be set at 13.8 while inopen circuit, then battery conncted and charged . If the PSU is Ok it should not drop much while charging and at thend it will only come 13.8.

 

[watzmann]

i have a found a 12 volt battery charger in the market and supply 3000mA.

my battery is 12 volt 7Ah....and the merchan recommend to use charger current up 2.1 A.

do you think this 3000mA will damage my battery?

 

[chemelec]

i have a found a 12 volt battery charger in the market and supply 3000mA.

my battery is 12 volt 7Ah....and the merchan recommend to use charger current up 2.1 A.

do you think this 3000mA will damage my battery?

YES it will damage your battery.

You are Better to use a LOWER Current, than Too Much Current.

This Simple Charger would also work for you:
**broken link removed**

And Looking in my Junk Box, I have one Already Built up.
It is a Prototype I Built long ago, but it is Tested and Works.

I could Send to you, For FREE, Other than the Postage Cost to Mail it to you.

Unfortunately, that would Cost you $15.00 in US Funds.

Gary