Simple battery charging question..

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plainman007

Joined: 30 Sep 2009
Posts: 26
Location: gandhar

30 Sep 2009 18:06 Simple battery charging question..

Hi,

I have what seems to be a sealed battery. Its a black block like thing. Dry sealed battery. Id like to know the proper way to store such batteries as ive heard they can lose their ability to perform if left idle for a few months etc. Id like to know how to charge and discharge this battery. How to know how much power is in it, maybe by using a digital multimeter ? And how to discharge it (maybe by attaching a particular voltage bulb and letting it burn till the battery goes dead). As this battery is needed to be used only once in 6 months or so. So id like to know how to keep the battery alive during storage.

Thanks a lot...

ark5230

Joined: 29 Jun 2009
Posts: 188
Helped: 15
Location: India

30 Sep 2009 20:02 Simple battery charging question..

It is advisable to avoid using a component that could not be identified. There are hazards. Check for hazards.
Raoof

pauloynski

Joined: 06 Oct 2004
Posts: 277
Helped: 34
Location: Brazil

30 Sep 2009 21:38 Re: Simple battery charging question..

Sealed bateries come in standardized sizes. Capacity depends on size and since there are many competitors in the market, the same size means the same capacity (almost always). So, give us the size or a photo.

FvM

Joined: 22 Jan 2008
Posts: 5154
Helped: 767
Location: Bochum, Germany

30 Sep 2009 23:33 Simple battery charging question..

Everything you need to know should be printed on the battery case (nominal voltage, capacity, often even charging conditions). There are also manufacturer datasheets available.

Audioguru

Joined: 19 Jan 2008
Posts: 1147
Helped: 95
Location: Toronto area of Canada

01 Oct 2009 0:38 Simple battery charging question..

Your sealed battery might be lead-acid, Ni-Cad, Ni-MH or Lithium.
They are all different.
You don't say which type you have.

hussong1555

Joined: 03 Jul 2008
Posts: 13
Helped: 2

01 Oct 2009 3:27 Re: Simple battery charging question..

as for discharging methods, I tend to use a halogen car head lamp it will rapidly and safely discharge the battery. as previous post said most of these batteries have the same characteristic depending on their physical size. if you post the info and maybe include a pic that would help a lot in helping you with the capacity info.

plainman007

Joined: 30 Sep 2009
Posts: 26
Location: gandhar

01 Oct 2009 4:50 Re: Simple battery charging question..

Hi, Im so sorry. Im not exactly an elctronics expert. I will post a pic immediately. But i think being a new member may not allow me to post or attach pics here. Or i will first go get the battery and come and list whats printed on the label.

Plz give me a few hrs as im at home now.

Thanks.

plainman007

Joined: 30 Sep 2009
Posts: 26
Location: gandhar

02 Oct 2009 13:44 Simple battery charging question..

Hi,

Its a 12v, 0.8ah battery. The dealer says its a jelly type battery. Its sealed and is nothing but a plastic block with just 2 terminals thats all. The rest is like one plasticine block.

My reason for this post is that i would like to learn how to properly maintain this battery since its going to be used only once in 6 months to run a small motor in a gadget. The rest of the time its just going to remain idle and i dont want it to die out on me.

My friends have advised buying a mutimeter and checking how much voltage is in the battery maybe once in 15 days and then charge the batt accordingly before shelving.

Another friend suggested a simpler method to just charge the battery fully and shelve it. And maybe once a month take it out and charge it. And he said its better to drain it to almost a dry stage and then charge it fully before shelving again for another month. He said instead of the mutimeter the bulb would be more layman and would not only show how much power is in the battery by brightness and also help to drain the batt efficiently.

Kindly advise.

Audioguru

Joined: 19 Jan 2008
Posts: 1147
Helped: 95
Location: Toronto area of Canada

02 Oct 2009 14:01 Simple battery charging question..

I guess that your battery is a sealed lead-acid gell type. It dies in 1 month or 2 months without being trickle-charged. You can trickle charge it with a small solar panel.

If you discharge it (your friend said to drain it) then it is ruined.

pauloynski

Joined: 06 Oct 2004
Posts: 277
Helped: 34
Location: Brazil

02 Oct 2009 15:05 Re: Simple battery charging question..

Here you can find some hints http://en.wikipedia.org/wiki/Lead-acid_battery
The best way to store it is keeping it charged to its floating voltage, that means to source it a very small current (about 5 to 10 mA) and controll the voltage which should stay in the 13,6 to 14V range. Some types float at 14.5V and this is easy to see because they keep the voltage under very small charging currents. A too high voltage can damage it and also, discharging it to a low point (usually less than 12V) also will, surelly, damage it. If you can´t keep it in the floating region then fully charging it every two months will be enough. The same apllies to other battery types (NiCd for example) but the voltages are a little bit diferent. Before reaching the floating point the charging current should be limited, usually to 1/10 of the rated capacity of the battery.
Regards

plainman007

Joined: 30 Sep 2009
Posts: 26
Location: gandhar

02 Oct 2009 17:50 Simple battery charging question..

Hi,

Audioguru > My second friend did mention however not to drain to completely flat too. He told me that. He said that would also damage the battery. Thats why he said to start charging it when the bulb dims out itself.

Paul > I use this battery only once in 6 months. Can i just charge it fully, store it, then just pick from shelf after 2 months and charge fully again (without bothering to check it etc) and store. Or should i check. If yes. Then how should i check ? Multimeter or bulb method please ?? Bulb method would help check and drain battery too if its still at half capacity right, cause they say its bad to charge a battery which is not 90% discharged either, right ?

Thanks

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pauloynski

Joined: 06 Oct 2004
Posts: 277
Helped: 34
Location: Brazil

02 Oct 2009 18:20 Re: Simple battery charging question..

I suggest your checking the voltage and if it goes near or bellow 12V charge it again. I think 6 months is too much time for a low rated capacity as 0.8Ah. Experience shows it must be done every 1 or 2 months. Some new batteries retain charge for 3 to 4 months but this time declines after aging.

plainman007

Joined: 30 Sep 2009
Posts: 26
Location: gandhar

02 Oct 2009 19:48 Simple battery charging question..

What does the 0.8ah mean in laymans terms ? Does the amps per hour mean how long it can hold power or how long it can supply power or how long it takes to charge ? 12v is the power right ? Whats the ah mean then please ?

Thanks Again

Last edited by plainman007 on 02 Oct 2009 19:57; edited 1 time in total

pauloynski

Joined: 06 Oct 2004
Posts: 277
Helped: 34
Location: Brazil

02 Oct 2009 19:56 Re: Simple battery charging question..

0.8Ah means you can sink 1A during 0.8h from it or wathever results in a voltage x current product that results 0.8. But be carefull, there is always an upper limit on the current you can sink without damaging it. 12V is just the nominal output voltage.

plainman007

Joined: 30 Sep 2009
Posts: 26
Location: gandhar

02 Oct 2009 19:59 Simple battery charging question..

Hi Paul,

So based on my previous post. Which is the best method to adapt. Bulb draining or just on the shelf for 2 months to completely discharge the battery ?

Thanks

pauloynski

Joined: 06 Oct 2004
Posts: 277
Helped: 34
Location: Brazil

02 Oct 2009 20:10 Re: Simple battery charging question..

If you want to measure the battery capacity, discharge it using a constant load (like a bulb or a resistor) and measure the time for the output voltage to drop to about 12V. Please note that a filament´s resistance shows some variation after heated. If you want to store it, just leave it on the shelf.

Added after 1 minutes:

You don´t need to completely discharge this type of battery to charge it again. This is a recomended procedure for NiCd batteries instead.

Audioguru

Joined: 19 Jan 2008
Posts: 1147
Helped: 95
Location: Toronto area of Canada

02 Oct 2009 23:16 Re: Simple battery charging question..

pauloynski wrote:

No.
All lead-acid batteries have their capacity rated when the discharge current is at the 10 hours or 20 hours rate so the current is fairly low. This little 0.8Ah battery can supply 80mA for 10 hours or 40mA for 20 hours. It might supply 800mA for 15 or 20 minutes. It will be anout 10V when dead.

pauloynski

Joined: 06 Oct 2004
Posts: 277
Helped: 34
Location: Brazil

03 Oct 2009 5:20 Re: Simple battery charging question..

Please find attached the spec. of a similar battery. Please take a look at the specified capacity with respect to discharging time.

Sorry, but you need login in to view this attachment

Audioguru

Joined: 19 Jan 2008
Posts: 1147
Helped: 95
Location: Toronto area of Canada

03 Oct 2009 16:03 Re: Simple battery charging question..

pauloynski wrote:

Please find attached the spec. of a similar battery. Please take a look at the specified capacity with respect to discharging time.

The Yuasa 12V/0.8Ah battery has a capacity of 0.8Ah at the 20 hour rate which is a current of only 40mA. Its capacity is 0.74Ah at the 10 hour rate which is a current of only 74mA. The end voltage is 1.75V per cell so the 12V battery will be only 10.5V.

pauloynski

Joined: 06 Oct 2004
Posts: 277
Helped: 34
Location: Brazil

03 Oct 2009 16:34 Re: Simple battery charging question..

I´ve just sent the pdf to show how is it specified and to give an example of what can be expected from such a battery. I agree with you Audioguru. No need to reply.

plainman007

Joined: 30 Sep 2009
Posts: 26
Location: gandhar

04 Oct 2009 8:27 Simple battery charging question..

Dear Paul,

You said "If you want to measure the battery capacity, discharge it using a constant load (like a bulb or a resistor) and measure the time for the output voltage to drop to about 12V."

Can you kindly explain what you mean by that. I understand discharge it using a constant load. But what do you mean by measure its capacity please ? Does that mean measure how much the battery is CAPABLE of handling. Or how much charge it CURRENTLY contains ?

Sorry im asking so many questions for such a simple concept as i dont know much about this.

pauloynski

Joined: 06 Oct 2004
Posts: 277
Helped: 34
Location: Brazil

04 Oct 2009 16:48 Re: Simple battery charging question..

Means you are going to measure the actual amount of charge the battery contains. As noted above, you need to use a light load. I suggest your using a 330Ω / 1W resistor to discharge it for about 20h if it is fully charged.

plainman007

Joined: 30 Sep 2009
Posts: 26
Location: gandhar

05 Oct 2009 7:41 Re: Simple battery charging question..

Dear Paul,

I have absolutely no experience in electronics and capacitors and resistors etc. Im just a layman who happens to work with some electronics in my work and needed advise towards some of my work related stuff.

I can however understand discharging the battery using a 12v bilb etc as thats more on a mundane level.

I think in order for me to understand the way the charge works is to let you know that ive charged the battery which i had on the shelf unsed for about 8 months or more. So i connected it to a charger which is like a cellphone plug in charger and has a label on stating 220V. It was provided by the guy who designed the motor display thing for an exhibition and this is the battery is to be used in that gadget, but very occasionally. Now after 8 months of storage i charged the battery using this charger for about 20 hrs. Then i measured it the next day using a mutlimeter and it displays 12.2 or something. Whats does this mean at the moment, it contains a full charge ? or just that its giving out 12v ?

Thanks

pauloynski

Joined: 06 Oct 2004
Posts: 277
Helped: 34
Location: Brazil

05 Oct 2009 12:57 Re: Simple battery charging question..

If you left the battery on the shelf for 8 months or more chances are that some sulfatation happened to the battery´s plates because it was fully discharged. In other words, maybe it has no longer the full capacity as when it was new. When it is fully charged the voltage reaches about 14 to 14,5V with a very small current needed to keep this point (called the floating point). After reaching the floating point, if you turn off the charger, the voltage rapidlly decays to 13,6 to 13,2V (in a few minutes) and then goes slowly to about 12,6V with no load. Voltages may differ somewhat depending on the battery type and manufacturer. If you are reading 12,2V it is probably not fully charged OR you are experiencing the effects of a damaged or long time used battery. My suggestion is:
1- Keep it charging for more time and see if it reaches the floating point (just measure the voltage with the charger connected)
2- If the voltage keeps within the expected floating value, leave it charging for more time (1 or 2 days). Usually those batteries recover part of the damage by sulfatation (not all).
3- Apart from the fully charged and fully discharged voltages, any other voltages you read can´t tell you anything about the amount of charge of the battery.

plainman007

Joined: 30 Sep 2009
Posts: 26
Location: gandhar

24 Oct 2009 18:32 Simple battery charging question..

Hi,

Sorry to return to this thread late.

So the multimeter can only tell me what voltage is coming out. Not how much of the charge is in the battery or if its draining to fast ? (lost its capacity).

This battery is meant to drive a small motor of 12v DC with heavy torque. Is the best layman way to identify gow the making an automobile 12v battery and connecting it to this battery. If the battery is good it should burn bright and long ? Or at least i will know how long the battery will supply a 12v power ?

Please do let me know. Thanks for your immense patience trying to explain this to me.

Audioguru

Joined: 19 Jan 2008
Posts: 1147
Helped: 95
Location: Toronto area of Canada

24 Oct 2009 18:47 Simple battery charging question..

You destroyed the battery by leaving it sitting for months without a charge.

It is lead-acid like a car battery that is supposed to be charged almost every day.

I have a Lithium battery from my daughter's first cell phone that is about 12 years old and it is still charged. It was last charged about 11 years ago.

snafflekid

Joined: 09 May 2007
Posts: 118
Helped: 16
Location: USA

25 Oct 2009 18:17 Re: Simple battery charging question..

Agree, your battery is dead. The lead acid gel batteries are especially delicate because the electrolyte is not a liquid. Damage to the plates by sulfuration is not reversible and rapid charging will cause gas to form between the plate and the gel electrolyte which then makes them lose contact (usually permanently) Never let one of these batteries go below 50% discharge to keep them long living. I know I have ruined my fair share of them.

plainman007

Joined: 30 Sep 2009
Posts: 26
Location: gandhar

02 Nov 2009 4:44 Simple battery charging question..

I dont know if my battery is the lead acid type. Its like a hard plasticine thing. Fully sealed. And just two metal plate terminals peeping out.

Snafflekid > I dont understand how one could never let these batteries go under 50% charge ? First off theres no way of immediately telling how much of the fully charged battery has been used. So how would i determine if its around 50% charge. Ive still not understood how to use the multimeter to find out when the charge is dropping. When a 12v 8mah battery is fully charged how much would it show on a multimeter ? And when the battery is at 50% charge what will the multimeter show then ?

AudioGuru > I have walkie talkies that work on lithium polymer batteries (Li-Poly). Im using the radios on a regular basis so i think that way im safe. Also the radio manual says to wait for the batteries to get fully discharged (the raidos batt low indicator sounds) before recharge. Also it mentions that if not in use for around 2 months or so that we should completely charge and discharge several times to regain the batteries full capacity. Whats your take on these batteries ? If i dont plan on using them for a long while, should i just completely discharge and reacharge the battery maybe once in a month to keepgood battery life ?

Thanks

Audioguru

Joined: 19 Jan 2008
Posts: 1147
Helped: 95
Location: Toronto area of Canada

02 Nov 2009 16:06 Re: Simple battery charging question..

A car battery is a lead-acid type and it never sits for months without a charge and it is never discharged below about 80% of a full charge. Then it lasts for about 5 years.

Your little 12V/8Ah battery must never sit for months without a charge and must never be discharged below 50% of a full charge.

You can measure its voltage when it is charging (and not loaded) and it will be 14.0V to 14.5V when still charging but fully charged. If you let it sit for 10 minutes without a load then its voltage will drop to 13.2V to 13.6V. In two days the unloaded voltage will drop to 12.6V. When the unloaded voltage drops to 12.2V then it should be charged.

A lithium battery cell is 4.2V when fully charged and the 4.2V charging voltage must remain until the charging current drops to a few percent of its capacity. A circuit must disconnect the load when the voltage drops to 3V. I think your radios have the low voltage disconnect circuit and then the charger is probably simply a timer that assumes the battery is discharged to 3V.

A lithium battery cell holds its charge for years if it has no load. Maybe your radios have a clock or something that slowly discharges the batteries.
It does not need to be discharged to be recharged unless the charger is simply a timer like yours.

An old Ni-Cad battery loses much of its charge sitting for a couple of months. They were discharged then recharged frequently.

plainman007

Joined: 30 Sep 2009
Posts: 26
Location: gandhar

02 Nov 2009 20:55 Simple battery charging question..

Hi,

But the radios say they are li-poly batteries. Ofcourse the radios are extremely light for a pro 2 way radio. Its a lithium polymer battery as the manual mentions. Now if its a lithium battery, why does the manual say if not used for more than 2 months to completely charge and discharge several times to regain their full capacity ?