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  1. #1
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    Is this battery suitable for inverter?


    I urge to use dry battery with dc-ac 12v(300w) inverter.
    Can some one suggest, how much max load is best for this battery.
    Here 12V battery size avail is from 18 to 150Ah/10HR in market.
    Last edited by pnjbtr; 10th September 2011 at 19:04.

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    Re: Is this battery is suitable for inverter?

    It all depends on how long the battery is meant to support the invertor. For instance if you use a 20AH battery, this is 12 X 20 watt hours, at a draw of 300 it would last for 240/300 = .8 Hrs before it needed charging. Because you are draining the battery so fast you won't make the .8 Hrs and the batteries actual life will be shortened. So it depends on how often the battery will be used and for how long.
    Frank



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    Re: Is this battery is suitable for inverter?

    If you refer to inverter with charger, then, you need to consider that as well. Your charger needs to charge the battery properly, making sure it doesn't overcharge it and also it can keep charging current level within safe levels and handle the maximum charging current. By the way, is this for a UPS?

    You need to decide how long back up is required. Then you need to acknowledge that you can only discharge the battery down to a certain level, let's say 50% to lengthen battery life. So, for 300W inverter having an efficiency of 80%, connected to a 300W load, with requirement of 2 hour back-up, you need (300/0.8)*2 = 750W. With 12V battery, allowing lowest discharge level to be 40%, you need (750/12)/0.6 = 104Ah battery. So, you can use a 100Ah battery.

    You also need to keep in mind how frequently back up is required and if the battery can be charged in between. If not, you need a larger battery to provide longer back-up.

    Hope this helps.
    Tahmid.



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    Re: Is this battery is suitable for inverter?

    Thanks for suggestion.
    But dealer is asking that one can only draw current from battery 1\10 of total capacity.
    I mean if a battery,s capacity is 100Ah.
    So,max load should be only 10amp(10*12=120watts).
    Battery specification is as below,
    12V 100AH/10HR(VRLA BATTERY).
    He is emphasising on capacity/10HR.
    HR mean hour rate.
    That,s why i consult data sheet at manufacturer,s web site.
    But could not understand charts of constant discharge current.



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    Re: Is this battery is suitable for inverter?

    Quote Originally Posted by pnjbtr View Post
    Thanks for suggestion.
    But dealer is asking that one can only draw current from battery 1\10 of total capacity.
    I mean if a battery,s capacity is 100Ah.
    So,max load should be only 10amp(10*12=120watts).
    Battery specification is as below,
    12V 100AH/10HR(VRLA BATTERY).
    He is emphasising on capacity/10HR.
    HR mean hour rate.
    That,s why i consult data sheet at manufacturer,s web site.
    But could not understand charts of constant discharge current.
    Dealer is only worried about his complains about battery. Statics show some 70% batteries ara damaged due to wrong charging. He is not that technical but every battery dealer knows somthig about 1/10th ratio as it is standard practice for car batteries (lead acid) to charge at 1/10th rate of battery capacity. He is telling otherway round.
    For example if your battery's capacity is 120 ampers per hour(AH), it is charged with 12 amperes for 10 hours.
    It can be drained more rapidly.
    I know. I know. And once more - I don't know.
    I am too old and would not have enough knowledge to judge, and only have made some remarks in order not to be called ignorant.



    •   Alt11th September 2011, 01:15

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    Re: Is this battery is suitable for inverter?

    HI,

    Battery Storage Capacity Ratings
    Two standard ratings are used to measure a battery's storage capacity.

    1. Amp Hours:
    The Amp Hour rating tells you how much amperage is available when discharged evenly over a 20 hour period. The amp hour rating is cumulative, so in order to know how many constant amps the battery will output for 20 hours, you have to divide the amp hour rating by 20. Example: If a battery has an amp hour rating of 75, dividing by 20 = 3.75. Such a battery can carry a 3.75 amp load for 20 hours before dropping to 10.5 volts. (10.5 volts is the fully discharged level, at which point the battery needs to be recharged.) A battery with an amp hour rating of 55 will carry a 2.75 amp load for 20 hours before dropping to 10.5 volts.

    2.Reserve Minutes:
    Reserve minutes is the number of minutes a battery will carry a 25 amp load before dropping to 10.5 volts. (10.5 volts is the fully discharged level, at which point the battery needs to be recharged.)
    This is for general use (in your case the Inverter). And if you have 300 watts inverter I do not think you can run it on its full capacity as a loading margin is necessary for the inverter safety.
    Now here Lower the Load Longer time battery will go__Higher the load less time battery will work.
    Hope it helps.



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    Re: Is this battery is suitable for inverter?

    Quote Originally Posted by pnjbtr View Post
    Thanks for suggestion.
    But dealer is asking that one can only draw current from battery 1\10 of total capacity.
    I mean if a battery,s capacity is 100Ah.
    So,max load should be only 10amp(10*12=120watts).
    Battery specification is as below,
    12V 100AH/10HR(VRLA BATTERY).
    He is emphasising on capacity/10HR.
    HR mean hour rate.
    That,s why i consult data sheet at manufacturer,s web site.
    But could not understand charts of constant discharge current.
    Then I guess he's saying wrong. You can take up to 50%-60% without damaging the battery provided you charge it properly. You can charge it quickly but make sure you don't overcharge it.

    Hope this helps.
    Tahmid.



    •   Alt11th September 2011, 11:05

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    Re: Is this battery is suitable for inverter?

    Thanks of all respected members.
    Please see attach file,we can charge 100ah battery with 30amp max charge current.
    And floating voltage are 13.6-13.8.
    But drained current from battery?
    Though charts show constant discharge current and constant discharge watts.
    But F.V/TIME and battery volts in chart have some confusion.



    •   Alt11th September 2011, 13:41

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    Re: Is this battery is suitable for inverter?

    Datadheet also says, you can take 1000A for 5 seconds eg use it for spot welding.
    Internal resistance 5-mohm. At 25 Ampere, maximum 4 hours needed to fully charge.
    You will get at least 3 hours backup at 300 watts load.

    25 to 30 amperes for charging and discharging equels 300watts.
    From where you are getting this battery and at what price?
    Last edited by ALERTLINKS; 11th September 2011 at 14:28.
    I know. I know. And once more - I don't know.
    I am too old and would not have enough knowledge to judge, and only have made some remarks in order not to be called ignorant.



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    Re: Is this battery is suitable for inverter?

    Quote Originally Posted by ALERTLINKS View Post
    Datadheet also says, you can take 1000A for 5 seconds eg use it for spot welding.
    Internal resistance 5-mohm. At 25 Ampere, maximum 4 hours needed to fully charge.
    You will get at least 3 hours backup at 300 watts load.

    25 to 30 amperes for charging and discharging equels 300watts.
    From where you are getting this battery and at what price?
    I urge to purchase this battery from DAV,college road Rawal pindi.
    And its price is approx,Rs,12000.
    You means that chart shows if we use battery with 25 t0 30amps,3 hours.
    So,we decrease battery,s capacity to 75 instead of 100amp.



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    Re: Is this battery is suitable for inverter?

    It is aways better to use hi capacity you can afford. Therse specifications are for new bateries in ideal conditions. With time, batery capacity decreases. And it is the charge/recharge cycles and at what levels it is discharged (even if is is a deep dischare batery) whitch determines the battery life . So a high capacity battery will last long in addtion to proiding extra backup in hours of need.
    Last edited by ALERTLINKS; 13th September 2011 at 09:21.
    I know. I know. And once more - I don't know.
    I am too old and would not have enough knowledge to judge, and only have made some remarks in order not to be called ignorant.



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    Re: Is this battery is suitable for inverter?

    Yes i agree with you.
    Specification is for new batteries,with 25 TEMP.
    But here temp in summer season 40,
    Even room temperature almost 30c.
    What do you suggest,we can use this type battery with desi ups.
    Or float charger is essential for these batteries.



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    Re: Is this battery is suitable for inverter?

    Hi ! pnjbtr
    no you should not charge this 100AH battery with 30 amps current
    The hard and fast rule is to charge at 1/10 th the battery AH capacity, so for this 100AH battery you need to charge at 10 amps max current to give long battery life.
    The battery dealer has wrong concept of charging



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    Re: Is this battery is suitable for inverter?

    1.

    I agree that 30A is too heavy current for a 100AH battery. That is a charge rate of C / 3.

    Then if you have problems, the battery dealer may say you abused the battery by giving it too strong a charge.

    He knows that people are tempted to buy an undersize battery because of it being less expense. Then they bring it back wanting to exchange it because it failed on the job. The dealer often finds the battery is no longer in condition to sell to anybody.

    So the dealer is not anxious to exchange the battery after you take it home.

    2.

    Can you confirm the charger will push 30A into a 12V battery?

    Or is that the reading from testing the charger by connecting a very low resistance load to its output?

    To find its maximum charging current, the charger must be tested by hooking it up to a battery.

    3.

    You mention floating charge. Does this mean your charger does a taper charge?

    Taper charge is the proper way to charge a battery. It adjusts the charging current according to battery voltage.

    So it will reduce the charging current as it senses the battery rising to float voltage 13.5-14V or so. That way it will not overcharge the battery.

    If that is how your charger works then it will produce 30A for less time, during a period called bulk charging. The 100AH battery may be usable with such a charger.

    It will be better if it's AGM type. These can stand up better to overcharging and over discharging.

    Avoid the gel batteries. They can be ruined by one overcharging.

    4.

    Warm temperature is okay with batteries. The 100AH battery will get warm simply by getting a charge current of 10 A.

    However the acid will start bubbling more easily if you charge at high current. You want to avoid making the acid bubble away.

    5.

    Do all you can to avoid making the dealer afraid to have you for a customer. You don't want to cost him money.



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    Re: Is this battery is suitable for inverter?

    Hi,
    The temperatures here in Summer some times rises to 48°C and the 90% UPS here are charging the batteries at about 30 amps to 50 amps (according to UPS wattage) and the batteries still last for not less than a year. I have designed and assembled one for me with current limiting capability and I have limited the charging current to 15 amps for a 92AH (maintenance free battery) and it is working yet for the last 6 months fine. And unfortunately load shedding here some times is AFTER EACH HOUR for one hour. In my experience people here have connected 140 AH batteries (24 volts) with 1000 watt UPS and still they work fine. Only care is (in case of WET battery) keep the water level perfect.
    Wish you all the luck.



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    Re: Is this battery is suitable for inverter?

    It is ideal to charge at 1/10 rate of battery capacity. But practically it can be increase to max 1/3. Slow charging definitely extends battery life. I put two 65AH batteries(Exide car batteries) on a 300 watts 24V UPS for two fans and two 24 watts energy savers. After three and half years of continuous use when found not providing full backup replaced the batteries with 85AH batteries. Two yeass of use, no problem yet. Charge rate not exceeding 8 Amps. Similarly a 1000 watts 24v ups for 4 fans 6 savers and a computer installed with two 150-AH Osaka batteries two and half years ago, still batteries are in good condition. Rememer these batteries are Pak man. They are not made to international standars. Exide, an international company guarentees for only one month for full refund while in india they provide 5 years warentee. and here if you think you can avail warenty without some reference, you are wrong.
    At my place i am using 150AH with 1000W ups. I experimented using a 80AH car battery charging batery at 35AH which was serving for one year and condition still ok, It was destroyed in two months.

    AGM batteries can be charged at 3 to 4 times charge rate than their capacity. A 100AH battery can be charged in 15 minutes.
    Most important battery should not be overcharged neither get overheated. In summers it get overheted and then overcharged. Maximum voltage for charge cycle depends also on temperature.
    I know. I know. And once more - I don't know.
    I am too old and would not have enough knowledge to judge, and only have made some remarks in order not to be called ignorant.



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    Re: Is this battery is suitable for inverter?

    @Alertlinks,did you arrange extra treatment with battery?
    Because 3.5 and 2 years is a long time for wet battery.
    Here 90% ups user complain that battery,s life is only 12 to 14 month.
    @RAZA sab,can you illustrate how can we arrange current limiting capability in ups,(to control charging rate).
    @Bradthred,here float charger almost use with high frequency transformer(SMPS).
    With chip TL494 or UC3843.
    Yes one can adjust floating voltage from 13.5 to 14.4v with trimpot.
    Current is also adjustable with trimpot according to battery size.



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    Re: Is this battery is suitable for inverter?

    Hi,
    Controlled current capability is designed in the main circuit. And if there is a microcontroller in the control circuit it is embedded in the program and if it is a discrete design then it has a feedback system which controls the Series elements (Thyristors or Triacs) to control the main charging transformer for the preset Amparage.



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    Re: Is this battery is suitable for inverter?

    Quote Originally Posted by Raza View Post
    Hi,
    Controlled current capability is designed in the main circuit. And if there is a microcontroller in the control circuit it is embedded in the program and if it is a discrete design then it has a feedback system which controls the Series elements (Thyristors or Triacs) to control the main charging transformer for the preset Amparage.
    Thanks.
    As i am not familiar with micro controllers.
    And with discrete components a board is avail in local market.
    This board is consist ol BTA16(triac),LM324,MOC3021 etc.
    Unfortunately board,s performance is not satisfactory.
    I even hear noise in wiring of distribution box(main board), when i add this board in series of phase and transformer in my ups.
    Although this circuit control charging rate as our desire or according to battery size.
    If you have any specific design for charging control circuit please share here.



    •   Alt13th September 2011, 19:42

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    Re: Is this battery is suitable for inverter?

    Quote Originally Posted by tipu electronics View Post
    Hi ! pnjbtr
    no you should not charge this 100AH battery with 30 amps current
    The hard and fast rule is to charge at 1/10 th the battery AH capacity, so for this 100AH battery you need to charge at 10 amps max current to give long battery life.
    The battery dealer has wrong concept of charging
    HI,how can i set charging current at 10amp.
    I have only centre tape 12+12 volt 30amp transfoermer,with full wave dc supply.
    Which method(aglorithm) i should use to control charge rate?
    best regards.



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