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  • FIRST POST
    • 50Twuncle
    • By 50Twuncle 12th Mar 17, 2:42 PM
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    50Twuncle
    Cost of charging 2 batteries
    • #1
    • 12th Mar 17, 2:42 PM
    Cost of charging 2 batteries 12th Mar 17 at 2:42 PM
    Could someone please tell me roughly what it costs to charge a pair of 12v 35Ah batteries ?
    At about 14p per kwh
    I can't remember how to work it out...
    thanks
    Last edited by 50Twuncle; 12-03-2017 at 2:44 PM.
Page 1
    • st999
    • By st999 12th Mar 17, 3:24 PM
    • 1,140 Posts
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    st999
    • #2
    • 12th Mar 17, 3:24 PM
    • #2
    • 12th Mar 17, 3:24 PM
    at a rough guess, 10p?
    • Heedtheadvice
    • By Heedtheadvice 12th Mar 17, 3:32 PM
    • 428 Posts
    • 205 Thanks
    Heedtheadvice
    • #3
    • 12th Mar 17, 3:32 PM
    • #3
    • 12th Mar 17, 3:32 PM
    Worst case rule of thumb approx .....ish
    Two batteries 75Ah 12v about (12*75) 800VA power so allowing for efficiency losses call it 1000watts. Just about 1kW so 14p.

    Lots of other factors to consider but that might be close enough?
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    Is that ok uncle? I can call you uncle can I not without getting banned by admin?
    • 50Twuncle
    • By 50Twuncle 12th Mar 17, 3:44 PM
    • 7,594 Posts
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    50Twuncle
    • #4
    • 12th Mar 17, 3:44 PM
    • #4
    • 12th Mar 17, 3:44 PM
    Thanks Both
    This is for my new "toy" - a mobility scooter
    It has 2 x lead acid batteries and will need regular charging....
    Just wondered what it would cost .
    Last edited by 50Twuncle; 12-03-2017 at 3:46 PM.
    • Strider590
    • By Strider590 12th Mar 17, 5:31 PM
    • 11,304 Posts
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    Strider590
    • #5
    • 12th Mar 17, 5:31 PM
    • #5
    • 12th Mar 17, 5:31 PM
    You simply can't work this out at all, you don't know the specifications of the charger. You don't know how much current it's putting into the battery and therefore don't know how long it'll take to charge and a battery takes less current at 90% than it does at 20%, so you can't even work from a constant value.

    The only way to know, is to plug it into a power consumption meter.
    Having the last word isn't the same as being right.......

    "Never confuse education with intelligence"
    • firefox1956
    • By firefox1956 12th Mar 17, 5:49 PM
    • 1,088 Posts
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    firefox1956
    • #6
    • 12th Mar 17, 5:49 PM
    • #6
    • 12th Mar 17, 5:49 PM
    Worst case rule of thumb approx .....ish
    Two batteries 75Ah 12v about (12*75) 800VA power so allowing for efficiency losses call it 1000watts. Just about 1kW so 14p.

    Lots of other factors to consider but that might be close enough?
    .
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    .
    Is that ok uncle? I can call you uncle can I not without getting banned by admin?
    Originally posted by Heedtheadvice
    If Uncle is his first name probably not
    • were
    • By were 12th Mar 17, 5:52 PM
    • 455 Posts
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    were
    • #7
    • 12th Mar 17, 5:52 PM
    • #7
    • 12th Mar 17, 5:52 PM
    Listen to Stryder590 for good advice. Nice to have known you But even using a power meter it will vary due to below, and temperature too.

    Stolen from a battery page "The Lead Acid battery is not 100% efficient at storing electricity - you will never get out as much as you put in when charging. Overall, an efficiency level of 85% is often assumed.
    The efficiency will depend on a number of factors including the rate of charging or discharging. The higher the rate of charge or discharege, the lower the efficiency.
    The state of charge of the battery will also affect charge efficiency. With the battery at half charge or less, the charge efficiency may be over 90%, dropping to nearer 60% when the battery is above 80% charged.
    However it has been found that if a battery is only partially charged, efficency may be reduced with each charge. If this situation persists (the batteries never reaching full charge), the life of the battery may be reduced."
    • Heedtheadvice
    • By Heedtheadvice 12th Mar 17, 7:00 PM
    • 428 Posts
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    Heedtheadvice
    • #8
    • 12th Mar 17, 7:00 PM
    • #8
    • 12th Mar 17, 7:00 PM
    All true about accuracy chaps......But come on my uncle only wants an approximation!
    • were
    • By were 12th Mar 17, 7:22 PM
    • 455 Posts
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    were
    • #9
    • 12th Mar 17, 7:22 PM
    • #9
    • 12th Mar 17, 7:22 PM
    About 14p

    https://ccfmobility.co.uk/2009/09/29/mobility-scooter-faq-battery-charging/

    from http://lmgtfy.com/?q=uk+cost+to+charge+mobility+scooter
    Last edited by were; 12-03-2017 at 7:25 PM.
    • 50Twuncle
    • By 50Twuncle 12th Mar 17, 7:31 PM
    • 7,594 Posts
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    50Twuncle
    Thanks all
    Somewhere between 10p and 20p is accurate enough for me
    • forgotmyname
    • By forgotmyname 12th Mar 17, 9:13 PM
    • 25,300 Posts
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    forgotmyname
    How efficient is the charger? Whats does the label on the charger show as its max current?
    Punctuation, Spelling and Grammar will be used sparingly. Due to rising costs of inflation.

    My contribution to MSE. Other contributions will only be used if they cost me nothing.

    Due to me being a tight git.
    • Strider590
    • By Strider590 12th Mar 17, 10:59 PM
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    Strider590
    Thanks all
    Somewhere between 10p and 20p is accurate enough for me
    Originally posted by 50Twuncle
    Even that's miles off.......

    A single 7w CFL bulb, in use for 24hrs a day, would cost around 60p to £1 per month to run.

    A battery charger might start out at 20W (mains side) and be down to 2W by the time the battery is almost fully charged.
    More costly if it's a linear power supply inside the charger, less if it's a switch mode power supply.
    Having the last word isn't the same as being right.......

    "Never confuse education with intelligence"
    • EdwardB
    • By EdwardB 13th Mar 17, 5:49 AM
    • 412 Posts
    • 329 Thanks
    EdwardB
    Listen to Strider590

    It is going to vary, are you going to discharge it down every day?

    I have a device I got off eBay for £10 that tells you your cost, but you have to try it for a while and write it down each day.

    Whatever you come up with multiply by 3.159261 and divide by π
    Please be nice to all MoneySavers. That’s the forum motto. Remember, the prime aim is to help provide info and resources. If you don’t like someone, their situation, their question or feel they’re intruding on ‘your board’ then please bite the bullet and think of the bigger issue.
    • Robin9
    • By Robin9 13th Mar 17, 6:03 AM
    • 1,478 Posts
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    Robin9
    I used to service Mobility Scooters and my general advice was - if you use it every day charge it every day; weekly charge it weekly.

    These scooters thrive on work - the ones that gave trouble were the ones laid up for the winter.

    OP don't worry about running costs - use it .
    • johndough
    • By johndough 13th Mar 17, 9:39 AM
    • 633 Posts
    • 246 Thanks
    johndough
    Hi

    Some have lightweight Li-Ion batteries, and could you not add a solar panel to trickle charge?
    • 50Twuncle
    • By 50Twuncle 14th Mar 17, 7:55 AM
    • 7,594 Posts
    • 1,749 Thanks
    50Twuncle
    Even that's miles off.......

    A single 7w CFL bulb, in use for 24hrs a day, would cost around 60p to £1 per month to run.

    A battery charger might start out at 20W (mains side) and be down to 2W by the time the battery is almost fully charged.
    More costly if it's a linear power supply inside the charger, less if it's a switch mode power supply.
    Originally posted by Strider590
    It Just says :
    Input 240v - No max current
    Output 24v 22amps
    • kwikbreaks
    • By kwikbreaks 14th Mar 17, 10:27 AM
    • 8,798 Posts
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    kwikbreaks
    Don't forget to figure in the calculator battery cost if you follow all the complexities suggested

    Also don't forget the cost of replacing the scooter batteries periodically and wear and tear on the scooter itself which could easily double the power costs.

    Take a flyer at 25p all in (including the battery replacements and a calculator) and you should be in the ball park IMO.
    • pogofish
    • By pogofish 14th Mar 17, 11:54 AM
    • 7,247 Posts
    • 7,282 Thanks
    pogofish
    Absolutely nothing if you try to do all your charging at work..!
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