Powering an amp with car battery + inverter for busking

TgabyTgaby Frets: 0
Hello there, 

I was wondering if it was doable to power a Laney cub12r with those two : 

Power inverter :
https://www.tayna.co.uk/inverters/12v-pure/vps300/

SMF Battery : 
https://www.ebay.co.uk/itm/Yuasa-YBX5075-Car-Battery-Calcium-Silver-Case-SMF-SOCI-12V-620CCA-60Ah-T1-/282765440891

Generators are too expensive and I was wondering if it is a liable solution...
After doing some researches, this is what I came up with but I'm not sure about the electric figures ...

Could I play with this setup without risks ? could it work for a 2/3 hours gig?

Thanks in advance, any help would be awesome. 
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Comments

  • uncledickuncledick Frets: 211
    Buy a leisure battery, they're built to withstand full charge and discharge cycles.  Ordinary car batteries - even good ones - don't like it at all.  FWIW, I'd steer clear of Yuasa except for motorcycle fitments.  I run a garage and most of the Yuasa batteries are coming back under warranty.  I'd currently recommend Varta, Bosch or Exide.
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  • TgabyTgaby Frets: 0
    Thank you so much for your help! Legend !

    Do you think that this model is ok :

    https://www.tayna.co.uk/leisure-batteries/varta/lfd60/

    Or the 75ah would be a better fit for my purpose ? (just running the amp) 
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  • uncledickuncledick Frets: 211
    That battery should be fine.  Make sure you have a good charger - CTek or similar - which can be left turned on without boiling the battery in between gigs..  That way, it will always be ready to use.  If you're going to stop playing for more than, say, 10 minutes, turn off the amp and the inverter.
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  • ICBMICBM Frets: 30905
    Bear in mind that without an earth connection, a valve amp may be very noisy. It won’t be dangerous because the supply is fully isolated - even in the worst case of a short to the ‘earth’ in the inverter, there is no return path for the current so you can’t get a shock.

    The only easy way to test if it will be noisy without buying the inverter and battery is to deliberately remove the earth connection temporarily - if you’ve got a power cable with a non-moulded plug you can do this, but be careful. (And make sure you re-connect it properly!)
    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone."
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  • TgabyTgaby Frets: 0
    Thank you again for your help guys. 'Much, much appreciated !  

    I see, I didn't think about the ground problem, that's an excellent point. I'm not the electro professional guy so I'd rather take no risk by getting into these sort of handlings... it could be dangerous without almost no basics of electricity.

    I've done researches on the internet today, seeking a simple solution to offset that matter ... but I guess there's no miracle cure when busking outdoor. 

    I've found a youtube video where you can see a bloke trying this setup with a Bugera V5 (valves):

    To someone asking him if he had encountered any noises issues in the comments section, he said no. 

    Also, I assume that a surge protector wouldn't be effective to protect the gear without grounding. 
    ... but does a fuse holder with a 40A ANL fuse between the battery and the inverter could do the trick ? 

    And with the 60Ah battery, how many hours could I spend on my guitar outdoor roughly? 

    (Ah ... so many questions I have now !)
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  • ICBMICBM Frets: 30905
    A surge protector won't help with grounding, but if it has a basic spike filter it may reduce noise if the inverter isn't perfectly clean. No need to worry about fusing because the amp has internal fuses, and the inverter should have too.

    There's no shock risk to worry about either, unless you wire yourself to the inverter - as long as you're only touching the guitar strings or the amp there can be no shock hazard because the inverter's 'earth' is not actually earthed, so there is no way of completing the circuit.

    The amount of time you can play for is simply a function of the amp's power draw. With a 60Ah battery and an amp that draws 1A, you could play for 60hrs. The actual power draw of a Cub 12 won't be that high, more like 1/2A at the most even at full tilt, and probably about half that... so probably about 150-200hrs.
    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone."
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  • uncledickuncledick Frets: 211
    ICBM said:
    A surge protector won't help with grounding, but if it has a basic spike filter it may reduce noise if the inverter isn't perfectly clean. No need to worry about fusing because the amp has internal fuses, and the inverter should have too.

    There's no shock risk to worry about either, unless you wire yourself to the inverter - as long as you're only touching the guitar strings or the amp there can be no shock hazard because the inverter's 'earth' is not actually earthed, so there is no way of completing the circuit.

    The amount of time you can play for is simply a function of the amp's power draw. With a 60Ah battery and an amp that draws 1A, you could play for 60hrs. The actual power draw of a Cub 12 won't be that high, more like 1/2A at the most even at full tilt, and probably about half that... so probably about 150-200hrs.
    The 12R power consumption is rated at 50W max.  If we assume 100% inverter efficiency that's still more than 4A from the battery.  200hrs? No way.  
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  • markblagdonmarkblagdon Frets: 563
    Surely it’s 60Ah at 12v, so that’s 720watt hours, so about 3 Ah at 240v.
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  • ICBMICBM Frets: 30905
    Yes, sorry - not thinking correctly :). The 50W is at 230V, so it’s about 220mA. At 12V it’s more like 4A, so you would only get 15hrs from a 60Ah battery. The inverter won’t be 100% efficient, but the power draw from the amp won’t be continuously at the full power either, so it will probably roughly balance out.
    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone."
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  • mr-macmr-mac Frets: 149
    edited June 8
    Any chance any amps use close to 12v or 24v after ac transformer? Could maybe mod a connector to pop battery in after the transformer that way.  Did this with a hi-fi amp as an experiment before
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  • ICBMICBM Frets: 30905
    mr-mac said:
    Any chance any amps use close to 12v or 24v after ac transformer? Could maybe mod a connector to pop battery in after the transformer that way.  Did this with a hi-fi amp as an experiment before
    Only solid-state amps of under about 15W. Even most of those use split-rail power supplies so it won’t work with a single battery.
    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone."
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  • mr-macmr-mac Frets: 149
    ICBM said:
    mr-mac said:
    Any chance any amps use close to 12v or 24v after ac transformer? Could maybe mod a connector to pop battery in after the transformer that way.  Did this with a hi-fi amp as an experiment before
    Only solid-state amps of under about 15W. Even most of those use split-rail power supplies so it won’t work with a single battery.
    ah Cool, wasn't sure if it would work
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  • TgabyTgaby Frets: 0
    Thank you so much for all your comments guys. 
    I think I've got all the informations I need and I hope it will help others too. 
    You guys rock !! 
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