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03-19-2018, 05:58 PM
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#1
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New Member
Join Date: Dec 2017
Posts: 6
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Trickle Charge Battery For Power while Drawing on it?
Hi there,
I've read through a bunch of forums and I still don't have a solid answer to my scenario, though I think I know it.
I'm building a party bus and I wanted to run the stereo from the rear of my blue bird. I have 120 A/C power (from a genset) run under all of the seats and to the rear of the bus. I planned on using 2 stereo specific batteries to power the stereo system (head unit, 400 watt amp, 1200 watt amp) but I don't want to draw any from the existing bus batteries or alternator.
My question is, can I use a trickle charger, powered by the 120 outlet, to provide the continual power to the stereo system, and will it be able to keep up? I'm looking at using something like this https://www.amazon.com/NOCO-G1100-Ul...t%2Bpower&th=1
In theory, this is how laptops work...the wall charger charges the laptop, even when you're using it.
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03-20-2018, 11:15 PM
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#2
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Bus Geek
Join Date: Sep 2017
Location: Owasso, OK
Posts: 2,627
Year: 1999
Coachwork: Thomas
Chassis: Saf-T-Liner MVP ER
Engine: Cummins 6CTA8.3 Mechanical MD3060
Rated Cap: 46 Coach Seats, 40 foot
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Generally no, you can't.
Most battery chargers won't even switch on unless they detect a battery attached.
Presumably the equipment you want to run is 12V or you'd just plug it into the genset.
Why can't you just buy a 120V to 12V power supply to run it?
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03-21-2018, 05:39 AM
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#3
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Bus Nut
Join Date: Mar 2015
Location: hills of sw virginia
Posts: 889
Year: 1996
Chassis: thomas
Engine: 8.3 cummins
Rated Cap: 11 window
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look for an inverter/charger. its charge function will keep up with the biggest of stereo's. it will invert your battery power to 120 ac until you plug that inverter into shore power. when you plug it in the inverter it becomes a charger and will charge your batteries or keep them topped off.
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03-21-2018, 08:08 AM
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#4
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Bus Crazy
Join Date: Nov 2010
Location: Andrews,Indiana
Posts: 2,430
Year: 1991
Coachwork: Bluebird
Chassis: AARE
Engine: 3116 Cat 250hp
Rated Cap: Just the two of us.
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I have this, it will do what you want and power a bit more. $75 plus shipping if you're interested. It works, I just out grew it.
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03-21-2018, 08:16 AM
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#5
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Skoolie
Join Date: Dec 2017
Location: southern maine
Posts: 114
Year: 2010
Coachwork: Coach & Equipment MFG
Chassis: ford E350 superduty
Engine: 5.4 liter v8
Rated Cap: 7 passenger
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my calculations show you will need a charger that supplies 13.3 amps to keep up with the stereo,
__________________
2010 ford e350 superduty v8 7 passenger bus
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03-21-2018, 10:19 AM
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#6
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Bus Geek
Join Date: May 2016
Location: Eastern WA
Posts: 6,401
Year: 2002
Coachwork: Bluebird
Chassis: All American RE (A3RE)
Engine: Cummins ISC (8.3)
Rated Cap: 72
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Quote:
Originally Posted by pbeggs
my calculations show you will need a charger that supplies 13.3 amps to keep up with the stereo,
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I am not sure I follow your math?
I=P/V
Max power = 1600 watts
Battery voltage 12 volts
I suspect that you may have slipped a decimal point. I come up with 133.33 amps. That would be peak load and you are unlikely to run the amps at full output for any period of time.
OP did not specify what the battery voltage is but I am assuming that battery powered stereo gear would be 12 volt.
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03-21-2018, 10:20 AM
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#7
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Skoolie
Join Date: Dec 2014
Location: central texas
Posts: 170
Year: 1990
Coachwork: Thomas/International
Chassis: 3700
Engine: 7.3
Rated Cap: 72
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stereo
If I read it correct you plan on using a trickle charger connected to two dedicated stereo batteries to power your stereo, I assume you will use an inverter connected to the batteries to connect to the stereo.
If this is accurate you can power your stereo, but the 3.5amp charger will not work.
one amp AC is equal to about 10 amps DC.
Calculate how many amps Ac your stereo will use and them multiply by 10 for the DC equivalent. probably better to multiply by 12 or 13.
Make sure the charger can handle charging for the numbers of hours you need, some may need to rest and cool down after a few hours.
Unless you use bus bars you will probably want batteries with top and side posts to make all your connections.
DC wire diameter matters as well as how long the wires are, keep all DC wires as short as possible. You can find wire size calculators online.
Use only a real deep cycle battery, not a marine battery, not any battery that lists CCA.
Wet lead acid batteries will off gas while charging, you will probably want an AGM battery if you want to keep the battery inside the bus, make sure your charger is made specifically to charge this type of battery, most chargers cant properly charge an AGM battery.
Until we know the AC power draw we cant discuss proper battery size.
But on the other hand if you can power a trickle charger why cant you just plug in the stereo?
__________________
my bus thread, https://www.skoolie.net/forums/showthread.php?t=8860&highlight=bubb
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03-21-2018, 10:35 AM
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#8
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Skoolie
Join Date: Dec 2017
Location: southern maine
Posts: 114
Year: 2010
Coachwork: Coach & Equipment MFG
Chassis: ford E350 superduty
Engine: 5.4 liter v8
Rated Cap: 7 passenger
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i dropped a 3 in there my mistake
__________________
2010 ford e350 superduty v8 7 passenger bus
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03-21-2018, 10:41 AM
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#9
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Bus Geek
Join Date: Sep 2017
Location: Owasso, OK
Posts: 2,627
Year: 1999
Coachwork: Thomas
Chassis: Saf-T-Liner MVP ER
Engine: Cummins 6CTA8.3 Mechanical MD3060
Rated Cap: 46 Coach Seats, 40 foot
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Let's not get carried away with the apparent enormous power here.
Amplifiers rated at 1400W do not consume 1400 watts of electricity. Depending on how they are rated (RMS or PMPO), they could be consuming as little as 1/10th of that, even cranked up.
The 1400W figure is usually an estimate of the maximum, and fleeting technical capacity often only reproducible in a lab for a fraction of a second.
The true RMS output is considerably smaller, and even that is only for the maximum highs.
Speaker loudness, and what the amp can drive is more a function of impedance and sensitivity.
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03-21-2018, 10:51 AM
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#10
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Bus Nut
Join Date: Mar 2015
Location: hills of sw virginia
Posts: 889
Year: 1996
Chassis: thomas
Engine: 8.3 cummins
Rated Cap: 11 window
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Quote:
Originally Posted by bubb, the real one
If I read it correct you plan on using a trickle charger connected to two dedicated stereo batteries to power your stereo, I assume you will use an inverter connected to the batteries to connect to the stereo.
If this is accurate you can power your stereo, but the 3.5amp charger will not work.
one amp AC is equal to about 10 amps DC.
Calculate how many amps Ac your stereo will use and them multiply by 10 for the DC equivalent. probably better to multiply by 12 or 13.
Make sure the charger can handle charging for the numbers of hours you need, some may need to rest and cool down after a few hours.
Unless you use bus bars you will probably want batteries with top and side posts to make all your connections.
DC wire diameter matters as well as how long the wires are, keep all DC wires as short as possible. You can find wire size calculators online.
Use only a real deep cycle battery, not a marine battery, not any battery that lists CCA.
Wet lead acid batteries will off gas while charging, you will probably want an AGM battery if you want to keep the battery inside the bus, make sure your charger is made specifically to charge this type of battery, most chargers cant properly charge an AGM battery.
Until we know the AC power draw we cant discuss proper battery size.
But on the other hand if you can power a trickle charger why cant you just plug in the stereo?
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wrong! ac and dc amps are the same, its a unit of measurement.
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03-21-2018, 12:16 PM
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#11
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Bus Geek
Join Date: Sep 2017
Location: Owasso, OK
Posts: 2,627
Year: 1999
Coachwork: Thomas
Chassis: Saf-T-Liner MVP ER
Engine: Cummins 6CTA8.3 Mechanical MD3060
Rated Cap: 46 Coach Seats, 40 foot
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Quote:
Originally Posted by superdave
wrong! ac and dc amps are the same, its a unit of measurement.
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They are the same, but for an equivalent power you need a lot more amps at 12V than you need at 120V, hence the much bigger cables and their associated losses.
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03-21-2018, 03:46 PM
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#12
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Bus Nut
Join Date: Mar 2015
Location: hills of sw virginia
Posts: 889
Year: 1996
Chassis: thomas
Engine: 8.3 cummins
Rated Cap: 11 window
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Quote:
Originally Posted by Twigg
They are the same, but for an equivalent power you need a lot more amps at 12V than you need at 120V, hence the much bigger cables and their associated losses.
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that is incorrect sir, if a radio uses 5 amps on ac power it will use 5 amps on 12 volt or 24 volt that don't change. line loss does affect dc current more than ac absolutely, but it don't use any more. you need a bigger wire to get that 5 amps there.
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03-21-2018, 04:35 PM
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#13
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Bus Geek
Join Date: May 2016
Location: Eastern WA
Posts: 6,401
Year: 2002
Coachwork: Bluebird
Chassis: All American RE (A3RE)
Engine: Cummins ISC (8.3)
Rated Cap: 72
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Quote:
Originally Posted by superdave
that is incorrect sir, if a radio uses 5 amps on ac power it will use 5 amps on 12 volt or 24 volt that don't change. line loss does affect dc current more than ac absolutely, but it don't use any more. you need a bigger wire to get that 5 amps there.
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Learn something new every day don't we Twigg.........
I am going to have to track down that Ohm guy and straighten him out....
I guess it really isn't "Easy as P=I*E"..... Sorry, I couldn't help myself.
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03-21-2018, 05:58 PM
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#14
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Bus Crazy
Join Date: May 2017
Location: Chattanooga, TN
Posts: 1,413
Year: 2001
Coachwork: Thomas
Chassis: Thomas
Engine: CAT 3126
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Pretty sure amps = Watts/volts. A = W/V. A cable is rated for a certain ampacity, but the actual energy used is the wattage. 1200 Watts at 120 volts is 10 amps. 1200 Watts at 12 volts is 100 amps. That’s why we are all running 2/0 awg to our inverters, but 12 awg to our appliances. The higher the voltage the lower the amperage for a given wattage
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03-21-2018, 05:59 PM
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#15
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Bus Geek
Join Date: Sep 2017
Location: Owasso, OK
Posts: 2,627
Year: 1999
Coachwork: Thomas
Chassis: Saf-T-Liner MVP ER
Engine: Cummins 6CTA8.3 Mechanical MD3060
Rated Cap: 46 Coach Seats, 40 foot
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Quote:
Originally Posted by superdave
that is incorrect sir, if a radio uses 5 amps on ac power it will use 5 amps on 12 volt or 24 volt that don't change. line loss does affect dc current more than ac absolutely, but it don't use any more. you need a bigger wire to get that 5 amps there.
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You may want to rethink that ... or not.
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03-21-2018, 05:59 PM
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#16
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Bus Geek
Join Date: Sep 2017
Location: Owasso, OK
Posts: 2,627
Year: 1999
Coachwork: Thomas
Chassis: Saf-T-Liner MVP ER
Engine: Cummins 6CTA8.3 Mechanical MD3060
Rated Cap: 46 Coach Seats, 40 foot
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Quote:
Originally Posted by PNW_Steve
Learn something new every day don't we Twigg.........
I am going to have to track down that Ohm guy and straighten him out....
I guess it really isn't "Easy as P=I*E"..... Sorry, I couldn't help myself.
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Apparently Ohm's Law is fake news
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03-21-2018, 06:08 PM
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#17
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Bus Nut
Join Date: Sep 2016
Location: NY
Posts: 487
Year: 2000
Coachwork: Carpenter
Chassis: International 3800
Engine: T444E
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Quote:
Originally Posted by superdave
that is incorrect sir, if a radio uses 5 amps on ac power it will use 5 amps on 12 volt or 24 volt that don't change. line loss does affect dc current more than ac absolutely, but it don't use any more. you need a bigger wire to get that 5 amps there.
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You're grossly incorrect. A 1kW load will use just 8.33 amps at 120v, but will use 83.33 amps at 12v. Voltage = Amperage x Wattage. Amps = Watts/Volts. Might want to brush up on your education before you start correcting people who know what they're talking about ...
__________________
Roads? Where we're going, we don't need ... roads.
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03-21-2018, 08:27 PM
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#18
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Bus Crazy
Join Date: May 2010
Location: Farmington Hills, Mi (Detroit area)
Posts: 1,968
Year: 2000
Coachwork: Eldorado Aerotech 24'
Chassis: Ford E-450 Cutaway Bus
Engine: 7.3L Powerstroke
Rated Cap: 19
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Quote:
Originally Posted by superdave
that is incorrect sir, if a radio uses 5 amps on ac power it will use 5 amps on 12 volt or 24 volt that don't change. line loss does affect dc current more than ac absolutely, but it don't use any more. you need a bigger wire to get that 5 amps there.
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While it is true that a given appliance will draw the same wattage whether powered from a 120v source or a 12v source, the amperage drawn from the power source will be different according to the voltage of the source.
For example, your radio that draws 5 amps at 120 volts (600 watts) will draw 50 amps from a 12 volt battery bank (also 600 watts) through an inverter. This ignores the power draw of the inverter itself.
Watts is "true power" (doesn't change with voltage) while amps change with the voltage of the system.
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03-21-2018, 08:49 PM
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#19
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Bus Nut
Join Date: Mar 2015
Location: hills of sw virginia
Posts: 889
Year: 1996
Chassis: thomas
Engine: 8.3 cummins
Rated Cap: 11 window
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well when my fridge is on 3.1 amps ac it draws 3.1 amps dc on my 24 volt system. that's just reality. try again
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03-21-2018, 08:51 PM
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#20
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Bus Nut
Join Date: Mar 2015
Location: hills of sw virginia
Posts: 889
Year: 1996
Chassis: thomas
Engine: 8.3 cummins
Rated Cap: 11 window
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Quote:
Originally Posted by warewolff
You're grossly incorrect. A 1kW load will use just 8.33 amps at 120v, but will use 83.33 amps at 12v. Voltage = Amperage x Wattage. Amps = Watts/Volts. Might want to brush up on your education before you start correcting people who know what they're talking about ...
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back at ya
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