Amp output on battery charger ?

tahoejag

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Jul 4, 2009
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Requesting knowledge - Battery chargers have diff output amps i.e. 5, 10, 15 amps. My ? is what is the diff; faster charging time? if charger is plugged in for say 24 hrs, does it make a diff, are not the btrys getting the same charge as the end result? I'm a bit confused with amp output and amp draw..my MK has a 56 amp max draw; meaning drawing current?? Again, just requesting some knowledge; would like to understand this amp output/draw thing better. Thanks All!
 

Boatist

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Apr 22, 2002
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Re: Amp output on battery charger ?

A large group 27 or 31 battery to fully charge can take 3 days. Also the type of controller the charger has can make a big difference.
Like a float charger or battery maintainer can take a Long time to charge.
A unregulated trickle charger could overcharge and damage the battery.
A good quality Automatic or Smart charger and on board charger usually will do a good job.

However if you Prefish the day before a tournament and stop at noon then charge the battery over night untill 3 AM when you have to head out for the 4 AM Blastoff Your battery will not be fully charged unless you have a high amp charger.
 

RickJ6956

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Re: Amp output on battery charger ?

Faster charging time is the difference, but many chargers also can be used as converters. Converters power 12v DC devices from 120v AC shore power so the house batteries are not drained.

The MK's rating means it can draw up to 56 amps. That's why the wiring needs to be very heavy (small gauge number), and you need some beefy batteries to deliver that power.

Think of it as a tank of water: Drain a gallon out and you have to put in a gallon to keep it topped off. Problem is, the drain hole is much larger than the filler hose.

If the MK draws 56 amps and you use it for one hour, it uses 56 amp hours. With a 15-amp charger it will take just about four hours to replace the power you've consumed in just one hour.
 

Boatist

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Re: Amp output on battery charger ?

If the MK draws 56 amps and you use it for one hour, it uses 56 amp hours. With a 15-amp charger it will take just about four hours to replace the power you've consumed in just one hour.

That would be true if the charger provided 15 amps but it does not.
It might start out at 15 amps but after an hour its going to drop down to less than 5 amps and before it fully charged to less than 1 amp.

A good charger supplies a voltage to charge the battery, then the battery determins how many amps it will take.
A completely discharged battery will take 15 amps for a while but as it charges the battery will take less and less until it reaches the point where no current is flowing.

To reach this full charge takes a good amount of time.
 

joed

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Re: Amp output on battery charger ?

Higher amps = faster charging. It can also = more heat and boiling the battery.
 

Silvertip

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Sep 22, 2003
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Re: Amp output on battery charger ?

Batteries can be safely charged at 20% of their AHr rating. A 100 AHr battery could therefore be charged at up to 20 amps without damage. Some of the hi-tech batteries however do have specific charge profiles that need to be followed to prevent damage.
 

tahoejag

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Re: Amp output on battery charger ?

I have a Promariner ProTournament 100 10 amps / 2 banks that i use to charge the 24v system. I was fortunate enuff to get my hands on an MK I-Pilot; it is all of what it is advertised for!!! Thanks one and all for the feedback!!!!
 

asm_

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Re: Amp output on battery charger ?

Requesting knowledge - Battery chargers have diff output amps i.e. 5, 10, 15 amps. My ? is what is the diff; faster charging time? if charger is plugged in for say 24 hrs, does it make a diff, are not the btrys getting the same charge as the end result?

I studied batteries, not just Pb, but NiMH, NiCd, Lipo, etc in my previous hobby. :)

In any case, assuming your charger is a decent one. Meaning it is CC/CV type charger. CC means Constant Current and CV means constant Voltage. This type of charger is designed to charge your battery in at least two phases. During the first phase, or CC (constant current), the charger only regulate current output. This could be 5, 10, 15 Amp, depending on your selection. Battery voltage will begin to increase in this phase. When the battery voltage reachs 14.4v, the charger begin its CV phase (constant voltage). During this phase, the charger is regulating the voltage at 14.4v. In order to accomplish this, charging current is reduce gradually. Depending on charger, some will terminate the charge cycle at 2A, other may take it all the way down to 1A.

Therefore, regardless which mode you selected, the end result will be the same. one side note, charging at high current does stress the battery more, which could possibly reduce its useful life. However, assuming you are using at least 27 size group Pb battery, 15A is not a lot current.

I'm a bit confused with amp output and amp draw..my MK has a 56 amp max draw; meaning drawing current?? Again, just requesting some knowledge; would like to understand this amp output/draw thing better. Thanks All!

Amp draw on a power supply meaning the max current can be drawn from the PS. 15A setting on charger mane the max current will be supply to the pack during charging.

By the way, you don't have to spend $200 for a decent charger. Assuming your don't charge your boat while its in water. A common automotive charger at $60 price range are usually CC/CV type charger.
 
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