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Author Topic: voltage drop, battery to ESC  (Read 2537 times)

william08098

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voltage drop, battery to ESC
« on: June 13, 2012, 04:12:14 AM »

 {:-{  Not very good with the electronics so . . .   Have a 12v battery, fully charged at 12.3 v.  I run wires to a distribution block.  From the block to the ESC for the two motors, that's one ESC to run both, and then power to 2nd ESC to run bow thruster.     Then from block to a on/off switch to run various lights, sound etc.  Problem is at the block I only get 10 or less volts and at the ESC only getting about 8 volt input.  Am using 18gauge wiring for all.  I do have a fuse between battery and distribution block and an on/off switch before the fuse.  Why the voltage drop??  I just can't get a handle on it.  Help, Thanks,
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boneash

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Re: voltage drop, battery to ESC
« Reply #1 on: June 13, 2012, 08:16:11 AM »

Hi,
12.3 is not a fully charged battery.
If your charger thinks it is then you probably have a duff battery and so any load drops the voltage to 10v.
Try a small bulb across it with your voltmeter attached and see if the volts die rapidly.
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Mad_Mike

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Re: voltage drop, battery to ESC
« Reply #2 on: June 13, 2012, 08:29:26 AM »

this is possibly down to a couple of reasons:

1, too much resistance between the battery and the block

2, too much load on the battery. With 2 motors, a bow thruster lights and sound, the amp draw will be pretty high and when current is on demand the voltage drops the higher the current goes up.

make sure that the switch can pass enough current threw it with a bit of head room, 30 amps maybe, that will lower resistance keep amps down and volts up.

The distribution block, Is it like as basic as a chock block or does it have additional magic electricary?

soldering the connections is better than screwing them, less resistance.

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malcolmfrary

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Re: voltage drop, battery to ESC
« Reply #3 on: June 13, 2012, 11:15:17 AM »

Yes, check the voltage at the battery at rest and under load.  If it drops under load, the battery is dud.  Then check the succeeding points - the problem lies between where there is good voltage and not good voltage.
A fully charged 12 volt SLA (assuming an SLA) should show about 13.5, more if its just come off the charger.  It could also be that the charger is not capable of fully charging a 12 volt battery.  Been caught by that a few times.
I have never worried about actual wire gauge - I tend to use wire recovered from dead domestic appliances with a current rating higher than my guess at what the motor is going to pull.  Otherwise, it would be a trip to the car accessory shop for higher rating wire.
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Mad_Mike

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Re: voltage drop, battery to ESC
« Reply #4 on: June 13, 2012, 11:18:55 AM »

never thought of the possibility of a dud battery :embarrassed:
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william08098

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Re: voltage drop, battery to ESC
« Reply #5 on: June 13, 2012, 04:30:58 PM »

 :-))  Thanks guys for the comments.   Will try all starting with the possible dud of a battery.  Cnnections were all soldered.  Hope this answer gets to all that responded, I'm new at this forum posting.
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Mad_Mike

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Re: voltage drop, battery to ESC
« Reply #6 on: June 13, 2012, 04:37:18 PM »

tell us how it goes :-))
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william08098

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Re: voltage drop, battery to ESC
« Reply #7 on: June 14, 2012, 02:25:35 AM »

 :-)  So far so good, the battery was realy 13.2 not 12.3, typo!   It may be the switch, I ran wire direct from battery to block and got everything to work.   Will get around to replacing the switch and will be using a different fuse holder.   Hopefully by the end of the weekend.   Thanks again all for the help.  Being positive, I'll let you know when it is working! :-))
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Mad_Mike

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Re: voltage drop, battery to ESC
« Reply #8 on: June 14, 2012, 09:30:31 AM »

Id personally go without the switch at all and just use either a gold Deans or Traxxas connector. High amperage switches are overly chunky and quite expensive.
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CGAux26

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Re: voltage drop, battery to ESC
« Reply #9 on: June 14, 2012, 09:30:15 PM »

You did not say how many amps all your stuff uses, but 18 gauge wire sounds bit small for most boat power wiring.  Also, try checking voltage drop across the switch, and other components with full loads on.
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william08098

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Re: voltage drop, battery to ESC
« Reply #10 on: June 15, 2012, 02:56:57 AM »

 :-)) :-)  I replaced the switch, ran new wires, installed new fuse holder and fuse and all is working well! :-)  Now I can get on float testing for ballast and getting the decks on for real and maybe before summer is over I can be finished, that is if you are ever finished.  The switch I replacedd is the main on/off from the battery.   I use a DPDT.  the battery goes to the center poles, then the one side to the fuse and the main block.   The other side goes to an RCA plug, when in this position I can plug my battery charger in and charge the batterky with out wire clips and easy access to charging and not have to even see the battery.  The boat I'm buildidng is tghe Graemsly.  The advise was great, it's nice to know that there is someone out there that can help a fellow model boater. Thanks again.   
PS I'm in the states
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RAAArtyGunner

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Re: voltage drop, battery to ESC
« Reply #11 on: June 15, 2012, 04:56:33 AM »

:-)) :-)  .   
PS I'm in the states

Phew, For a minute there I thought you said you were in a state  {-) {-) {-) and was to say well, that is normal for mayhem. O0 O0 :-)) :-))
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ACTion

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Re: voltage drop, battery to ESC
« Reply #12 on: June 15, 2012, 08:38:55 AM »

Avoid those cartridge fuses in holders with spring contacts at each end. I have seen these melt due to the area of contact being almost a single point and therefore producing a high resistance at that point. Best type is auto-blade fuse with bags of contact area. Cheap, too!
DM
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