Distance of Inverter from batteries

11 Posts
Oct 29, 2008 01:29 pm
Distance of Inverter from batteries

New guy here - I see all kinds of warnings about getting sparks, including from my inverter,  to close to deep cycle batteries. The converter has about 3' cable with it.  How close is too close for an inverter to be to batteries? TIA MARK

27 Posts
Oct 29, 2008 02:47 pm
Re: Distance of Inverter from batteries

Far enough so the gasses from the batteries are not going to ignite. sounds crazy but a lot depends on where and how your batteries are stored.
JUST remember connect your negative cable last then plug in and turn on inverter and when disconecting remove negative cable first.
There should not be a spark when connecting if there is something is wrong
11 Posts
Oct 30, 2008 04:47 pm
Re: Distance of Inverter from batteries

Thanks for the quick reply.  The batteries will have all sides open.  Also, at this point, my plan calls for the inverter to be in the living room and the batteries just below in the basement, connected by a six foot cable.  That shouldn't be any problem.  I want to test it with both in the living room for now.  Sounds like that should be OK as well since again, the batteries will be out in the open.  Thanks also for the tip about the battery cables.  Mark
49 Posts
Oct 30, 2008 10:00 pm
Re: Distance of Inverter from batteries

I understand that unless you have batteries that can expell gas they shouldn't be enclosed inside, like the basement without ventilation to the outdoors.I have AGM batteries and put them within 3' of my 2 power panels.    good luck, Jim A.
11 Posts
Oct 31, 2008 05:04 pm
Re: Distance of Inverter from batteries

Thanks for your reply.  I have a new question: I have four wires coming out of my DC motor.  I assume red (positive), black (Negative), and two blue wires (one for grounding and one to attach to the 12/3 wire I am using to connect to the battery controller.  Does this sound right?  TIA Mark
220 Posts
Oct 31, 2008 08:07 pm
Re: Distance of Inverter from batteries

hi mark,
  this motor question is a tuff one. i can buy into the red=positive and the black=negative line of thought but those blue wires might be anything. if the (controller) you mentioned is for rpm adjustment the blue wires might be an electronic on/off for the motor. i would try to get more information on this motor to be sure of the proper connections. do you see any tag attached to the motor with a diagram? or the name of the unit.. it sounds like a pwm speed controlled motor. but not sure.

good luck.
15 Posts
Oct 31, 2008 08:21 pm
Re: Distance of Inverter from batteries

If the DC motor is not a permanant magnet motor then they may be to the field. Usually the red and black are to the armature so the other two would be to the field.
11 Posts
Nov 2, 2008 11:40 am
Permanent Magnet DC Motor wiring question

Thanks to everyone again who have responded to my previous posts. 

Here is what I know about the motor: Permanent Magnet DC Motor; model PA140A manufactured by Argord Corporation, Toronto Canada; 2.5 HP Treadmill Duty @ 130 VDC; 18.5 Amps; 6750 RPM; 25 degrees C; CW Rotation; Enclosure Open; External Fan; Thermal Switch 120 VAC, 105+/-5 degrees C; 1.5 HP Continuous duty @ 95 VDC. 

So far I have hooked it up to an AMP meter with the red (positive) and black (negative) wires and it shows production of Amps.  I find a significant difference in resistance of the motor to turn when I do this.  The motor becomes quite difficult to turn by comparison to when the wires are not hooked up to the AMP meter- I assume this has to due with the magnets actually working?

So I still have these two blue wires coming out that I don't know what to do with... could they be the wires to a device that controls the amount of resistance the treadmill has?  I have found a phone number for the Argord Corp. and will call them Monday, but thought someone might know the answer to this... TIA Mark
351 Posts
Nov 2, 2008 12:43 pm
Re: Distance of Inverter from batteries

As David suspected, the two blues will be speed control. If they are not needed, just tape them off.
What are you doing ? Thinking of building a Chispito Wind Turbine ?
11 Posts
Nov 2, 2008 05:57 pm
Re: Distance of Inverter from batteries

Actually, I'm trying to hook up a exercise bike to this to make electricity uaing a 12v system... Mark

Again, thanks to all for your ideas! 
1 Posts
Jan 10, 2009 01:29 am
Re: Distance of Inverter from batteries

I have the same motor and I am planning on building wind generator frames for it. Anyone interested let me know.
I am going to try to design the frame to support the PA140B and the Ametek motor for wind power.

11 Posts
Jan 10, 2009 01:17 pm
Re: Distance of Inverter from batteries

The motor that I have been trying to use turns out to be almost impossible to turn with my exercise bike.  When I do get it going, it burns up the wheels transferring energy from the bike to the motor.

It is 2.5 horse power motor.  I have ordered .5 horse power motor to see if it will turn more easily... I'll let you know.  Mark
220 Posts
Jan 11, 2009 02:07 pm
Re: Distance of Inverter from batteries

 hi mark,

 sounds like your having fun with that pedal power rig your building. i have not tried building one of those YET but from an armchair quarterback point of view (read as: take with a grain of salt) there are a few things you might try while waiting for that new motor to come in.

 sounds like we are trying to pull way too much current off that generator and it is bogging down. if you feel like playing, we can try putting a regular incandescent light bulb in line with either of the conductors. ie: the positive from the gen wired thru a standard edison base fixture using something like a 100 watt bulb then on to the battery and see if it might limit the current. we might get a current limit of say 1 amp throughput and some percentage loss of that 100 watt bulb. a big 500 watt floodlight might let thru 5 amps (not sure on the actual values). also if you still have those 2 blue wires handy you might try a variable resister from an auto interior dimmer controll (even an ac dimmer switch would test the concept). as a test try shorting out those two blue wires and see if the generator spins freely.

 have fun! regards, dave

edit: i assume you already have a one way gate setup at the output? ie a diode? the rube goldberg bulb setup would go between the gen and blocking gate (diode) cheers!
« Last Edit: Jan 11, 2009 03:22 pm by david ames »
11 Posts
Jan 11, 2009 06:16 pm
Re: Distance of Inverter from batteries

Thanks Dave.  I'll give your ideas a try.  I am a total novice when it comes to electricity. I would love to use the 2.5 hr motor. If I didn't say before, when I have the motor turning (while burning up the rubber wheel) it shows 10 amps being produced.  I put an amp meter on it just to see what it can produce. Does this mean I want to get it down to 2 or 3 amps for it to be easier to run?

My next project will be wind and I know already there is no way will the wind turn this motor. I have another one like it I was hoping to try to use with wind.

11 Posts
Jan 11, 2009 06:27 pm
Re: Distance of Inverter from batteries

OK, I just noticed something in an ad for a amp meter: It says to connect in-line on the  positive line.  I think I have mine connected with both positive and negative lines.  Again, I am a total novice... Can this be the reason for the load making it difficult to pedal?

220 Posts
Jan 11, 2009 07:22 pm
Re: Distance of Inverter from batteries

 hi mark,

 heres a link that gives a good visual on the ammeter connections. could be that it's hooked up as a dead short.

 as far as using that size dc pm motor for a wind machine? it would need a gear up ratio and somewhere in the 8-10ft prop range...i'm in no way any expert on the subject but it would be fun to help work out the ratios if needed..that said, there are better starting places to look for pm generators/alternators..one that has a proven design without the complications of the whole gearing issue.

best regards, dave

220 Posts
Jan 11, 2009 11:51 pm
Re: Distance of Inverter from batteries

 oops..sorry but now i see there were some questions left unanswered.

   "OK, I just noticed something in an ad for a amp meter: It says to connect in-line on the  positive line.  I think I have mine connected with both positive and negative lines.  Again, I am a total novice... Can this be the reason for the load making it difficult to pedal?"

 you are correct on that..the loop of wire from the gen through the "paralleled" ammeter(amp meter)is trying to operate at a short circuit from the gen..and also will be a short circuit if wired to the battery that way (the meter won't last long connected that way)

  "Does this mean I want to get it down to 2 or 3 amps for it to be easier to run?"

  correct on that to..that sounds like a good starting point when getting up to speed. then try for higher current (amps) later, some of the numbers i see say a human can sustain about 140watts output. thats about 12 amps (140watts/12volts = 11.66amps)
  some good info here if you have not seem it.


happy trails and trials, dave
220 Posts
Jan 13, 2009 02:35 am
Re: Distance of Inverter from batteries

 hi folks,

 all this talk of pedal generators has inspired a new project. i have access to several stationary bikes to choose from and have selected this little scooter motor. the target will be 100watts output at 12vdc nominal. the exercise bike has a 20" flywheel and a comfortable cadence with the friction bands on is 92 full pumps (184 half pumps) of the pedal per minute. with this bike the flywheel goes around 3 1/2 times per pedal rotation and we would like the pm motor shaft at 2500 rpm.. the nameplate rating for the motor.

 lets see.. thats 92rpm x 3.5 (1:3.5) ratio gives a speed of 322rpm at the flywheel. we need 2500rpm so 2500/322=7.76 gear ratio needed. to increase the 322 to 2500 with a 20" driving sprocket (the rubber flywheel) at a 1:7.76 thats 20/7.76=2.57" driven diameter. i have a 2 1/2" rubber skateboard wheel that may work out.

 i believe i'll try going into the 12 volt nominal battery unregulated thru just a 30amp schottky diode with a 20amp fuse.

         here is a cut and paste of the motor specs.

 24 Volt 250 Watt Electric Scooter Motor
24VDC 250W 2500RPM electric scooter motor. Powerful four brush permanent magnet electric motor design with 100% ball bearing construction. Includes 14 tooth drive belt cog for 5mm pitch drive belts. 12" long power leads with 1/4" push-in connectors. Shaft rotation reversible by reversing power leads. Dimensions: 4" wide x 3-1/4" long excluding shaft, 4-1/4" long including shaft. Mounting bracket measures 4-1/2" x 2-1/8 with 4 threaded mounting holes. Weight 4.3 lbs.
item # MOT-24250BCompatibility: Razor E300 Belt Drive Scooter, X-Treme X250, Sunl, Dolfin, Boreem, E-Scooter, Star II, Z Scooter Lightning SE, plus other similar makes and models.
Cross references motor numbers: MY1016, MY1018, BD250

 looks like it might be under a hundred bucks out the door!

 any observations, overlooks, advice etc welcome.

 cheers, dave

-wish that shaft were longer..only 1"

 edit 1/13: heres the link to that motor source.


edit 3/19: project results posted.
« Last Edit: Mar 19, 2009 03:27 pm by david ames »
351 Posts
Jan 13, 2009 01:28 pm
Re: Distance of Inverter from batteries

I am not following you.
You say you want 100 watts at 12VDC.
You then talk about driving the motor at rated rpm. That is a 24VDC 250 watt motor. Driven at 2500 rpm, it should produce about 200 watts at 24VDC.
Your 100 watts at 12VDC should occur lower in the RPM range. You might want to find someone that has a good lathe (or variable speed drill press).  Spin the motor at various RPMs with a load on it, and find your target RPM.

220 Posts
Jan 14, 2009 02:16 am
Re: Distance of Inverter from batteries


  good eyes on that rpm issue. don't want to try pulling more than about 10amps or so. and like the drill press idea, that would save remaking the driven cog of the motor/gen a bunch of times chasing the rpm/power curve around for best input cadence. (we only know rated power rpm, and off rpm at this point). would you know if the volts per rpm stays constant throughout the rpm range? if so then we also know cut in speed is 1250rpm at 12 volts..(24v/2500rpm=0.0096volt per revolution)? i see on some of the pedal gens the use of a small flywheel on an extended shaft of the pm generator with an additional bearing support on that side of the armature shaft. not sure if that is for bearing pressure, twisting forces or what? some jpg images

 anyway should be fun to poke around with this...

 best regards, thanks. dave

edit 3/19: project completed.
« Last Edit: Mar 19, 2009 03:29 pm by david ames »
351 Posts
Jan 14, 2009 07:13 pm
Re: Distance of Inverter from batteries

The unloaded speed of a dc motor is essentially lineal.  In other words you will get X rpm for every volt applied.  However, we don’t know what that unloaded speed is. All we have is the loaded speed, which is some percentage of the unloaded speed.

When you drive it as a generator, the voltage is not directly lineal to rpm. 

In a quick glance of at the images, the flywheel and added bearing appeared when they are driving the generator on an extended shaft, using a light bicycle wheel.  Extending the shaft adds the bearing and the flywheel is (presumably) to cut down on surges from the peddling.

Most of the exercise bikes that I have seen, have a heavier wheel which acts as a flywheel to limit rpm surges, so you probably will not need to add one. If you drive the motor with the current shaft length, it should be designed for the forces. Lengthen it too much, and additional support will be required.
2 Posts
Feb 24, 2010 02:28 am
Re: Distance of Inverter from batteries

I have came to learn many useful tips of how to look after inverter and its batteries too.
6 Posts
Feb 25, 2010 06:50 am
Re: Distance of Inverter from batteries

Locate large inverters as close to the batteries as you can, but not in the same compartment unless you construct a shield or mini-compartment). Battery gas "eats" electrical components (and inverter sparks can ignite battery gas).

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