Trying to solve a 12v D.C. Problem, Need Help

[Ottomoto]

I have some 12v D.C. LED lights in my boat, that are on a dimmer. When I run the Freshwater Pump, the lights all pulsate with the pump motor.

The lights, dimmer and pump all return ground to the same buss bar. The lights are all running at less than 10a and the fresh water pump is running at less than 15a.

Can I use a capacitor to prevent the lights from pulsating? If so, what size & type would I use. Also, would running the return ground from the pump to the battery, which is 30 feet away in the engine room solve the problem?

Would appreciate any help on this

 

[Gryd3]

I have some 12v D.C. LED lights in my boat, that are on a dimmer. When I run the Freshwater Pump, the lights all pulsate with the pump motor.

The lights, dimmer and pump all return ground to the same buss bar. The lights are all running at less than 10a and the fresh water pump is running at less than 15a.

Can I use a capacitor to prevent the lights from pulsating? If so, what size & type would I use. Also, would running the return ground from the pump to the battery, which is 30 feet away in the engine room solve the problem?

Would appreciate any help on this

A capacitor will 'smooth' out the effect.
The problem could be a poor conducting ground, poor conducting power line, or a battery that simply cannot provide enough power without dropping in voltage.
What type of Dimmer are you using on your LED lights?
How fast is the pulsating?
If you take a mater and measure the voltage to the LED Dimmer or Pump, do you get the same values when you read directly from the battery?

 

[ketanrd01]

Yep, adding the capacitor of a few uF would serve your purpose.
You dont have to run the ground from pump to battery.
If you want to go troubleshooting,
1.Try replacing your battery
2. Using the meter, what voltage are you getting at the LEDs

 

[Gryd3]

Yep, adding the capacitor of a few uF would serve your purpose.
You dont have to run the ground from pump to battery.
If you want to go troubleshooting,
1.Try replacing your battery
2. Using the meter, what voltage are you getting at the LEDs

If the pulsing affect is slow enough, a few uF won't do any good if the sum of the LED lighting current is high. Some test and more info would be ideal.

 

[Ottomoto]

The Gnd feeder is a 2/0 cable to the breaker panel buss. The wire sizing to the Pump is 12awg, and all connection points look to be corrosion free and tight.

The dimmer is from Blue Sea Systems and says its LED compatible.

I'm seeing between .1 & .2v drop between the battery and the breaker panel, and I typically see around .2 to .3v difference battery and pump or LED module.

How may uF capacitor would you recommend?

 

[KrisBlueNZ]

How may uF capacitor would you recommend?

LOTS! I'd recommend a small battery - something like a 2 Ah or 6.5 Ah SLA/VRLA - local to your lighting and just connected in parallel with your main battery through an independent cable.

 

[Gryd3]

LOTS! I'd recommend a small battery - something like a 2 Ah or 6.5 Ah SLA/VRLA - local to your lighting and just connected in parallel with your main battery through an independent cable.

Would he require the use of a diode to isolate the lighting battery?

Could this be caused by poor wiring or a connection somewhere?
If the battery voltage does not pulsate with the lights, then it would seem like the issue lies in some rogue resistance from poor cabling or termination.

 

[davenn]

..........................
Could this be caused by poor wiring or a connection somewhere?
If the battery voltage does not pulsate with the lights, then it would seem like the issue lies in some rogue resistance from poor cabling or termination.

reading through this thread several times over the last couple of days
It would seem you have possibly misunderstood the problem.
The lights ONLY pulse when the motor is running. This is a direct inference that its the motor's
variable high current drain during use that is causing voltage to fluctuate on the power system
resulting in the variations of the light output of the LED lighting

Kris's suggestion is probably the best for supplying a more stable supply to the LEDs
That battery will as a very large smoothing capacitor


Dave

 

[Gryd3]

reading through this thread several times over the last couple of days
It would seem you have possibly misunderstood the problem.
The lights ONLY pulse when the motor is running. This is a direct inference that its the motor's
variable high current drain during use that is causing voltage to fluctuate on the power system
resulting in the variations of the light output of the LED lighting

Kris's suggestion is probably the best for supplying a more stable supply to the LEDs
That battery will as a very large smoothing capacitor


Dave

Yes, but I brought this up again because the op has the pump and lights connected to the same ground bus bar. I am unsure about the powerline or not. But if the ground bus bar, or ground for the battery were loose, corroded etc. it would have a higher resistance which would cause a higher voltage drop when the pump kicked on and pulled more current through it.

That said, I am unsure exactly how the lights respond... if they dim in synch with the pump movements, or if they flicker the entire time the pump is on.

I do agree that the secondary battery will be a solution though. it was more of a generic question.

 

[KrisBlueNZ]

Would he require the use of a diode to isolate the lighting battery?

No, I don't think so. Probably a big PTC fuse would be a good idea. Something like http://www.digikey.com/product-detail/en/LR4-900F/LR4-900F-ND/1113483 in series with the positive wire, at the main battery end.

Could this be caused by poor wiring or a connection somewhere?

Yes, sure, I agree. Any resistance in the connection from the main battery to the fan and LEDs will cause variable voltage drop. He should inspect all of the connections in that path.

If the battery voltage does not pulsate with the lights, then it would seem like the issue lies in some rogue resistance from poor cabling or termination.

Yes, and I'm sure the main battery voltage doesn't vary, unless it has lost almost all its capacity or has a very high ESR. But some resistance in cables is unavoidable and assuming there's no corrosion etc, the simplest fix is to add a small battery at the other end.

Connect it across the wires anywhere that's not closer to the main battery than the point where the fan and the lighting feeds split off. In other words, you can connect it at the Y junction point, or right at the fan (this might be the best place to start), or right at the lighting circuit (do that if you still get flicker with the battery connected straight across the fan).

 

[Ottomoto]

I don't really like the idea of an extra battery, although it might be one solution. The boat is a 50' twin engine boat with an 8D house battery, approx. 220 Ah, and the boat/batteries are very New. It would seem that if there was corrosion issues, I'd see voltage drop in the circuit, perhaps not, I'm certainly not an expert.

The boat also has a 100a charger for the house battery that I pretty much keep on most of the time. As a test, I charged the batteries overnight and had only the pump and affected lighting circuit turned on, with the charger still online. I still see the same pulsing lights in time with the water pump.

To me, it seems like there's plenty of supply power, and the wire sizing seems adequate for the load mentioned earlier and the connection points all look clean and treated with corrosion inhibitor as a preventative measure from the factory. The manufacture reports they do see this on other boats, but are unsure of how to fix the problem. They also said, and I agree, the pulsating is very slight and most people don't complain. If you're not looking up at the lights, you really don't notice it. I'd like to solve the problem, so it doesn't come up in conversation when I entertain on the boat and someone notices & questions what's going on.

 

[KrisBlueNZ]

I don't really like the idea of an extra battery, although it might be one solution.

It might be your only solution, or your cheapest and simplest solution.