7 replies to this topic

[esimmers]

I purchased from PowerStream <http://www.powerstream.com/> a PST-BC1212-15 DC charger for charging my 12 volt camper battery from a 10-15 volt source (my truck alternator and starting battery). It has a 4 stage, 3 level microprocessor controlled lead acid battery charger built in and outputs about 7.5 amps. If I drive long enough, it does an excellent job of topping off my camper battery.

I have one problem with the unit about which I'm corresponding with the manufacturer who, I must say, is quick about responding to emails. The charger is normally activated by an ignition-on wire which is supposed to close a relay allowing the charger to accept current from the + input wire. Alternatively, there is a rocker switch which activates the charger when there's no ignition signal. I only want to use this rocker switch sparingly since it draws current from the truck battery with the engine off.

When I activate this rocker switch, 12 volts is output to that ignition-on terminal of the charger. That's a problem because my truck aftermarket stereo is activated by the ignition-on circuit. Whenever I activate the rocker switch, my truck stereo turns on.

I've written PowerStream and was told there shouldn't be any current applied to the ignition wire when the rocker switch is turned. I've asked for a replacement unit that doesn't have this fault.

If you have one of these units, would you test it to see if activating the rocker switch sends a 12v signal to the ignition-on wire? I'd sure appreciate it.

Thanks

Ed

[UglyScout]

If the wire from the ignition + and the rocker + go to the same terminal on the control box - you will get 12v's back feeding into your iginition circuit when you flip the rocker. Sounds to me like it needs to be wired differently or you could put a diode inline with the ignition feed to prevent backflow.

[pods8]

I just went to check mine, it does do what you are saying. However I never use the switch option (in fact I keep a piece of duct tape over it to make sure it is never flipped) because I don't ever want to be pulling off the truck battery without it running so its a non-issue in my mind.

[esimmers]

Since I first posted this thread, I've upgraded my truck to a 2011 F-250 with a 7-pole trailer connector. I wired the power, ground, and running light from the trailer connector to the Hawk. Works great. An added bonus is that when the truck's ignition is off, the truck's power management disconnects the truck's battery power from the connector so no need for the Hawk's battery separator!

When the truck is running, the truck powers the PowerStream DC-DC charger and recharges the battery just fine.

The only downside is that I haven't figured how to use the truck's battery and alternator to run the 3-way refrigerator when I'm driving. The fridge draws about 14 amps, and since the PowerStream only charges the battery with 7.5 amps, there would be a net discharge of 6.5 amps from the battery. It's too bad since the truck puts out plenty of amps to do both. I need to figure out a way to disconnect the camper battery from the camper distribution panel (and fridge) when driving but then automatically reconnect the camper battery to the distribution panel when the truck's ignition is turned off.

Any ideas? A relay?

[K7MDL]

The Powerstream manual should talk about this case I would hope. Here are my ideas

Option 1, Install an Isolator Between the truck and camper batteries. Perhaps the Powersteam when turned off passes through this current like an isolator would? An isolator in this example is a diode based device that allows current to flow in one direction only. When the Powerstream is charging the camper battery would be at a higher voltage and work as it does now. When not charging (or switched off) the camper battery is at or below the truck battery voltage and current flows from the truck alternator.

Option 2, Manually switch the Powerstream charger in and out of the circuit. This would rquire a large capacity relay or switch. I would think this should be builtin to the charger. I am not familiar with it though.

[UglyScout]

Remove the powerstream and let your truck alternator/trailer charge circuit do the thinking. Place a 30 amp fuse in place of the powerstream and call it a day

It would charge when you drive and automatically disconnect when you shut off the ignition.

I know the powerstream is a cool gadget and does provide a cleaner charge for you battery, but it has its limitations and you've found one of them. Modern trucks have pretty smart charging systems, I think we can over think things.


**Side note: I have my camper setup very similarly, I use a 7-way RV plug on the camper to the 5'th wheel/gooseneck trailer plug in the bed of my truck. Powers off the trucks factory trailer charge wire and is super easy to connect! If I get creative I could wire in the running lights and backup lights off the same plug to the camper.***

[K7MDL]

It helps to have minimal voltage drop between the batteries (run heavy wire, keep it short) and the same type of battery chemistries for the alternator to do it job best via a low voltage drop battery isolator/solenoid device.

A DC-DC converter is great when your charging source is low voltage, not adjustable, or you want to run some equipment at a constant voltage while the supply battery voltage drops. Radio transmitters for example. The power output falls as the voltage does, and they may not operate below a certain voltage, leaving unused capacity in the source battery which might operate at even lower voltages until final cutoff voltage is reached.

[pods8]

Does the fridge even run well on 12V? I've never bothered to use it due the large amp draw. I just put a propane pilot reignitor on and ran in on propane the whole time.