Where to connect DC-DC converter or solar controller?

[esimmers]

Several folks on the forum have talked about installing DC-DC converter/chargers and/or solar controllers to charge camper batteries. Since many camper also feature an AC-powered converter/charger, I'm wondering how all of these components are connected together to perform their functions without interfering with each other.

My 09 Hawk is typical. The camper battery is charged by the IOTA DLS-30 converter/charger when the IOTA is plugged into 120v AC. The camper battery is also charged by the truck's starting battery and alternator via the SurePower 1314 battery separator which keeps the starting battery from being over-discharged by camper use.

I assume that the IOTA converter/charged is protected against damage when the starting battery and alternator are charging the camper battery since they are all connected at the same time.

Now what if we add a DC-DC converter/charger, particularly one with sophisticated charger circuitry? How is it connected? Do you move the battery separator and place it between the starting battery/alternator and the DC-DC converter/charger? Do you then connect the charging output of the DC-DC converter/charger to the battery? Do you need to worry that you now have two charging systems (the IOTA and the DC converter/charger) connected to the battery at the same time?

And then what if you add solar power through a solar controller/charger? Does this also get hooked directly to the battery? Do you need to worry that you now have THREE charging systems (the IOTA, the DC-DC converter/charger, and the solar controller) connected to the battery at the same time?

Does anyone have current recommendations for a small DC-DC converter/charger, and the solar controller? Also, any recommendation for for a small DC to AC converter to power my laptop (maybe 150-200 watts)?

All ideas and suggestions appreciated.

Thanks

Ed

 

[oldnslow]

The outputs of the DC-DC charger and the solar controller should be connected directly to the battery. Keep those wires as short as you reasonably can so they can "read" the battery voltage correctly.

There is no problem having 3 sources charging your battery at once. They are all designed to be back-fed by the battery when they aren't charging it, so another charge source will not bother them either.

I originally had my solar controller about 10 feet from the battery and I wasn't getting the battery fully charged due to the voltage drop of those long wires. I was only getting about 14V at the battery. I now have it about 3 feet from the battery and I'm getting a full 14.4V at the battery before the controller kicks out. Now I can run the laptop in the evening and still have enough charge in the battery to run the furnace. And thats with running the Engle all day too.

Solar is good, at least in the west where we see lots of sunshine.

 

[pods8]

As oldnslow mentioned each type of charger should be connected right to the battery and are designed not to back feed (otherwise the battery would back feed in them when the motive power on the other side of the charger is removed).

Depending on how you want to wire the DC-DC charger you could just add it after your current surepower if you don't want to mess with that wiring and it'll correct the voltage as required for the battery or you could remove the surepower entirely if you want. My DC-DC charge has a setting to take remote input to turn it on or off (similar to a preamp line on a car audio amplifier if you are familiar with those, which only turns on the amp when the radio is on). I have that line wired into a switch that is fed by an ignition hot line which means no matter what it turns off when the truck does, additionally I can manually turn that switch off on my truck dash to turn off the charger while the truck is on if I want (thus when my truck is only in accessory mode and not running I can turn off the charger for instance).

When I was looking for DC-DC chargers I really only found two sources in the US market: ProMarier makes what looks like a higher quality and expensive 12V to 12V charger in their digital mobile series: http://www.promariner.com/productFeature.php?ProductNum=05504
The other is sold by powerstream, a more basic model and 7.5amp capacity PST-BC1212-15. Seemed suitable enough for my battery needs and battery bank: http://www.powerstream.com/DCC.htm

I have pondered briefly how well feeding a basic solar controller into the input of the DC charger to get the stage charging w/o buying a more expensive solar controller but since I don't have solar at this point I didn't pursue it further in thought.


As for powering a lap top, a basic inverter you can get at most stores should treat you fine. We have a cheapie that works for us.