Charging Auxillary battery

[Napa Valk]

Hi Everyone,

I just got through building a trailer to drag behind my 2000 tourer for camping trips with my wife.  I was thinking about putting an spare car battery in it to power some lights, stereo etc.  If I wire it up to my existing battery will it charge while cruising, or will that be to much for the system and burn something up?  Where we camp there is no power at all, and I want to be able to light things up at night if needed.
Thanks,
Doug

[Hoser]

I don't know the answer, but I THINK IT'S A GREAT IDEA!  Hoser 

[bentwrench]

You could try a splitter from a rv store.Your bikes batt. will be isolated and won't run down while your using acc. power.

[Patrick]

Maybe a solar charger ?

[pancho]

You can connect it up to the charging system of the bike without causing any problems. Wire it in parallel and it will charge when the bike is running. I would suggest putting a switch between the two so when you are using the trailer battery, you will not drain the bike battery and it will always be ready to start the bike. While this will cause no problems, it will put more miles on the alternator and the brushes will wear down quicker as it is delivering more continuous amps.... If you use the trailer 10% of your miles, it will shorten the life of the alternator maybe 15% or 20%.

[sandy]

If your lights are LEDs, you won't need a car battery. It's too heavy anyway. Just get a small MC battery. When the trailer is in use, I'd guess it'll be unhooked from the bike so you won't need an isolator to prevent bike drain. In my tent trailer, I use LED lighting with AA batteries. It's all I need.

[Napa Valk]

I guess my next question would be what size wire should I run?  I guess I might use one wire size bigger than the battery cable on the battery.  I know as 12v wire gets longer you may need a bigger wire.  Any input?

thanks

Doug

[Mr.BubblesVRCCDS0008]

If you use LED lighting and just a radio a MC battery will work great. Wire you a power plug/ cig lighter outlet plug. Plug the charging wire in when traveling and unplug while camping. Should work perfectly.

[pancho]

I guess my next question would be what size wire should I run?  I guess I might use one wire size bigger than the battery cable on the battery.  I know as 12v wire gets longer you may need a bigger wire.  Any input?

thanks

Doug

Since you should never be delivering more current that the alternator can put out no matter how drained the battery is, you would be safe using 10 ga. multistrand. It may seem like heavy wire, but better be safe than sorry....  Be sure to fuse the battery at the battery itself,, your carrying a lot of potential energy in a large battery,, more than enough to cause a fire and damage if a problem occurs, or weak procedures are used in the installation.

[Big Mike]

I have a third battery in my diesel pick up. I use it with an inverter for the block heater in the winter. If you use 10G wire,  make absolutely certain to install a capacitor on the positive wire, this will prohibit any power from feeding back into the system from the extra battery when trying to start. The capacitor allows the electrons to flow just one way. I would hate to see what would happen if 24v went through the bike.

[97Valk_CT_Euless]

Big Mike, I think you mean diode, not capacitor.  Diode is definately a good idea though.

Also, if you wire the batteries in parallel, which you should, you won't develop 24V to worry about.

If you wire a relay off of the ignition, so it pulls in with the key, and run your trailer wiring from that, you won't have to worry about it pulling the bikes battery down.  But it would also be a good idea to put a manual switch in it, in my opinion, or a resistor to limit the max current.  Once you use that battery down all weekend, then tie it to the bike battery by turning the key or any other means, potentially alot of current can flow to the trailer battery.  May pull the bike down enough to not start, and pull the alternator hard enough to work on it, if not hurt it.