Hawley12

So Im planning on adding a couple different light sources to the roof of my jeep. Mainly to be used as ambient lighting at night not so much as for while actually having the car running off road. So my concern is that, I worry in a situation like this I could easily strand myself with a dead battery and won't be able to get home. Now I know the idea of running two batteries in an xj from Bleeping Jeeps videos, but I'm looking for a less permanent and simpler option. My intention is to have a decent sized panel attached to the roof and have a small battery in the trunk that the panel can charge which in turn, can run my auxiliary lighting. The difficult thing I want to know is if theres a way I can actually attach the lighting to both batteries? The reason being I want to use the one small battery for when the car is off and just sitting parked and then actually use the cars battery when running the lights off road this way I don't have to worry if they die in the middle of the night. Is this possible?

AbbadonTD

You can make 2 independent systems that interconnect when you flip a switch. That way you keep the engine battery off when you are using lights, but could use it or charge it.

Charging with a solar panel is easy, but it takes time. If you discharge a 1100 amp battery it will take days to charge on something small enough to sit in the XJ. I use a 45 watt array to power my RV. By power I mean it keeps the LED lights running, the thermostat running, and all the automatic sensors and pilots lit. I cant run the fridge too long, and certainly not the AC or a TV or a power outlet via inverter for very long.

If you use more LEDs, and less lamps, you will pull less power, and that is VERY good idea.

Battery power is easy, CHARGING batteries is hard. If you got 3 or 4 45watt panels you could charge faster, but you will never reach a balance.

I would wire up two batteries to everything, and have a panel set that you can attach on when you want to. The charge controller will do its job and just charge when it can, and not when the battery is full (I assume you dont need your lights during the DAY?)

AbbadonTD

I have solar powered RVs via the car, I had a 1979 viking pop up that had a solar nintendo. I just used the batts in the jeep and ran a cord. Kept the inverter in the jeep, no water, no NOISE and slept in the pop up.

Hawley12

So what would be the easy and most importantly, the cheapest way of doing something like this? It seems to be that the hardest part is charging this auxiliary battery back up.

AbbadonTD

Yes, recharging takes MASSIVE amounts of time vs discharge.

Your battery will be around half of the cost. You want a Deep Cycle Marine Battery for recharging and power discharge. This is the reason to not use your Car Battery. If you take the Amp Hours is the stat that shows how much "charge" it holds. you can read all you want about batteries, and figure out which is for you. But this is why 2 systems is a better idea.

Our good friends in China give us all kinds of solar options. Harbor "I assume all of china smells like this" Freight carries a $150 Panel to battery system. It just clamps onto car battery terminals. 45 watts, its enough to keep your life going, but you can build from there.

I would keep the systems independent. You can always connect them via a cable if you need to steal some charge, or, in the above example, just attach the panel to EITHER battery.

AbbadonTD

Let me be a little more clear

Fast charging small solar = expensive
Slow charging small solar = Cheap

Hawley12

So all in all would it be a better idea to just go with a battery isolator or do I have a shot with the solar panel theory? Sorry Im new to this and power consumption always confused the heck out of me

AbbadonTD

I understand, that is why I am being blunt but not condescending. (im happy to help)

Yes, I personally believe it is a better idea to have your light system be isolated completely. The main difference being that a slow drain slow charge system [like lights and solar] you would want a different style battery than the one in your car.

Don't touch the car system and you cant mess any part of it up.

You will see that Amp Hours are better on Marine/rv batteries. But you will need to INVERT that DC12v to AC120v current, and inverters are cheap for 200 watts or less, but for more than that, they are EXPENSIVE, LOUD, and BIG.

That means your best bet is a dedicated lighting system on a deep cycle battery. if you want it to be really long lasting, use the 12v DC directly off of the charge controller from your solar system. if you dont have to invert it back into AC, it saves power. get a 75w inverter for your cellphone/laptop/tablet, but run the lights DC.

the hard part as i say is charging. if a battery is at 99% charge, it takes 1% to charge it. If a battery is at 98% charge, it takes about 2.1% to charge it. The lower you go, the MORE it takes to fill it back up, its Exponential, not linear. Thats why it takes so long to charge back up.