Need battery advice for car camping

[Jack.Straw]

So i'm converting my Honda Element into a micro-camper. I would like to be able to run a 12v fan at night, recharge our cell phones, and turn on the light occasionally. The light usage would be minimal, just for a few minutes while getting ready for bed. The small fan could run for 6-10 hours though if it's warm weather camping. My wife and i both have iPhones that we would plug in at bed time to let them charge over night. Most of our camping trips last from 2 to 5 days.

So i see 2 possible solutions here. 1st, and easiest, would be to use the car's rear power outlet (which i've rewired to be hot all the time instead of just when the engine is on) and the car's battery. I worry that if the car doesn't get driven for a couple days that the battery may go dead, leaving us needing a jump. There seem to be countless mini (pocket sized!) car jumping solutions available for a reasonable price. However, i'm unclear on the effect a full discharge has on the over-all life of my car battery. I'm also unsure if the car battery will have enough life to supply my stated power needs for 2-5 days.

The other solution would be to get another battery/power station that lives in the back with us. Again, there seem to be countless options out there, and i'm not knowledgeable enough to know what battery chemistry is going to be the best solution. I hear people say things like "deep cycle" and "marine battery", and i see "li-poly" & "lead-acid" listed on most of the power station units.

So... what would you recommend for my needs?

 

[BradtheRad]

i'm unclear on the effect a full discharge has on the over-all life of my car battery. I'm also unsure if the car battery will have enough life to supply my stated power needs for 2-5 days.

Each full discharge will reduce useful life of your car battery. A lead-acid battery likes to be kept fully charged as much as possible.

If you connect a 1 Ampere load overnight, then you risk having your engine unable to start in the morning.

Therefore it's best if you add an auxiliary battery. It can be a smaller size. Say, a motorcycle battery. (Or maybe a pocket starter.)

If you decide to rely on the single car battery, then add a low-battery alarm. Plan to run the engine at odd times each day, to recharge the battery.

 

[Jack.Straw]

Ok, thanks... sounds like i should go with an external battery. If i go with one of the pocket starters, do you think it could be recharged via the cigarette lighter while i'm driving?

 

[Anna Conda]

General rule of thumb for campers etc, get the biggest battery you can for the auxiliary battery, and a decent set of jumper leads, then if necessary, you can use it to start the van if something happens to the engine battery...

 

[kam1787]

The biggest unknown is your fan.How much current does it draw?

I would lean towards recommending a second battery [deep discharge type aka marine/truck]

 

[Truedeal]

Get a battery isolator and a deep cycle battery. The isolator keeps your starting battery safe from discharging and the deep cycle will workout just fine for the above mentioned drains and situations mentioned.
The deep cycle batteries are used for trolling motors on bass fishing boats. The construction of the batteries allows light drains (20 amps) for long periods of time rather than 800 cranking amps for short term use.

 

[red_alert]

You should consider buying a small PV (photovoltaic) panel. You can mount it on your van roof (once you're camping) though you might not want to park your car in full sun (due to high temps you're worrying about). Of course, you could mont it on the ground, too, in a sunny place around your van.

Anyway, this portable PV could be used to recharge your starting battery during the day (if you decide to not buy a separate one for camping).

There is a special kind of PV panels (thin film/amorphous) which could be bended/rolled (they are flexible) so you can mount them on the sides of your van, too. A small 50W panel should be enough for your power demands during night.

 

[Truedeal]

These are not specifically recommendations for your application. These are generally just for demonstration of the process I would use.
This is how my motor home was rigged up. Never had a dead starting battery and the 12 volt lighting system did not run out. In very remote areas I could start the engine and charge it back up. Also had a battery charger running off of the generator if needed.

https://www.autozone.com/batteries-...ry-isolator/lynx-battery-isolator/379952_0_0/
**broken link removed**