Questions: 2nd battery for my sweet, sweet minivan?

[MaximusTnC]

Hi RV.NET peeps!

I have installation/configuration questions that I'm hoping you'll be able to help me with, and/or point me in the direction of a person/company that could help me out.

I wish to add an excellent AGM battery to my 2006 Chrysler Town & Country minivan as a SECOND battery for all of my electronics stuff.

Nothing crazy: laptops, tablets, cell phones, battery chargers (camera/flashlight/etc). We go rough camping quite a bit, and don't want to keep thrashing my main car battery, prevent getting stranded, etc. - so, I'm researching the best route.

The battery will be inside the van (hence an AGM battery), in the van's Stow-n-Go seat-well (I removed the middle-row seats, and now have wells that are pretty deep & spacious) - here's a couple of example pictures of this space. I don't have exact measurements, but I'm pretty sure a battery will fit.



Additionally, I know I should to put the battery into a nice battery-enclosure, and secure it to the floor for safety.

Beyond the battery & enclosure, I'd ideally want to have the battery get charged by the van when it's running, so I'll need to have this wiring done, plus I'll need to purchase a battery charging / controller system that's compatible with the battery requirements.

Lastly, I'll need to purchase a power inverter to wire-up to this new battery, and then secure it to a convenient location - likely on the existing console between the driver/passenger seats.

So, basically, I think I'll need to buy the following for this fun project:

(1) AGM battery
(1) Battery enclosure
(1) Battery charger / controller
(1) Power Inverter w/ AC & USB outlets
(1) misc cabling / connectors / etc...

I'm sorry to have written such a long question, but I'm not to sure whom I should talk to about this project - I'm not an expert, but I know you guys are, so that's why I'm here buggin you. I'm planning on spending the right amount of money for this project, and will need to locate a professional (freelance or in a shop) to do the work. I know when I should defer to an expert for something, and this is one of those times. I don't want to do it wrong and royally screw up my van.

Again, thanks for your consideration in helping me out here, and I hope that I can get most everything answered I need for this project from you folks. 🙂 Chat soon! -MAXIMUS (Las Vegas, NV USA)

PS - I'm a computer expert (PC), so if any of you have questions, I can probably help you out. Networking, Windows, etc...

[MEXICOWANDERER]

• MEASURE. Close only counts in Horseshoes and Thermonuclear
• You can provide a great vent right in the compartment. Hydrogen gas rises - fast so put the vent at the top of the well
• You need to use a device that will send full alternator voltage potential to the well battery. I recommend a 200-amp automatic battery combiner like a Sure Power
• If you are not a road warrior camping at RV parks but rather heading off into the sticks with no hookups, it is silly to purchase a 3-stage "smart" charger. Choose a small and inexpensive multi-stage battery maintainer and plug your rig in when you get home
• By the way that battery combiner should be BI-directional so it allows the battery maintainer to charge BOTH RV and engine battery automatically, Both batteries will love you for it
• Install 60 ampere rated circuit breakers at BOTH ENDS of the big wire that will connect both batteries. The positive + wire
• 8-Gauge wire is plenty for your amperage and length of circuit
• House the charge lead wire INSIDE a slit length of fuel line hose you buy at a parts house. It must be kept distant from hot exhaust components underneath the car. The mechanic should strap the hose to components along the way with BLACK plastic cable ties. Do not use white ties!
• Don't choose a silly sized inverter. That would be like choosing a V-10 pickup on a 30 dollar a month gasoline budget. Use a propane stove and coffee press rather than a short circuit powered electric coffeemaker
• Good luck with your project, you're going to have a nice setup when you're done!

[mena661]

AGM's will out gas if you overcharge them. The batteries don't have to be in an "explosive condition" for that to happen. BTW, if you use too high a float voltage for the temperature, AGMs will out gas a bit.

[wwest]

NEVER mount a battery in a way that out-gassing can affect passengers.

AGM batteries OUT-GAS only in EXPLOSIVE conditions, rare but it does happen!

NEVER recharge a DEEPLY discharged battery from the engine alternator/VR system, those are not designed for that purpose and you run the risk of boiling off the electrolyte....HEAVY out-gassing.

[Harvey51]

I used a jump starter for a few years. Something like this: http://www.amazon.com/PowerStation-PSX-Multi-Purpose-Vehicle-Compressor/dp/B002YVU8WS
Mine had a built in inverter.

It plugged into the cigarette lighter for charging. Easy to put on the picnic table for lighting. Useful when not camping for boosting or using a power tool in the yard.

[TomG2]

Am I wrong, again, or can't AGM batteries be mounted in any position? Laying them on their side might alleviate the problem with low headroom. Just asking.

[subcamper]

I did the same thing on both of our Suburbans. The sound systems, video systems, lighter sockets, and a pair of rear-facing floodlights on the back of the Sub roof for camping were connected to a second battery (deep-discharge type). In my case, there was room under the hood for the second battery.

I agree with the others that there doesn't seem to be much height available in the well. Some batteries can be mounted on their side (like Optimas) so you might think about that to reduce their height.

I used an isolater/combiner from the following place:

Isolater/Combiner

These have been very reliable and have a lot of features. They are more expensive than relays and regular diode isolaters, however.

Steve

[KD4UPL]

The "Charging device" you need is an automatic charge relay (ACR) Blue Sea makes a nice one but there are others. This devices monitors the voltage of the vehicle electrical system so it knows when the alternator is running. When this happens it connects your 2nd battery so it will charge. When the engine is off the voltage will drop and the 2nd battery will be isolated.
If you use a relay hooked to your key switch and then leave the key on, like to listen to the radio, it will still drain both batteries.
If you use an old fashioned diode type isolator you will not get a proper charge on your batteries.

[cruz-in]

Please do some research.

Many folks are of the "opinion" that AGM batteries do not need vented...

AGM batteries DO need vented.

Check out any battery site, they all say install in a sealed, vented compartment.

IMHO especially if you are placing in the passenger compartment of a vehicle.

[Golden_HVAC]

It would also help to know what kind of load you want to run.

A cell phone might take 10 watts for a full charge, computer about 20 watts per hour. DVD probably also 20 watts. Flat screen TV about 80 - 100 watts per hour.

A 100 amp hour 12 volt battery will store up to 1200 watts, but you already realize that if you discharge 100% then the battery will get used up sooner, and have much shorter life. So figure that it is safe to use about 50% of the total capacity, and still be able to recharge about 1,000 - 1,500 times.

I have a pair of 26 AH batteries in my handicap scooter. They look like they would fit, and cost me about $33 each at a battery store. They are about 6" X 5" X 4". You do not need to be brand specific, or size for that matter.

I guess the remaining problem is how to power your interior lights without running the car battery down to much. LED lights would answer the problem.

AliExpress.com then search for 24 each 5050 LED panels. They each draw about 0.2 amps, and will run hours on a few amp hours. Most will come with a adapter for several types of interior light fixtures.

Good luck,

Fred.

[mena661]

Honda 1000 takes up WAY more space than a battery plus you'll have gas fumes inside your van. No thanks. The AGM battery plus small inverter is a WAY better idea. Get us some dimensions of that compartment. That will make finding the right battery much easier.

[ed6713]

Or. A small, portable generator like this.
Honda1000

Use it to run all your "stuff", coffee pot, fan on hot days, plus charge the car battery as needed. You can run a small inverter off the car battery then recharge the battery from the generator if you have to.

We have a small cargo carrier we use to carry the generator, gas can, lawn chairs, BBQ grill, etc.


Like your battery idea. It's nice and quiet but the generator gives a lot more flexibility.

Replacing your standard starting battery with a deep cycle marine battery might be worth some thought. They have a much higher amp hour capacity than your basic staring battery.

[Tiger4x4RV]

You'll need an isolator, which allows you to use the AGM battery and not draw down the van starting battery. Also something to secure the battery to the floor so it doesn't go flying around on rough roads or in an accident.

The rest of your list looks pretty good, except that I am not sure about those wells being anywhere deep enough. My AGM batteries are pretty tall.

The experts who will chime in soon will give you a LOT more advice, probably better than mine. Good luck with your project.

[Golden_HVAC]

Hi,

Try this place. http://www.batteriesplus.com/

You might be better off buying a 1800 watt UPS system, on sale, and then take out the battery from it. Normally they run on 12 VDC, and would work. The problem is that most batteries are 9" to 12" tall, and it does not look like you have that much space. A pair of 25 AH emergency light batteries, or other small batteries might be your best thing.

You really don't need a battery charger, just a 30 amp fog light relay under the hood that is energized at all times when the ACC position is on, or the radio is getting power, then it will turn on. Connect one side to either the alternator output (for higher voltage) or the battery +12 terminal (about 0.8 volts less) then go to a 20 amp fuse, then to the new batteries. They will run from the alternator while the engine is on, and battery when the engine is off.

Then install a couple of cigarette lighter receptacles to plug in whatever. You can wire the inverter directly to the battery too - use a 20 -30 amp fuse.

This battery is only about 7" tall. http://www.trojanbattery.com/product/12-agm/

Fred.