Best automotive replacement battery switches according to redditors

It's a key from a battery disconnect switch.

Like this:

https://www.amazon.com/HELLA-002843011-Rating-Battery-Master/dp/B0000AYAFE

You know how to use a multimeter? Disconnect negative cable, put meter in series with battery, set to amperage. Then pull fuses one at a time until you get 0 amps being pulled. This will at least tell you what's causing it. Also this thingy
https://www.amazon.com/Battery-Disconnect-Knife-Switch-Terminal/dp/B06XD9344Y/ref=sr_1_1_sspa?s=automotive&ie=UTF8&qid=1517617758&sr=1-1-spons&keywords=Car+battery+post+switch&psc=1

Like this.

Amazon battery isolator

With a budget of $400, I'd start with a small Alpicool for around $200. That's a good price on those, and they sip around 1/2 amp/hour@12v, meaning you'll need at least 36Ah of battery (.5Ax24hx3d).

Bump to 50Ah of usable power, for some wiggle room, and you can pick up something like this for $170.

The only other thing you'll need is wiring. A kit like this has most of what you need, toss in a cheap manual isolator to keep it from draining your starter battery, and you're left with a few crimp connectors and maybe a socket (might as well get a kinda-nice one).

That puts you $10 over-budget, but it'll do everything you asked for and more, and be a nice little setup to expand someday with solar or inverter or whatever. If you can score a cheaper second-hand battery initially, that'll help budget-wise, but I wouldn't bother skimping on anything else except maybe the 12v socket. The one I linked is just a nice feature to have USB and volt meter built-in, so you can reduce cord/adapter clutter if you like, and have an idea where you're at on power reserves, monitoring it manually. Downgrading that to a simple, "dumb" socket would put you within the $400 budget.

No it's absolutely not worth it. Send me your address in PM and I'll gladly come down from Canada and take it off your hands ;)

The absolute WORST case scenario is you spend $13 and buy a battery disconnect switch:

https://www.amazon.ca/NOCO-ID220S-125-Amp-Battery-Disconnect/dp/B006EH9WUC/ref=asc_df_B006EH9WUC/?tag=googleshopc0c-20&linkCode=df0&hvadid=293024472479&hvpos=1o1&hvnetw=g&hvrand=16510593331390089077&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9001172&hvtargid=pla-570576828713&psc=1

When you stop the vehicle, just pop the hood a twist the switch. Boom, battery disconnected. But really, it shouldn't be too hard to fix.

Finding the current draw is easy; dump an ammeter on the battery, start pulling fuses one at a time from the fuse panel/relay box. When the power draw stops, you've found your culprit circuit.

Does it make a humming noise sitting idle? Any chance the fuel pump relay's stuck and running the fuel pump all the time?

There are also These I've got them on a few vehicles, very handy just a 1/2 turn or so and the battery is disconnected. They're installed on the negative side and work very nicely.

They make a battery clamp that unscrews and disconnects the beg battery cable when a vehicle will be sitting for a long time. It is commonly used on motor homes and campers. Easy to pick up at most auto parts stores.

Here is one. Top Post Battery Master Disconnect Switch https://www.amazon.com/dp/B001N729FS/ref=cm_sw_r_cp_api_i_98GCCb732JJV6

Youll need an isolator to charge from the alternator and a little bit larger alternator since being a Kia its probably the bare minimum needed to keep one battery charged.

edit : this kit - https://www.amazon.com/gp/product/B00400D6WU/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

maybe im missing something here but my whole setup was like $250 at most. I got my deep cycle battery on offerup for $40, used this $15 isolator (bigger ones arent much more expensive), and this $20 box. Then i also added this voltage meter/usb port/ power socket to the box for $10. Then all the wiring and fuses were maybe $100 total.

The paint on the inside of the battery terminals doesn't look like it would help with a nice connection with the battery.

I had one of those battery disconnect switches that came with my car and the "gold plate" added quite a bit of resistance that I was losing around 2 volts just going through it.

Ran an electrical system in my Subaru with an auxiliary battery charged off the alternator.

80 Amp isolator relay (switches charging on while car is running):
https://www.amazon.com/Stinger-SGP38-80-AMP-Battery-Isolator/dp/B001HC6UJ0

100AH 12V AGM battery: https://www.amazon.com/Universal-UB121000-45978-100AH-Cycle-Battery/dp/B00S1RT58C

2Ga Wire running the length from the Relay in the engine bay to the battery.

Kinda Extra things:
Kill Switch: https://www.amazon.com/Ampper-Battery-Switch-12-Disconnect/dp/B07413JWLD
100A inline Fuse
Multimeter (read current voltage, Amperage, etc): www.amazon.com/bayite-6-5-100V-Display-Multimeter-Voltmeter/dp/B013PKYILS/

Either take the battery with you or put one of those 12v kill switches on it that boaters use. The battery will still slowly go flat, though at a slower rate than before with no parasitic load on it.

The starter relay is stuck closed. Working properly, that provides power to the solenoid to engage the flywheel and turn the starter when you engage the key to the START position. Power should disconnect when you turn the key out of "START" but it's not going to remove the power if the relay is seized closed.

From the starter, run the POS wire back to the engine bay... that wire will be connected to the starter relay. Tap on that a bit and it may temporarily work correctly again, or disconnect the wires from it completely. With the wires disconnected, try to start... nothing should happen. Then touch the wires together and the van should attempt to start. The starter circuit is disengaged in reverse due to the neutral safety switch, which makes sense.

EDIT: I had the same issue once. I recommend getting one of these for your battery to allow you to quickly and easily disconnect the power when needed: https://www.amazon.com/Ampper-Battery-Disconnect-Isolator-Vehicles/dp/B07JZ9NDH2/ It's just a good little $15 upgrade addon.

I can't answer all of your questions but I can say that yes the batteries should have been left on a trickle charger over the winter.
The symptoms all seem to just point to dead batteries, hopefully after charging for a couple days they'll regain their ability to hold a full charge.

As far as jump starting, I see no reason why you would not be able to, as long as your truck's battery can provide similar cranking amps.

For my merc 5.7, I use a dual purpose for starting the engine and deep cycle for boat electronics. I've got them wired with this guy: https://www.amazon.com/gp/product/B00400IYTK/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 that way both can charge when the engine is running and I don't have to worry about the boat electronics draining my starting battery.

You can wire in a low voltage cut off so it shuts off the electronics you're using before the battery drops to a point it won't start. You can also just pick up a jump box and bring it with you then either run the stuff off the jump box or use it to start your Jeep if the battery gets too low.

First thing I would do is take out the brake lamp bulbs and see if it's still draining. If that fixes it, add them back in one-by-one until the vampiric drain comes back -- at least that will narrow where the problem is.

If that doesn't fix it (and I would guess that it won't, honestly -- I don't see how a bulb could trigger a vampiric drain, but I'd still want to test it because it's easy to check off), you're unfortunately looking for a short somewhere (which is going to suck tracking down).

The possibly-easier-but-maybe-a-terrible-idea (and honestly what I'd probably do in an older car, though this will be harder in a more modern car) would be to move the electric feed for that circuit from always-hot to ignition-on. That's not ideal (because now your brake lights don't work with the car turned off, which is how they are supposed to work) but its better than the battery dying all the time.

Other, less invasive/janky options: plug it in nightly. You can get a quick-disconnect battery tender (http://products.batterytender.com/Automotive/Battery-TenderR-5A-Power-Tender-Series-High-Efficiency.html) but you (obviously) need one that can cover the 5A draw, so the cheaper (low-amp) ones won't save you.

But the easiest and cheapest option is get a battery disconnect (like https://smile.amazon.com/Ampper-Battery-Disconnect-Isolator-Vehicle/dp/B07413JWLD/ref=sr_1_4), but if you have stuff that depends on a constant feed (like radio settings or whatever), that could be annoying. And, of course, you have to remember to switch it off when you park it.

Alternators give out anywhere from 60-130 Amps, depending on what model came with your van. A single 100W solar panel, laid out flat, is going to produce in the neighborhood of 80W for about 5 hours on a good sunny day, or roughly 400W per day. Even the smallest available alternator will produce twice that much energy in an hour of driving per day.

If you are going to charge your "house" battery off of your alternator, be sure you get a battery isolator circuit that will prevent your house electronics from draining your starter battery. Something like this: http://www.amazon.com/Smart-Dual-Battery-140A-Isolator/dp/B00400IYTK

I use one of these that I use to disconnect my 12V Deep Cycle RV/Marine battery from my starter battery:

http://www.amazon.com/HELLA-002843011-Series-Rating-Battery/dp/B0000AYAFE/

I have it in a location where it is easy to see it so that I remember to turn it, but an automatic one like the Battery Buddy would be nice in case I forgot.

More like a plate of figure 8 shaped noodles. Was pleasing indeed, and quite simple once I pared it down.

New setup is a bit weird (no surprise there).. There's a battery cut-out, so I can totally kill all electronics when needed (parking / maintenance), and only a few things actually run through the normal key switch.

That effectively makes it a two key system; you need the battery cut out "key" to even be able to use the normal key. Wonkey, but it works best for the fuse block I bought (which has a common hot terminal and LEDs that indicate ground faults) and results in a lot less wire between the battery and things that need lots of power. Only the ignition, starter switch, and tail / brake light run through the key switch and its 12g hot lead. Everything else, including any accessories I install, can pull right off a fuse block that hooks to the battery through a big fat 6g wire. That's probably a good thing, since I'll be running dual headlights, probably a light bar as well, maybe an inverter, maybe CB radio, maybe some heated grips, etc.

Upvote. If you're not getting it fixed right away, this will ease some of your headaches. I prefer this style, but to each their own. http://www.amazon.com/Post-Battery-Master-Disconnect-Switch/dp/B001N729FS

From what I can tell from this article, the smart alternator only charges the car battery when needed (voltage < 13.8V). The reason this would mess up a typical VSR is that from the point of view of the alternator, when it's done it's job charging the starter battery (and possibly the leisure battery) it would stop, closing the VSR. It's also possible the VSR would never open in the first place because there would be no excess voltage to detect.

Normally the VSR would activate when a surplus voltage is detected (probably > 14V) indicating that the ("stupid") alternator would be running and that the car battery would already be topped (otherwise the voltage would be less as it would be charging). With a smart alternator this would never happen as the alternator would shut off once the battery was charged.

I believe what you could do would be to use a regular 12V automotive relay and get it to activate when you switch the ignition to the ACC position (when all your car electronics come alive). Think of your circuit as wiring a car stereo that turns on when you turn on your car, except the stereo is a battery. When the car is off, your leisure battery would be on a separate circuit and when it's on it would charge. It would also have more amps to crank your engine :)

The reason it would charge when connected is that from the smart alternator's point of view, it would simply see a larger than normal battery to charge, since both the starter and leisure battery would be connected in parallel

This would probably work

*EDIT: just realized, if you hook it up to ACC, it might also make your car worse to start if the leisure battery was drained since it would put more load on the starter battery. You could just wire it to a switch on the dash.

Nice score, looks like it has a lot of potential and is near done. If i may add a suggestion, toss a cover on the positive terminal and make sure it is well insulated all the way to the starter/alternator so it doesn't short out. Maybe toss a quick disconnect terminal on the negative side so you can disconnect it if you leave for awhile, or in a hurry if something fishy is going on with your electrical system, never know when those gremlins can attack.

> but at that rate I'm better off charging my batteries with my diesel's alternator

Yep. I frequently ask people on this sub why they think solar is so important when they're driving around in something that generates electricity already. Solar is expensive. It doesn't work in Seattle except for three weeks in August. Unless you're in the desert southwest, you need to have sufficient battery capacity for multiple days without sun which means you need an even bigger solar panel array to recharge that battery pack on the 2 sunny days during a two week period of overcast and showers.

Unless the van is parked somewhere for days and days without moving, just charge the house battery from the alternator. Even if it's parked on a sunny day, there's a huge incentive to park it in the shade to prevent the interior temps from killing anyone inside.

Using the alternator is easy. The absolute brute force, quick-n-dirty, cheap way is to run a #2 or #4 gauge wire from the positive terminal of your your van's battery to the positive terminal of your house battery through a simple switch and a high capacity (100A) fuse.

Under $10 crude switch from any auto parts store: https://www.amazon.com/Post-Battery-Master-Disconnect-Switch/dp/B001N729FS/ You use this to 'disconnect' the wire between the batteries when you park. This prevents that 60W fan you're running 24/7 from running down your starter battery. Get a better switch as your budget allows.

Better is an 'isolation relay' - there are two basic kinds. The inexpensive kind https://www.amazon.com/gp/product/B005JCX8OY/ requires that you also find a 12v power source that goes active when your ignition is turned on. This powers the relay to connect your house battery to the alternator/starting battery. It's not a big deal, but possibly a small hassle. Any Napa, Reibes, Pep-Boys, Autozone, etc auto parts place will have one.

Or, an automatic type that senses when the voltage on your starter battery rises due to the alternator and then automatically connects your house battery so it gets charged, too. https://www.amazon.com/gp/product/B00400IYTK/ You take the 12v cable from your van battery to one terminal. The 12V from your house battery to the 2nd terminal. And, the last terminal goes to ground.

BTW, I wasn't trying to 'burn you' but rather put some realism into your needs. At least you didn't mention electric heater or electric air conditioning like some folks do. For heating or cooking, gas/propane is the practical way to go. (There are some great, BUT EXPENSIVE, diesel heaters that can tap into your van's fuel system).

For air conditioning, there isn't any van-sized alternative other than a gas powered generator or an electrical outlet near the van.

Good choice on the fridge. And, you're right - it's not a 'now' sort of requirement.

Those battery powered LED things last forever. If you haven't bought any yet, try to get ones with diffusers - intentionally stay away from the brightest ones you can find. The issue is that in the small confines of a van, they just sear burn marks in your retinas. 'dimmer is better' I have these - multi brightness, magnetic stick on to my van's metal interior: https://www.amazon.com/gp/product/B01H731UNS/

I got the non-rechargeable ones but use Amazon Basics Eneloop- equivalent rechargeable AAA batteries: https://www.amazon.com/AmazonBasics-AAA-Rechargeable-Batteries-12-Pack/dp/B007B9NXAC/ and a USB recharger for them sort of like this: https://www.amazon.com/gp/product/B00PZ6V99U/

I have one of these. You do not want this 2 ft from your eyes in a van: https://www.amazon.com/BUYGO-11-LED-Outdoor-Lantern-Camping/

Non-mobile: http://www.amazon.com/dp/B001N729FS/ref=pd_aw_sim_auto_2?refRID=1GHJA1JCE9CTZC5R36SK

^That's ^why ^I'm ^here, ^I ^don't ^judge ^you. ^PM ^/u/xl0 ^if ^I'm ^causing ^any ^trouble. ^WUT?

https://www.amazon.com/Voltage-Battery-Disconnect-Auto-Detect/dp/B0147DYUN8

https://www.amazon.com/SMAKN-Converter-Power-Supply-Module/dp/B00CXKBJI2

Most auto parts has a + battery terminal replacement that has a on/off switch.. Also doubles as engine kill switch. Cant start it unless someone knows to turn the knob.

Thanks for the reply. I was able to get a look at the batteries today to check the connections and noticed one seems to have been leaking. I removed it and so far the system works fine on the remaining battery.

So I'm thinking it developed a crack OR the leak is due to overcharging. How can I figure this out?

Maybe you can help me answer this question: If my batteries were topped off and then I drove for 10 hours, would my battery isolator be overcharging the batteries? And one of them finally quit?

This is the smart isolator I'm using-

https://www.amazon.com/gp/product/B00400IYTK/ref=ask_ql_qh_dp_hza

I feel like that type of switch won't hold up well. I've seen them used, not on cars, but the clamp force between them needs to be tightened. Still, it should work as intended. Might arc a bit connecting it, but what doesn't.

This is the switch I've seen used before many times.

http://www.amazon.com/gp/aw/d/B001N729FS/ref=pd_aw_sim_auto_2?refRID=1GHJA1JCE9CTZC5R36SK

For camping, a small led light bar should be able to run during your waking-but-after-dark hours without needing an additional battery, assuming you occasionally start the car if it's an extended multi-night camping trip. However, a nice coleman lantern may be a better option given the cost of a dual battery setup.

If you are serious about dual batteries, I would strongly suggest an AGM type battery (oddysey pc1500 or similar, as mentioned elsewhere in this thread) and I personally prefer an automatic disconnect, over a hardwired or "manually switched" dual battery setup. I've had good success in the past with this one: https://amzn.com/B00LMGPHW2

Also, there are kits on the market now for jk/jku's that have the same smart isolator in them. genesis offroad has one. The kit is nice, but really, it's the isolator that does all the magis. they just sell you a nice mounting kit that is prewired for easy setup.

This particular smart isoloator also has a momentary switch option where.. if your cranking battery is low and can't start your vehicle, you can press a button and connect both batteries for 60 seconds, effectively jumpstarting yourself.

Manual selecter switches.. I've found I always forget to change the setting, and either.. never disconnect the two batteries when I should, or I forget to reconnect them for charging later meaning one battery is always really low. so I've personally given up on manual switches.

(Since this reads a lot like an ad now, let me just say.. I have no affiliation with cole hersee, other than having a great deal of success with that product I linked. I've run dual battery setups in several vehicles, and this is my personal preference. but like all opinions.. everyone has one, and none of them are "wrong" as long as it works for that person)

Everything will need to be grounded or it will not operate. The easiest way to do this is to use a fusebox as you mentioned. The number of items you'll want to power should determine the number of terminals you'll need. Connect your Anderson Powerpole terminals to their corresponding spots on the Blue Sea Systems fuse box (12 terminals with negative because you can always not use some, but you can't add any on the 6 terminal model).

https://www.amazon.com/Goal-Zero-Terminal-Connector-Cable/dp/B00URTHQTC/ref=sr_1_1?s=lawn-garden&ie=UTF8&qid=1496442293&sr=1-1&keywords=yeti+1250+terminal+ring

https://www.amazon.com/Blue-Sea-Systems-Blade-Block/dp/B001P6FTHC/ref=sr_1_1?ie=UTF8&qid=1496442487&sr=8-1&keywords=blue+sea+fuse+box+12

Use a disconnect switch below and a ring connector cable to make sure you don't draw any power when not intended. It will go between your positive leads.

https://www.amazon.com/gp/product/B011EYWMDS/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

https://www.amazon.com/Camco-47453-4-Gauge-Battery-Assembly/dp/B00JGJGCV2/ref=sr_1_9?ie=UTF8&qid=1496442659&sr=8-9&keywords=4+awg+cable

For the wiring to indidual 12v sources I use copper-clad aluminum because I'm cheap and use 12 gauge (non-awg because it's cheaper and only slightly smaller in gauge diameter) and it hasn't given me any problems because for the price I go a bit bigger than I might need.

https://www.amazon.com/PRIMARY-POWER-GROUND-100FT-ROLLS/dp/B00OU0IIFU/ref=sr_1_6?s=automotive&ie=UTF8&qid=1496442827&sr=1-6&keywords=12+gauge+wire

For the fridge though you may want to go to 10 gauge.

https://www.amazon.com/GAUGE-GROUND-PRIMARY-STRANDED-COPPER/dp/B01C7O8166/ref=sr_1_6?s=automotive&ie=UTF8&qid=1496442902&sr=1-6&keywords=10+gauge+wire.

Look at the 12v chart below and make sure you're within the range for the length of wire you want to run which I can't imagine you wont be since everything you're describing is super low amp.

https://s-media-cache-ak0.pinimg.com/originals/57/22/80/57228076ef240ed796b328a7d6387eac.jpg

Then to connect the equipment to power you can either solder the wires together or use these below to crimp them (crimping video below that). You're wire stripping pliers should have a crimping portion on them already. if not buy the ones in the 4th link.

https://www.amazon.com/Hilitchi-Insulated-Terminals-Electrical-Connectors/dp/B01D8HIQ2K/ref=sr_1_4?s=automotive&ie=UTF8&qid=1496443951&sr=1-4&keywords=12-10+gauge+wire+connectors

https://www.amazon.com/Glarks-Electrical-Insulated-Terminals-Connectors/dp/B01E7SY49I/ref=sr_1_11?s=automotive&ie=UTF8&qid=1496444024&sr=1-11&keywords=12-10+gauge+wire+connectors

https://www.youtube.com/watch?v=Svja8zEcKNQ&t=9s

https://www.amazon.com/VISE-GRIP-Multi-Tool-Stripper-Crimper-2078309/dp/B000JNNWQ2/ref=sr_1_cc_2?s=aps&ie=UTF8&qid=1496443370&sr=1-2-catcorr&keywords=wire+stripping+pliers+irwin

You'll then use the terminal rings from the link above (pretty sure that's the correct size ring) to connect the end of those wires to the fuse box on the negative and positive sides. Fuse based on the amps you'll be drawing. Since I think someone somewhere will complain that this is expensive and there are cheaper ways to do it, I set you up on the "new everything" route since I don't think you'll have any of these things and if you're getting a goal zero I don't think price is a limiting factor. Unless you already have a lot of experience with wiring this is the basic version with everything you'll need pre-made as much as possible.

you would connect a wire to the positive terminal of your battery using an electrical lug you can pick up from any autoparts store. Then that wire goes to a switch (need to make sure it is rated for the current.) and the other side of the switch goes to the wire that was on the battery before. Or you can buy a battery lockout switch and be done...here's one on amazon https://www.amazon.com/Post-Battery-Master-Disconnect-Switch/dp/B001N729FS

I also just have one fuse, right on the output of the battery, an automotive 58V 70A MAXI fuse from Littelfuse in an inline fuse holder. There's also a 100A manual power switch from Hella and a small precharge button.

You can use a breaker fuse, but I’m always worried that the lever arm will wear out. I would use a high amp battery switch like this: Ampper Battery Switch, 12-48 V Battery Power Cut Master Switch Disconnect Isolator for Car, Vehicle, RV and Boat (On/Off) https://www.amazon.com/dp/B07413JWLD/ref=cm_sw_r_cp_api_i_Y5LzDbHDH0EDK

This fits the "breaker or switch" suggestion perfectly and is exactly what its for, albeit a bit more expensive than a manual switch ;P

https://smile.amazon.com/dp/B00400IYTK/

I went the lazy route on this one. I don't use my truck for months at a time and I was tired of coming back to a dead battery. It's a piece of shit so I wanted to "fix" the problem as cheaply as possible. Instead of tracking down the parasitic draw, I just installed a battery disconnect switch from Amazon for $10.

A deep cycle battery and a battery isolator. Makes it so both batteries charge straight off the alternator, but keeps them seperate so that you can hook all your accessories up to your secondary battery and not have to worry about draining your main. The nicer ones(such as this) will charge the main battery before the secondary, and with the press of a button will temporarily join them in case your main battery is dead so that the starter can pull from both batteries. You could supplement it with a solar charger as well for longer endurance.

I have some property in a similar area. I understand 100% and doubly recommend making your van as unenticing as possible. Don't make your dad carry the battery. Something like this properly but discreetly installed, combined with a lack of anything of value.

On one of my old trucks, I kept one of the windows broken with "you're too late" written on the cardboard that covered the hole.

If you're willing to pop the hood every night, something like this would make it relatively painless: https://www.amazon.com/dp/B071D55VM3

I use a battery switch installed on the battery post and disconnect it whenever I store the camper. We did the same thing on all our vehicles/equipment growing up. Preserves the battery during storage. Once clamped on the pole very simple to open and close without tools. With a good interstate battery have had no issues connecting it after months and using the power tongue jack to hitch up.

Auto Battery Disconnect Knife Blade Switch Top Post Top Terminal Car Battery Cut Off Shut Off https://www.amazon.com/dp/B06XD9344Y/ref=cm_sw_r_cp_api_Dl13BbS7GVWVD

> I need to take a look and see if I have the space for it under the hood (probably) but would be best if I could use a battery box in the bed of the truck.

Either way works, but it's a lot more fairly expensive wire to get back to the bed.

This is what I'm using (or something really similar): http://www.amazon.com/Smart-Dual-Battery-140A-Isolator/dp/B00400IYTK/ref=sr_1_8?ie=UTF8&qid=1416450132&sr=8-8&keywords=battery+isolator

Yeah, cheap chinese stuff. But it's been fine for a couple of years so I don't feel like it owes me anything. Expect that much more in properly sized cable and cable ends.

I had this and all the accessories on a previous plow truck: http://www.hellroaring.com/bic75150.php

It's really nice, but more than I wanted to spend for the foul weather/off road toy the new setup is on.

First hit. It says it charges both batteries. Maybe you bought the wrong unit.

Dual battery you will at least need this:
https://www.amazon.com/Smart-Dual-Battery-140A-Isolator/dp/B00400IYTK

https://www.amazon.com/Scoshe-EWFH-Single-Fuse-Holder/dp/B000KIR8M0/ref=pd_bxgy_263_img_2?ie=UTF8&psc=1&refRID=Y4S68RZF6CFYXAZBN52B

https://www.amazon.com/Absolute-ANL200-2-Pack-Fuses-Plated/dp/B005EUTLYW/ref=pd_bxgy_263_img_3?ie=UTF8&psc=1&refRID=Y4S68RZF6CFYXAZBN52B

Then its on to pwm vs mppt charge controller
and a panel and wiring.

In lieu of the switch I have on there, would this be a better alternative?

Edit - The goal is to not have to open the case in order to turn on power. I would also like to leave the inverter in its original state so it could be easily removed and used outside of this unit.

You could get a kit with the cable and terminals included if you don't want to get them crimped or do them yourself.

However, I like this style isolator better where the alternator output goes to one pole and each of the other poles go to the batteries. This way it truly isolates them vs the other which is more of a charging relay and basically connects the batteries in parallel for the purpose of charging because it requires bridging from the battery terminal itself.

Cool, I plan on using one of [these] to isolate the two. (https://www.amazon.com/gp/product/B00400IYTK/ref=crt_ewc_img_dp_1?ie=UTF8&psc=1&smid=A1Z9PJN6YB119)

You mean one of these?
http://www.amazon.com/Post-Battery-Master-Disconnect-Switch/dp/B001N729FS

Ask your dealer if that $150 includes KY or whether that costs extra, too. If you can open a can by yourself, you can install one in about 5 minutes. You just need a wrench (or socket) that fits the nut on your car's battery terminal (the black wire that attaches to the battery).

Yea. Uses a wingnut thing. https://www.amazon.com/Post-Battery-Master-Disconnect-Switch/dp/B001N729FS

I have a battery disconnect switch.
https://www.amazon.com/NOCO-ID220S-6V-24V-Battery-Disconnect/dp/B006EH9WUC/ref=sr_1_7?s=automotive&ie=UTF8&qid=1525995005&sr=1-7&keywords=battery+disconnect+switch+for+car

That would work well.

There's also the low-tech version

Turn on when vehicle is running, turn off when vehicle is off.

Okay, then obviously the first step is to buy a deep-cycle storage battery and get it wired into your van's charging circuit, so it will be charged when you drive around or run the engine.

Two 6 VDC deep-cycle storage batteries (like golf cart batteries) wired in series creates one big 12 volt battery, or you could wire two 12 VDC deep-cycle storage batteries parallel which gives you more amp/ hours storage. Even one decent 12 VDC deep-cycle storage battery would give you quite a bit of 12 VDC capacity. I bought two 6 VDC batteries (wired in series to deliver 12 VDC) that are 185 amp/hours apiece, but you may not need that much.

On Amazon you can buy an adapter that has a "cigarette lighter" type auxiliary outlet on one end and two battery terminal "alligator" clips on the other, connected by a couple of wires. This allows you to plug your 12 VDC appliances into your "house battery." Eventually, you can install a 12 VDC multiple outlet fixture that has several places to plug in "cigarette lighter" type 12 VDC plugs.

I strongly recommend that you put a battery isolator of some type between your storage battery and your alternator to protect your "starting battery" from being depleted by your "house battery circuit." If you run down your house battery, you don't want to also run down your starting battery. The two circuits should must be separated from one another, so when the engine is running, both batteries are being charged, but when the ignition is "off", the starting battery is protected.

https://www.amazon.com/Cole-Hersee-48160-Battery-Isolator/dp/B001FQOGK8

https://www.amazon.com/Stinger-SGP38-80-AMP-Battery-Isolator/dp/B001HC6UJ0

https://www.amazon.com/PAC-PAC-500-500-Amp-Battery-Isolator/dp/B001YIPXR2

(LOL. Removed a quote about Thomas Paine. How did that get there, LOL?)

Years ago, a friend who worked at a golf course gave me a couple of large, wet-cell 6 VDC golf cart batteries, and I used them to power a CB radio at my house. The CB didn't use much power, and I charged them up with a regular battery charger about once a week.

Wet-cell batteries are okay for an off-grid residence, but not very good for an RV or a van. If they tip over or break loose in a wreck, THEY CAN LEAK BATTERY ACID. Absorbed glass mat (AGM) batteries do not contain liquid battery acid. The acid in AGM batteries is a gel. It can't spill. These are much more desirable for RV or van living.

You never want to run down a deep-cycle storage battery lower than 50% of its amp/hours. If you do, it harms the battery. So if you use 50 amp/hours a day of stored battery power, you must have a battery rated at MORE than 100 amp/hours. I own batteries rated at 185 amp/hours. That means the most amp/hours I can use up without re-charging is 92.5 amp/hours.

https://www.amazon.com/Post-Battery-Master-Disconnect-Switch/dp/B001N729FS

​

While you are figuring out what the issue is. . .

Maybe something like this? https://www.amazon.com/Smart-Battery-Isolator-Voltage-Sensitive/dp/B00400IYTK

A better way? It depends. If your time is more important than the few bucks you'll save, then I would recommend using an off the shelf battery cutoff box like the ones at this link.

Otherwise, you can do it easily with an Arduino: it's a good learning project. Just use a latching relay like modoleinad suggests to reduce battery drain.

I have posted 2 links below. The first is "dual sense" and it turns on if either battery is charging at more than 13.3 volts. The second is "single sense" and only turns on if the one side is charging over 13.3 volts. It sounds like you want dual.


https://www.amazon.com/Voltage-Sensitive-Relay-Battery-Isolator/dp/B0741Y7YCZ/ref=mp_s_a_1_fkmr1_1?ie=UTF8&qid=1536727246&sr=8-1-fkmr1&pi=AC_SX236_SY340_FMwebp_QL65&keywords=vsr+voltage+sensor+relay.

https://www.amazon.com/Voltage-Sensitive-Single-Battery-Isolator/dp/B073XF46GM/ref=mp_s_a_1_fkmr1_2?ie=UTF8&qid=1536727246&sr=8-2-fkmr1&pi=AC_SX236_SY340_FMwebp_QL65&keywords=vsr+voltage+sensor+relay.

Leave the positive alone and disconnect the ground. Also if your are going to leave the vehicle sitting for extended periods you should get a quick disconnect. Something like this http://www.amazon.com/Post-Battery-Master-Disconnect-Switch/dp/B001N729FS.

great idea. something like this? https://www.amazon.com/Battery-Disconnect-Knife-Switch-Terminal/dp/B06XD9344Y/ref=sr_1_4?ie=UTF8&qid=1503852609&sr=8-4&keywords=car+battery+knife+switch

For now (without this kit), I should only remove the negative (black) cable from the battery, while keeping the positive (red) attached?

One thing to keep in mind is that normal lead-acid batteries require charging over long periods of time. If you drain your lead-acid house batteries to 50% charge (which is the maximum for deep discharge lead-acid/AGM) it will take hours of charging to bring them back up to 100%, and many people just don't drive that many hours. That's why there is usually solar which will charge all day long.

Nowadays, you can also buy Lithium Iron batteries, which don't suffer from being part discharged, and which charge much faster. But that's a bigger up-front investment.

As for how you hook up your battery pack to the alternator - you need a smart battery isolator that first fills up your car battery, and only then switches to send charge to your house battery. To keep your voltage drop to a minimum, you need thick wires to go 18 feet (which is 36 feet total, as the number that matters is the full round trip, not just one way.)

https://www.amazon.com/Smart-Battery-Isolator-Voltage-Sensitive/dp/B00400IYTK for example.

Requires 4 screws be tightened over the wires.

You could get one of these:

https://www.amazon.com/Universal-Disconnect-Terminal-Isolator-Vehicles/dp/B074HW532B

Battery Switch, 6V 12V 24V 48V 60V Battery Disconnect Master Cutoff Switch for Marine Boat RV ATV UTV Vehicles, Waterproof Heavy Duty Battery Isolator Switch, 275/1250 Amps, On Off Position https://www.amazon.com/dp/B07HT19T5V/ref=cm_sw_r_cp_apa_i_iiMlDbNXDRHQB

There are switches rated for all sorts of current and voltages. Are you sure you know what you are talking about?

That is not why we have solenoids.