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Discussion Starter · #1 ·
You'll point me to other threads that talk about batteries, I'm sure; but not going to lie, a lot of it is above my head and doesn't make a ton of sense. I guess what I'm looking for is a simple answer: how do I set up a battery to run a small fridge (50W Dometic), a maxxair fan, and some LED lights. I do mostly weekend trips racing. I guess I'm looking for a clear answer on what parts to buy and why, not necessarily a guide to hook everything up, but I have yet to really see anything on here that doesn't seem like blabbing on about different parts without seemingly mentioning what they do, etc etc. Appreciative and thankful for any help, in advance. A few things about my van: There is no aux battery or EK1, but the space for the aux battery is currently empty (under the driver's seat. There is a battery under the passenger's seat).
 

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You've defined your basic needs, which is a great first step. You'll need to figure out just how much you'll be using the frig, the fan and the lights to know how big of a battery will suit your needs. The frig and fan will be by far the biggest power users.

For example, to power the frig for 12 hours you'll need 600 watts (50 watts x 12 hours). Divide 600 watts by the voltage of the battery (12 volts) and you'll need 50 amp hours of battery capacity. But you'll need a much higher capacity battery since you don't want to completely drain the battery. Its pretty much like donating blood. Sure you have about 4 quarts of blood in you but its not conducive to a long life to donate all 4 of those quarts at one time.

If you're just doing weekend trip, a portable battery and charging system might work fine. If you permanently install the battery, you'll want to get a sealed battery like an AGM or lithium. A regular lead acid battery would need to be vented so that you don't get a build up of sulfur dioxide inside of the van.

Then think about how a power source to charge the battery. If you want to leave the battery in van, you'll need a charger that gets power from the alternator, or solar or from plugging into the grid. Or some combination of those 3 sources.

What ever charging source you select, you'll need a device that actually charges the battery. To use the alternator on the van, you'll need something like a battery to battery charger. Solar requires a charge controller. Plugging into the grind would require a battery charger. The charger needs to be compatible with the battery type.

I hope that is helpful.
 

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This is self promotion, but one approach is to buy a "canned" solution.

We are not the only company that makes products that can work, but for example either of these will work for you:

https://squareup.com/store/WirlNet-com/

Either the 1x1 or 1x3.

Basically you bolt or strap them in and go.

If you ever decide to add solar panels (either mounted on the vehicle or not) the required electronics are already inside.

They will power your fan, fridge, lights etc. Just put a 12 volt plug on the wires and plug them in.

You didn't ask, but they also include an inverter so that you can make coffee and toast.

The difference between the two units is mostly battery capacity related. The 1x1 is good for a weekend, the 1x3 can go longer.

The 1x1 is the same shape and size as a suit case. The 1x3 is the same foot print, but taller (so more like something you would sit on)

If you are within ~ 200 miles of San Jose, CA I can even help you with install.

Harry
 

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In case it is interesting, I make a small donation to this web forum for every system sold to a forum member.
 

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Don’t tell Creag that. XD
I think that it is reasonable to make a payment to a web forum if someone buys a product or service from me. They are providing a very convenient sharing platform.

I do it on other van related forums. I will be honest though - I really don't get enough sales off of these forums to be worth the time I spend on them so if I were honest with myself, posting on these forums is just the hobby side.

I mostly tell people exactly how I build things and where to look for information so if they have the time and inclination they can do it themselves. All they have to do is search on my profile. Of course not everything that I say is correct - even though I like to imagine that it is.

In theory these web forums could be good places to make sales. In reality, forum members are such DIY oriented people, they would probably make their own tires if someone showed them how to do it and made a series of posts.
 

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Discussion Starter · #10 ·
You've defined your basic needs, which is a great first step. You'll need to figure out just how much you'll be using the frig, the fan and the lights to know how big of a battery will suit your needs. The frig and fan will be by far the biggest power users.

For example, to power the frig for 12 hours you'll need 600 watts (50 watts x 12 hours). Divide 600 watts by the voltage of the battery (12 volts) and you'll need 50 amp hours of battery capacity. But you'll need a much higher capacity battery since you don't want to completely drain the battery. Its pretty much like donating blood. Sure you have about 4 quarts of blood in you but its not conducive to a long life to donate all 4 of those quarts at one time.

If you're just doing weekend trip, a portable battery and charging system might work fine. If you permanently install the battery, you'll want to get a sealed battery like an AGM or lithium. A regular lead acid battery would need to be vented so that you don't get a build up of sulfur dioxide inside of the van.

Then think about how a power source to charge the battery. If you want to leave the battery in van, you'll need a charger that gets power from the alternator, or solar or from plugging into the grid. Or some combination of those 3 sources.

What ever charging source you select, you'll need a device that actually charges the battery. To use the alternator on the van, you'll need something like a battery to battery charger. Solar requires a charge controller. Plugging into the grind would require a battery charger. The charger needs to be compatible with the battery type.

I hope that is helpful.
Been looking for a battery-to-battery charger...do you have a link with a part in mind?

With regards to the rest, thank you! i'm looking at buying a 200 Ah AGM battery and installing it to the alternator permanently. The fan and lights would be used mostly at night, with the former being used intermittently and the latter only at night for a couple hours max. If I get this set up, I might consider solar as an option down the road, but I'm trying to do this cheaply at first.
 

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It helps to know what climate you are in for better recommendations.

Items that might work in mild climates won't necessarily work in tougher climates - example battery types.

If you just plan to hook a random AGM battery to your alternator directly and expect that to keep your refrigerator running and the battery to properly charge - it won't work consistently and the battery will die an early death from under charging. It will also overload your Metris electrical system and possibly damage it.

If you don't care all that much if the refrigerator cuts out randomly or the battery life being 1 yr vs multiple, then simple / cheap might work.

The modern MB van electrical systems are much more sensitive than even a 2005. The EPA mandates that have enabled the fuel efficiencies of modern vehicles forced all car makers to use more sophisticated approaches in all aspects of the vehicle operation. This eliminated simplicity.

Your desire to not learn these details is completely understandable but either you need to learn (and invest appropriately) in them, or hire someone to help you though it.

Take a look at some threads started by RansomRidge. He has posted pretty good details on what he used and why. If you are wondering what a specific part does, feel free to ask in this thread. I am assuming that you know what a fuse, breaker, and inverter are? Of course there is always duckduckgo and wikipedia but people here are always willing to answer a specific question.

A 12 volt refrigerator is a wonderful thing, but it also uses power constantly. It is like adding another hungry child to the family and wants to be fed regularly, even if you aren't in the mood. That is why solar panels are so commonly used with them.
 

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Sterling and Tek both make battery to battery chargers, I went with a Sterling. This thread covers my thinking (and the installation) on the Sterling as well as the benefits that the Tek has to offer. One Tek model can also serve as a solar controller for a smaller solar system. My 270 watt panel was too big for the Tek, which is one reason I went with the Sterling. They're slightly different tools for the same job.

https://www.metrisforum.com/forum/4...sterling-battery-battery-charger-install.html
 

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My Metris camper conversion, which is just now being completed by Daniel and Travois in Ottawa, has two deep cell marine batteries to power the house loads (Dometic fridge, water pump, electric stove top, Webasto furnace, LED lights, GFCI AC outlets and USB charger ports). Travois installed a Blue Sea Systems ACR (Automatic Charging Relay) to charge the house batteries while the engine is running. Daniel has this system on his own Metris Camper Van and is quite happy with the performance. He said house batteries with 50% discharge will charge back up to 100% in about 15-20 minutes of running the engine. So when off the grid in the winter when the solar charging system won't keep the batteries topped off due to shorter days and snow on the panels, the ACR system should do the trick. We ski in the mountains of the Western US and Canada and now we'll be based out of our Metris Van when visiting the various resorts.
 

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My Metris camper conversion, which is just now being completed by Daniel and Travois in Ottawa, has two deep cell marine batteries to power the house loads (Dometic fridge, water pump, electric stove top, Webasto furnace, LED lights, GFCI AC outlets and USB charger ports). Travois installed a Blue Sea Systems ACR (Automatic Charging Relay) to charge the house batteries while the engine is running. Daniel has this system on his own Metris Camper Van and is quite happy with the performance. He said house batteries with 50% discharge will charge back up to 100% in about 15-20 minutes of running the engine. So when off the grid in the winter when the solar charging system won't keep the batteries topped off due to shorter days and snow on the panels, the ACR system should do the trick. We ski in the mountains of the Western US and Canada and now we'll be based out of our Metris Van when visiting the various resorts.
Unfortunately, it might seem like these house batteries are recharged that quickly, but that isn't what is actually happening.

Starter batteries are a specialized lead acid type which can tolerate short cycle / high current charging and discharging.

Deep cycle and marine batteries require multiple charge "stages". The "bulk charge" stage is fairly rapid, but the finishing stages are much slower - as in hours. In a 20 minute charge time, what is actually happening is that your house batteries are not receiving a full charge and their life time will reflect this, as will their performance in general. (unless the drive is fairly long - so it might work for you for ski trips)

This is why camper vans often include some solar panels - to do this long slow finishing charging.

Some indications that could start to show up are:
  • The 12 volt compressor refrigerator starts showing low voltage warnings when the battery pack should still be fairly well charged
  • Similar for the heater, especially espars.

Just curious - what type / size of battery sertup is being installed?
 
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