Many years of my life I have spent living in vans. My first travel van was an old 2001 Honda Odessey that I outfitted with a bed to sleep in. I put over 200,000 miles on that van and traveled all over the US and Canada with it. My second van was a 2004 Dodge Sprinter that I bought and converted into a veritable palace which I owned for over 10 years. Some of my best memories are in that Sprinter and I put over 60,000 miles on it before I sold in. More recently my wife and I bought a 2009 Toyota Sienna which we outfitted with a bed and a fridge and we have taken many trips in across the country to photograph the homeless for her photo project The Unwanted. This article is about how you can easily and safely use your ebike batteries to power a fridge and a 120V AC powered inverter in your RV or homebuilt conversion van.
It doesn’t matter what nominal voltage your pack is, you can use almost any ebike pack to power the accessories in your rig. The trick to making it usable is to pair it with the right charging system and AC inverter. In the US it is extremely difficult to find 120V AC inverters that run on the right voltage for your ebike pack, but luckily there are tons of them available from China for almost any voltage. The AC inverter I have experience with is a 48v one that I bought for about $110 US shipped. A quick search on Aliexpress for “120V AC 5000W Inverter 48v” brings up a ton of hits. When shopping from stuff from China I tend to use Aliexpress instead of Alibaba because it is often easier. Be aware that the Chinese tend to grossly exaggerate the Wattage abilities on their inverters, so if you want to be able to do 2000W then buy a 5000W inverter. I have found that I don’t need to pull more than about 2500W peak. It makes sense to turn your AC inverter off when not in use, as it will drain down your ebike battery just with a vampire leech load.
What battery should I use?
The best battery to use is one you already have. If you have to pick a new battery to buy, I would recommend getting a 60V Sur-Ron pack which is a great deal at $1600 here (plus an extra $100 for the AC charger). This pack is 32Ah at 60v so it holds a whopping 2Kw of storage. That is enough power to run my wife’s entire house for 4 days. If you want something smaller the Dire Wolf is an amazing choice and it will do 50Amps continuous and is a 52v pack with 21Ah of storage for a total of about 1Kw for $795 here. The Dire Wolf is made to be waterproof and shockproof so you don’t ever have to worry about manhandling it.
Doing a new van conversion? Don’t even think about using Lead Acid
To give you some idea of how much power these ebike batteries have, my wife and I spent $1400 for a bunch of new lead-acid trojans for her home. They also have about 1Kw of usable power and take up about 1 cubic meter of space and weigh 472lbs. A Dire Wolf will have the same available power, last twice as many charge cycles, cost half as much, weighs about 14.5lbs and takes up about 1/2 cubic foot. If you are still using a spare lead acid battery to power your RV or van conversion you are really making a serious mistake. AGM batteries are the safest lead-acid to use inside a van or RV and I have never had an AGM last more than 4 years, 3 years is about the average (I’ve burned up 3 of them in the Sprinter). If you use a normal Lead Acid battery inside a vehicle you have to vent it outside or there is a risk of it building up hydrogen gas and causing a fire hazard.
Lead Acid is dead, long live Lithium.
Wiring the inverter up
So what I did with my Sprinter is I ran a bunch of standard 14/2 Romex in the walls and put in normal AV wall plugs all over the sprinter. I wired up a toaster oven and microwave under the fridge and then wired all the wiring together and just threw a cheap screw-together AC plug from Lowes at the end of the Romex wire that then would plug into the AC inverter. It was totally ghetto, but it worked for 10 years without any issues. I didn’t use a circuit breaker system because everything was on the inverter and the inverter would not pull more than 20 Amps at 120V anyway without shutting down. This system worked very well for me. With the DC end of the inverter, you can just get an XT 90 with pigtails and solder or crimp on some very large copper ring connectors which then screw onto the end of the inverter. I used to solder everything, but nowadays I’m moving over to high-quality crimp connectors which seem to work extremely well if you’re using multistranded wire. If you have the Sur Ron pack you will need to get the power connector that works for that battery which you can get here for $21. This connector is rated for 200Amps which is way more than you will ever pull. and the Sur-Ron BMS is only rated for 80 amps.
Buying the right fridge and getting it to work
I have had good luck with the Edgestar series of fridges available here from compactappliance.com . I have bought 2 of them and after about 8 years the first one failed and I could not get a replacement compressor circuit board from the manufacturer. After wasting a bunch of time with their customer service they offered me a 15% discount off a new fridge which was disappointing. They are still about 1/2 the price of a comparable Norcold which is the other high-quality brand of fridge out there to get. The problems with the Norcold is they tend to open out like a normal fridge so you lose all your cold, the chest freezer design is a much better one as your cold stays in when you open it. In the Sienna, we were able to easily remove the third row of bench seats and put the fridge down in the recession where that set of seats would fold into the floor and then put the bed on top of it. I built the bed frame so that it was the same level as the top of the fridge and the whole setup worked quite well. We had to lift up the matress when we wanted access to the fridge, but the bed kept it well insulated so it stayed colder.
To power the DC fridge you will need a step-down converter that will go from whatever voltage the ebike pack is down to 12v or 24v DC (the Edgestars will work with either). I prefer using the higher voltages because that means lower amps so something like this converter for $30 would be perfect. In general, I tend to avoid buying step-down converters directly from China. Any converter you have should have a heat sink on it to shed heat better. It is a huge mistake to try to power your fridge off AC. Any AC powered fridge is going to be WAY too inefficient and you also lose a lot of efficiency going from DC to AC then back to DC again. Get an EdgeStar or Norcold, don’t rig up a cheap $100 dorm-style fridge, they are crazy inefficient.
Now you have to figure out how to charge your ebike battery on the road
There are 2 main options with this. You can steal power from the car and use that to charge your ebike batteries or you can add solar panels to your rig and keep your power system and your car’s electrical system completely separate. There are benefits and drawbacks to both. Solar is easier so we’ll start with that.
Going solar to charge your ebike batteries
You will need to buy and mount a solar panel on the roof of your van somewhere. I bought an $80 120W flexible panel from ebay and siliconed it onto a large cargo box then ran the wires into the van through the top of the rear liftgate. This setup works well, although water would seep in through the seal of the gate as it traveled along the wires. I used Anderson PowerPole connectors everywhere which are quick and easy to crimp on. Then I paired it with a variable voltage solar charge controller like this one here for $37. Although this controller is tricky to program (forget about the manual, use youtube videos) it works pretty well and is powered by the panels and not the ebike battery so there is no leach load. Make sure to program it for the right voltage for your pack, don’t go over 54v for a 48v nominal pack or 58v for a 52v nominal pack. If you try to overcharge your lithium batteries and your BMS doesn’t have overcharge protection then BOOM.
Charging ebike batteries from your car alternator
There are 2 ways to charge your ebike batteries off the power of your car. You can tap into the cigarette lighter or fusebox and wire up the solar charge controller shown above, or you can hook up a 120v inverter and use your normal ebike charger to charge your batteries. If you wire the solar charge controller into your 12V automotive system (as if your car battery was a solar panel), you should make sure you can turn it off or disconnect it at night. The solar charge controller has a leech load and it could drain your car battery down if it is left on while the car is left for extended periods. In my setup, I just use a set of Anderson power pole connectors and stick them above the sun visor and unplug them when I don’t want to charge my ebike batteries. This DC->DC system is a much more efficient way to charge your batteries than using DC->AC->DC shown below.
You can also install use a 12v inverter then I just plug in the normal AC charger that comes with my ebike battery. This usually takes a few hours to charge and I will only do it while the car is running and when I am done I shut off the AC inverter. All AC inverters have leach loads which if left alone will drain your car battery down after several days. Ebike battery chargers usually drain 150-300W and I have had poor luck with DC inverters that are designed to plug into the cigarette lighter. I usually just wire the 12V DC-AC inverter directly onto the battery terminals with a large 200A fuse where the positive line is connected to the battery terminal. Because the ebike batteries will generally last several days without needing to be charged you can also just guerilla charge them at campgrounds or on the road and forget about trying to charge them off your car battery at all. The large Sur Ron pack will probably last a week or two powering your rig without being charged at all before it will need to be charged.
Not only are ebikes a key component of Van Life not to be missed, you can also easily use your ebike batteries to power your entire setup. Having a fridge and not having to deal with ice makes a huge difference in your enjoyment levels being ‘on the road’. Using an ebike battery that you normally would bring with you anyway on trips to power your fridge and your AC inverter just makes a whole lot of sense, especially when the investment is so low. To run an AC inverter off your ebike battery is going to cost you less than $125 and to setup a solar charging setup will be $38 for the charge controller and $80-300 for the panels. If you already have the ebike battery anyway, it makes all kinds of sense to use it where ever you can.