got my webasto for $1300.00 out the door, thats a fair deal.. the problem i am having is finding the right isolator switch for it, i was told to get a 250 to 300 amp isolator, but all i can find is a 150 amp am having problems finding the 250 300 amp ones, if anyone knows where i can get one, please tell...thx
A battery isolator won't work with a Bosch (or Valeo) alternator on a Sprinter. Instead you need a
Battery Separator. The one at the link (
model# 1315-200) is the one to get. You don't need to get that particular brand, of course, as any Battery Combiner/Separator that does the same thing is perfectly fine to use.
Here is a PDF of the Battery Isolator application guide (which alternators will work with a Battery Isolator, and which will not) to let you see why an isolator won't work with the Bosch alternators. Pay close attention to the notes in Group 3 and Group 4.
Here
Here is a PDF that shows the installation instructions for the Separator.
You install the Battery Separator in the engine compartment, close to the battery, and run a battery cable from the cranking battery to the Separator. The cable should be #4 AWG or thicker. Then you run another cable from the Separator up into the van to the aux battery. Same #4 AWG or thicker. You don't want to connect the cable from the Separator to the aux battery directly, but rather connect the cable to a 150 amp ANL or Class-T fuse (do not use MEGA or AMG), then connect the fuse to the battery.
Do not skimp on the wiring, as the cable from the Separator to the aux battery will be 10 feet or more, and wiring that's not thick enough will have too much resistance, will cause too high a voltage drop, and could create a fire hazard.
You can buy the cable at many places. Get 20 feet of it, assuming the aux battery won't be installed very far behind the driver's seat. Flexible cable or welding cable is the best. You'll need the appropriate cable lugs (with the correct size holes for the battery terminals and bolts). Those can be gotten at Gray Bar (cheapest) or any electrical supply house. Panduit or Burndy are the brands to get.
Unless you plan on running inverter loads of more than a light and laptop charger, then you'll need just the one battery. If you plan on running more inverter or 12-volt loads, then two aux batteries in parallel would be needed. All you need is a decent marine deep cycle or truck battery (or two of them). A Group 31 deep cycle marine, RV or truck battery is all you need (or, again, 2 of them). Something with at least 100 amp hour capacity or 200 reserve capacity minutes. Walmart, Sears, Autozone, Interstate Battery, hunting and fishing stores, lots of places will have them.
An RV place, a boat mechanic, or any car dealer or repair shop with a mechanic that is even semi-knowledgeable in automotive electrical can install all this stuff. It's best if you have everything you need, even if you don't cut the cable and install the cable lugs (the mechanic can do that easy enough during the install), but the mechanic can certainly order in whatever you need.
I have a local repair shop that works on anything, cars, trucks, tractors, boats, planes, you name it. They even fabricated a rack to mount my satellite dish to the roof of the Sprinter. That's the kind of place you want, but any car dealer can do this.