Thanks for the link to this 70 amp tap in point. Really useful info.
Hi, I am helping with a promaster auxiliary electrical system project.Battery/Alternator Attachment and Aux Power Connectors
I'm starting to look at how to wire a "house" battery system into the alternator for charging while driving, and I was hoping to add a fuse to the high-current fuse block, but like some others in the thread with 2017 vans, all my connections are full.
I went and traced cables, and I'm almost certain that the 250A MEGAVAL fuse is connected to the additional fuse box in the passenger B-pillar. There are two additional fuses where other vans have empty slots:
- 70A fuse wired to the Upfitter Power Connector and documented in the body builder guide
- 250A fuse wired to a second 50A fuse, with a narrower-gauge wire than the one for the Upfitter Power Connector
See photos below - I didn't pull my seats off or run a continuity test to be certain, but the wiring is pretty conclusive that the 250A fuse is used for both the Auxiliary Switches and the Auxiliary Battery Prep. The aux switches provide 2 20A fused connections in the passenger B panel, with relays controlled by the dash switches. See Promaster Accessory Connector for details.
I have the switches but not the battery prep. This would explain why the 250A fuse is so large, and has the secondary 50A fuse for the wiring I do have.
Since I do have the Auxiliary Switches option (LHL), as does beewill, and the switches provide 20A as above, the 50A fuse would make sense. From my wire tracing it looks like the narrower-gauge wire feeds into the fuse and relay block adjacent to the upfitter connector, with several 20A fuses. Someone else reported they had a 2017 without the 250A fuse, and they did not have Aux switches or battery prep.
Based on this, I'm thinking I'll tap off the 250A fuse with a second lug and wire (sized for 250A, or add a secondary fuse) for house battery charging.
50A fuse attached to block cover:
Upfitter and second wires - driver's side
Upfitter and second wires - passenger side
Thanks. I have not yet found an "official promaster van statement" on what the max current is that can be pulled from various locations but I am guessing from your statement that 70 amps continuous is viable / routine.Look under the bottom cover of the B pillar or his Monrony but you can tell if he has the upfitter power block if the fuse and wire are there. Many here have connected to the battery terminal with another fuse similiar to those you show and routed the wire along the channel proved at the side left side of the driver’s seat to get to batteries or controllers behind the driver seat. If you have no plan to use the upfitter connector it isn’t there perhaps removing the wire from it’s fuse or connecting to that empty lug and connecting to the existing fuse or adding a fuse would be a good choice. Do not try to connect to the alternator. Route the power to the passenger seat fro the Stearling.
This is for the B pillar accessory connection if you have it.Thanks. I have not yet found an "official promaster van statement" on what the max current is that can be pulled from various locations but I am guessing from your statement that 70 amps continuous is viable / routine.
I think it somewhat depends how continuous “continuous” is, but connecting to the battery at the points I used will get you a peak of 200+ A. I’ve used it quite successfully at ~90A for up to 8 hours (mostly) continuous while driving to charge my lithium bank.Thanks. I have not yet found an "official promaster van statement" on what the max current is that can be pulled from various locations but I am guessing from your statement that 70 amps continuous is viable / routine.
Did you ever tint the Tern windows? That's my main hesitation with them at this point....To my knowledge that isn’t a default option, but I didn’t ask. I’m figuring I’ll be tinting all windows at some point, so I’ll do this one then. Since these are dual pane acrylic windows, I suspect supply chain would make offering various tints challenging, but I suppose they could add a film at the factory.
Good find on the Dorman 800-186. I never looked for anything else; just used what was recommended at the time. Hope others find this info.Update: I later decided to search for a better-fitting Dorman connector, and found the Dorman 800-186 which uses a 6 mm barb and the same connector as the 800-123 for the Promaster tank fitting. Much easier to fit the 5 mm I.D fuel hose over the 6 mm barbs than the 5/16" (almost 8 mm) barbs of the 800-123 or 800-081.