Part Identification - Board and Busbar for Automotive Application

Hello. I’m in the process of doing an engine swap for a car (Acura motor in older Toyota MR2).

I need help in selecting two parts:

  1. I’d like to get an insulated, non-flammable board to mount some circuit breakers and bus-bars that will go the positive and negative battery terminals. This will then be mounted to the chassis in the trunk. A friend of mine told me about something made of fibreglass or epoxy, but he couldn’t provide a part number. Sizes I’d be interested in looking at would be 12"-24" squares that I could easily cut if necessary.

  2. Busbar for positive battery terminal. Something with high capacity (200-250 amps) and 4-6 larger terminals.

Could you recommend something? This will be for an automotive application so the voltage will be 12V but some higher amperage (starter, alternator, etc).

  1. Your friend was likely thinking about a product known in the circuit board industry as FR4; a fiberglass reinforced epoxy material that’s standard fare for construction of printed circuit boards. 12X12WE looks like the largest non-plated slab of the stuff we have on hand. A possible issue however, is that the stuff is only 1/16" thick, and thus not great structurally at larger sizes.

  2. The distribution block product family has quite a few beefy items for utility-type applications that may have appeal, but likely better would be some products aimed specifically at automotive applications cleverly hidden here among the fuse holders, many of which also provide a distribution block function.

I’d also point to this selection of larger-size ring terminals that a person may want for such a situation, mention Qualtek’s Q5-4X heat shrink tube as my go-to choice for such things, and suggest use of a suitable contact grease such as Sanchem’s No-Ox-Id.

Thank you for your helpful response. I’m a little concerned about the 12X12WE being structurally strong enough. Is there something else that could make a good plate to assemble the components on and could safely be mounted in the engine bay?

I have quite a few connections which are all fused but they are currently all going to the battery terminals which makes it very messy. What I’d like to do is run the wires to fixed bus bars in another location and then run a large wire to each battery terminal to clean things up. There are so many choices. Do you sell busbars there? Most of them look like fuse blocks.

Thanks so much for helping me out!

It’s possible to get PCB material laminated thicker, but it’s not the sort of thing that folks in the electronics biz keep around as a stock item. McMaster might have something similar in a thicker weight, but if a person does a reasonably clean wiring job I see no reason to insist on a non-conductive mounting surface.

The term “busbar” is going to summon different images for different folks… It’s possible you may be thinking of something like these barrier blocks, others may understand the idea as a simple hunk of metal.

Fusing in automotive applications is mostly about imagining what happens if there’s a short to ground at any point in the wiring harness, because that can happen and it’s bad if 20’ of wire snaking through the chassis starts glowing like a lightbulb… Something like the 07985001ZXS might be good for branching out from your battery terminal; similar products such as this one might be useful further down the chain.