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1st draft layout - trailer system - take it apart...

rlaggren

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Joined
Jun 12, 2022
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Here is a drawing of the physical layout to scale. Space is a huge problem - small trailer. It includes all the "near battery" parts mounted on a horizontal platform directly above two batteries. Nothing in the battery box below except batteries and bus-bar connections to get the Pos and Neg upstairs to where the parts are mounted.

Pos and neg bus-bar poke up through the middle of the electrical platform vertically, maybe about 2-3". A short horizontal bus (w/a tight 90d bend) immediately connects each to a 2-pole junction. This allows disconnecting the whole electrical platform (2 nuts each, pos and neg) from the batts and lifting the whole platform, everything still mounted, straight up to access the batteries (after disconnecting the small stuff, of course). Or to work on the platform parts in a comfortable position. The small stuff leaving the platform headed to the panel will probably get a 6 or 8 post connector strips each side _outside_ the box. Or maybe inside if I can find a way.

Tight, tight, tight. The Victron DC/DC charger is notorious, by now, for running very hot; and IAC, I'd probably want to enhance ventilation anyway. So There Will Be Fans.

Here, I'm hoping to get input on the bus-bar concepts. The bars will be copper, likely 1/8x1 or 3/4. I figure to round and shape the ends to better fit the junctions I have. These bars are not assembling cells, but rather combining, parallel in this case, ready made batteries.

What thoughts on bolting bus-bars together? I have, on each side, besides direct connections to batteries:
. 1 3-piece sandwich bolted together in open air (this forms the "riser" out of the lower battery box).
. 1 2-piece bus-to-bus bolted together in open air
. 2 or 3 possible bus-bar to post or junction - instead of heavy wire. It looks like it may actually fit better because if the short, tight layout. TBD. I don't have a problem making up heavy cable connectors, but they don't look to be as compact and adaptable as purpose-built short bus-bars.

On the circuit plan:

The current plan puts that DC/DC charger output direct onto the positive battery (one way or another). I'm trying to decide whether it merits a fuse at the charger... The charger runs directly off vehicle B+, from a 40amp breaker under the hood. If the charger tried to make it's own little fire, it could only get 40amps to do it and all the wiring in and from the engine will support that until the breaker under the hood opens.

Another foggy area is the grounding. I don't _think_ I need a heavy (200+ amp) ground connection to chassis. The positive side is fused at batteries and panel feed. The inverter lives in it's own little copper bus-bar world. It cannot get amps w/out going through the fuses on the batteries. There is an inverter AC ground which has to go to chassis which, again, is not a big wire. There is normally a chassis ground from the Neg battery terminal, and it looks to me to be fine as, say a #10 or #8. All the panel circuits will be balanced, no returns wandering through the frame.

Well, here's hoping the image shows up nicely. All thoughts are appreciated.

Rufus

elect-platform_1.jpg
 
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