A thought on spagetti wiring control

1450 Views 5 Replies 5 Participants Last post by Roy Von Rogers, Jan 6, 2011

Jimdear2

Discussion Starter · Jan 5, 2011

To all,

Since I'm about to start on a battery and charging / monitoring system for a 50 cell LiFePo4 battery, I've been looking for a way to control the wiring so that the battery will look neat.

Here is what I've come up with for the monitoring section;

SCSI cables (Small Computer Systems Interface) Mac and Sun and a lot of others used this, some still do.

They have 25, 50 and 68 wire shielded cables in many lengths. Every one of them I've looked into has all of the wires color coded. The gauge appears to be 22 or 24 awg. Good enough to carry a voltage signal for a monitoring system.

You can get one long enough to do the job you need and cut it at some suitable midpoint and then get a gender changer to attach to one end connector, for some reason all the ones I've found are male/male. This give you a nice secure connector without a big expense. I think I've seen cables up to 20 feet for around $20.00 and gender changers for 5.00 on eBay.

You can split the outer cover and pull out wires at the distance you need tie them off and go on to the next, keeping all of the unused wires neat untill you get to the point of cable routing where you need them.

Hope this idea helps somenody else, I sure will help me.

Jim

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PTCruisin

· #2 · Jan 5, 2011

Jim,

I'm doing a similar setup to monitor cell voltages on a 38-cell pack. I have the pack in two boxes, with 20 cells in one box and 18 in the other. I used 25-conductor printer cable I had in a junk box to make the wiring harness and DB-25 connectors for termination. I am using small alligator clips to attach to the battery straps and 1/2" split cable tubing to neatly route the small wires to the batteries. No spaghetti wiring here! I'll post a pic later.

Ralph

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rwaudio

· #3 · Jan 5, 2011

Just try and make sure the wire is rated for your total pack voltage since the two extremes might end up side by side somewhere in the cable. I'm going to use optocouplers and a multiplexor to keep the pack isolated from my monitoring system.

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Jimdear2

Discussion Starter · #4 · Jan 6, 2011

rwaudio said:
Just try and make sure the wire is rated for your total pack voltage since the two extremes might end up side by side somewhere in the cable. I'm going to use optocouplers and a multiplexor to keep the pack isolated from my monitoring system.

rwaudio,

Glad you brought this up I should have mentioned it. I planned on simple fusing for each Cell Log leg. Since I'm not "electronic" I do after a long time now understand optocouplers but you got me on multiplexing.

Batteries finally got here, now once I get the boards here and a Cell Log I plan to build a double or triple 3 cell buddy pack mini battery (I have 10 spares) and then get some proto board I can mount to the tabs of the buddy pack buss bars and see what it takes to attach the DC-DC to the proto board and feed in the power from the 48 volts parallel buss and take out the 3.6 volts to the battery.

I also planned on a fuse or fuse wire loop mounted on the proto board for the Cell Log taps.

I want each board mounted above the battery set it services. I also want to put several temp thermisters (is that right) onto the proto board in locations around the battery to check and turn on fans as required.

I'll wait until you have it all figured out on a single board for plug and play and do beta for you. Then you can go on and become a millionair and I can run aound and say I knew him when.

Jim

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rmay635703

· #5 · Jan 6, 2011

rwaudio said:
Just try and make sure the wire is rated for your total pack voltage since the two extremes might end up side by side somewhere in the cable. I'm going to use optocouplers and a multiplexor to keep the pack isolated from my monitoring system.

Many low voltage cables can handle high voltages, just remember to replace the wires fairly often as a single crack causes you to blow your cable to smitherines. Luckily 20+ guage wire works great as a fuse link and won't pass too much current.

The military tests low voltage harnesses (where I work) by attaching 500vrms to between the ground in the harness and each of the wires within the harness for 5 minutes each, if it doesn't get warm its good to go.

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Roy Von Rogers

· #6 · Jan 6, 2011

Also dont forget Cat5-6 cable, since the connectors are easy to get, not to mention twisted pairs.

Roy

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