Connectors


Where do you find high quality alligator clips?

Where do you find high quality alligator clips?
beefing up some clips for high current
I wanted a quantity of alligator clips that could handle currents in the 10 A range, and bought some nice looking ones with # 18 wire. As I usually do with chinese made products, I always want to see if the product is made well or if some shortcuts have been taken in materials or workmanship.
I removed one end with a trick I learned many years ago.
You put a large diameter shaft (phillips driver) into the clip, which makes the shape like a ramp, so the insulating cover can be slid off, and then back on.
In this case, I used some long nose pliers to force the jaws open, so I could grab the jaws to pull off the cover. The deeper you go with the pliers the better the ramp and the easier the covers slides back.
One look at the connection, and I knew that this clip, despite the nice wire and tough clip, was not going to pass the current that the wire should comfortably handle. The bare copper was not crimped metal to metal, instead they crimped it with the rubber, which while capable of handling an amp or so, if we start passing 5- 10 A, the joint would rapidly heat up and soften the wire insulation, and thus decrease the clamping force, which would raise the joint resistance, which would raise the temperature in a death spiral that would end with fire.
My investment would be wasted if I did not fix this only weakness in an otherwise good product for a fair price.
I carefully pried open the two clamp pins
Cut of the mangled end of the wire and make a new strip.
twist the fine strands, pass through the hole from the inside
Solder the wire to the clip with a heavy iron so the heat does not have time to heat the spring in the clip and soften it
The solder joint wants to present a smooth surface to the insulating cover, so flow in enough solder to form that surface
After the clip cools (blow on it to speed the process) bend the two clamps back over the insulation
Using the Phillips driver to create the ramp. slide the cover back into position,and you have a first rate alligator clip that can handle some high currents, and will last.

Making an isolated hall effect current sensor with ring terminals

Making an isolated hall effect current sensor with ring terminals
simple isolated current sensor
Needed an isolated current sensor to sense the current in my cell level test fixture. Found a neat part made by alegro that has a compensated hall effect sensor with built in current shunt. Unlike a regular current shunt where the resistance of the shunt produces a voltage when current flows through it, this device has an integrated hall effect circuit built in. The device comes in many flavors, with unipolar or bipolar sensing up to +-150A. The best part is that the hall circuit is electrically isolated from the current path. The down side was that the device was designed to mount on a PC board, so attaching it to the big 1/4" studs that I required was dificult. I carefully straightened the heavy copper buss bar leads and sawed a slot in some heavy 1/4" ring terminals. The terminals were soldered to the straightened leads, and the fine hall effect wires were connected to three wires and strain relieved with some hot glue.
Works like a charm.

Quick way to make a connector for checking the subpacks

Quick way to make a connector for checking the subpacks
Battery tap rotary switchvoltage tap reader
After several hours of trying to find the BCM connector that is the mate for the battery tap harness connector,I gave up.
Using a pack that had no cells,so the connector would not have power.
I took a small clear plastic bag, and carefully taped the cut up bag over the harness connector,and secured it with black tape near the base, where the wires come out.
Next I inserted the pins pulled from one of the 104Pin headers used in the MIMA plug and play adapter, through the plastic into the harness connector female pins.
Making sure that the pins were inserted fully,I covered the plastic covered connector with epoxy putty, allowing the pins to stick through the epoxy.
I taped the epoxy with black tape to hold the shape.
When the epoxy cured,I soldered a ribbon cable to the pins, making the order of the ribbon follow the taps from the - end to the HV + end in sequence.
An aluminum duct tape dam that was adhered to the epoxy, made a cavity on the rear where the ribbon attached to the pins.The cavity was filled with hot melt, casting the wires and pins in place.
I put a 12 pin .1" OC straight male header on the other end of the ribbon.
The voltage taps can be read here, or I can plug in another female 12 Pin header, also attached to a ribbon, into a pill bottle(it was handy).
I mounted a 20 position break before make dual pole rotary switch on the base of the pill bottle, and two terminals on the cap for the volt meter.
I also made the conector for a civic pack, that plugs into the same female header on the rotary switch /pill bottle, so the same switch can do either.
To use it, one unplugs the voltage tap connector from the pack, and attached a voltmeter to the two pill cap terminals, and I can monitor each 12 cell stick , in sequence, as well as the whole pack voltage.
It took less time to build than I spent looking for the connector, and It can do both a civic and insight.
The connector plugs in reliably and securely, after the plastic is removed.
Not pretty, but it works well and is pretty rugged and safe.

How I splice audio cables

How I splice audio cables
Splicing delicate shielded wires
I got some nice amplified speakers the other day, and expected to plug them into the two audio out jacks on the back of my TV.I take it out of the box and find that it has a cable with a 1/8 " stereo plug, not the RCA plugs that my TV has.The speakers were designed for PC audio or gaming.
I dig into my huge cable case and find a nice dual color coded RCA audio cable that was cut off to make an audio input cable for a device I built.Never throw away anything, so heres the proof that you should save everything that can be used again.
Audio cables are a difficult splice because the wires are so delicate. This splice is stronger than the wires on either end, fully insulates and encapsulates and waterproofs the splice, and is tough as nails. works for other splices as well.

Auto brake light

Auto brake light
MIMA regen auto brake light
Calpod asked that a regen based brake light activation be designed for MIMA equipped Insights, as the car can slow down pretty fast if full regen is applied.
Without the brake lights to warn the guy behind you that you are slowing down, you could get rear ended if he is not awake.
The software is already working, and the Violet MIMA aux wire will pull low when the regen is greater than 15A.
The problem was how to interface to the car. If the brake switch was shorted by a relay, that would work, but as soon as the brake light is activated, the car will try to apply full regen, as that signal feeds to the MCM.
In looking at the schematics, I chose the connector in the passenger side B column as the best place to tie in. This spot is where the drive signal for the high mounted brake light is located. With this circuit, only the high mounted brake light will activate when MIMA or the car is over 15A of regen.
Any small 12V relay with SPDT contacts should work.

Those useful Prius subpacks

Prius NIMH batteries are called on to produce over 100A, and can be charged at 100A as well. I have been collecting the batteries and have quite a few, and have been finding some nice uses for them. I have several vehicles that I only use occasionally, and keeping a good 12V battery in each is wasteful, and is not that good for the batteries. I tend to carry a battery to the vehicle whenever I use it, and remove it when finished. Lugging a 50-75 lb battery over 100 feet is a lot of work. Just to see how it would work, I connected two 7.2V prius subpacks in series, and using a 100A Anderson connector, plugged them into a dodge caravan. The car cranked just like a new 12V battery. I put a connector on my 1965 John Deer tractor, and bang, it cranks effortlessly.
My lawn tractor uses the same configuration. The batteries do not need charge regulation, as the alternator or vehicle charging system will regulate to 13.6V , about 80% SOC on the NIMH.
A 5 lb starting battery compared to a 50 lb one. What a labor saver.
Those useful Prius subpacks
prius subpacks start van