First job, change the oil in the differential.
I didn't have a tool that would open that. So, I just made one from an old rail spike.
This time I was ready for water. But I didn't think there would be this much of it.
Two and a half fucking gallons of it.
Plus a little bit more in the little pan.
So, there should have been 6 gallons of oil in the differential. I would guess there was actually around 4. But, given all the water in there, at least the oil would have been covering the all the gears and such, so it should be in decent shape. I also took out the remains of 2 corks from the bottom of the axle shafts, right at the bottom of the large bellhousing. I'm pretty sure these are there just to allow you to drain any oil that leaks out of the differential and into the axle housings, but I'm not positive on that. I need another bag of corks to properly seal them up again, so I didn't put in the gear oil today, I'll do it Sunday.
While I let the oil drip out, I drilled a bunch of 5/8ths holes to use these 12" bolts for my battery "tie-down". The c-channel is just about the right size.
Tore all the motor mounts, shafts, and tensioner bits out of the frame so I can clean all my leftover tapping fluid and drilling detritus off. Re-primered where necessary.
Re-cleaned (because they started rusting) the fiddly bits and primered them. I'll put some grease on the friction surfaces when I get everything back together so it's easier to slide the tensioner a bit.
Cleaned, primered, and painted the battery components.
Then I had to call it a day faily early. But, I had some mail to pick up at the post office first. I had to get a new contactor with a 12 volt coil. The last one I ordered had a 72 volt coil, but I thought it was rated for 72v across the contacts. So, it's my fault, but really, who the hell uses 72 volts to operate a friggin relay?
And...It works!
This contactor is much bigger than my old one. Easily 2x larger and 3x heavier, the contacts are bigger, and the copper bus plate is much thicker. It was even cheaper, amazingly.
What uses 72V coils, It's not common in North America for EV's but it's not unheard of for specialty vehicles. It's more common for Asian and European vehicles. 60V is similarly uncommon but does exist. The most common are 36V, 48V, 80V and maybe 96V.
ReplyDeleteAS for a more or less current 72V vehicle in NA take a look at
http://www.taylor-dunn.com/vehicle_details.aspx?mode=base&id=74
Robert
No I mean it needs 72v to activate the coil. Why would a control circuit (not the main power circuit) be 72v? I can certainly understand using 72v through the motor though, that makes sense.
ReplyDeleteMike, in EVs the contactor coils are almost always at bus voltage. So 72V coils for a 72V vehicle.
ReplyDeleteThere are no vehicles that I'm aware of that use 12V coils on a vehicle with a higher battery voltage.
There are quite good reasons for doing this BTW.
Robert
Can you explain why? I can't fathom it. It just seems odd, you'd have to use much stronger switchs and components to work everything. I'm just using a 12v circuit to power all my controls and accessories and the 48v circuit is purely for the motor.
ReplyDeleteI'll cover the two extremes. Before that consider the current needed by a contactor. As the voltage increases less current is needed, so a 48V coil needs approx. 1/4 the current of a 12V coil.
ReplyDeleteNow first the case pre-electronic control. Speed was controlled by switching resistors or in some cases field windings. Interlocks, direction selection etc... by relay and switch logic. DC-DC conversion with such technology is too expensive and maintaining two battery systems way too error prone. So by far the cheapest and most reliable approach was full voltage coils.
Now moving on to modern electronic controls. The motor control is done with switching power components. The control and interlocks is done digitally at low voltage (5V or less). This logic has to control the contactors coils. As it turns out this is cheaper with full voltage components at lower current where it matters. In fact at the current and voltages we are talking about it generally doesn't make much difference. Again DC-DC converters introduce additional costs and failure points as would a separate DC bus. So again full voltage coils are less expensive (or at least no more expensive) to operate. Some manufacturers that use several different voltage busses have standardized on a single voltage coil to save the cost of stocking multiple coil voltages. They PWM higher voltages to the lower coil voltage. In addition the PWM lets them reduce the voltage after pull-in. So no extra stress on the components.
Just about the only difficult part is lights. There are several approaches to that. Use high voltage lights, use lower voltage lights in series, PWM the lights directly or use a DC-DC. Most existing vehicles use one of the first three.
I could probably go on ;)
Robert
Hmm, very interesting, thank you.
ReplyDeleteHey, nice looking project. I'm curious about where you found that contactor so good and cheap- care to share?
ReplyDeleteIt's been a long time since I ordered it, but I think I got it at Cloud electric.
ReplyDeletehttp://www.cloudelectric.com/category_s/4782.htm