Adventure EV

Controller

Battery Box Update

by on Dec.15, 2009, under Battery Boxes, Controller, EV Land Rover, Fabrication, Heater

Did I already do a battery box update?

The one continuous thread throughout the conversion has been the fabrication of the battery boxes.  It seems these things take forever to build.  But it’s been cold… and I’m being whiny.  I must admit that they are pretty heavy duty, though.  Far more robust than they probably need to be, but probably beefy enough to handle off-road rigors, if necessary.  Like everything in this Land Rover, they’re built tough… very fitting.

Most people build a tray that the battery cells sit on, usually located somewhere in the engine bay, or more commonly, in the trunk.  I wanted to build sealed enclosures that sit completely under the vehicle, out of the passenger compartment.  Since I’m using lithium cells this shouldn’t be a problem.  Flooded lead-acid batteries, in comparison, vent hydrogen gas when they charge.  You wouldn’t want one of those in a sealed container…

There are four boxes in total, carrying 64 LiFePO4 battery cells.  Two sit on either side of the vehicle where the stock fuel tank locations were, just under the seats.  A larger rear box sits tucked up between the rear axle and rear frame crossmember.  The final box sits in the front of the engine bay.  All of it is made from 1/8″ mild steel in various forms; angle iron, square tube, strap, sheet.  Aluminum sheet is used to fill in the gaps and cut down on weight, but even with that saving measure I’m guessing all the boxes will add at least 150 pounds to the rig.  Not great, but they’ll last forever and be able to take some abuse.

Here’s one of the side box frames being held in position under the chassis by a Harbor Freight transmission jack.  Once full with batteries the jack will be the only way to get the boxes in place (the rear box will weigh about 260 pounds), a very worthwhile investment!

Side FrameThe rear box sits between the rear road springs and hangs from the rear crossmember.  Another piece of angle iron stretching between the frame rails anchors the front mount.  There’s a nice, empty space under the short-wheelbase Rover.  I had previous modified a Jeep fuel tank to fit back there.  Now the space is home to a different fuel.

Rear Frame

Crossmember DetailThe Rover has an unusually short rear overhang.  Great for off-roading.  I probably lose a couple of degrees with the rear box hanging down, but it shouldn’t pose a problem.  All in all, it’s quite an elegant fit.

Rear Clearance Since the top of the boxes are angle iron to provide strength and a lip to seal the top lid against, they pose an obstruction for the cells, so notches were strategically cut to allow groups of strapped cells access.  Not having the cells made this hard.  I just have to trust that the dimensions will allow for the clearance.

The final frames were painted with POR-15, and aluminum sides were cut to size.

Frames OutsideOK, granted the thin aluminum sheet isn’t exactly the toughest stuff in the world… But finally, something that cuts like butter!  And here’s the tool that does it.  Harbor Freight electric metal shears that make quick work of the box walls.  Say what you will about the quality of Harbor Freight stuff, but it’s cheap, and gets the job done for the few times people like me need something done.  And having the right tool for the job makes all the difference!

Shears

Once the sides are cut, they’re riveted to the frames.  A combination of the paint and sealing caulk ensures no galvanic reaction between the steel and aluminum, and helps seal the box from the elements.  Here’s Dad helping out with the riveting.

Dad Helping

A very nearly finished rear box.  I suppose I could leave it this way, but the plan is to spray self-etching primer on everything and coat with a semi-gloss black.  However, it’s been too cold to do any of spray painting.  All in good time.

Rear BoxI’ve sized the boxes to be slightly larger than the cells so that I can place some insulating foam around the perimeter.  This will help against shock and increase the insulation factor for the cold season.

The LiFePO4 cells should be fine just sitting in the cold, but they don’t like being charged in sub-zero weather.  To help performance in colder months, heaters are employed.  The bottom of each box gets two layers of aluminum.  One layer acts as the exterior wall.  A layer of foam (temperature tolerant Ionomer Foam from McMaster-Carr)  sits on that, and then thin battery heater plates from KTA Services, Inc sit on the foam.  These heaters are rated at 35w each and run off of 120VAC.  The idea is that these heaters will connect directly to wall power when the EV is charging in the winter.  As the cells discharge during normal driving, they should create enough internal heat to suffice without the heater pads active.  The second layer of aluminum sits on top of the battery pads, not only to protect them, but also to help spread the heat under the cells.

Heater

The hardest box to build was the front box.  I had originally designed the rear box to contain three rows of eight cells, for a total of 24 cells, but the rear differential pumpkin got in the way.  One of the rows of eight had to go, and in its place I got a compromised sideways row of three.  I had to find a place for five more cells.

The Rover does have a bunch of hiding places for more battery capacity, but rather than try and mount a fifth battery box, I decided to modify the front box.  It turns out space is becoming a premium if I want to keep everything moderately contained and relatively simple.

Instead of only needing to house 16 cells, the front box was widened to contain 18, and a small side box was welded to the back providing the space for the final three cells.  It’s weird, but it works as well as it can without the actual cells on hand.  I really hope I’ve left enough wiggle room.

The front battery box will have a clear acrylic lid for extra “bling-factor.”

Here’s the basis for the front box.

Simple Front FrameThe frame bolts directly into the frame rails.  Another set of brackets was fabricated to carry the bigger electronic items, the charger and motor controller.  The charger is another piece I don’t actually have yet, so I’m hoping the dimensions I found online are correct.

TrayThe charger sits a few inches above the motor, behind the battery box, and the controller sits a few inches above the charger.  The front of the “components” frame is bolted to the back of the battery frame so that it can be removed separately if needed.  The rear of the frame bolts directly to the vehicle’s bulkhead/firewall.

Once everything is tight the whole assembly ain’t goin’ nowhere.  It’s extremely solid!

Full Frames

Again, gotta love that access!  The Rover makes this conversion so easy in some ways.

Hopefully, all the miscellaneous electronics (fuses, contactor, shunt, relays, etc.) will sit behind the controller, up against the bulkhead.

Wait, I have the controller!  What’s that look like in place?

Electrics FinishedWhat are four, deep-cycle, flooded lead-acid batteries doing in the battery box?

Controller UpdateWhy, helping test out the motor controller, of course…  That’s an ethernet cable attached to the Soliton-1, with the controller’s configuration page on my netbook…

I can’t end the story there… can I?

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First of the goodies arrives!

by on Nov.03, 2009, under Controller, EV Land Rover, Motor

A big truck left a big box with me today… And in the big box were a couple of nice pieces.  More on the design and details to come, but these are two of the big components; the motor and motor controller!

The motor is a 192v 11″ Kostov EV motor and the motor controller is an EVnetics Soliton-1.

Kostov 192v 11" DC Motor

Kostov 192v 11" DC Motor

EVnetics Soliton-1 DC Motor Controller

EVnetics Soliton-1 DC Motor Controller

Many thanks to Sebastien and the guys at Rebirth Auto (www.rebirthauto.com) for supplying these goodies!

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