[Bowser330]

any updates on your brushless motor?

[david85]

Originally Posted by Bowser330

any updates on your brushless motor?

Nope, I still have to have a formal quote before I send a deposite. Louie tells me he is assembling several motors at the moment, so I am going to patient for now. As I mentioned before, I can always fall back on a warp 9" if this doesn't work out.

[david85]

The rear battery box is nearly done. It gonna be a real beauty and fits perfectly. Pix will be posted when its finished (should be tomorrow).

[david85]

As promised. Pictures of the rear battery box. There will be room for the 18 of 48 cells and possibly the charger ( I'm still not sure how big the charger will be though). Still have some figuring out to do, but more could go where the fuel tank was and the rest in the engine bay. The lid for the front smaller compartment still has to me made, but the box is basically done.

It drops in like a glove and is very light but strong. It will be fastened with a series of U nuts and 1/4" bolts all the way around the perimeter flange of the box so it will become a structural component of the car. It will also be sealed to the floor semi-perminant with a high performance automotive urethane adhesive sealer. Once the trunk mat goes back in, you will never know anything is under there

It hangs below the bumper edge be about 1" so even that is hard to spot.

[Qer]

Originally Posted by david85

As promised. Pictures of the rear battery box.

Looking great! What material have you done it in? Ordinary steel or stainless?

[david85]

Originally Posted by Qer

Looking great! What material have you done it in? Ordinary steel or stainless?

Aluminum, hence the low weight.

[aktill]

Hi David,

Looking very good! Did you intentionally decide not to make allowances for insulation, or do your batteries not need it? I've found small lithium polymer packs suffer in cooler temps, but don't know about these bigger batts. I hope to have enough funds to use them myself, so I'll be following your build closely.

Also, simple question, but what did you use to cut the trunk floor out? I'm looking to upsize my tools before continuing on my own conversion in the spring. I Went through three fibreglass cutoff wheels on a Dremel tool cutting my exhaust system in half in the fall... was too stubborn to stop working and go buy a proper tool Want to remedy that now.

[david85]

I used a 5" angle grinder with a steel cut off wheel to make the rough cut, then trimmed the rough edges with tin snips. The front of the hole had rounded corners, so that was also a place for snips. I also have a plasma cutter, but didn't feel like dragging it out, and it turns out I didn't have to. A dremel is good for arts and crafts, but for cutting into a car body, you need an angle grinder. Even a 4.5" will do for most situations. (just make sure those sparks can't reach any glass).

There is some room for insulation in the battery box, however I may not put any in. The specs for the battery state that they will discharge well down to about -20C, so for my climate I am more concerned about heat in the summer since ideal operating temp is 20C. And again, it comes back to my choice of using aluminum for the battery box, since aluminum has excellent heat transfer properties.

Even in cold weather, the batteries will generate their own heat once under load for a little while (I observed that with my sample testing), so an electric blanket under them may be all thats needed to get them started in the morning if the cold becomes a problem or if they are allowed to cool off before recharging (ideally then are no colder than 0C for recharging).

[RKM]

Originally Posted by david85

As promised. Pictures of the rear battery box. There will be room for the 18 of 48 cells and possibly the charger ( I'm still not sure how big the charger will be though). Still have some figuring out to do, but more could go where the fuel tank was and the rest in the engine bay. The lid for the front smaller compartment still has to me made, but the box is basically done.

It drops in like a glove and is very light but strong. It will be fastened with a series of U nuts and 1/4" bolts all the way around the perimeter flange of the box so it will become a structural component of the car. It will also be sealed to the floor semi-perminant with a high performance automotive urethane adhesive sealer. Once the trunk mat goes back in, you will never know anything is under there

It hangs below the bumper edge be about 1" so even that is hard to spot.

Very impressive David. I plan on Al batt boxes too. A few questions... What gauge did you use? What is the reinforcing rib on the lid of the box? What is the small forward compartment for? Can you provide the name of the adhesive you will be using? Will you be securing the cells to the box? Is the divider wall within the box for structural purposes?

Do LFP batts need any venting or cooling for summer? I intend to insulate and have heated boxes (cold in Manitoba).

Thanks.

Rob

[david85]

Hi Rob,

Yes it is colder in manitoba, I bet it rather bitter at this very moment.

I used 1/16" sheet.

Yes the center rib is structural, but also to help secure and line up the cells.

Yes, the cells will have to be strapped to the box. That part hasn't been made yet.

The sealer will be ProForm PF224 Urethane sealer, an automotive windshield adhesive will also work well. Any real autoparts store will carry something like that (i.e. other than crappy tire)

The reinforcing on the box lid was done with a roller machine, so nothing was wielded on. It did warp it a little, but it doesn't matter because it will be bolted down and forced into the correct shape.

I don't know if ventilation is required. The unit cells have a vent port on the top center of them, but they arent supposed to "gas up" unless something is wrong. Flooded Lead acid batteries have a water based electrolyte, so production of Hydrogen and oxy is a fact of life with them even when all is well. One of many reasons why they loose efficiency under higher load.

There will be enough room for forced ventelation if I decided to add that later. For now, i am not convinced that its required though.

The front part of the box is not large enough to fit any batteries, so I'm hoping the charger will fit in there. If not, it will work as a junction box to tie the two rear battery banks together and then send power to the front of the car. I'm sure I'll find a use for that space.

I'm thinking the battieries might require cooling in the hotter summer months, so thats why I won't put any insulation from the start and allow the aluminum box to transfer the heat out unimpeded by insulation.