[david85]

I have finally started the real part of the conversion.

The engine and transmission are out, and I did some minor measurements under the hood to see how the 200Ah lithium cells would fit. Still have to pull the fuel tank, lines and exhaust system. A cold snap is on the way, so the warm weather is over. Shop is not heated.....

The amount of room behind the front bumper is very encouraging. I figure I can fit at least 24 of the cells under the hood. I will know more once the motor and drive are installed, but at the very least I already have room for 24 of the 48 cells. There is also lots of space behind the bumper corners, not sure what I can install there...maybe the vacuum pump and a few inches of sound insulation on top.

The aluminum sheet metal for the battery boxes is on its way. Sorry, no updates on the brushless motor yet. But I am considering a warP 9" if that proves to be too hard to get in a timely manner. I could always upgrade later and sell the brushed system.

The battery shown here is my sample and the cells are the same model as what the 144V battery will use. There is room for a string of 12 cells right where the radiator used to be, and another 12 cell string against the firewall. The rest should fit below the trunk floor in a custom drop box, so cargo room will be the same after the conversion. In theory, there is also more room at the fuel tank location, but considering how hard it is to get to, I might just leave that empty for now since I already have all the room I need. The only catch is I won't have a place for the spare tire anymore, but it may even fit under the hood. Will have to see.

 

[rctous]

very cool I didn't know you were doing lithiums,, wished i had them in my budget but NO WAY,, if you are considering the Warp 9 be sure to look closely at the length of the motor they are pretty long, I have the Warp 9 impulse which is shorter,, I will show you pics of it in the bay and then you will know for sure about the length. I was surprised at how close it was in the Storm, a Warp 9 never would have fit. You know I will be following this!!

Brian

 

[david85]

I concluded that there was 20" of space from the transmission mating face to the structural beam on the opposite side of the engine bay. The engine block is 18" if I remember right. Isn't the warP 16" and change? What sort of space did you find in your car?

Yep I'm using a 200Ah 144V LiFePO4 battery direct from mainland china. I'm aiming for 100 miles of real world range, but with a brushless motor, more is likely (less loss, and regen). The battery is rated at 1C constant and 5C peak rated, so it should perform well. Not quite a tesla roadster, but might out run a stock saturn even with the humble warP.

 

[rctous]

I concluded that there was 20" of space from the transmission mating face to the structural beam on the opposite side of the engine bay. The engine block is 18" if I remember right. Isn't the warP 16" and change? What sort of space did you find in your car?.

never took any measurements on the Saturn I know I have plenty of room for the Impulse motor.

 

[rctous]

looks like the old engine from the back of the block to the very front bolt on the pulley is about 19 inches,, also mt motor adaptor is 1- 1/2" thick as well so that needs to be factored in. It looks like the Warp 9 is about 3 " longer than the Impulse,, that would not have fit in the storm but I should have this one mounted by Thursday and we can look at the pics to see if the room is there.

 

[david85]

Work on the rear battery box has started. The hole in the floor is cut, and I hope to start work on the actual aluminum battery box tomorrow. My Dad is nearly finished with a metal break he made for the shop press, and I just wrapped up the cad drawing this evening.

The rear beam for the suspension is in the way, so I will not be able to fit 26 cells directly under the trunk, but I can use the space left by the fuel tank to make up for that. This would make for a nice low center of gravity as well as preserving all the interior space. There might be room for the charger in the space over the rear beam but I will have to see once that arrives.

The wood blocks seen under the car are mock ups for the battery cells.

 

[rctous]

what was the width of the hole in the trunk? Also from the back of the hole to the frame there,, what is that distance? Do you know?

 

[david85]

No problem. I've got the notes right in front of me.

The width of the hole is exactly 30" and from the rear of the hole to the beam is 21", with the overall length of the hole being 26.5". Depth is about about 8.5" without hanging below the rear bumper or pushing up past the trunk floor. My battery will be about 9" tall, so the battery will hang down slightly to keep the foor flat.

I have no idea if your saturn will be the same being a coupe though.

 

[rctous]

ya that sounds about the same, I am attacking the front first to see how many I need to put in the back, hoping 5 only in the rear and I think 7 will go up front,,,, shoot to get 5 batteries side by side I need 34 inches,,, is there 34" between the frame or did you cut flush right to it? As well adding 320 pounds to the rear will certainly lower the car probably too much bit we'll see.

 

[david85]

I'm not sure if the weight will be too much on mine but I will have to see as well. I think you are talking about your car regarding the 320 lbs, but actually, thats about what I expect my car to end up with on the rear. My car is rated for over 3000lbs GVW so it would in theory still be within the limit, but harder springs might be needed anyway.

I cut the floor out flush with the outer edge of the wielded flange of the chassie, so if I really wanted, maybe another 1.5" of side clearance could be scrounged up, but that would affect the structure more than I want. I am a little spoiled because my batteries will fit in any orientation so I have a lot of flexibility to use up every last inch of space if I have to.

 

[Bowser330]

any updates on your brushless motor?

 

[david85]

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]

As promised. Pictures of the rear battery box.

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

 

[david85]

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]

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.