My official Prius Plus mods thread.

<div class='quotetop'>QUOTE(John in LB @ Dec 6 2006, 03:09 PM) [snapback]358634[/snapback]</div>

I've been looking into building a cheaper charger myself (I'm also working on a CalCars style conversion.) (even $800 seems like a lot to spend on a charger for SLA batteries which don't really require fancy charging algorithms.) There are a few problems with just rectifying the AC to DC like that:

1. House 240v AC is actully right around 240 volts and the battery's nominal voltage (the voltage which the battery reaches when it is discharged) is 240 volts. If you measure the actual voltage of 20 12 volt lead-acid batteries, you end up with something in the 250-260 volt range. To charge the battery, you must use a voltage higher than that. The voltage issue could simply be fixed by adding a transformer. A transformer would also allow you to use 120v power anyway.

2. For safety, the charger needs to be isolated. This (as long as the power source is AC) should be able to be solved with an isolation transformer (could be the same transformer as for adjusting voltage.) I know this is an issue with the PFC based conversion since the PFC doesn't provide isolation.

3. Ideally, SLA batteries should be charged with a constant current at first, then switch to a float (top off) charge to charge the last 30% of the battery. See: http://batteryuniversity.com/partone-13.htm for more information on charging SLA batteries.

As far as solar panels on the roof of the car, its a good idea, but current solar panels provide more drag than they will overcome and will only provide a very small amount of power because they are limited in the size they can be. See: http://calcars.org/faq.html

 

<div class='quotetop'>QUOTE(Cheap! @ Dec 8 2006, 03:03 AM) [snapback]359174[/snapback]</div>

I always wondered about those vents. I question if they are really worth installing. With essentially just a couple of holes in the floor it is possible there really won't be any air circulation at all. Hydrogen gas will be rising, going the opposite direction of the vents. Even if a fan is installed there to pull air out of the car you're still fighting the natural upward flow of the hydrogen, and of course if there is a spark when the fan starts, we know from the Hindenburg what will happen. Is it possible to remove the rear wiper and vent it there? It would be a much smaller diameter, but in a much better location.

Also, if they are installed it would probably be good to put a wire mesh and filter in them. Mice can fit through incredibly small holes. I guess having the elbow and "T" will prevent water from coming into the car, but also what about the exhaust gas which is apparently close to where the vent is? Awhile back some have said that there is so little CO from the Prius that you don't need to worry, but I would still want to make sure.

 

This is a fascinating thread. The idea of solar panels got me to thinking...

Now, my information isn't exactly expert here and I know that I may be missing something, but ... what about home solar panel systems? I think they make special 12V batteries that weigh like 100lbs or more for lots of capacity compared to car batteries. And I'm pretty sure there's inverters that run off the 12V DC battery to provide 240V AC for homes in Europe. If you could just get that output from AC to DC then that'd be exactly what you'd want for a Prius mod, right? And then you'd just have to replace the solar panel's output with a charger unit that you plug into the wall.

I know I'm not an electrical engineer so I may be missing something, but really, how close are the parts in these home solar kits to what you need to EV a Prius?

<div class='quotetop'>QUOTE(sub3marathonman @ Dec 8 2006, 12:54 PM) [snapback]359388[/snapback]</div>

I have to agree. I don't know how the factory vent works, but I'd imagine it scoops some of the air to create a turbulence inside of the vent area. (Otherwise what would be the point.) Where as the added vents may not do that without adding a forward-facing 'input' tube in addition to the rear-facing 'exhaust' type and/or a straight down tube with a scoop like an ^ to guide fresh air up and in and dirty air back out and away. Or something like that. But then I also don't much know what the air flow is like under a car. I've never been strapped down under one while it's movng to feel what it's like.

<div class='quotetop'>QUOTE(sub3marathonman @ Dec 8 2006, 12:54 PM) [snapback]359388[/snapback]</div>

You could always glue into the inside of the cap a 'filter' made from chickenwire or screen door/window mesh. Then no mouse no matter how squishable is getting through that without a fight. :lol:

 

And I may need to be smacked for this, but what about a package of 200 NiCad D cells?

 

Ok, before I sound too off the wall here, has anyone looked at _smaller_ Lithium ion batteries? Originally I would have never even considered these, as they are only good for <10A drain or so... That was until I got curious and looked at what the guys at Tesla did on their EV.. Tesla Roadster was using 18650 Li+ batteries. These are the same batteries used to power your laptop, etc. Granted, they're using almost 7k pcs of them..

In my experimental tests, I have been able to pull some ~15-20W off a single cell for fairly long periods of time, without anything too negative happening to the cell. Even my laptop pulls >120W off of a 12 cell pack. The RC car guys are pulling even more from equivalent volume LiPoly cells, but they're a totally different ballgame.

10-20W dosen't sound like much, but when you start thinking that the 25kW peak that the Prius pulls, but it's that for only ~5-10 sec. Once you start playing with your can view, you'll probably see something similar.. like ~10kW for EV only cruising.. That's only 500-1000 cells!

These can be found in fairly large quantities for fairly cheap too.. IIRC, with the right vendors and the right volumes I think you could pull ~$2-$3 ea?
As this is an semi electric vehicle, you might need some ungodly quantities of these anyways..

As you're talking significant outlay of money for a PbA pack, this might be something to look at, even goof with experimentally (on a small scale!)

Just remember to be REALLY careful with them! Li+ _did_ have that small problem of blowing up recently...




Ok, enough rambling, what are everyone's thoughts on this?

 

Silver Phoenix's idea has some possibilities. The initial connecting is a bit complicated. But the recharging gets very complicated. I have no idea how much a charger and Battery Monitoring System for these battery packs would cost.

You also have to decide the range you want to be able to travel on electric. The problem with PbA is that you really can only use 30% of the capacity without destroying the battery quickly. But with the Ni-Cd I'm figuring you can use 80% of the capacity and get a similar lifetime to the PbA battery. The prices are noticibly different, but the weights are much less.

I figured a minimum range of 8.73 miles, just because that is how the calculations worked out.

You could have 600 Sanyo or Saft D batteries, weighing in at around 200 lbs, for around $3000 or $4000 respectively.

You could have 400 Saft D batteries, but higher Ah, giving you 10.47 miles range, weighing in at 141 lbs, for around $6000. (If you kept the range at 8.73 miles you would greatly extend the lifetime of the NiCd batteries, possibly enough to offset the 50% higher cost.)

You could have 200 Saft F batteries, with the 8.73 mile range, weighing 110 lbs, for around $4400.

Or you could have the 20 CSB EVX12340, with 7.42 mile range, but axle busting weight of 520 lbs, for around $1600.

There are other PbA battery possibilities, but that 7.42 mile range is about the highest possible that I've been able to find. I figure that going over 520 lbs would not be acceptable.

In my opinion the PbA battery is the only way to go for many reasons. You have much more weight, but much less complexity, much lower price, and far fewer batteries. You might be able to find a better deal on a lighter and lower Ah PbA battery, use it for greater than 30% of the range, and still be better off than going with NiCd.

 

<div class='quotetop'>QUOTE(sub3marathonman @ Dec 9 2006, 12:43 AM) [snapback]359633[/snapback]</div>

Hello all, if you decide to get your feet wet on "self experimenting" and have unlimited money resources, by all means, go for the lighter and costly type of batteries, if we are foundling with ideas on how to select what others can use, by all means, choose the more long lasting, difficult to acquire and expensive batteries but if have to break your piggy bank to subsidize the PHEV car conversion let me tell you that every decision is ruled by how many cents will be left in your pocket.

Experimenting ( taking a chance that everything or part of it can go wrong and wasted) and production of something is to different ball games. Before the production line-up time, is a lot of R/D and testing + more testing and then caos.... + more testing an so on. That's the reason why some times final products are so goddamn expensive; for all the wasted resources to get to them.

For us, the few individuals taking action in this types of projects, we can't take chances of loosing, at least myself.

For the experimenter from "scratch" there is not fail safe, for the "experimenter" buying pre-assembled or DIY projects, there is no risk, you put basically some labor and "presto!!" is almost ready to work and the last, the experimenter involved in R/D for a Corp.or an entity ( of any Kind ) monetary and supply resources are basically not an issue.

For the few of us, AGM's is the intelligent choice of the moment regardless of weight, mine ranging 485 lb in total added weigh in this project, until replacement time.

In the future will be other more economic choices of products already known today, mean wile I will keep driving the PbA's until the lights go dim.



EDIT:

December 10, 2006

My DUAL PWR-PHEV 2004 Prius was oficialy presented to the public as a completed project in our Long Island Prius Owners Group ( LIPOG) Dec 2006 meet-up B)

 

<div class='quotetop'>QUOTE(Cheap! @ Dec 10 2006, 06:02 PM) [snapback]360189[/snapback]</div>

Actually, from your photo it looks more like "Driftwood Pearl", the color of my car, than Silver.
Also, I just noticed your hub caps. Is that for styling or aerodynamics?

Since you mentioned cost on the V4 I have to ask something. I expect my V3 to show up in the next few days. Norm emailed me that he'd gotten it to the post office yesterday afternoon. He said there would probably be an import customs fee. How much is that? I want to have my money ready.

As I've said before, it'll be a long time before I try to do a PHEV conversion. I want to have the money saved up for the batteries, and hopefully have better batteries available by that time.

Anyway, keep up the pioneering.

Dave M.

 

<div class='quotetop'>QUOTE(Cheap! @ Dec 14 2006, 08:37 AM) [snapback]362183[/snapback]</div>

I looks from your diagram like you're using the jack with its screw under tension. You could be okay, since I assume there's a big safety factor in the specifications. You'd have to look at minimum screw diameter to figure out the tensile stress, but if your drawing is relatively accurate, you have a very adverse mechanical advantage as you're just starting to lift it. That improves as it get further up though. If you want (assuming I have the time in the next few days), I could try to do a force analysis. Or if you're not in a hurry next week sometime.

BTW, I'm very pleased Altairnano replied. I was thinking of driving down to Reno to visit friends during Christmas break, but their daughter just died, so my main reason for going collapsed. She was almost like another daughter to us. She and our son were best playmates for the first 5 years of their lives. Even further off topic, but we called them "Pebbles and Bam Bam".

Anyway, the relevant part of this discussion is that I was hoping to visit Altairnano when down there. Since they did take the time to reply, perhaps I could see their testing lab, etc. the next time I do go to Reno. Maybe talk to some of the engineers. I haven't been there since last Christmas.

Dave M.

 

<div class='quotetop'>QUOTE(Cheap! @ Dec 14 2006, 10:37 AM) [snapback]362183[/snapback]</div>

You're using a screw jack, right? I mean with a 500lb battery box, the last thing anyone wants to do is accidentally open the release valve too quickly and WHAM! Oops. :lol: The only problem is screw jacks are so darn slow and fiddly.

But the drawing also reminds me of the folding staircase from the attic in my old house. It used tension springs to counter the weight of the staircase so that you didn't drop it like a sack of bricks on your head, and so you could easily shove the thing back into the ceiling when you're done up there. I wonder if the same thing could be done here. Tension springs to make lifting the battery box easy? Then you wouldn't have to fiddle with any jack. You could just unlatch, lift, and get to your spare. And when you're done just pull it back down and relatch.

And with the spring method for sure, but maybe even with the jack method, you'd probably want some sort of lock on the legs to keep the box from falling on your head when your munchkin in the backseat decides it'd be funny to climb onto the battery box while you're getting your tire out or something equally silly or dangerous.

<span style="color:#FF6666">EDIT: Der! Instead of tension springs added to the whole mess, what about a system built into the legs themselves, the same as the handy-dandy arms that help you open and close the hatchback to begin with. :lol: Well, okay, maybe a bit stronger than those are, but the same idea.

 

<div class='quotetop'>QUOTE(Cheap! @ Dec 14 2006, 02:03 PM) [snapback]362459[/snapback]</div>

By adverse, I just meant that the tension in the screw would be greater than 500 lb, rather than less. It's not really a technical term.

Dave M.