Got a prius, should be interesting to mess with....

[MetroMPG]

Relatively easy installation (it's a cartridge style heater):

1.5 L Toyota block heater

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Given that you're in Michigan, how is the car for rust?

I've seen a few gen 2 Priuses that were rusty enough that they were scrapped.

Usually the first signs of tinworm on this car is the area of the rocker panel just ahead of the rear wheel.

[hayden55]

If you are feeling frisky the gen 3 Prius has an exhaust heat recovery system. You could probably get it from a junkyard for next to nothing.

[ps2fixer]

Originally Posted by MetroMPG

Relatively easy installation (it's a cartridge style heater):

1.5 L Toyota block heater

===

Given that you're in Michigan, how is the car for rust?

I've seen a few gen 2 Priuses that were rusty enough that they were scrapped.

Usually the first signs of tinworm on this car is the area of the rocker panel just ahead of the rear wheel.

Only real rust on the car is the driver's door bottom edge, the front side track seal for the window is gone, so I guess it's been gone a long time since it's the only door showing rust stains on the rockers.

The 2009 I have has the rocker panel rust in front of the rear tires if I remember right, it's mainly cosmetic though and the car is silver so a bit harder to notice (white shows rust real easily).

I normally drive vehicles from the 90's so a little rust isn't a problem as long as the suspension section of the car is solid. I drove my 97 corolla until the gas tank straps failed from the body rust, could be fixed and drove more but 305k miles and it needs basically all maintenance items done and front end suspension work. I miss the car, drove it everywhere including in the woods on state land lol.

Never heard of the tinworm term, here we call it cancer, or Michigan cancer since this state is known for using the worst salts that causes the most rust. In recent years they've cut back a lot on the salt, barely the center of the road gets cleared, problem is they only plow once wait a day or longer and they might hit it with a little more salt but the 2nd run they don't put the plow down even if there's a fair bit of slush build up, would be more effective to plow the slush away, but that's a whole rant waiting to happen lol. I wish they'd use dirt when the temps are more mild since it's effective for melting the snow and also providing traction.

For the block heater, I don't really have access to a power outlet outside, I can't plug in my diesel too easily unless I run an extension cord out the door, then I'm loosing heat in the house and making the home heating system less efficient. I'd like to build a garage/shop some day so maybe the location of it and such can be situated so it's in a good location to be close enough to the house for plugging in the car or truck.

I'm thinking a 12v based system since it seems like the computer avoids charging the battery while the engine is cold, so I'm thinking it should be an increase in mpg. Problem is, 800w of heat might take 30 mins or so to warm things up, but I'm looking at around a 10 min round trip, and the engine coolant comes up to temp in about the first 5 mins. With the extra electric heat it might shave off around 1 min for the warmup time.

Here's a pic of one, I guess this one only does like 300w though with lower amp glow plugs.


https://ecomodder.com/forum/showthre...tml#post510043

I've seen a thread talking about this and the concept of using a diesel glow plug directly in contact with the coolant was mentioned. The powerstroke diesel glow plugs are pretty cheap, like $11 each for the OEM ones and they draw around 280-300w based on my math. 2-3 of those wired to a thermostat based controller would give around 600-900w of heat to the engine coolant. That should be around 75 amps at 12v, fairly sizable draw. I'd probably target a single one at first for testing if/when I get time to mess with it. Longevity of the glow plug is the only thing I'd be concerned with, but if the coolant is always flowing when it's on, it shouldn't be a problem. I'm pretty sure I have my old used glow plugs from when I replaced them in my diesel, there were like 3 that still worked well, I just replaced them all since clearly it's been a long time since the engine had them replaced (if ever). It was getting real hard starting below 20F lol.

Looks like there are similar glow plug based heaters that are actually sold/pre-made.

https://ecomodder.com/forum/showthre...tml#post510043

Originally Posted by hayden55

If you are feeling frisky the gen 3 Prius has an exhaust heat recovery system. You could probably get it from a junkyard for next to nothing.

Yea I saw them, they are tiny though. Concept I have in my head, is a copper pipe run around the exhaust (have to test how much wrapping is safe) and add the extra cooling load to the cooling system, or use an EGR Cooler which is basically the same thing as the 3rd gen prius system but like 3x larger. Maybe it would extract too much heat from the exhaust, but at the same time, heating the coolant up faster should help a lot.

Here's the prius one for $185:


And here's the one for a 6.4L Ford diesel that's $45



Looks like the ford one is about 2-2.5 times longer than the prius one. Worst case, my dad's wanting to learn to tig weld with his new welder, he could try to cut it in half and add a tank and flange to each end to convert it into 2 units. I technically have 2 cars, and the other one has no cats at all, no pipe or anything so it's nice and loud lol.

Of course this setup is slightly counter productive since it increases the coolant capacity a little, but the extra heat in the system sounds to be a net gain overall as long as the cooling system can keep up.

[Blacktree]

My Jetta had a turbodiesel engine, and it used those things to help the engine warm up faster. It had an EGR cooler (which is also a coolant warmer). Plus it had a housing with some glow plugs in it, to heat the coolant. I don't remember how much current the glow plugs used, but it wasn't anything crazy.

Oddly enough, a lot of the VW guys delete the EGR cooler "because reasons" then complain about the longer warm-up times. LOL

[ps2fixer]

On a "normal" engine, a small extra load has a byproduct of creating a lot higher load on the engine via the alternator. 100w of heating element might make the engine work harder and create 400w more heat in the coolant system, but you're using a ton more fuel. In that case, just driving the vehicle to load the engine would give good results I'd think. If the engine is oversized, the heaters might push the engine in a more efficient load range with the side effect of quicker warmups.

On Diesels, deleting the EGR helps increase MPG, however the EGR cooler should be left in tact for the coolant warmer effect. The actual EGR valve going into the intake is what they should be focusing on and working out a way to either dump the exhaust under the car, or pipe it back into the main exhaust pipe. I haven't done too much thinking on the best way to redirect the flow, and what to do with that flow. It seems some sort of a valve and pushing the exhaust back through the orig muffler would be the most logical setup.

Some cars have the "exhaust manifold" built into the head with a water jacket around it. Effectively it's an EGR cooler purely for heating up the engine coolant faster. It's always active, so the extra heat once fully warmed up has to be expelled via the radiator. I suspect at higher loads, the cooling load would increase quite a bit. Besides that negative, it seems to be all positives to the design, it's probably the most efficient way to recover extra heat from the exhaust system with the least moving parts.

I should probably look more into how the prius system is designed since it's likely sized about right for my engine, the other ones might be a bit too big.

I suspect that system will help a lot for winter driving as well since with the HVAC set to warm it will need to run the engine to generate the heat, so engine off costing will happen less often at those lower speeds. Probably not a huge factor for me since most of my driving is above the EV speed threshold.

I'm starting to wonder if my hybrid battery has a poor charge/discharge efficiency for some reason, or maybe the 12v battery is a solid draw on the system. I suspect since the 12v battery basically does nothing once the car is in ready mode, I could remove the 12v battery once in ready mode and replace it with a capacitor just to smooth out the voltage. One of those 200v caps from a power supply I think would be large enough. It should charge effectively instantly and be more or less 0 draw on the 12v system for charging. This test I have in mind should simulate roughly with a lithium ion battery would be like in the car. Of course when I turn it off it needs more power than what the cap can store to kick on everything. Some jumper cables and leaving the cap always hooked up could be a pretty simple test for the effect on charging that weak battery.

I just checked the battery voltage for giggle, currently sitting at 12.42v. When the car was cleaned it was ran low 11.9v and It has about 5 hours or so of powered on time since then, so it's still charging up, or the battery was charged and the load of the car has drawn it down that low already.

[hayden55]

Thats is an EGR cooler not an EHRS off a prius

https://priuschat.com/attachments/ex...ius-jpg.58103/

EHRS ^

Since the Prius just uses the Voltage of the battery and not the cranking amps it takes a while to notice when your battery is bad. 11.85V is 80% dead for reference.

[ps2fixer]

Interesting, makes sense it's after the cats since they make quite a lot of heat from their reaction. Technically both recover heat from the exhaust, just the EGR one is focused on cooling the exhaust gases going into the engine. I didn't realize there was 2 systems on them.

So I take it the EHRS always has coolant flow and exhaust flow and the extra heat once everything is warmed up is needed to be removed at the radiator then.

[ps2fixer]

Alright, I got my scope working with my laptop yay. So it seems it's not exactly uncommon for the battery to be under 12.6v the prius draws a lot for a while before it does to low draw 120ma in my case. It sits drawing 2 amps for quite a while, seems to be related to the brake vacuum monitoring system, if you touch the brake pedal it jumps back up to the 2 amp draw (25w). Interior lights seem to draw around 2 amp as well which makes sense if they are 10w per bulb. It takes a few minutes at 1amp draw before it drops lower. I didn't wait any longer to see if it drops any more.

Seems like one of the ways to make the 12v battery hold a charge for longer would be to change out the interior lights to all LED. Hitting the brake and kicking off the vacuum pump seems to draw around 28 amps on my car, there's a sudden spike of around 6 amp that's really short lived to kick on the electric motor of what I'd guess is the brake booster.

Once I hit the start button, it jumps from battery voltage (started out 12.6v after a short drive, was 12.52 when I checked it with the hatch open (2 amp draw on it). The charging system doesn't mess around, it hit over 60 amps of charging, beyond my low amp probe's ability, I have a high amp probe, I just didn't swap it out to get the peak. It tapered down quickly and then sat around 8 amp of charging. Battery charging drops to around 1 amp and the power fluctuations go past the 0a line a bit (draw from battery vs charging battery). From the drive, the battery was on 1 amp charge most of the time, that seems to be roughly the float charge on this battery in it's current state.

I didn't compare the scan gauge voltage vs real battery voltage, past experience the scan gauge generally sees a lower voltage vs directly at the battery.

Oh also when you insert the "key" in the ignition, it wakes up some system and it draw around 2 amps.

It seems like a bare min spec for the battery should be around 60 amp peak output and enough capacity to handle around a 2 amp draw for 10 mins after turning off the car + 0.2 amp load for say 1 week. My quick math comes out to 34ah of capacity, seems like the battery I got the car with matches those specs pretty well, that was unexpected lol.

Based on those figures, there's roughly 430wh wasted per week just by the draws on the battery with the car "off" using higher values to include a bit of safety margin. It would be interesting to find the largest power draws as it's pretty common for a car to sit not being driven for a week at my place. My Matrix does a great job managing a low power draw and keeping the battery good, it can sit over a month between starts and it fires up no problem. My Lexus LS400 on the other hand has a dead battery after about a week. My F250 powerstroke diesel has never given me problems except once when I left the lights on and it can sit for a month+ with no starts too.

If the largest draw item(s) aren't too critical to keep powered, I might modify things so those draws are disconnected and only reconnected when in ready mode or similar. Like I mentioned before, I don't care much about the security system, at least for when it's sitting at my house. The wireless key fob isn't needed when it's at my house, things like that. I think I'll be swapping out the interior lights to LED to help lower the draws on the battery. It seems like the battery is performing fine, just the capacity might be lower than it once was.

I uploaded the scope reading, but this server resizes the image so small it's not super readable. Red line is voltage, blue is amps.

Reuploaded to a different server, looks way better.

[ps2fixer]

Seems like I'm getting better. Something like a 28 mile round trip to the far away post office again. 45mph for the not so major back roads and 55mph for the main one (bulk of the trip), got to the post office with 53mpg, got back and the scan gauge says 55mpg. Windy day, think it said 63F which is similar to the last time I went there if I remember right.

Might not be insane numbers, but it's slowly getting better with just driving style. Overall tank according to the in dash display says 51mpg.

I'm just about caught up on orders for my business, so besides restocking I should be having some spare time soon to mess around with a better lower grill block, upper grill block, smooth belly pan at least for the front of the engine area and probably install the hitch I bought. Wheel covers I suspect will make a bit of a difference too even though it has the stock rings yet.

It seems to me I still hear a slight miss sometimes coming from the engine, I should scope it and see if I can pair up the feedback signal to the noise I've been hearing once in a while.

Oh, also the car sat for a couple days with out driving, and battery was at 12.1v according to the scan gauge. Based on a google result, that should be about 55% state of charge. I was reading 120ma draw with all the electronics sleeping, so assuming that's the average draw, the battery had about 6ah of draw on it (72wh). This should mean the battery's capacity is around 11ah (132wh) so I think it's pretty safe to say the 12v battery is on it's way out. I guess the missing puzzle piece would be how fast is it self discharging, 2 days should be basically zero effect unless the battery has a higher than normal internal draw.

Anyway, the prius is down to about 50% tank left, so should be interesting to see if I can fill up roughly at 17.5% again and see if it takes the same amount of fuel roughly speaking.

[ps2fixer]

Little update. On the way home from my parents, I stopped at the ATM then went to my house. Probably 20 mile trip and later at night so next to no traffic. 45mph there, 45 mph most of the way back, then I did 40mph for a bit. Car ran in EV mode down to 53.5% before the engine kicked back on, seemed like it took 2-3 miles for it to charge the battery back to around 59% but the MPG did seem to jump up quite a bit from that cycle. It seems like I couldn't get it to do that closer to my house, there's some small hills so might be too much of a load to keep it in EV mode at those speeds. Either case the trip on the scan gauge reported almost 61mpg.

I have warmer temps coming in, so I'm expecting the average mpg for trips to increase a fair bit with temp. It would be neat to data log with the scan gauge mpg figures per trip and log things like outside temp, starting engine temp, distance, etc to get a reasonable idea of mpg vs weather. Lot to log manually but I guess that's possible too.

I really need to do that EV button mod, I think in some situations pushing the car into EV mode to run off battery could be a net gain. It seems like the engine doesn't recharge the battery too fast, but when traffic allows, using EV mode then switching back on the engine to simulate a pulse and glide basically would probably help mpg overall. Of course if traffic is clear, normal pulse and glide would probably be more efficient.

I used to use neutral a lot, but now I find myself hitting the sweet spot pretty well for the engine off costing. For the speeds higher than the limit it shows the engine charging the battery and it seems to coast pretty well as well. That might be part of how I've bumped up my mpg a little, the other part I'd blame the weather on lol.

Getting closer to the next fill up. I'm hoping to be averaging around 50mpg for the tank this time with more or less a stock car.