Plug in option with no batter mods

Here in Canada we call them "circulation" or "thermosiphon" coolant heaters. All the ones I've seen are "passive" meaning no pumps, and usually you can purchase a 1,000 watt model from Canadian Tire for $65 Canadian. I have one on my old 1984 Ford F-150 truck that I keep at my hobby farm.

It is plumbed into the heater core hoses. When you plug it into the wall, the coolant in the little tank heats up and expands. This forces a check ball against a spring and the hot coolant escapes. Cold coolant is drawn back into the little tank through another check ball and spring, and the process repeats.

While in operation you hear this quiet charming "chufffff .... chufffffff ... chuffffffff" noise from under the hood. Depending on how long you leave it plugged in, and the capacity in watts of the heater, eventually the entire engine block and heater core is toasty warm. The nice thing is the heater is instantly effective.

Otherwise most cars and trucks here have a "frost plug" heater element. As the name suggests, a small electrical heater element is fitted into one of the block frost plugs. Most are rated 500-800 watts, and only heat the immediate area around the frost plug. Better than nothing, especially at -40, but a poor substitute for the "real" thing.

It's very easy to plumb a circulation heater into an old-fashioned car or truck with manual heater temperature controls. Newer cars and trucks with vacuum operated or electrically operated heater valves cannot use the circulation heater.

A lot of commercial and industrial diesel powered equipment make use of the fuel powered heater, simply due to the fact in many construction and remote sites there are no convenient plug-ins. Properly installed and maintained they are safe to use.

Actually the coolant thermos is standard equipment on all Canadian and American market Prius cars. This system is used primarily for emissions reduction during cold starts.

I have seen little if any benefit to actual cold temperature heater performance. Here in Winnipeg the heater will lose the battle in city driving at -25 C or colder. At -40 you had better be well dressed or suffer the consequences.

The best way to extend the life of a motor that is routinely operated in temperatures of -18 C to -40 C or colder is to use the proper engine lubricant. Inevitably that means a synthetic lubricant, preferably a 0W-30 or 0W-20 viscosity.

A conventional 15W-40 should not be used in temperatures below -15 C. A conventional 10W-30 should not be used in temperature below -20 C. A conventional 5W-30 should not be used colder than -28 C.

 

If you're curious here are some automotive and industrial/commercial coolant heaters:

http://www.phillipsandtemro.com/pub_DataSheets.asp

 

I got to thinkin about your charger.... I think its a great idea.... however other than for the fun of it.. it may not be real practicle.
What I mean is there may not be a real payoff from your efforts.
From what I've read the prius will actually go out of its way to discharge a battery that It thinks if overcharged..... but at any rate there is a link showing how far folks have gotten in pure EV mode alone.. or running just on batteriy power...I see anywhere from one mile to around 4 miles. Which means if you charged your battery all night you would still only get about 5 miles before the regular prius protocols would take over. 5 miles is only 1/10 of a gallon savings?

The reason some have done well making chargers is that they have done three things:
1. they have used bigger batteries
2. They used lithium which allows deeper discharges safely.
3. They reprogrammed the computers to allow deeper battery discharges before the ICE would kick in to try and charge them back up.

By being able to discharge furthur as well have have bigger banks.... you effectively multiply the battery capacity ability....I would think at least 4 times more capacity... maybe as high as 10 times...I don't know.

But the present NiMH systems in the present prius's are made to have the engine ever closely bailing them out when they get low.

In other words "again" I don't think your efforts will pay off too well with the existing format of the prius.

But you will have a good platform to grow if you can get your hands on some lithium..or more NiMH to run in parallel. changing the existing computer system to drain the batteries furthur is prob not a good idea unless you have lithum batteries.

However, I would like to see the benifits of tripling the battery bank size of the NiMH systems. I would think that the existing computer system would not have to be altered at all?

 

Thanks for the comments on the proposed system. The benefits would be minimal for long drives and bigger for short commutes.

Ideal driving cycle with charger at home would be to charge overnight to full green and then operate in EV mode for ~ 0.5 to 1.5 mile until mid way on blue bars. On the return trip to home, operate EV mode until 2 pink bars, then charge overnight to full green. (perhaps 1-3 miles?). For a total savings of ~ 1.5 to 3.5 miles (more if you had a charger at work). Note: I have a long stretch of school zone 25 mph...

I am about 4 miles away from work, so for me a 1.5 to 4.5 mile savings over 8 miles RT is worthwhile, especially since mileage over this short distance is ~ 40 mpg. Granted, that's only 0.2 gals per day but 3.5 miles RT in electric is 71 mpg and 1.5 miles is 50 mpg.

Savings could be greater if you had a charger at work as well.

I think the total cost could be kept to less than 500 dollars. True, the savings would not be great but the cost is less than the 12,000 quoted for LiPO battery systems. Plus there is the satisfaction of bringing the battery from pink to green without the engine running.

Other potential mpg savings ideas:

1. Low friction wheel bearings (higher maint grease/oil but lower drag?)
2. Low drag brakes (pulls pads farther from disc/drum)
3. heated front window (vs running defrost)
4. drag covers for rear wheels? (Insight?)
5. Lower vehicle weight? Spare? rear seats? Gas is ~6 lbs per gallon.
6. all the other tricks already discussed.

I'll let everyone know how it works out. One concern I have is how the battery system measures SOC. If it is current in/out then my plan will not work. If it is battery voltage + temp correction then it might. Anyone know?

Eric

 

Each module's voltage is measured by the battery ECU and sent to the HV ecu. Current is also monitored, but I suspect that is for operational reasns, and not to calculate SOC.

 

ABout that EV mod.... does that affect warranty?..
and it looks a bit complicated to get it all in right...

Is there anybody doing it for other folks for a fee?

 

I'm sorry, but I'm unable to provide the algorithm how the SOC of the HV battery is monitored as I promised. I keep searching. If I remember it correctly, current is also a factor in the calculation of SOC.

jayman

Thanx for the information about heaters, I very much appreciate your experience. We very rarely get such conditions as described (I'd say once a decade, and it's overdue this year *smile*) but now I'm confident that my good Prius will survive, since this is going to be my first winter with my baby.
Yeah, frost plug heaters don't seem sufficient. Since we do not have such a climate as you up there in Canada (which I'd love to visit) prices for the coolant heaters you recommend are about 8 to 10 times higher, for these devices are considered luxury and not essential. So I'll closely monitor all parameters over this winter and decide what to do next year.

Best regards

 

Hi all... greeting from Slovenia (EU)!

Tinspoon, the thermally isolated reservoir and its dependable pump are being fitted as standard equipment in SI. As i was being informed by my local toyota dealer (and a good friend of mine - that's another reason for buying a prius B)), it is standard in the whole EU as well.

As of my knowledge, there are only two option packs for '05 prius in EU - All available options + Navi & Bluetooth and a version with all available options but without the Navi & Bluetooth.
For your information, MSRP in SI for fully packaged version is exactly the same than in the US for the very basic version, without any additional options.

Tinspoon, the word for "webasto" is Vorheizung or "preliminary heating".

Regards,
Jure

 

Full green down to pink bars is all of about half a kwh.
.
_H*

 

So about 4 cents on the dollar to fully charge the battery. Nice.

 

I am probably the biggest proponent of plugging-in the Prius to recharge it for EV miles of everyone on this whole board!

BUT even I wouldn't suggest that plugging in to recharge the OEM pack is worthwhile. The latest (2004) Prius stores only 1.3 kWh, of which it only allows you about 500-650 watt-hours, and towards the lower limits of this it gets progressively harder for the software to let you have it.

Typically, a Prius can go about 5 miles per kWh in EV mode, so you WOULD be looking at a max of maybe 2-3 miles EV range if the software allowed you to use all the "available" 650 Wh (in practice it doesn't, and the gasoline engine will kick in long before then, unless you reprogram it somehow).

So to make it worthwhile, you'd be best adding some extra capacity. This capacity does not need to be a lot. Steve Lapp has made a solar Prius using only a 12 volt lead acid battery. This stores the energy from the solar cells on the roof, then slowly injects it into the HV pack while driving. Perhaps surprisingly, the HSD computers have no problem with this extra ampage. He has seen a 10% reduction in gasoline use with his first version (based on a Classic).

Taking this approach could be safer in terms of HV battery abuse too. Toyota did not intend the Prius battery pack to be deeply cycled in this manner, and making it do this could bring it to the end of its life quite quickly. Put one buffer battery in the way and this problem could be solved. Two 10 kg 12V deep-cycle lead acid batteries could store about 600 Wh, which would be enough for 3 miles EV.

 

Here is what I got from the article:
The PV Prius uses a 12-volt PV source with a small lead acid battery and battery voltage controller, inverted to 120 VAC, transformed to 345 VAC, then rectified with current control to nominal 300 VDC. The charge from the PV batteries flows into the Prius hybrid battery when the ignition is on.
The 300 VDC output of the solar subsystem is attached to the switched side of the original Prius battery, so the PV battery cannot recharge the NiMH while the ignition is off. The PV system can inject a maximum of up to 2 amps continuously into the battery while the ignition is on. [...]
________________
The stock NIMH battery is carefully controlled by the cars battery ECU, and we do not want to mess with that, so an additional battery will be added and charged from the solar array, this battery will then feed into the main original battery through a custom designed power converter that is controlled by the battery SOC.

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Although a fun project... seems very expensive and
Sounds like alot of energy loss in all the conversions?..

Wouldn't it be cheaper and more efficient to have a 300v.. "or 200volts with the post 2003 models" solar array to infuse directly into the battery? Put a simple cutoff switch that would stop current to the battieries from the solar array should they get fully charged while the car is parked.

For space sake, you would have to use smaller photo cells and link in series to obtain your 201 volts.

You could use your EV switch the last few miles to the house or work to get the batteries into the pink... giving a place for the energy to go when parked.
I think there is "alot" of wasted energy from the sun while I'm at work for 10 hours.. it would be nice to get a free ride home!

 

The Prius battery holds very little energy, since its purpose is not to propel the car but to balance the load and provide power for those very brief times when the engine would not have enough torque, as well as to recover some energy from regenerative braking.

Nobody's going to get 5 miles in EV unless it's downhill, or maybe at slow speed if there are no stops. One mile is more likely, or a mile and a half.

Figuring a very conservative 45 mpg in normal operation, it costs about 7 cents (at $3 per gallon) to go a mile.

So if you could charge the HV battery off the grid without electrocuting yourself (200 v is very dangerous!) you'd save about seven cents in gas cost each time (minus the cost of the grid electricity.) Do it twice a day (overnight and again at work) and you'd save 14 cents a day if you stole the grid electricity. (As is common in Mexico: people tap into the overhead power lines.) Five days a week and you could save $36 per year. And, as other posters have pointed out, probably shorten the life of your batteries because of the deep cycling which the computer tries to prevent.

In my opinion, It just ain't worth it.

 

I think it would be easier and better to add a plug in engine heater. The heater would bring up your MPG for the winter, decrease engine wear and give you instant heat .

here is a link
http://www.jcwhitney.com/webapp/wcs/stores...catalogId=10101

 

I totally agree - at least with the current options available.

I have ordered installation of an engineheater myself - including a cabin heater as well - for my 06. The latter will also help saving fuel, as the car will be preheated inside on cold days.

http://www.defa.com/heating.php3?lang=3

 

I have my power supply ~ 300V - now I just need time to hook it up. As other have pointed out, it is not going to be a real savings except under limited circumstances. My unit is ~ 50 Watts so 10 -16 Hrs needed to add 500 Wh. (Battery charge efficiency is ~ 60% of incoming power) It could also be used for solar applications (also for minimal savings).

Solar cells in series: I considered this, but it is much easier and cheaper to buy a standard panel and convert output voltage to ~ 300V. Shadowing would be a big issue for a custom array. Solar cells are in short supply so it is very tough to find a good price on 50 W panel.

Solar to lead acid to system during operation that was linked: Complicated charging scheme, there are other options now that would be more straightforward. Advantage is it uses Prius system for regulating battery SOC.

I wonder if Toyota would market a plug in option for existing Hybrids down the road? I expect that as batteries push the 8 to 10 year mark there might be a decent aftermarket of people willing to replace for something bigger or with more capability. I also think by that time there will be general market acceptance for plug in options.

As soon as I have some free time I will hook up and test, then report results. My expectations are modest. I think a block heater (system prewarmer) could have greater benefit to reduce initial low mileage numbers.

Happy Thanksgiving!