# Planning 1975 Volvo c304 electric expedition camper



## brian_ (Feb 7, 2017)

Very cool project. 

One thing to consider from the beginning is the battery pack. It needs to have enough capacity, it needs to fit into the vehicle, and you need to be able to buy it.

While not big by RV standards, this is still a massive box to drive electrically, with poor aerodynamics and six off-road truck tires. If you can estimate how much energy it will take to move, you can estimate your energy storage requirement... and it is going to be huge.

For instance, if you need one kilowatt-hour to move one mile, your 200 mile range will require 200 kWh of battery. That's double the largest Tesla pack, and more than the largest pack in the recently announced Rivian R1T pickup. That's a lot of battery to buy, a lot of space taken up in the vehicle, a lot of weight that can't be used for camper equipment, and a lot of energy to replace when you get to somewhere that you can recharge.


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## brian_ (Feb 7, 2017)

I don't know if comfortably cruising at 65 mph is a realistic expectation. A stock C304 probably can't reach that speed. Although the limitation of the stock vehicle may just be engine power, making the electric version more powerful may not be practical, and cruising at that speed in a vehicle with the aerodynamics of a barn will consume a lot of energy.

Wikipedia lists the top speed as 62 mph (100 km/h). There are better sources, of course, but that gives an idea of what is reasonable in these vehicles.
Volvo C303
(a C304 is a 6X6 variant of a C303)


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## brian_ (Feb 7, 2017)

tmoney said:


> I would love to get a 200 mile range (more would be great) I think 200 miles would at least get me to a different scenery until I could charge the batteries by solar/wind/diesel generator.


This raises the issue of how you would charge the vehicle. That's a little different for RVs than for most vehicles, because RV owners normally want to go different places than the average EV (that is, to remote places or natural areas, not cities). Another difference is that many RV owners stay at campgrounds with services (including power), while others stay in places with no services at all... and power service is significant to recharging.

The idea of an electric RV comes up frequently. These are some of the previous discussions, which might provide some possible answers, or raise more questions. They cover a range of vehicle types and sizes, which should be kept in mind for context. Some are also quite old, so information about available components (particularly batteries) are out of date.

(2008) Concieve the electric RV
(2015) Electric RV
(2017) RV / Bus ev motor?
(2018) RV Project
(2018) Van (or larger) Camper Conversion + DIY EV?
(2011) design questions- 8000 lb RV, with regnen,
(2014) RV Conversion with Smith Electric
(2018) Mercedes Sprinter conversion help

Common themes include:

the high energy consumption of a large vehicle
plans for solar charging, usually with unreasonable expectations
need for a much larger motor compared to typical conversions, or multiple motors
the RV never actually gets built or converted
There have also been several discussions of hybrid (usually diesel-electric) RV ideas, but if you're not planning a hybrid these would probably not be very helpful, so I left out most discussions of potential project vehicles with short electric-only range. I also found a few more discussions which appeared to contain no useful information, so I left them out.


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## brian_ (Feb 7, 2017)

Since you have the troop carrier - not the ambulance or radio unit with the taller body - there isn't much headroom. One set of specifications that I found online say that there is 1250 mm (49") of floor-to-ceiling headroom in the cargo area. Do you plan to add a pop-top (which appears to be the popular choice), or a raised roof? I would want the taller roof, but that would increase drag (increasing the battery capacity requirement or decreasing range).

So, for the "where do I start" question... I think you start by understanding what you need (such as ceiling height), then what that means for energy and power requirements, so that can be followed by design choices to meet those requirements.


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## tmoney (Dec 6, 2018)

Thank you so much Brian for your help with researching. I think after looking at what I would actually need (or think I need) for battery capacity (somewhere in the 300-400kwh range) and at $100/kwh price which I think is actually on the low end. I am looking at 30-40k in just batteries. Its not quite a feasible option at this point. I planned on spending around 15k on the electric conversion. I think a diesel/electric hybrid would possibly work for me though and get me through the next decade until power storage devices can reach a better point. 

I would use multiple motors either directly attached to the differentials or somehow directly attached to each wheel. 

I do plan on either building a new box completely or modifying the box I have to accommodate the headroom needed for a comfortable place to stay. I plan to widen, heighten, and lengthen the box so a new box might be easiest since this body is built from aluminum. (however the body unbolts and leaves a lot of easy points to add in pieces)

How feasible are the hybrid builds for bigger vehicles? Some people say that converting mechanical into electric then back to mechanical seems to be inefficient but ive also ready that with the phenomenal efficiency ratings of the electric motors now day (im not sure the generation how efficient it is) that it can make sense to go this route.

What are your thoughts there?


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## brian_ (Feb 7, 2017)

*Pure battery-electric RV feasibility*



tmoney said:


> I think after looking at what I would actually need (or think I need) for battery capacity (somewhere in the 300-400kwh range) and at $100/kwh price which I think is actually on the low end. I am looking at 30-40k in just batteries. Its not quite a feasible option at this point. I planned on spending around 15k on the electric conversion.


I agree that pure battery-electric is not economically reasonable. It has been done with even larger vehicles, but only by companies that have business objectives and the money to pursue them, and normally in applications that are better suited to an EV.


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## brian_ (Feb 7, 2017)

*Multiple motors*



tmoney said:


> I would use multiple motors either directly attached to the differentials or somehow directly attached to each wheel.


I also like the idea of three or six motors both to avoid the need for a very large motor, and to allow full-time 4WD without inter-axle differentials.

Motors are heavy to mount directly to the axle final drive housings, but it is done with buses and trucks, and it would make packaging enough battery between the frame rails easier. I think that a way to do six motors would be to build de Dion axles with the portal drop boxes on the ends, and pairs of motors mounted to the frame at each axle line. You could also replace the centre section of each axle with a pair of reduction gearboxes and motors connected to them, but to that much fabrication and still have the mass of the motors (and gearboxes) riding on the axles doesn't seem like the best compromise... although that's what some production and planned-for-production heavy bus and truck electric axles do; the ZF AVE is even a portal design (designed to be used inverted for low-floor buses, but also used upright for the Mercedes Urban eTruck).


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## brian_ (Feb 7, 2017)

*RV coach body*



tmoney said:


> I do plan on either building a new box completely or modifying the box I have to accommodate the headroom needed for a comfortable place to stay. I plan to widen, heighten, and lengthen the box so a new box might be easiest since this body is built from aluminum. (however the body unbolts and leaves a lot of easy points to add in pieces)?


I'm not sure about the off-road plans, but in tight spaces a wider body might be problematic. Bolting on a taller roof and keeping the current width might be a more functional option.

On the other hand, the C304 has sloped side walls above the beltline, so replacing them with a box which is the same width as stock at the floor, but with vertical walls, might make a more usable interior space without hanging out the sides further. I suspect that sloping the walls in had a purpose, such as being less likely to hit stuff when tilting on rough and narrow roads/trails.

I hate to suggest the weight and complication of slide-out sections, but moderate slide-outs may be the way to get good liveability without more width in travel mode. I do have some thoughts on slide-outs, if you're interested...


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## brian_ (Feb 7, 2017)

tmoney said:


> ... I think a diesel/electric hybrid would possibly work for me though and get me through the next decade until power storage devices can reach a better point.
> 
> ...
> 
> ...


Hybrid design certainly works for large vehicles; 25-ton hybrid urban transit buses are common.

There seems to be a common assumption that a hybrid should be a series design. While that has some advantages including an effectively infinite choice of gear ratios (engine to road speed ratio) and freedom of engine/generator location, an RV spends most of its time on a highway in a narrow speed range, so the most efficient is going to be a *parallel configuration*. Even at 85% efficiency per conversion, converting from mechanical power to electrical and back again saps a third of the power produced by the engine. Parallel also avoids the need for a generator which can handle the full output of the engine. 

It looks like the Volvo has no rear inter-axle differential, so there's some appeal to breaking the mechanical connection between them (for less scrubbing and thus less energy use). It also has part-time front drive, since there is no centre differential, so if the original mechanical driveline is kept it can't drive the front axle on the highway. To me, that leads to something like this approach:

driving the leading rear axle with the engine and mechanical transmission (not using the stock transfer gear to drive the trailing rear axle)
driving the front and trailing rear axles only electrically (with one motor per axle or one motor per wheel)
adding a motor-generator at the engine (or between engine and transmission, or connected to the PTO)
regeneratively braking whenever possible
using the motors on the front and trailing rear axles only when required for traction, or when using battery power, or when braking
With the leading and trailing rear axles not mechanically connected, the trailing rear axle could be converted to steering (using steering knuckles as with the front axle) and steered in proportion to the front to allow tighter turns. Of course that might be expensive: I don't know what a C304 front axle costs, and then there's the steering gear. It could be a later enhancement.

A large (but not hundreds of kilowatt-hours) battery would allow

capture of energy in regenerative braking (by all axles)
power boost for acceleration (by driving front and trailing axles)
lots of energy for use while camped (can charge using motor-generator connected to engine)
plug-in charging to displace some fuel consumption

As an alternative, the most minimal hybrid would be a *mild parallel hybrid*, with a single motor-generator used for regenerative braking and for a bit of acceleration or hill-climbing boost and a battery sized more like a plug-in hybrid car than an EV. Current production mild hybrids typically run at only 48 volts, but the 200+ volts of a common non-plug-in hybrid might be a good match for a system that easily produces 120 V AC power when camped. These are usually connected by a belt drive to the engine, and replace both the alternator (in combination with a DC-to-DC converter) and the starter motor. In my motorhome I would like just enough to limit speed on mountain grade descents without resorting to engine or friction braking, and a large battery for power while camped; a mild hybrid system would do that.


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## tmoney (Dec 6, 2018)

The only issue with that idea is then I have the expense of an electrice drivetrain and a mechanical one. 

The current state of the project is motorless so it will need a new motor and transmission as of its current state otherwise keeping the factory motor intact could have been an option.

I would prefer to go with an all electric drivetrain so in the future I can utilize upgraded battery technology to gain higher ranges and eventually downsize the generator needed... and also I wont have the double expense of an electric drivetrain and a mechanical one. 

from what ive read and calculated I will need at least 1kwh / mile to move this thing fully loaded so a 100kwh batter would give me around 100 miles. What would I need for a generator wise to produce enough electricity to keep be moving forward... This particular RV wouldnt be used to cruise long highways at 70mph it would be back roads with frequent stops at 35-55mph most likely on the dirt.

What are your thoughts? I would love to make this work as a hybrid but if not my next option is a small mercedes diesel or maybe the new cummins 2.8 repower crate motor.


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## brian_ (Feb 7, 2017)

tmoney said:


> The only issue with that idea is then I have the expense of an electrice drivetrain and a mechanical one.
> 
> The current state of the project is motorless so it will need a new motor and transmission as of its current state otherwise keeping the factory motor intact could have been an option.
> 
> I would prefer to go with an all electric drivetrain so in the future I can utilize upgraded battery technology to gain higher ranges and eventually downsize the generator needed... and also I wont have the double expense of an electric drivetrain and a mechanical one.


Yes, that's true of any hybrid; you need something to handle the engine output. In a series hybrid you have the same transmission as a straight EV (with one motor), but you need a generator on the engine capable of taking the entire engine output, which is not cheap or small.

Even with no engine (and no transmission?) to start with, an engine and transmission (presumably not the same as the Volvo originals) would be less expensive than an electric powertrain... but I realize that's not the purpose of the project. 



tmoney said:


> from what ive read and calculated I will need at least 1kwh / mile to move this thing fully loaded...


That's roughly what I'm thinking, on the basis that both rolling resistance and aero drag will be about three times as great as for a large modern car.



tmoney said:


> What would I need for a generator wise to produce enough electricity to keep be moving forward... This particular RV wouldnt be used to cruise long highways at 70mph it would be back roads with frequent stops at 35-55mph most likely on the dirt.


If you take either the series hybrid approach, or a parallel system with enough electric power to make up the difference between a small engine and whatever is needed at maximum power demand, then the engine can be sized for not much more than average power demand. There are very few production series hybrid light vehicles; the BMW i3 REX does have only a small engine, while the Honda Accord has nearly the same engine power as the non-hybrid. The BMW i3 REX shows that a small and hard-working scooter engine is not an efficient way to power a car.

As an example, if you're using 1 kWh per mile to run at 60 mph, you're using 60 kW average. That's not much less than the original engine, and if you use any less engine you won't be able to sustain that speed (or a lower speed while climbing), but you're saying that's okay. Perhaps an engine that can produce 30 kW efficiently (rather than at peak output) would keep up suitably.

I think I might pick a Prius engine - the 2ZR-FXE produces anything from about 13 kW to 30 kW while staying within 5% of its impressive peak efficiency (of 220 grams of fuel per kWh of output) - but it's gasoline, not diesel. You might get away with an off-highway equipment (e.g. tractor) diesel of some sort; among road vehicles available in North America the engine from a VW car or the Chevrolet Cruze are the only reasonably small diesels that comes to mind, although of course there are smaller engines from other markets.

In a series hybrid the engine needs a generator; if they are directly linked (not through a gear, belt, or chain drive) then the generator turns at engine speeds and needs to handle the maximum engine output torque.



tmoney said:


> I would love to make this work as a hybrid but if not my next option is a small mercedes diesel or maybe the new cummins 2.8 repower crate motor.


This is a great example of what the Cummins 2.8 crate motor package is intended for. I don't know what it costs, or if a used Duramax 2.8 or Powerstroke 3.2 might be cheaper (and presumably cheaper to maintain than anything from Mercedes or BMW).


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## tmoney (Dec 6, 2018)

Thank you Brian for helping me through this. 

My concerns right now are

What can I expect to pay for a full electric drivetrain with a 100kwh battery for drive on all 3 axles.

I am also concerned with having the electric motors directly driving the axles and not having a second speed gearing for more efficient cruising speeds.

What would the downside of running one bigger electric motor through either a transmission and transfer case or possibly even just a 2 speed transfer case to drive all 3 axles?

I can find many different options nearby for a medium to large diesel generator. I am looking at 10kwh-20kwh generators. I wouldnt need to sustain forward movement if I had a 100mile ish range I can go and park for a while.

I plan to have a lot of solar and now I have even thought about building a separate small trailer with extra batteries and a solar array that I can deploy at a "campsite"

Thoughts?


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## brian_ (Feb 7, 2017)

*Gearing and power distribution*



tmoney said:


> I am also concerned with having the electric motors directly driving the axles and not having a second speed gearing for more efficient cruising speeds.


With suitable AC (permanent magnet or induction) motors and enough voltage, that's not a problem - it's how production EVs are configured. If you try to get away with brushed DC motors or half the voltage a typical modern EV, I agree that the speed range will be an issue. With three axles to drive, multiple ratios mean either multiple transmissions, or a single central motor and keeping something like the stock system of transfer cases.

A compromise solution might be to use single-ratio electric drive to one or two of the axles only at low speed, and to disconnect (or just idle) those ones at higher speed. Apparently at least a couple of production hybrids or EVs leave the secondary axle's motor connected but unpowered at high speed for efficiency.



tmoney said:


> What would the downside of running one bigger electric motor through either a transmission and transfer case or possibly even just a 2 speed transfer case to drive all 3 axles?


Most transfer cases are unable to drive just one output, or to drive both outputs with differential between them, in low gear; they have "2 Hi", "4 Hi" and "4 Lo" modes, but not "2 Lo" or a full-time "4 Lo". That's true of the Volvo's transfer case - it has no centre differential. If you only want low gear for traditional "4 Lo" conditions, that's okay; if you want two ratios for both high-speed road use ("2 Hi") and low-speed road use ("2 Lo"), it's hard to find one which will be suitable without modification.

The C304 has no inter-axle differentials, so with one motor

you can't drive the front axle on the highway, and
the tandem rear axles scrub due to turns or any tire size mismatch
With a single motor, you can either live with these limitations, or upgrade. The transfer case (assuming that you still have the stock one) could be replaced by one with a centre differential. The simple power take-off on the leading rear axle (which drives the trailing rear axle) could be replaced by an assembly with an inter-axle differential (also called a power divider), but I don't know what's available in a suitable size and I doubt there's anything like this designed to work with the Volvo C304 axle.


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## tmoney (Dec 6, 2018)

so if I were to do 3 motors on 3 axles and wanted to go 55mph (maybe a bit faster) Which motors would you use? to move 10k lbs? and where is the best place to get 100kwh worth of batteries?

I need to start looking at price values so I don't keep wasting your time if it does not make sense to me at this point in time... 

If I had $15k to spend on this electric drivetrain with 100kwh of battery would I be able to pull it off? Just talking parts here. I plan to fabricate and install it all myself or with the help of a few friends.


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## Duncan (Dec 8, 2008)

Hi tmoney

The cheapest (and best) batteries are from a production EV

I would suggest that the best way to get what you want would be to buy three crashed EV's 
Something like three Leafs 
That will give you three power units and about 75 kwh of batteries

Don't know what you would have to pay for a crashed Leaf - guess about $3000


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## tmoney (Dec 6, 2018)

Hey Duncan!

I will definitely try to look around and see what I can find for wrecked leafs.

Is there a way to change the 350v packs down to a 144v pack and effectively double the capacity? or would that be a bad idea?


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## Duncan (Dec 8, 2008)

tmoney said:


> Hey Duncan!
> 
> I will definitely try to look around and see what I can find for wrecked leafs.
> 
> Is there a way to change the 350v packs down to a 144v pack and effectively double the capacity? or would that be a bad idea?


Hi if you get the controller and charger and everything out of the Leaf it will all work together

You can re-arrange the 48? modules that make up a Leaf battery in any way you want but I don't see the advantages - you would be better off sticking to the Leaf voltages

If you arrange the Leaf Battery in two packs you get twice the Amp hours but half the voltage
So the same amount of energy and the same range


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## tmoney (Dec 6, 2018)

I see what you are saying though..

3 leafs for 3 axles with 3 batteries and motors.. Could possibly work. It does look like you can buy these wrecked for around the 3-5k mark.

I wonder if the leaf can get the 100mile range if I could get 100 miles with 3 of them.


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## brian_ (Feb 7, 2017)

The three-Leaf approach makes sense to me.  The feature which is less than ideal might just be that the Leaf motors are larger and heavier than necessary (if you're mounting motors on axles), given that they are designed for 80 kW (107 hp) each; that's reasonable for the mass of the vehicle, but more than double the power of an original C304.

Other recent production EVs are usable, too, but the Leaf is the most common... other than Teslas. I suspect that multiple Tesla motors and corresponding battery modules would be expensive.

If specifically using the Leaf battery, I think it would make sense to rearrange modules physically to package them into the vehicle, and maybe to connect sets of three modules in parallel then those sets in series (to make battery monitoring easier) if combining them into one large battery... but as Duncan explained there is no advantage to configuring for a lower voltage. Keeping the full design voltage is important to maintaining motor performance at high (motor) speed.

With 3.44:1 ring-and-pinion sets at the differentials, and 2.06:1 reduction in the portal boxes, a motor connected directly to an axle's input will be reduced by 7.09:1, which is almost as much as the stock Leaf reduction gearing. The tires are taller than a Leaf tire, so overall the motors will be geared a little taller than ideal, given the modest top speed expectation for the C304 compared to a stock Leaf.


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## Duncan (Dec 8, 2008)

I just had a horrible thought about that Volvo whistling along at 100 mph! - terrifying!


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## tmoney (Dec 6, 2018)

Duncan said:


> I just had a horrible thought about that Volvo whistling along at 100 mph! - terrifying!


Definitely not going to be doing 100mph in that thing... 65 hopefully... Is this leaf option the best approach or ive been watching videos of building my own battery banks using 18650 cells. And running different motors and controllers.

A wrecked leaf is about 5k and there is the risk of some of the components I need being damaged.. and then also ive read reports of the batteries not holding their full capacity. So I am a little weary going about it this way but I suppose if I go visit each one I can determine weather or not to buy them


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## MattsAwesomeStuff (Aug 10, 2017)

tmoney said:


> Is this leaf option the best approach or ive been watching videos of building my own battery banks using 18650 cells.


Good god, no.

An 18650 has about 8-9 watt-hours.

So for 100,000 watt-hours you'd need, what, 11,000 of them?

I think good cells go for $5. In bulk you might get them for $3 each?

$33,000.

If you're quick at soldering, you might get a cell in and soldered in 10 seconds. 6 per minute. That's 28 hours of non-stop soldering.

You'll have to add bus bars, holding pieces, etc to them as well. And probably 20 lbs of solder.

Unless you're getting 18650s for free, there's no reason to ever use them in a vehicle. And even then, (I am), it's a crappy solution.

OEM is definitely the way to go.


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## tmoney (Dec 6, 2018)

I will have to check around.. I just saw that civic hybrid batteries are 144v and 20kwh... 2011+

Wonder how much I can pick them up for? What motors should I be looking at if I dont buy 3 complete leafs?

Also what are the average cost of each equipment piece I would need to purchase?

BMS?

Motor controller?

Inverter?

What am I missing? besides batteries?


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## brian_ (Feb 7, 2017)

tmoney said:


> I will have to check around.. I just saw that civic hybrid batteries are 144v and 20kwh... 2011+


A non-plug-in hybrid has a small battery; in this case, I think it is a battery with 20 kW output power rating (to support the 23 hp motor), but the energy capacity will only sustain that for a few minutes at the most... it is likely closer to 1 kWh than 20 kWh energy capacity.

Honda specs for a 2005 Civic hybrid show


> *Nickel Metal Hydride (Ni-MH) Battery*
> *Output	*144v (120 cells @ 1.2v)
> *Rated Capacity	*6.0 Ah


That's 6.0 Ah x 144 V = 0.864 kWh

The capacity of any non-plug-in hybrid battery is so low that you would need dozens of them. Even plug-in hybrids are typically under 20 kWh, so you would need several.


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## tmoney (Dec 6, 2018)

Brian 

as far as I can tell those 20kwh 144v batteries are only in 2012+ civics. I know the 05 era had really bad issues with the batteries and most likely because it was those nickel batteries.

What are your thoughts so far Brian? I am almost leaning towards just doing a traditional diesel motor swap and building out the vehicle completely with the camping and expedition portion and letting the EV (mainly battery) technology catch up a bit..

Though I really do love the 3 leaf idea... I might be keeping my eyes out for a few of those!


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## brian_ (Feb 7, 2017)

tmoney said:


> as far as I can tell those 20kwh 144v batteries are only in 2012+ civics. I know the 05 era had really bad issues with the batteries and most likely because it was those nickel batteries.


While the first two generations of Honda Civic Hybrid apparently had lots of battery problems, that's not the fault of the NiMH chemistry. Toyota has no problem with NiMH, which it has always used in all non-plug-in Prius variants. Honda made hybrids early, and continues to make them now and then, but Toyota is the master of reliable hybrids. You don't want NiMH for a plug-in vehicle (not enough energy density compared to lithium), but NiMH not working for the Civic is entirely Honda's fault.

Unfortunately, while Honda published reasonable specs for the 2005 Civic hybrid, their promotional machine churned out stupidity for the introduction of the next generation, resulting in this for 2013 specs:


> *Lithium-Ion (Li-Ion) Battery*
> *Output (kW)* 20
> *Voltage	*144
> *Volume (Liters)	*16
> *Weight (lbs)	*48.5


They switched from NiMH to some lithium chemistry, and wanted to promote the increased *power* rating (up by 5 kW to 20 kW, so the previous NiMH battery must have been limited to 15 kW output), but as I mentioned earlier (with emphasis on the key concepts)...


brian_ said:


> A non-plug-in hybrid has a small battery; in this case, I think it is a battery with *20 kW output power* rating (to support the 23 hp motor), but the *energy capacity* will only sustain that for a few minutes at the most... it is likely closer to 1 kWh than 20 kWh energy capacity.
> 
> Honda specs for a 2005 Civic hybrid show
> 
> ...


The 2012+ lithium battery capacity is not specified in the promotional material or owner information from Honda, but the volume (16 litres) and mass (48.5 pounds) are consistent with a few kilowatt-hours (they're about the same as a single Tesla Model S/X module). In lithium chemistry it will have higher energy storage capacity than the same size of NiMH battery, or the previous Civic battery, but not much higher power output... and certainly not 20 kWh in that volume or mass.

Just to fill in the variations, the second-generation Civic hybrid had (according to Wikipedia)


> 158.4 V (132 x 1.2 V) Nickel-metal hydride batteries with 5.5 A·h capacity


That's 158.4 V x 5.5 A·h = 0.871 kWh

Where are you seeing this 20 *kWh* spec for any Civic?


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## brian_ (Feb 7, 2017)

tmoney said:


> What are your thoughts so far Brian? I am almost leaning towards just doing a traditional diesel motor swap and building out the vehicle completely with the camping and expedition portion and letting the EV (mainly battery) technology catch up a bit.


We are still at a point that an EV conversion is more expensive than a conventional drivetrain. If you swap in a used (rather than crate) engine to keep the cost down, and size it relatively small to suit a later hybrid upgrade, that might make a lot of sense. It's likely to take a while to build out the camper and get enough experience with it to know what you really want.


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## tmoney (Dec 6, 2018)

brian_ said:


> We are still at a point that an EV conversion is more expensive than a conventional drivetrain. If you swap in a used (rather than crate) engine to keep the cost down, and size it relatively small to suit a later hybrid upgrade, that might make a lot of sense. It's likely to take a while to build out the camper and get enough experience with it to know what you really want.


At this point I am looking at going with nearly the same motor that was in the sprinter vans in the 2003-2006 range. People report 20+ mpg easy with them and over 700k miles. I think I will get the 6cyl version the om648. This might be a tad big for a hybrid setup in the future but we will see what happens. I think youre absolutely right by the time I get it completely built out and enough experience with it then I will have more options and a better idea of what to do. I am just afraid at this point to jump in and throw 15-20k at the drivetrain and not end up using it for its intended purpose..

So at this point I think getting it running with a traditional drivetrain and then finishing the rest of the vehicle will be my best option. (all the while keeping an eye out for a good deal on a wrecked tesla or a few of those leaf things =P)


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## brian_ (Feb 7, 2017)

tmoney said:


> At this point I am looking at going with nearly the same motor that was in the sprinter vans in the 2003-2006 range. People report 20+ mpg easy with them and over 700k miles. I think I will get the 6cyl version the om648.


The OM648 might be hard to find in North America - the only model I could find which would have it would be an E320 CDI from 2005 or 2006 (and later E320 diesels had a V6). The first-generation Sprinter only came with the OM612 (earlier) or OM647 (later) 5-cylinders. Although the five-cylinders are not powerhouses by the standards of modern vehicles with 5 tons of gross combined weight, they are still a lot more powerful than the C304's original engine, and the 5 tons is within Mercedes' rating for it in the Sprinter. With all of the accessories of a (relatively) modern diesel, I wonder about fitting any diesel six-cylinder into the Volvo.

One good thing about the 5-cylinders might be that Sprinters seem to have been designed with an auto-dissolve feature, so the first-generation ones should all be rusted to destruction by now, making their engines (and transmissions) available for salvage.



tmoney said:


> This might be a tad big for a hybrid setup in the future but we will see what happens. I think youre absolutely right by the time I get it completely built out and enough experience with it then I will have more options and a better idea of what to do. I am just afraid at this point to jump in and throw 15-20k at the drivetrain and not end up using it for its intended purpose..
> 
> So at this point I think getting it running with a traditional drivetrain and then finishing the rest of the vehicle will be my best option. (all the while keeping an eye out for a good deal on a wrecked tesla or a few of those leaf things =P)


Back to the *EV or hybrid* idea...
The space under the floor is largely a wasteland in a cargo truck, but it is valuable real estate in an RV, and in an EV or hybrid. An EV/hybrid RV has far more stuff to potentially put under the floor than will fit, so one thing to watch in designing the camper setup might be to leave space for a later large battery pack.


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## goingbush (Jun 20, 2017)

Just found this thread, 

I'd be tempted to remove the middle axle and convert to 4x4 . 

No one has mentioned the Volvo runs on portal hubs, (yay) they are going to chew a bit more energy than a straight axle(boo)

I've already converted my LandRover & now I have plans on converting my Iveco Daily 4x4, a fair bit bigger than the Volvo and am thinking 160kwh will do me . I'll use 2 motors , one on the gearbox input to the transfer case and one the PTO output ( Both connect to the same shaft internally so turn at the same speed) 

Im using 440w/h per mile in the LandRover and expect about double that in the Iveco for a 200 mile range .

this is my Iveco if your interested http://unsealed4x4.com.au/u4x4/issue057/#35

and the EV LandRover http://unsealed4x4.com.au/u4x4/issue056/#55


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## brian_ (Feb 7, 2017)

goingbush said:


> No one has mentioned the Volvo runs on portal hubs, (yay) they are going to chew a bit more energy than a straight axle(boo)


Well I did, but it was pretty deeply buried in a previous post:


brian_ said:


> With 3.44:1 ring-and-pinion sets at the differentials, and 2.06:1 reduction in the portal boxes, a motor connected directly to an axle's input will be reduced by 7.09:1...


I think the portal axles are basically the point of these Volvo trucks. Having looked at the price and awkwardness of available aftermarket bolt-on portal beam axle conversions, I can see preferring Volvo's hardware. They are one of the few available factory portal-axled vehicles, and other than the Unimog and the HMMWV / Hummer H1 they might be the most available. The other well-known but even more rare example would be the Pinzgauer (which is outright weird ). I'm impressed that anyone finds any of these vehicles in North America.

The Volvo portal gears are straight-cut, which is supposed to reduce their drag a bit, although it makes them noisy (compared to helical gears).



goingbush said:


> I'd be tempted to remove the middle axle and convert to 4x4.


The 6X6 configuration does add weight and complication, but I think if one wants a 4X4 of this size the C304 is the wrong place to start. It would be easier and presumably cheaper to stretch a C303 (the 4X4 model of the same range of vehicles) if there were one available.

I can see three issues in a 6X6 to 4X4 conversion offhand:

The 6X6 C304 uses a very different suspension from the 4X4 C303 at the rear, and one axle can't be just removed while leaving a functional suspension. It would be possible to remove the leading axle, remove the leaf springs, replace the locating function of the leaves with a track rod or Watts linkage, replace the spring function with air bags or coils, and build a frame-supported intermediate bearing to carry the prop shaft in place of the leading axle's power take-off... but is that worthwhile? It would also be possible to completely replace the rear suspension with a single-axle suspension copying the C303... but then it would be easier to just start with a C303.

Removing the leading rear axle leaves the remaining rear axle right at the back with a 3.35 m wheelbase; the axle load distribution would be questionable and the frame might not handle the span under load. A stretch of a C303 4X4 could place the rear axle in the optimal position... but that's not what is available.

The axle capacities of a C304 are 1700 kg (front) plus 3000 kg (rear total), which is suitable for the GVWR of 4400 kg, but even with a C303 rear axle capacity of 1750 kg, the 4X4 conversion total would be only 3450 kg... probably not enough for the longer truck, even considering the weight saving of omitting an axle (especially with a hybrid or EV conversion). The 5-ton (4500 kg) loaded mass doesn't need three axles... but a two-axle vehicle of this mass (such as that Iveco) needs higher-capacity axles.
Of course there might be lots of factors and possibilities that I'm missing.


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## Duncan (Dec 8, 2008)

Or you could leave all three axles and only drive two of them


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## brian_ (Feb 7, 2017)

Duncan said:


> Or you could leave all three axles and only drive two of them


That's fine on the street... in fact, on pavement it is only a 6X4 anyway, since the front axle drive is disconnected. Other vehicles with tandem rear axles often have a disconnect for the trailing axle so they become a 6X2 (only the leading rear axle driven) on pavement, but the C304 doesn't have this feature; it could be added for lower drag on the highway (for more range), either on the output from the leading rear axle or on the input to the trailing rear axle.

If it doesn't retain full 6X6 functionality when desired, I don't see any point in the vehicle at all - it exists to be a high-mobility off-highway truck.


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## brian_ (Feb 7, 2017)

goingbush said:


> I've already converted my LandRover & now I have plans on converting my Iveco Daily 4x4, a fair bit bigger than the Volvo and am thinking 160kwh will do me . I'll use 2 motors , one on the gearbox input to the transfer case and one the PTO output ( Both connect to the same shaft internally so turn at the same speed)


The Volvo FD 51 transfer case (or auxiliary gearbox, in the manual) has a similar PTO setup, although there is an add-on PTO gearbox to use it; this is probably typical of transfer cases in which front and rear outputs are in line with each other, offset from the transmission output shaft. An EV conversion of the C304 could use a similar approach to mount two motors, and a parallel hybrid conversion could use the PTO to connect the electric motor (while the engine and transmission remain in the original configuration).

Why use the transfer case with two motors? Is the idea just that a large enough single motor is not available?

Don, can I assume that the transfer case would be retained for the low-range gearing? In a typical transfer case - such as the one in the C304 - low range can only be used with the front axle output engaged (which the C304 can't use on dry pavement because it isn't like the permanent 4WD of the current Iveco Daily 4X4 transfer case with its centre differential), but that could be modified. It looks like current Daily transfer case also offers two reduction stages (four ratio combinations), so it's quite a useful transmission.


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## tmoney (Dec 6, 2018)

I think I will try to store most of the water tanks inside the cabin so I dont have to worry about heating the water tanks as well. I will try and leave the underneath between the frame open for the future battery modification.

I found a wrecked 2005 e320 cdi for sale i should be able to get it to my door for ~$4,000. It will be my engine and transmission but I will still need to source a transfer case. 

I believe it will fit because there are kits you can buy for the volvo that will drop in a om606 or om603 which are both 6cyl 3ish liter variants of mercedes diesels. So I would imagine I can make it fit

As for the EV. I will plan to keep certain storage open for batteries for the future. I still do like the idea of a small trailer with extra battery storage and a solar array that I can deploy and charge the 400mile range in a week or so. But 400 mile range of batteries right now would cost me too much for me to justify right now. However once its completed and being used I will be more inclined to spend a bit more.


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## brian_ (Feb 7, 2017)

tmoney said:


> I found a wrecked 2005 e320 cdi for sale i should be able to get it to my door for ~$4,000. It will be my engine and transmission but I will still need to source a transfer case.


Sounds good. 

It sounds like the original C304 transfer case isn't with the vehicle. I guess that makes the choices

find a Volvo transfer case and adapt it to the Mercedes transmission
high effort and expensive to adapt
no real reason to do this, since the vehicle is not a stock restoration

use a transfer case which bolts onto the Mercedes transmission
easy bolt-on, but...
there may be no suitable transfer case from this model (4Matic version), but the same transmission is probably used on many other models
mounting a transfer case may require a different tail housing
output to rear is likely in line with transmission output (centered), not in line with output to front (offset) to match the C304 axles

find a suitable divorced transfer case
mounts separately to vehicle frame, and connects to transmission with a short jointed shaft
works with any transmission
but not common, heavier, bulkier, requires additional shaft

If not using the original Volvo transfer case, you can get something that provides permanent/full-time 4WD (but is still lockable). If you might use it later with a single electric motor, it would be nice if it can run in low ratio on dry pavement (meaning it has a centre differential or allows reduction when not driving front axle).


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## goingbush (Jun 20, 2017)

brian_ said:


> The Volvo FD 51 transfer case (or auxiliary gearbox, in the manual) has a similar PTO setup, although there is an add-on PTO gearbox to use it; this is probably typical of transfer cases in which front and rear outputs are in line with each other, offset from the transmission output shaft. An EV conversion of the C304 could use a similar approach to mount two motors, and a parallel hybrid conversion could use the PTO to connect the electric motor (while the engine and transmission remain in the original configuration).
> 
> Why use the transfer case with two motors? Is the idea just that a large enough single motor is not available?
> 
> Don, can I assume that the transfer case would be retained for the low-range gearing? In a typical transfer case - such as the one in the C304 - low range can only be used with the front axle output engaged (which the C304 can't use on dry pavement because it isn't like the permanent 4WD of the current Iveco Daily 4X4 transfer case with its centre differential), but that could be modified. It looks like current Daily transfer case also offers two reduction stages (four ratio combinations), so it's quite a useful transmission.


Yes Brian, the Iveco TC is a divorced TC , it would be a reasonable solution for the Volvo. it has some design issues but I have overcome these . 
see here http://goingbush.com/iveco4.html 

Two small motors are better than one big motor plus the layout of the TC is ideally suited to two motors , or even keep a small diesel up front and electric at the rear.

Look here where a fellow owner had added a Telma Retarder to help with braking , now if that energy wasting retarder was a motor , how good would that be . Marcus is now kicking himself as he could have bought a Hyper9 and a load of Batteries for the $20k it cost for the retarder. 

https://youtu.be/SvJLherxBMU


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## brian_ (Feb 7, 2017)

goingbush said:


> Yes Brian, the Iveco TC is a divorced TC , it would be a reasonable solution for the Volvo. it has some design issues but I have overcome these .
> see here http://goingbush.com/iveco4.html
> 
> ... the layout of the TC is ideally suited to two motors , or even keep a small diesel up front and electric at the rear.


That's what I was thinking of in an earlier comment about a parallel hybrid configuration using the PTO (and the motor connection point). That works with both the original C304 hardware and the SCV transfer case in the Daily 4X4, as well as apparently old Land Rover transfer cases. Unfortunately, the Volvo unit isn't with this vehicle any more, and that very capable SCV unit is enormous and expensive. I don't know what's available at a moderate cost.



goingbush said:


> Look here where a fellow owner had added a Telma Retarder to help with braking , now if that energy wasting retarder was a motor , how good would that be . Marcus is now kicking himself as he could have bought a Hyper9 and a load of Batteries for the $20k it cost for the retarder.
> 
> https://youtu.be/SvJLherxBMU


Well that was an interesting detour... 
The retarder looks like a nice unit, but not $20K nice! (in anyone's dollars) Marcus does provide a nice illustration of how a motor could be mounted for a parallel hybrid, with regenerative braking.The arrangement couldn't be quite the same in the C304, because the shafts are too long: the engine plus transmission plus a shaft plus transfer case plus another shaft plus a motor would be longer than the space available from front axle to leading rear axle.

In general the idea of much lower than usual EV voltage doesn't seem appealing to me, but as moderate-power hybrid system with a battery used to run an inverter (and HV DC to ~12V DC converter) for RV use, the Hyper9 might make sense, and can exert a couple hundred newton-metres of retarding torque.


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## tmoney (Dec 6, 2018)

I do have the original equipment out of the volvo. I figured I wouldnt be using the transfer case because I thought I might have other options with the new engine and trans choice. I am sure I could find a way to adapt the original volvo transfer case. I would have to do some reading about it to see if its up to the task of an engine with much more HP and Torque.

I need to learn more about the different hybrid setups and about the components to do an electric swap. But the battery cost and performance is what has killed it for me. Which seems to be the biggest issue with electrics moving forward.


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