# Very Atypical Application Question: Genius Needed



## ElectricVirgin (Mar 27, 2011)

I have a very atypical application that I just applied for a patent on that I am having a very tough time getting some answers on; I have posed these application questions to a total of 7 different engineers in the EV industry but none have been able to answer the question yet. I just signed up on this forum in hopes that somebody may either be able to direct to me to right person or company -- or maybe even be able to answer it themselves. If somebody here can answer this question I would be eternally grateful. It's been three months of blank stares from everyone I've asked; 

1. This is a series-hybrid application (from what I understand) 

2. It involves an electric machine that will be permanently mounted to the bed of an ICE cargo van used as a "transport vehicle" for the machine. 

3. The machine has an occasional MAXIMUM horsepower requirement of 26 horsepower (under a full load) but an AVERAGE overall horsepower consumption of only 17 horsepower during actual operation. (averaged out)

4. The machine will only have access to a 110 volt 15 amp circuit for a battery charger - but will ALWAYS be plugged into this circuit during operation. There are no 240 volt 30 amp outlets anywhere on the ranch. 

5. The machine will only operate an average of 5 hours per day - but on rare occasion will require up to 7 hours of operation per day. 

6. The "transport vehicle" is a Ford or Chevy conventional cargo van and has two alternators; One alternator is truck's the stock alternator (which does not come into play in the application) and the second alternator is a specially adapted alternator/generator "piggyback" installation -- and is mounted with a custom bracket and installed next to the first alternator, using a longer serpentine belt. This "piggy-backed" alternator produces 260 amps at 14 volts (MAXIMUM) while the transport vehicle engine is driving (transporting) the machine from one end of the ranch to another. 

7. The average speed of the transport vehicle is 45 MPH while driving between job sites. When average idle speed and driving are calculated together, the piggy-backed generator will produce an AVERAGE of 210 amps and 13 volts. 

7. The actual AVERAGE daily run time of the truck's ICE engine is about 2.5 hours per day while driving between job-sites - and the average operation time per job is about 1.5 to 2.0 hours. On rare occasion - the machine will operate as many as 5 hours at one single job site. 

8. The machine will be plugged into a 110 volt 15 amp circuit for the battery charger every night for a minimum of 9 hours.

9. The ICE transport vehicle's engine cannot be running while the machine is in operation. (But the machine's battery charger can always be plugged in to a 110 v 15 amp circuit which are available everywhere on the ranch) 

10. It must be noted - The machine will ALWAYS be receiving power for the charging of it's batteries (even during operation) - 24 hours per day - 7 days per week from one of three different sources; Either 1: when it is plugged in overnight (110 volts access only) - or 2: while the machine is being transported between job-sites (from the piggy back 250 Amp alternator) OR 3: while the machine is in operation (from a conventional 110 volt 15 amp outlet).

11. My (hopeful) assumption regarding actual results is that the operator will leave in the morning and arrive at the first job site with a full charge from being charged overnight - He will arrive at the job-site, plug in the battery charger, turn the machine on - and even though he is receiving a trickle charge from a 110V battery charger, the battery consumption from the machine will cause him to leave the first job with only 80% battery capacity left by the end of the job. Then, he starts the truck engine up and drives 20 to 30 minutes to the next job (and due the piggy-back alternator/generator charger) will arrive at his second job with about 85% charge... By the time he finishes the second job he will be down to a 65% charge - but then he starts the vehicle engine and drives to the second job... arriving with a 70% charge... and so on. 


Here is the question; Do you think this can be done with a lead acid battery pack that weighs less than 1200 pounds? 

And if so - what do you think would be the correct type/size and configuration of components - (i.e. battery management system/ battery type/ charger type/ electric motor type etc.) 

I have designed and have similar patents in a different industry but my knowledge is limited to internal combustion engines. I am completely virgin in my knowledge of electricity (as you can tell). 

Thanks in advance to whatever genius can possibly answer these questions. 


I can be reached at 801 432 0759. Ask for the Electric Virgin.


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## major (Apr 4, 2008)

ElectricVirgin said:


> Here is the question; Do you think this can be done with a lead acid battery pack that weighs less than 1200 pounds?


Hi EV,

26 horsepower machine at 12 volts. No. Not practical, if at all possible. You need a higher voltage system to power the machine. Then it does sound like to me that it may be possible. Lead acid might not be the best choice if this has regular use and you anticipate a service life of more than a year.

I have other work today so don't have time to figure all the watt hours back and forth. But it isn't a real tough problem to figure the size battery needed. You'll likely need a higher voltage alternator piggybacked on your engine.

major


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## ElectricVirgin (Mar 27, 2011)

Sorry - I'm still learning the nomenclature of electricity. I don't expect this to be a 12 volt system. I have no idea what the right voltage would be for the best efficiency. I'm assuming that the final (mass produced) system will be more than 144 volts (or even more). The reason why I'm aiming at lead acid is because the product needs to have a maximum retail price point lower than $26,000 - including the non-electrical portion of the machine. The "non-electric" components of the machine will cost me nearly $11,000 in quantities of 200 units per year. 

This application is nearly identical to that of electric cars. The only difference is that I have the luxury of being able to plug the machine into a conventional 110 electrical outlet for "constant opportunity charging" while the machine is in use (and also an alternator/generator under the hood of the machine's transport vehicle to charge the battery pack while driving between job-sites). 

Imagine a hybrid-electric vehicle like the Chevy Volt with a 300 mile long extension cord (and a _really_ fast midget running behind the car to keep the cord from getting tangled up on the freeway) lol -  and it will be easy to understand what Im trying to pull off. 

I didn't expect to power the machine with 12 volts. Sorry for the confusion. 

Thanks.


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## dtbaker (Jan 5, 2008)

a couple things you need to know to figure the size of battery pack you need....

- using a 15amp 110v circuit through a normal battery pack charger is going to put in about 1kW to 1.25kW per hour.

- running your machine at 17hp-26hp is going to be pulling about 15kW

...so for every hour of operation you will use about 14kWhr of battery, even when plugged in and charging on 110v. Every 14kWhr of battery is going to cost pretty close to $6k, be about the size of a large suitcase, and weigh about 300#. If you are talking 5 hours of operation, you'll need $30k in LiFePO4 prismatic (large format) batteries; and probably have to have separate chargers for each 'pack' if you need to charge the whole thing back up at night in 9 hours. 

The charge you could pull from truck while driving between jobs won't make much of a dent, and cost a fair bit to set up... probably not worth it.

I would not even consider Lead for this application.

Without knowing any more about it, I would consider making some kind of PTO from the vehicle's combustion engine, or an old-tech belt drive you could power with the vehicle wheels.


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## rfhendrix (Jan 24, 2011)

A couple of things to consider:

1. How much trouble to upgrade your ranch outlets to 20 Amp? If the wires are already #12 then you just have to change the breakers. Also it may be possible to use the existing wires and convert to 220 volt but at only 20 Amps which would still double the capacity (if 220 is available at the main panel box). If you are not sure have an electrician check it out. If I were there I would do it for free as it is just a quick inspection inside the panels.

2. As dtbaker suggested figure out a way to get more juice from the vehicle.

But don't do anything until you run the numbers. Off hand it seems like you are asking quite a bit from the batteries. Also you might consider using the transport vehicle as a kind of external power supply i.e., carry more batteries (since the engine can't be running).


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## Duncan (Dec 8, 2008)

Hi Virgin

Sorry but it ain't gonna fly

17Hp = 12.75Kw
110v - 15 amps = 1,6Kw (1,5Kw available if you'r lucky)

12.75 - 1.5 = 11.25Kw x 7 hours = 78.75 Kwhrs
12.75 - 1.5 = 11.25Kw x 5 hours = 56.25 Kwhrs

Truck - 210a x 14 v = 3Kw for 2.5 hours = 7.5Kwhrs

78.75 - 7.5 = 71.25Kwhrs needed for the day - batteries can't be completely discharged

71.25 x 1.2 = 86 Kwhrs

Lithiums - 86Kwhrs = ~860 Kg = 1892lbs - lead would be 5 x this 9,000lbs
Lithium - ~ $350/Kwhr x 86Kwhrs = $30,100

It gets worse
Overnight charge - 1.5Kw x 9 hours = 14.5Kwhrs - a wee tadge short of the 71Kwhrs needed

*if you can get 230 v and 20 amps*

17Hp = 12.75Kw
230v - 20 amps = 4,6Kw (4,5Kw available if you'r lucky)

12.75 - 4.5 = 8.25Kw x 7 hours = 57.75 Kwhrs
12.75 - 4.5 = 8.25Kw x 5 hours = 41.25 Kwhrs - concentrate on the shorter day

Truck - 210a x 14 v = 3Kw for 2.5 hours = 7.5Kwhrs

41.25 - 7.5 = 33.75Kwhrs needed for the day - batteries can't be completely discharged

33.75 x 1.2 = 40.5 Kwhrs

Lithiums - 40Kwhrs = ~400 Kg = 880 lbs - lead would be 5 x this 4,000lbs
Lithium - ~ $350/Kwhr x 40.5Kwhrs = $14,200


Overnight charge - 4.5Kw x 9 hours = 40.5Kwhrs - just enough for the 33Kwhrs needed


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## ElectricVirgin (Mar 27, 2011)

Wow! Had I known this forum existed two months ago... 

OK - I'm getting a much clearer picture now. I've also found a machine over the weekend that has virtually identical "actual operation" characteristics and horsepower requirements as mine (but in a non-battery powered, stationary configuration). It uses a, "Baldor 208/230/460 volt, 15 horsepower 3 phase electric motor, 43/40.6/20.3 amps". I have emailed the manufacturer and asked them if they can quote me an actual average Kwh consumption while the machine is in "actual" operation. 

I suspect that the overall "actual" average kwh consumption may be as low as 7 or 8 while the machine is actually in operation. I will post the actual consumption as soon as they respond. 

Having read all of your responses it is becoming apparent to me that Lithium Ion is a must - but I'm still not 100% sure - since the actual kwh consumption during actual machine operation _may_ be much less than I thought. Carrying extra weight is not as big of a concern here as eliminating the ICE operating costs (which are near $4,400/yr per machine currently - including gasoline fuel/maintenance, repair and downtime). With over 1,100 of these units running around a 2,940 hectacre ranch you can imagine the costs. 

220 volt is an impossibility anywhere at the ranch with the exception of three locations (at opposite ends and on the outskirts of the ranch) that we know we can definitely convert from 110 to 220. It appears that we will have to construct some new buildings (just "car-ports") and convert the wiring -- and this will have to be where the transport vehicles will have to be stored overnight for the "deep charge". However, during machine operation we will never have access to anything other than 110 volts, 15 amps. 

Having said that - (and after the "Come to Jesus" meeting ya'll just gave me)  I'm also thinking that it may be a better way to go about this by using the same motor that powers the machine as a "generator" while the transport vehicle is driving between the job sites - (instead of the "Zena" high output alternator/generator I was contemplating prior to the Come to Jesus meeting). 

Which brings me to the next question;


Does there exist a motor that has drive shafts on both ends so that I can hook one end (with an electric clutch) to the ICE transport vehicle (by means of a PTO shaft) to charge the battery pack while they are driving between sites - and then hook the other end to the machine -- And if the answer to that is yes - am I back on track again? 

In other words, just how much juice can be generated from the same 15 hp motor to charge the battery pack (when turned by the PTO shaft at the same speed as it is turned during actual machine use operating) when it's being used as a generator? Is it 1 to 1? Is it significant?

Thanks so much - I am VERY grateful - Lordy - It's like having a complete "Hot Shot" engineering staff at my disposal here.


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## dtbaker (Jan 5, 2008)

ElectricVirgin said:


> ...found a machine over the weekend that has virtually identical "actual operation" characteristics and horsepower requirements as mine (but in a non-battery powered, stationary configuration). It uses a, "Baldor 208/230/460 volt, 15 horsepower 3 phase electric motor, 43/40.6/20.3 amps". I have emailed the manufacturer and asked them if they can quote me an actual average Kwh consumption while the machine is in "actual" operation.



actual consumption totally depends on how much work you are asking it to do. The rating on the plate is just the MAXIMUM continuous work before you have thermal issues on electric motors. Gasoline hp ratings are far different than electric; gas usually states peak hp and electric shows max continuous,( and peak can be up to 3x continuous). 

How are you calculating how much work your device actually does? This might change your requirements significantly.

As far as a generator while in transport.... this might be easiest using an AC motor setup, and creating some kind of PTO. It would add a significant load to your truck during transport, basically feel like you're driving uphill all the time. Maybe you could add a belt-drive up thru bed of truck off driveshaft; but its gonna be a funky thing!

The cost/hr operation with the LiFePO4 ends up being half of Lead because of the longer life. smaller physical size, lower weight, and almost no voltage sag are just side benefits.

... how often does your truck/device return to the same site? or, is it not a set fixed sites at all? It may be better to have trailers containing packs of batteries and a solar panel setup; charge the battery pack for (days) and then deplete it when you visit the site... perhaps moving it to NEXT site to charge in the meantime.


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## major (Apr 4, 2008)

ElectricVirgin said:


> In other words, just how much juice can be generated from the same 15 hp motor to charge the battery pack (when turned by the PTO shaft at the same speed as it is turned during actual machine use operating) when it's being used as a generator? Is it 1 to 1? Is it significant?


Hi EV,

I've done this off the PTO with an induction motor and inverter. Figure it can generate at the same power level as it can motor. Actually it can do a little better, but figure about the same if you're talking about the same shaft RPM.

major


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## ElectricVirgin (Mar 27, 2011)

I still do not have an actual "real world" Kwh consumption figure of the application, (I should have this number by this Friday - or next Monday) but it has been narrowed down to between 7 and 11. So, for the sake of figuring until I get the actual kwh consumption number - I am running calculations based on 10 KWh per hour for each hour of machine operation; Here's the direction I intend on heading unless anyone can point out the flaw in my logic; 

Can I run a driveshaft from the engine of the van into one side of a double shaft ac induction motor (with an electric clutch on the ICE end) and then couple the other shaft end of the AC induction motor directly into the machine (with another electric clutch on that end) so that when the lithium battery pack runs low, the engine of the van automatically starts up and then starts turning the shaft, motor and the machine all at the same time? (They were hell bent on not wanting to ever run the ICE during machine operation but I have shown them the numbers you have all provided me and they understand now that it may be unavoidable unless they want to spend $30k worth of lithium batteries per machine.) 

The average job takes them about two hours. (Sometimes it takes 6 or 7 and sometimes it's only 30 minutes) but those conditions are very rare. 

The end result (if I am understanding ya'll correctly) would be that the machine would be powered 100% electric for the first two hours, and then, when the lithium battery charge drops to say, 20% capacity remaining - the ICE engine would automatically start up and be turning the PTO shaft, electric motor and the machine (with both clutches engaged) all at the same time. I understand that this would also require a device that will increase the ICE transport vehicle's RPM's to around 1500 RPM since engine idle speed isn't quite enough for 15 horsepower. 

Then, they leave the job site and drive (approximately) 30 minutes to the next job site. During those 30 minutes, (sometimes its as much as 60 minutes) the clutch on the ICE end of the shaft would be engaged, turning the motor as a generator - but the "machine end" clutch would be DISengaged (so that the machine is not running while they are driving around the ranch). *Would this result in a "rapid charging" of the battery pack? *

Under the conditions of driving between job sites the ICE PTO shaft would be turning as fast as 6,500 RPM - but during machine operation the shaft would only be turning at 1500 RPM (to produce the 15 Hp). The average PTO shaft speed while driving around would be probably around 4000 RPM for 30 minutes. 

I am assuming that if an electric motor running at 1500 RPM to power the machine requires around 10KWH per hour from a lithium battery pack - that turning it at 3000-6000 RPM from the ICE engine while driving between job sites for 30 minutes (or more) would "rapid charge" the battery pack to a near state of full recharge...(so that the next job is started with full (or near full) charge.)

* 1. Under the conditions in which the machine has been in operation for more than two hours - and the ICE PTO has to "kick in" because the remaining battery power is running too low (20%?)- would the ICE engine have to work twice as hard to power both the machine AND the electric motor at the same time? I mean - if the machine requires 15 HP to run, and the motor (used as a generator) also requires 15 HP to generate electricity, - does this mean that it would be drawing 30 HP from the ICE PTO shaft? *

* 2. Also, under the above stated conditions (ICE PTO turning both the ac motor AND the machine simultaneously) would these conditions also be charging the battery pack at the same time? Or - can the electric motor actually PRODUCE a small portion of power to run the machine at the same time it is RECEIVING a portion of power from the ICE PTO shaft? * (The reason I ask is because the PTO shaft/electric clutch can only handle so much when the ICE is only running at 1500 RPM's - they are not amiable to running the ICE faster than 1500 RPM while it's stationary - and I agree with them.)

* 3. Also, does anyone know what direction I should be looking for a double shaft AC motor that can produce 15 horsepower when run at 1500 RPM - but yet produce "rapid charging" type KWHours to charge Lithium (when run between 4000 and 6000 RPM) from an ICE PTO shaft while driving between job-sites? This motor would most likely require the capability of overhang loads because I assume that either one (or both) shaft ends may require V belts to get the ratios correct.* 

*4. Also, Is there any reason for me to be looking at "Ultra-capacitors" or "Flywheel" energy storage for this application?* If you remember from the above posts - the battery pack will ALWAYS be receiving a charge from one of three sources -- either from the 220V deep charge overnight OR the 110V trickle charge during operation OR from a generator powered from the ICE PTO shaft. 

Again - your expertise is SO appreciated here.


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## crap (Dec 5, 2009)

I think you are starting to arrive at a reasonable solution. Upgraded overnight charging capacity will help a lot. The ability to kick in the ICE during longer jobs will make sure it can always get the job done, at a reasonable price. The double shaft solution with two clutches should work fine. 

As to the question if the ICE will have to deliver 30kW instead of 15kW when batteries run out, the answer is no. Not unless you want it to. If you use an AC induction motor you can just disconnect the inverter and it will spin freely, not consuming any power to speak of. It will however also be possible to pull those 30kW and charge the battery while running the machine at the same time, enabling the vehicle to arrive at the next job with a higher state of charge, or if you want the ICE to run just half the time (run it for 30 mins then turn it of and run electric for another 30 mins, and so on).

just make sure your inverter can handle regenerative braking at rpm's way above nominal, so it doesn't burn out while driving between jobs. The motor itself should have little or no problems with double or triple rpm's, or being used as a generator/rapid charger.

As for ultracapacitors or flywheels, I say no.


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## ElectricVirgin (Mar 27, 2011)

OK Everyone. I finally got the answer to actual average KWH consumption! 

The machine will consume an average of 8KWH per hour of use. 

Now that I know this (and in combination with all of your help and expertise) I am making the following assumptions; 

1. A smaller lithium ion battery pack of 10 - 16 amp hours will be sufficient. 

2. The engine of the van will automatically start up at about the 1.0 to 2.0 hour point and begin supplying *some* of its fossil fuel power to the machine and *some* of its fossil fuel to recharge to the battery pack. 

3. The ICE of the van can run at idle and I will not need to use any device to raise the RPM's of the ICE to accomplish the end result Im looking for. 

4. While driving between job-sites the ICE will be turning a motor as a generator that will be able to rapid *charge* the battery pack at a rate of at least twice the rate of* consumption* when compared to when the machine is running. (In other words, every 10 minutes of driving will give me about 20 minutes of machine operation.) I assume this because while driving, the generator will be turning at two to three times the speed as is required to operate the machine. 

5. There exists a method or device to automatically determine the SOC of the Lithium pack that will request different amounts of energy from the generator when it is in use, which would be dependent on the conditions; For example: A full state of charge (from an overnight "deep" charge) while driving to the first job will not put a load on the ICE or generator at all while driving -- OR if the lithium pack is only at 20% state of charge, it will place a heavy request of energy on the generator while driving between sites and even heavier request when they let their foot off the gas pedal as regenerative braking. 

Somebody please correct me on any of the above if necessary.


So the questions remaining now are:


1. Should I use a double shaft motor mounted to the floor between the seats of the van that has one end connected to the machine and the other end connected to the ICE? (Both ends would have clutches) *Or* should I place one motor under the hood and use a separate motor to power the machine? 

2. If I use two sep motors does each motor need its own controller? 

3. Should I use AC or DC? (Cost IS a factor) 

4. Where should I be looking to purchase quantity discounts of lithium batteries and motors?

5. What brand/make of lithium batteries / motors / controllers should I be entertaining? 

6. Is lead acid still not feasible now? It looks like to me that the batteries could be used in such a way as a car battery in that it may never see much of a full discharge...

Thanks again in advance!


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## Duncan (Dec 8, 2008)

Hi Virgin

I was going to repeat the calculations with your new numbers but I can't pull the relevant numbers

Please give
- Power required
- time taken
- timeline for a days work

And I will have a look and see if its feasible


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## ElectricVirgin (Mar 27, 2011)

Duncan said:


> Hi Virgin
> 
> I was going to repeat the calculations with your new numbers but I can't pull the relevant numbers
> 
> ...


Hey Duncan! I didn't realize you had posted a response until today. Thanks. I usually get an email when somebody responds but I didn't this time for some reason. 

POWER REQUIRED: The power required is 8.4 kw for each hour the machine is being run. This figure was obtained by doing a time test. The machine occasionally peaks at 12 kwh under heavy load and as low as 6kw... But the AVERAGE consumption of the machine under real world conditions is 8.4 kw per hour of use. 

TIME TAKEN: The AVERAGE job duration is 2.5 hours. Sometimes its takes them 30 minutes and sometimes it takes 6 hours to complete a single job.

TIMELINE FOR A DAYS WORK: The average machine runs 4.0 hours per day. The average miles driven on the vans is 50 miles per day. 


NEW INFORMATION:

They have agreed to allow the van engine to IDLE during operation if I can provide them a satisfactory ROI proposal. 

I have found a dual alternator bracket kit and alternator that produces 202 AMPS at 14.4 volts at IDLE. (840 RPM ICE speed) This burns approximately 0.425 gallons of gasoline per hour. (They are currently burning 1.68 GPH) (While driving between jobs this alternator will produce 245 amps of recharge power.) 

What I am considering now is mounting a dual shaft motor (with clutches on both ends) to the bed of the van and running a serpentine belt through the floor of the van directly to the driveshaft of the van to assist the van ICE while driving between job sites and also provide regenerative braking to charge the battery pack. 

The other (clutched) shaft of the motor will power the machine (which consumes 8.4 kw average per hour) when the van is stationary. 

The machine will be plugged into a conventional 110v 15 Amp circuit during operation and provide 1.25 kw to recharge the battery pack and the (piggybacked) alternator will provide an additional 2.8 kw of charging for a total of 4kw per hour.

A switch will be on the dash that provides the user the option of optimal "driving economy mode" or "machine economy mode". For example: If they know they will be putting 6 hours on the machine (a big day) the switch will be positioned in "machine economy mode" and the electric motor will not ever engage to assist the ICE with any help for driving economy. It will however use regenerative braking to charge the battery pack when the operator lets his foot off the gas pedal.

Conversely, If they are on the way home from the last job of the day (or for example if they know that they only have one 1.5 hour job to do for the whole day) they will position the switch to "driving economy mode" which will use the electric motor (driven via serpentine belt to the driveshaft of the van) to "assist" the gas engine for speeds less than 35 MPH. 

I understand that Netgain makes a computer device called "EMIS" that does something very similar to what I am talking about. 


The only questions I am still in the dark about is:

1. Can I charge a battery pack from the "piggyback" second alternator AND from a 110v 15A charger at the *same time* while the machine is in operation? And similarly, can the piggyback alternator AND the electric motor (in regen mode) supply charging to the same battery bank at the same time while driving? 

2. Can I run a serpentine belt/clutch system and "side load" the shafts of an AC-50 or a Netgain Warp motor -- or do these types of motors require direct coupling?

3. About 40% of their job sites have electric dryers that are used to dry employee uniforms and are 30 amp 240 volt plugs. They wont allow for any rewiring though. Can a battery charger be plugged into a standard electric dryer outlet for those few occasions?


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## karmann eclectric (Mar 26, 2008)

Hey Virg., I'm late to the party so this may have been covered, but it appears that those dryer outlets are a godsend. A PFC-30 charger would allow you to max out those 240V 30A sources and refill batteries in a hurry, or 7200W would about cover the machine's average load while running (but not run and charge at the same time). A PFC30 charger can also treat the 120V 15A circuits as tenderly as needed. The Manzanita chargers can also be used as a big DC-DC, but that's recommended at voltages over 60, IIRC.. (disclaimer- no financial interest in Manzanita Micro, just a satisfied customer) Also, if the 40% of sites that have 240V 30A service are fairly evenly distributed, that could reduce the need for an increasingly complicated DIY hybrid vehicle/PTO/genset.


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## ElectricVirgin (Mar 27, 2011)

Are you saying that I can't hook up a charger to charge a battery pack at the same time I'm drawing current from it to operate the machine?


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## karmann eclectric (Mar 26, 2008)

ElectricVirgin said:


> Are you saying that I can't hook up a charger to charge a battery pack at the same time I'm drawing current from it to operate the machine?


 No, that's not a problem at all, just that even the 240V 30A circuit can't provide enough power to run the both machine and the battery charger at the same time, so it would take the load off the batteries, but not allow you add charge to them....


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## ElectricVirgin (Mar 27, 2011)

Oh! I understand now. Thanks for the clarification...

You're not the first person who has raved about Manzanita chargers. Seems everybody loves em. 

I've always wondered though...

Why don't people just use a small AC 110v electric motor to a power a standard "off the shelf" 250 amp 14.4 volt automotive alternator to charge battery packs?

It's less than $300 bones for a high quality alternator and another $500 for an electric motor to run it. 

I think I read somewhere that alternators just start free spinning when they sense the voltage has reached 14.4.

What am I missing?


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## Duncan (Dec 8, 2008)

Hi Virgin

Some assumptions and a plan,

First principle KISS

Standard Day
2.5 hrs at 8.4Kw = 21Kwhrs
Assume that during the day you are plugged into a 110v outlet for 4 hours 
1.3Kw x 4 hrs = 5.2Kwhrs
21Kwhrs – 5.2Kwhrs = 15.8Kwhrs
If you have a 16Kwhrs pack you are sweet, don’t need to use IC power at all

Running a bit short? – use the idle generator, or take a break while the charger catches up
16kwhrs at 80% = 20Kwhrs – need a 20Kwhrs battery pack

Big day 
6 hrs at 8.4Kw = 50.4Kwhrs
50.4Kwhrs – 16Kwhrs (pack) = 35Kwhrs needed
You know it’s a big day so you will use idle power as well
110v + Idle power = 4Kw
If you can be plugged in for 9 hours (35Kwhrs/4kw) – then you are OK

You would run for three hours – have a break (but leave the unit charging and idling) then complete the run when the unit was charged up a bit 

If you can find a 230v 30amp = 6.9Kw – then you don’t need to idle! Or take a break 

You then don’t need all of the elaborate clutching, belt drives…(KISS)

Suggest use 48v and a standard fork lift DC series motor
Motor - $3000,
Controller $2,000
Batteries $6,000 

If you really need to you can run the motor as a generator (at 48volts you won't need to advance the brushes) - but if you can KISS.....

The forklift motor will have brushes -but in this application it will be just like a forklift and will have a life in the decades! - may need to change the brushes every ten years or so


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## karmann eclectric (Mar 26, 2008)

ElectricVirgin said:


> Why don't people just use a small AC 110v electric motor to a power a standard "off the shelf" 250 amp 14.4 volt automotive alternator to charge battery packs?
> It's less than $300 bones for a high quality alternator and another $500 for an electric motor to run it.
> I think I read somewhere that alternators just start free spinning when they sense the voltage has reached 14.4.
> What am I missing?


A lot of low-dollar conversions use the original alternator to keep the 12V house battery charged, which works just fine. However, my dc-dc converter cost much less than good alternator setup and my car has no belts or pulleys as a result. Folks don't use motor-generators to charge traction packs because anyone with a substantial load is using at least 36 or 48 volts, because passing 8.4 kW at 12V means 700 amps. Stepping up to a 48 volt system would only require 175 amps. That means smaller wires and contactors, and less stress on the batteries (though you'll have 4x the battery quantity). A higher voltage system can provide the same power for less overall cost, especially when you're talking about passing more amps in the low voltage option than is possible with most 12V components. Also, losses are higher in a motor/generator setup than with a battery charger, and it'll take longer to charge the battery with a given amount of available 120V current....


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