Charging a High voltage DC battery bank...

[windstuffnow]

  I'm gathering parts for a winter project.  I purchased a 94 Chevy S10 a few months back and plan to convert it into a series hybrid although still sport the thoughts of a parallel system or the possibility of a paralell plug in.

  Anyway, contemplating charging the battery pack I realized I would be running the alternator at full load continuously if I only used a rectifier as a conversion from AC to DC.  I'm running the main electric drive at 144 volts, Fully charged should show a voltage of around 174 volts and equalizing should be at around 186 volts.

  So my question is, is there a simple controller available that would work with the high voltage DC and to break the circuit when it was charged.

  I've had thoughts of monitoring only one 12 volt pair and use a simple controller to drive a relay on the alternator.   This could incorporate a charge monitor as well as control the throttle position and/or shut the system down when its not needed.

  This is only if I decide to use a series hybrid system, a parallel system will only need to control the charge rate.  A parallel plug in won't require either.

  I'm not real sharp when it comes to electronics, I can identify most components and follow schematics but to work out the details on my own... I'm lost...

.

[RP]

A few questions/thoughts:

What will you use for an alternator?

For a series system, instead of regulating the alternator, regulate the throttle of the engine (or shut it off when charged).

A simple voltage divider made from resistors will drop that high voltage DC down to something managable by typical circuits.  For instance; connect a 10K resistor in series with a 90K resistor and hook the pair across your battery bank with one leg of the 10K hooked to ground and one leg of the 90K hooked to the positive.  The voltage at the junction of the two resistors will be 10% of the total or 14.4 volts which is quite managable by common circuits.

What do you plan to use for an engine?

Hope this helps

rp

[maker of toys]

Dan's rule of inventing:  never invent anything you can buy.

you might look into getting an integrated charger-controler for an EV, and modify that some to meet your needs;  the latest-generation controllers out there are pretty good, and there's not much point in reinventing that much of the wheel. some of them are even adaptable to a 'booster;' (a genset-on-a-trailer) -one of those controllers seems ideal for what you're contemplating. . .  you'd only have to invent the parts that make the s-10 engine declutch and shut down/restart.

If you're really into rolling-your-own:

one thing to remember about high voltage DC (above about 40 volts) is that DC arcs do not self-quench.  That means that you'll need contactors/ relays that are designed to break your voltage under load (in your case, figure on breaking 250Vdc. . .) not just whatever cheapo relay happens to be in the front of the junk drawer.  if you're set on unloading the alternator after the batteries have come up to charge, my recommendation is to kill the field first, then open the output. . . . and open the output BEFORE the recification happens, so that you are switching a zero-crossing current.  AC switchgear is much cheaper than DC on a per-amp basis.

(if you can swing the cost, there are a lot of solid-state relays out there that will switch up to 480Vac from a TTL signal. . .  some of them are good for 50 amps apiece or more.)

(I look forward to hearing how the project goes-  I've a couple people here that are thinking about having me do parallel hybrid/alternate fuel conversions on pickups-- if I can get enough time away from my real job.)

given gas prices, I could see making a tidy living at this sort of thing.

Dan

[thunderhead]

As I understand it, you're talking about a battery bank to power the car, and a genset (engine and alternator) to charge the batteries.

If you make your alternator voltage 110v or 220v, you can use EV charger components you can buy from your friendly neighbourhood EV shop.  (Try EV World, or Wilde, if you live in the US.)  That way you can also plug it into the mains for charging, so you don't burn anything for short journeys.

I think I'd make the genset removable, since gensets are useful elsewhere, and you can save the weight.

It sounds like a fun project, though: good luck.

[Nando]

Several questions:

What is the power you want to store (watts, amps etc).

What is the drive motor characteristics, is it a PMA or a Brush motor, are you going to have the drive motor as a generator when braking (dynamic or regenerative braking) ?.

What type of alternator are you using, voltage output and current

Are you going to use the house electricity to charge the battery bank ?.

One can charge a high voltage battery bank with the standard battery charging profile, but one needs to determine power limits into the battery and time as well.

So let me know what you need to give to you the necessary info.

There are several web pages that sell electric equipment to convert a gas car into a hybrid or an electric car -- that presently are quite busy due to the interest in converting cars into electric or hybrids.

Regards

Nando

[MelTx]

 I never built a EV either.But I have read somewhere that 3 wheel vehicles are subject to motorcycle rules and regs.When it comes time to insure, licence and inspect it for road use,you could save 100,000 dollars a day on fees and fines.You know the insane Oil-Burning dictator in the CasaBlanca, aint going to let you put nothing on the road that interupts their Petro-Revenue.

[windstuffnow]

  I'm looking at a few different diesels to use as the charging system and haven't decided on any of them as yet.  I'll most likely design an alternator to suit the needs for charging.

  Most of the "onboard" chargers for EV's are fairly expensive and only input around 1500 watts.  This makes it almost useless for using an onboard system unless you want it to run continuously... and defeats the main idea. There are more expensive units available that will charge at around 3000 watts, the cost of this defeats my prime objective of keeping the costs down.

  The goal here is to build a reliable conversion for less than 7000.00 and reach the 100 mpg mark.   Which is well within the grasp of todays technology.   Finding parts without the rediculous mark-up is a challenge in itself.

  I'm using an ADC FB14001B motor which I already have and adapting it to the 5 speed and utilizing the original clutch assembly.  

  If I continue with the series or parallel arrangement I will use 12v trojan 27 series batteries.  They are about 1/2 the Ah of the T105's and weigh very close to the same which cuts the storage weight by almost 1/2.  

  Also, by using the diesel it will run some accessories such as the power steering pump and vacuum pump along with a small alternator for the 12v system with provisions to drive the the second shaft on the ADC motor if needed.  

  At this point I'm still up in the air which direction it will take and some of the decisions will come down to cost and complexity.

  .

[kitno455]

ed- i dont know anything about this at all, but would it be possible to use your motor as a gen if you direct drive the other shaft with the diesel? then you dont need a sep. alt and a second set of large cables from the alt to batteries. charging would be hard to regulate, as it would be related to what gear you were in, unless you had a CVT or identical tranny between the ICE and the motor.

i am still confused as to how you intend to get 100mpg by adding the weight of the batteries and electric motor to the truck, without regenerative braking, i dont see how there is much more energy to be had. i guess you get to run the diesel in its optimum operating range, and the electric motor has a great torque curve, but in that case, why use the batteries at all? in that case you are looking at something a bit like hydrostatic drive, but with electrons instead of oil. (like how diesel locomotives work)

where does the energy advantage come from?

allan

[Bruce S]

Hello Ed;

  Hope you don't mind me putting my 1/2cents worth in.

I am in the midst of doing a similar project. I had to talk my nephew out of his little 91 Toyata first.:-))

Here's what I've been gathering up. The motor I plan on using is rated at 144Vdc mated with the two wheel drive 5 sp tranny. This I've chose more for simplicity that anything else.

I have learned from making up battery banks for our companies EV trike, that the motor and battery charger seems to like series sets. The pictures I have up on my diary has them in parallel then series, the ones that exploded were done in parallel then series. The ones we have now are done in series then parallel , have yet to blow up any, even during the same senario  that caused the first set to go.

I have also learned through asking; to use as a good rule of thumb for "HP" is for every 1000lbs you'll need 8HP to have a good balanced system.

I will be using the 1000s of NiCds we have here at work instead of sending them off to be recycled.

There is also two websites that I have been watching for a while. One is of a guy who did a similar project (using a newer truck) and he has used the same size motor for a few years with no problems.

The other website is evparts.com, they seem to be the defacto place to get quality ev parts. The prices are pretty good and the help staff have been able to answer all my questions without a hitch.

I plan on using a curtis charger and a few other items (home rebuilt) that I've gleened from blogs of people that have owned the Sparrow ZEVs.

The drive batteries will be series MGE cast offs, then pull those sets into parallel via cables.

 The NiCds come into place for on board charging.

The Curtis should handle the charging easily, but since the NiCds are free, I plan on using them through a simple 3000watt inverter to "ADD" distance charging .

Where are you going to locate all your batteries.

Seems Toyota, has a lot of room under the bed for multiple banks.

Getting the fund up for the motor/charger ( about $1200.00 up front for used stuff) is the biggie.

Hope some of this helps;

Bruce S

[windstuffnow]

  The motor can be used in regenerative braking but when you calculate the amount of energy you get back from that system it almost doesn't seem worth the extra complexity or cost of the controller to provide this system.  I live out in the stix and there are maybe 2 stop signs from here to town... not much benifit in that system.  You can save just as much by removing your foot from the throttle and judging your distance allowing the vehicle to use up the energy stored.  I've heard people say things about using the regenerative system to charge batteries while going down hill... well that may be so but you still have to power it over the next hill using up all that you've created plus some.   Experimenting with my gas S10 I've found you can absorb the energy of going down hill to crest the next with little to no power input.

  A better source of regeneration would be from the movement of your suspension.  Those are losses normally disipated in heat through your shocks and springs.  You have a certain amount of control over your horizontal movement but you don't have control of the vertical movement.   All roads have bumps, curves, contours etc so it makes a good place to capture normal losses without taking anything away from what you have.  

  The energy savings in a hybrid set up that is primarily driven by the electric motor is that the electric motor is in the 80% efficient range depending on how you drive.  The gas or diesel engines are most efficient when driven at a constant speed.  90% of your driving is out of the range of reasonable efficiency with either ICE type engine so your lucky to get 20% of the energy you put into it unless its driven on the hi-way most of the time at a constant speed.  Then you'll see upwards to around 25%.  So if you take a small diesel engine, say in the 12hp range and run it at a constant 1800 rpm driving a moderate constant load your using the engine at its peak efficiency burning very little fuel.  My 8hp diesel runs 6 hours on a gallon of fuel while driving a 3000 watt load. (give or take).

  Another place that seems to get overlooked is the air displacement behind the grill. Lots of aerodymic losses there.  Sure your car looks sleek and aerodynamic on the outside but what about the openings that allow the air to flow through the radiator and engine compartment.  I think 2 small wind turbines would go very well in that area since the large radiator will be removed.  A small turbine at 50 mph can make some pretty good energy, enough to keep the 12v system going and the main alternator will simply be freewheeling most of the time.  I think 5 to 10 amps should be reasonably easy to capture in that area and doesn't take anything away from the aerodynamics that isn't already lost.

  So basically if you look at all the losses, especially those that are usually taken for granted there are many ways to improve the vehicle's efficiency.  A 100 mpg vehicle should be a fairly easy task.  It's simply a group of smaller challenges.

.

[kitno455]

you dont need to sell me on your choice of hobby, who cares what i think- but....

i have some experience with CVT's- they provide the same benefit, without all the added weight of batteries and motor. the 'small things' you mention would benefit a CVT ICE vehicle too.

your belief in reduced efficiency at lower rpms leading to higher fuel consumption is a common myth. i took part in a series of experiments using a CVT to keep a tiny engine at torque peak. we found that overall consumption went up. think about it, yes, the engine has ~8% eff. at 500 rpm, but it is using almost no fuel at all! so keeping it wide open creeping thru the parking lot was using much more fuel.

what we finally ended up with was akin to hydrostatic vehicles, the engine is basically in a binary state, max efficiency rpm, or idling (though the max eff was actually a ramp related to loading)

the only major advantages your system appears to get is that you can charge the batteries via other means (cant make fuel quite as easily), and you can use a smaller ICE by using the battery bank to boost supply under load. but i am willing to bet that the added weight of the motor and batteries, and the added complexity (and danger!) of all that high voltage running around actually break even with a simple CVT.

my 2 pesos only, of course.

allan

[windstuffnow]

  I'm a little dense sometimes when it comes to remembering some of the Letter descriptions... brief me on CVT and I'll catch up.

  The statement on 8% efficiency and using very little fuel seems like a contradiction in itself.  A gallon of fuel contains about 40,000 watts.  You pay somewhere in the area of 2.75 a gallon for it.  So you get to use 3200 watts for every gallon you burn.  Or you take your 2.75 and use .22 of it and throw the rest away.  Even at 25% it seems like such a waste to me.  

  Yes you burn more fuel going faster but the engine is operating at a more efficient burn thus getting you more miles per gallon... doing more work for what your paying for.  If I idle my truck around town at 20 mph I get around 22 mpg, If I run it at 50-55 on the back roads to get where I want to go I get 37 mpg...  which is more efficient.  Still at 37 mpg I'm only getting a small portion of what I put in.  With the electric motor I get 80% of what I put into it so instead of 1100 watts per mile(mostly wasted) I only need 400 watts per mile to do the same work.  The accessories are driven by a much smaller ICE engine and it helps extend the range.

  Also, the engine that comes out of the truck is around 550 lbs, the electric motor weighs 140 lbs with the adaptor.  The diesel is around 140 lbs and the 12 batteries are around 800 lbs.  So I'm starting with a 3200 lbs truck pulling 550 out ( maybe more with the radiator, fuel and misc ICE components) and putting back in 1100 lbs bringing the truck up to around 3700 lbs.  So its not that drastic of a difference.  

  It will be interesting to see where it all comes out.  I'm really looking forward to the challenges ahead.

.

[ghurd]

Is there a 200V windmill in your future?

Talk about low line losses !  

G-

[windstuffnow]

  Yes, actually there is.   I've been working out some details for a HV turbine and it all seems quite do-able to charge the 144v battery bank.  

.

[ghurd]

A 200V conversion should be kind of easy?

I had an unloaded one pop 100PIV bridges with a 20" box fan blade.

Embarrassing for a 12V machine, LOL.

G-

[benjamindees]

I've thought about series hybrids before.  Lemme take a look at your numbers.

My 8hp diesel runs 6 hours on a gallon of fuel while driving a 3000 watt load.

That's about 4 horsepower.  You might try slightly different loads to see if you're at the optimum point on the efficiency scale.  Supposedly gas engines produce the best efficiency at their highest rpms, but diesels don't.

A gallon of diesel contains 139,000 btu.  That's 40,736 watt-hours of energy.  You've extracted (3000 * 6) 18,000 watt-hours from it.  This makes your diesel about 44% efficient.

By comparison, a gas engine may have an efficiency of 26%.  That means your diesel is (.44 - .26 / .26) 69% more efficient.  There are other factors, but if you start with a car that gets 30 mpg, you might get 50 mpg with the hybrid.

Also, I don't think you really need the transmission.  I'm no expert, but I think most electric conversions do away with it.

Here's something else to think about:  12 horsepower = 30,500 btu/hr = 0.265 gallons of gasoline (at 115,000 btu) per hour.  At 50 miles per gallon, 0.265 gallons of gasoline takes you 13.25 miles in an hour.  

I can't say I'm convinced by your other improvements, or that you'll get anywhere near 100 mpg.  Personally, I would start with a much smaller car, or at least something more aerodynamic.  But really the benefits of being able to charge from the grid, both cost and fuel security, sound like they make the project worthwhile.  Sounds like something I should think about again.