Mower based MV electrical design question

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Shoeshine
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Mower based MV electrical design question

Post by Shoeshine » Wed Feb 12, 2014 11:14 pm

OK so the donor vehicle for the 2014 small MV has been acquired... a grasshopper commercial zero turn mower.

23hp Briggs and Stratton ELS series engine driving two hydrostatic wheel motors. Drive train all settled. (well at least in progress)

Now comes the lighting question i.e. night licensing. The machine in question has a charging circuit, consisting of a multi-pole ring with coils of wire that is mounted inside the flywheel. Not something I have ever dealt with. As I understand it, this is just sufficient to keep the onboard 12v sealed battery charged for starting. No manual or specs that I have been able to find. I do however, want to create some lighting effects sufficient to illuminate this beast. I have on hand a couple of power chair batteries (12v 40amp hour each) that I am envisioning running the nighttime lights. I have removed the mower deck, as it is not in use for this MV. There is now a V-belt pulley available for use out of the underside of the engine(used to run the mower blades)

What is the feasibility of adding an alternator to keep a charge on these batteries?

I can do EL wire off these two batteries and last the week with a charge or two in camp. Downside being kind of dim. Would rather run a series of cold cathode bars like the stuff used in computer case mods, or similar lighting elements to get a brighter effect. Something with a significantly larger draw.

So my question is multi tier, can the type of charger on board adequately charge a couple more batteries wired in series? If not, is there an easily adaptable alternator that I could attach to the mower blade belt that would work? Sources? cost? How difficult is this build? (I am mechanically proficient, electrically not so much)

Regardless, this is in design stage. Maybe I am not thinking on this in the right way. Alternate ideas (no pun intended) welcomed.
Any thoughts or even links to more research would be greatly appreciated.

Thanks in advance
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Re: Mower based MV electrical design question

Post by GreyCoyote » Thu Feb 13, 2014 4:57 am

The charger you describe is rated about 10 amps total. It is only designed to power the blade clutch and recharge the starting battery. It isnt suitable for lighting, so you will need a real alternator.

If you want quiet, reliable power, consider building a small Honda/Yamaha/Etc generator into your design. These are very quiet and can put out far more juice than an alternator. Plus you can use them for power when you are back at camp. But if you want an alternator, GM makes one that has a built-in regulator and exposes just a single terminal (power output). Thses are available from 65 to over 200 amps and are bidirectional units (turn either way and it makes power).

Suggestion: the engine is designed to run at high throttle to cut grass, but you are not cutting grass. Drop the speed a bit for playa use and get better mileage. The limiting factor will be cooling. Spin it too slow under load and you will burn it up. There should be a sweet spot at about 2/3rds throttle where it will be happy and cut both noise and fuel use considerably.

Make provisions to blow the cooling fins out with compressed air. The playa dust will gleefully find any oily surface and coat it completely. Briggs mills are notorious leakers. You have been warned. :mrgreen:

Good luck! Sounds like an awesome bit of mischief is in the making!
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Re: Mower based MV electrical design question

Post by Shoeshine » Sun Feb 16, 2014 9:57 pm

Thanks Grey, appreciate the input.

We already have a Honda eu2k in camp so I'm not sure getting another for the MV would be the best bang for the buck. I have seen some knock-offs (talon, Honeywell, etc..) around 800-1000w in the $300 range. Anyone with experience with these? I understand that they will be noisier... but we are talking about something on an MV already making a fair bit of engine noise, not something running at 5AM in camp.'

have done some more research and have found several automotive models to be had for chump change ($20 at the U-pull it)

SO my question morphs into, alternator salvaged for next to no money but a more extensive build. or a turn key generator with more noise. also direct wire the genny to the lighting? or build in a battery to keep the light on when parked. what's needed in terms of a charge controller if I put the batteries inline?

thanks again,
Shoe

P.S. Good call on the throttle. I am already noticing that with the mower deck (and consummate power use) gone, I need to throttle the thing back, not only for fuel usage, but also for pure noise and "jerking" off a start.
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Re: Mower based MV electrical design question

Post by BBadger » Sun Feb 16, 2014 10:18 pm

You could also buy some deep-cycle batteries for the MV, and use the genny back at camp to charge them during the day. You'll have to budget your power at night though. Those cold cathodes use like 0.3Amp each; LED strands use quite a bit too.
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Re: Mower based MV electrical design question

Post by name redacted » Sun Feb 16, 2014 10:19 pm

You said jerking off....

Anyway, an alternator needs to spin at a fairly high rpm to be efficient. The question would be where you could run it from. You may need to overdrive it to get the rpm necessary.

I like the generator idea...
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Re: Mower based MV electrical design question

Post by GreyCoyote » Sat Mar 22, 2014 3:02 pm

Colonel Monk wrote: Battery of the Marine/RV - Starting/Deep-Cycle variety has a capacity of about 85 amp-hours (Ah). This means, it can put out 85 amps of power in one hour before it's dead (it will always be less) or it can produce much more power than that over time at a lower load - say like, 10A-20A.....
Just a quick correction to a great post: depending on the battery type, the AH rating is expressed at either 1/10th of the nameplate rating, or 1/20th. Go either side of that rating curve and things get very different.

Example: if you have a 100 AH battery, it will provide 10 amps for 10 hours (if its rated at the C/10 rate, which is typical). It will NOT produce 100 amps for 1 hour. In a like manner it will produce MORE than 1 amp for 100 hrs. The manufacturers produces curves to let you know how to rate expected performance on either side of the "standard" rating curve. Its important to get those curves and understand how they may impact your runtimes. :mrgreen:
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Re: Mower based MV electrical design question

Post by Elliot » Sat Mar 22, 2014 4:34 pm

The alternator that Captain Goddammit recommends is the General Motors CS-130. According to what I wrote down, these were used in late 1980s to early 1990s GM small cars and the Chevrolet S-10 pickup.

I can add that... the way they are used in cars, they connect with several wires. They must be converted to one-wire. This is done by replacing the (internal) regulator with a marine (boat) regulator, also called a self exiting -- SE -- regulator. This needs to be done by someone with the correct skills, but the regulator is not expensive.

:D

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Re: Mower based MV electrical design question

Post by Shoeshine » Sun Mar 23, 2014 1:11 am

Now Holy Crap!!

That is a damn sight of a post chock full of useful (and even better, actionable, information)

Thank You Cpt. Monk. ( & Grey and Elliot for clarifications)

The reason I am considering the alternator is there is that spot just itching for use i.e. the mower blade pulley. Easily mounted, easily changed to whatever size pulley needed to get needed rpm. There is the issue that until I get this thing built I am not sure at what portion of throttle it will run best. Long story, but I am running a set of sprockets w/ large roller chain to generate very low rpm/high torque. Regardless you are right, I have no lack of oomph to turn an alternator.

But like I said, actionable. I am not an automotive guy but this gives me some insight to look into the problem ...off to look up a bunch of specs and tap furiously at my calculator.

I do appreciate the input about real usage though. It's true that a good chunk of time on playa will probably be spent at rest. After all, cruising is a blast but the best part of TTITD for me is stopping to interact with all you glorious folk. I admit this is pushing me toward the turn-key solution of the small inverter/gen. When noise is not so much of an issue, It seems there are some honda eu1k clones that seem to have decent reviews barring db rating in the $3-500 range (not insignificant but also not huge when considering the cost of the project as a whole). I also like the idea that a dead starter battery can be solved with a can of gas and a brief wait.

Honestly, I might be overthinking this. My electrical draw shouldn't be enormous, I just want to have better capabilities than some EL wire and a pack of D-cells. As you said, headlights, significant glow, and perhaps a stereo.

But anyway... Damn... again... thank you
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Re: Mower based MV electrical design question

Post by GreyCoyote » Sun Mar 23, 2014 6:29 am

I want to go back to DaMonk's chart for a second. There is another key takeaway point in that chart that might have been missed.

Battery charging really shouldn't happen faster than the C/10 rate (ie, 1/10th of the nameplate AH rating. If you have a 100 AH rated battery, then your max charge current should be about 10 amps. In a perfect world you would actually charge at about C/20 to prevent outgassing, but nevermind that for now). So lets assume you have two of these 100 AH batteries as Monk suggests. That gives you a suggested charging current of 20 amps.

Now lets look at the alternator chart. Follow the 2000 rpm line upwards and you'll see even the smallest listed alternator at 2000 rpm gets you almost twice what you need. (Output is an even 40 amps). The higher-output alternators do even better at the same speed (about 70 amps). That is a LOT of current available, even at idle speed.

So the takeaway here is you don't need to spin that alternator fast at all to make enough current to both charge your batteries and power your lights/stereo at the same time. At a 2:1 pully ratio you could actually be at engine idle speed (about 1200 rpm on the crank, or 2400 rpm on the alternator) and get enough juice to do it all and then some.

I would consider pulling the fan off the alternator shaft and swap it for one with a very aggressive blade design. An alternator driven hard at low RPMs may tend to overheat, so you want to pull as much air though that thing as possible. Some summer-day testing with a stiff load and an IR thermometer might be a good idea before you take this to the playa. :mrgreen:

Alternatively, you could get a little Honda EU1000 or EU2000 coupled to a 30 amp charger and be done with it. :mrgreen:
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Re: Mower based MV electrical design question

Post by EspressoDude » Sun Mar 23, 2014 7:18 am

thoughts about the alternator fan: they can and do run HOT, but they are designed to sit behind a car radiator idling in traffic with the air conditioner, blower, stereo, and lights on; and have enough capacity to charge the battery. I would leave the alternator fan installed. The fan pulls air through the coils, not just over the alternator like an external fan would
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Re: Mower based MV electrical design question

Post by GreyCoyote » Sun Mar 23, 2014 10:38 am

EspressoDude: I agree completely. What I was suggesting was replace the stock fan with a more aggressive one. In other words, same location and still shaft driven.

The alternators found on older ambulances have exactly this mod. If the OP could find one of these, and just swap it onto the shaft, it would move more air.

The other mod is remote the diodes. This allows for much better cooling, but its a lot of work and futzing for what I suspect to be diminishing returns in this case. :mrgreen:
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Re: Mower based MV electrical design question

Post by Captain Goddammit » Fri Mar 28, 2014 8:41 pm

I'm gonna come back from the dead for long enough to answer this.
I have done both ideas here, a Honda EU generator aboard a mutant vehicle and added extra alternators with deep-cycle batteries and an inverter.
The alternator/battery/inverter system is hands down superior in every way! You're running an engine anyway, so why not use that power?
A mower with a ready made, ridiculously easy way to drive an alternator (the unused mower drive pulley) makes this an absolute no-brainer.

In my experience, on my mutant vehicle the Honda had issues getting choked up with playa dust. Since converting to alternators off the engine with deep-cycle batteries and a big inverter, I just magically have electricity, all the time.

I can go full-on electrical techno-speak but I'll keep this real-world simple as much as possible.

I use TWO CS-130 alternators. I like them because they make a lot of current at low speeds. They all come with serpentine-belt stye pulleys on them. You'll have to unbolt that and bolt on an old v-belt style pulley from some old alternator because your mower's drive pulley is probably a v-belt type. In actual practice on the playa, I can hold a 1000 watt 120-volt AC load through my inverter with the engine idling. I get them from junkyards for dirt cheap. I highly recommend a pair of alternators; you have the space and the power, why not. Even if you don't use all the power you could, it's a good idea because each one will be carrying a lighter load and will last longer. The playa also teaches you that redundant systems are a good idea. If one fries, you're still in business. I've had it happen.

You don't need to waste your money on any goddamm one-wire conversion. Wiring these things is extremely easy. There are four terminals on the alternators connector plug, you only use two of them - the "S" and the "L" terminals. The "S" terminal just needs to be wired directly to the alternator's Battery terminal.
The "L" needs to be hooked up to 12V power that is hot when the ignition key is ON. The only trick is you need to put a small 12-volt lamp inline with the "L" wire. You can use a small side-marker lamp or whatever from an auto parts store.
Yes, that lamp needs to be there… it originally would have been the "Alternator" warning lamp on the car's dashboard but it also acts as a resistor and prevents frying the regulator. The alternator won't function if that bulb isn't connected. They actually sell little wiring harnesses with the connector plug for a CS-130 and a resistor built in to make it completely "plug-and-play" but really, it's simple.
When I get the alternators out of the cars at the wrecking yard, I cut out the connector plug with it, or you can buy them new. They call it a "pigtail", it'll have the plug and a few inches of wire coming out of it.

So… "S" straight to the alternator's "BATTERY" terminal (the main power output) and "L" to switched 12V power, with a small 12V lamp inline with it. Easy.

Another on-playa in-practice lesson I learned is about inverters. Those shitty ultra-cheap ones are OK for incandescent lamps but they don't function well, if at all, with fluorescent lights and they don't work well with LEDs. You need a "Pure Sine Wave" inverter. NOT a "Modified Sine Wave" like those cheap pieces of shit the auto parts stores sell. The best deal I found was a Xantrex ProWatt SW. They make a ProWatt that isn't an "SW"… the "SW" means "Sine Wave". Don't get the non-"SW". I went with the 2000-watt model, it was about $300-ish from West Marine. They make smaller ones but they aren't that much cheaper.
There are a lot of cheap Chinese pure sine wave inverters on the market and according to al the reviews, they are crap. I have found it's cheaper to buy good stuff the first time.

The cheap inverters will make LEDs flicker annoyingly and only get about half-bright. Fluorescent lamps often won't "start up".

The most overlooked thing about inverters is that they can only put out what you put into them. It takes ten times the AMPS at 12 volts going in to make the same power going out at 120 volts. To put out 1000 watts from your inverter, you have to feed it almost 100 amps, and that requires BIG FAT battery cables, as short as possible. I use 2-gauge, and two of them. And it's not enough.

About lights: I like LEDS and fluorescents on MVs. You can get LED rope light around Christmas at Costco for cheap, or all year at Wally Mart, and fluorescents are cheap and very bright and have pretty low power draw for their output.

If you do the twin-CS130 alternator setup with a deep-cycle battery or two, you'll have plenty of power for all sorts of lighting, even cheap power-hungry incandescents. I just like the lower power draw of LEDs so I can run them longer when the engine is off.
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