battery chargers

seeker
seeker Registered Users Posts: 8
My Gawd, there's so dern much to learn!

I see posts about how to charge batteries when solar won't, mostly talking about gensets.

Is there any merit in mounting a number of standard car alternators to a small, stationary car motor for battery charging when the sun goes down, rather than using a genset and standalone chargers?

I believe a car engine would be more durable than any engine on a modestly-priced genset, and probably also cleaner and quieter.

I suspect a lot of the solar systems use exotic batteries, and wonder if these can even be charged by a car.... also, is it 'totally' nixed to used automotive/marine deep discharge batts for solar power systems?

(Yes, Rube Goldberg was a relative of mine, back aways....)

seeker:blush:

Comments

  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: battery chargers

    From an energy efficiency point of view, using a car engine to run an alternator would be hugely inefficient. It might use 1 or2% of fuel to actually charge the battery. (just a guess) A Honda Eu series driving a efficient charger with good power factor would be way more efficient.

    As for the "exoticness" of PV solar batteries,, I suggest that you read some of the following:http://www.windsun.com/Batteries/Battery_FAQ.htm#Lifespan%20of%20Batteries
    http://www.batterystuff.com/tutorial_battery.html
    http://www.batteryfaq.org/

    If you do, you will learn that these batteries are not really exotic,, but rather quite conventional, but they require proper voltages and amperages to charge properly, efficiently and without damage.

    Good luck,

    Icarus
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: battery chargers

    in actuality the voltages presented by car alternator systems don't properly charge batteries as the voltage never gets high enough to finish the job.
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    Re: battery chargers

    Hahaha. Well a true Rube would tweak the voltage regulators on the car alternators.

    Mounting a bunch of alternators on a car engine...I'm picturing it in my mind and it looks pretty whacky.

    If you're gonna Rube it up with car alternators, first do a google for "homemade generator" - pretty much everything has been tried at one time or another.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: battery chargers

    All comes down to how much power do you need, what kind of room do you have, what fuels available, etc...

    For me, I choose to go with a small genset because all I have to power is a fridge, freezer, and a few lights/radio... I don't have to power a A/C unit.

    Most gensets can be pretty efficient at 50%-100% load... When you drop below those points, you are using less power, but just as much fuel--or in the case of a diesel generator--they can start to "coke up" at low power.

    A "small" emergency 10kW home generator can consume ~1 gallon per hour of fuel between 0-50% load...

    Now, if you don't have power, you could justify running it 12-24 hours per day at $36-$72 (@$3.00 per gallon gasoline or propane equivalent)...

    But, when you look at needing to feed it 12-24 gallons of fuel per day (if you are not powering with natural gas)--that becomes a huge problem.

    Instead, I can power a fridge+freezer and a few lights for less than 2 gallons per day (eu2000i @ 400 watts; 15 hours on 1.1 gallons of fuel)...

    Now, storing 20 gallons of fuel, plus siphoning the family car--and I can easily go a week or two without a problem.

    Any home made system is probably going to use 2x, or more, the amount of fuel as the Honda eu... And be noisier too.

    For me, it is preparing for an earthquake... I don't have ice storms, hurricanes, etc. to worry about (or have a few days warning). If we are without power for more than 5 days--we probably have bigger problems (water, food, security).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    Re: battery chargers

    It's funny you bring this up, just last week I was doing some testing on my backup to my backup power plan.

    While I agree with what Bill said I do have a setup to go the "car" route. We have a VW Jetta TDI (diesel) with a 120 amp alternator. I bought a xantrex xpower 1750w inverter, 1500w continuous, and connect that to the idling diesel. This in turn feeds an iota 5415, 54 volt at 15 amp to charge our 24kw battery bank in a pinch. This setup works fine with the feed from the mod sine wave inverter to the charger.

    I tried this running on our van with an 80 amp alternator; it works for about 10 minutes before the low battery cutout shuts down the inverter. If I increase the rpm to about 1500 I can run about 45 minutes before I hit the low battery cut out. With the van running this way it was consuming .33 gallons per hour (according to a calibrated scangauge) or about 2400 watts per gallon of gasoline.

    Running the same setup on the TDI with the engine idling at 908 rpm and it will run the load as long as I have fuel. The TDI consumes far less fuel, about .13 gallons per hour. So on the TDI I would get about 6000 watts per gallon of diesel. The other big advantage is the TDI is used regularly and kept in working order because of its primary use.

    The initial reason I bought this setup was to run things from the car in a power outage or away from available power source and be able to power chargers or portable equipment. I tried and it does actually run our 18 inch electric chain saw, skill saw and jig saw. I keep that inverter in the trunk along with a couple of cords and a dreaded male to male jumper. I powered our uncles fridge and freezer two summers ago to get them cold again while he waited for power to come back on.

    Bill if you had to guess what would the Honda 2000i pulling 800 watts consume in an hour? Ultimately my plan is to use a 2000i in place of an idling TDI, but in a pinch...
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    Re: battery chargers
    Brock wrote: »
    Bill if you had to guess what would the Honda 2000i pulling 800 watts consume in an hour? Ultimately my plan is to use a 2000i in place of an idling TDI, but in a pinch...

    http://www.reviewcentre.com/review175467.html

    FatMike says:

    "My neighbour lives alone and had a light load for Wilma, she ran 24 hours a day heated the water heater for 2 hours a day and used less than 3 gallons a day. Without the water heater she used 2.25 gallons per day. Another friend finally had enough with his 4400 watt Homelite with a Briggs engine (7 gallons a day), and bought a eu2000i he runs a full size fridge and a full size freezer on the Honda, plus lights and a TV at night he gets 10 hours a tank filled all the way to the top, still less than 3 gallons a day."

    He also says:

    "This is the deal with these generators, they are 1600 watts continuous and 2000 watts peak for up to 30 minutes."

    And:

    "This year I ran my 20 year old wall unit A/C it draws 1032 watts, it used 1 gallon for 8 hours of run time."


    How does that compare with the VW? I leave the math to you.
  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    Re: battery chargers

    So the Honda was over 8000 watts per gallon, which I totally believe. I know our diesel consumes less fuel idling than a gasser, but it can't compete with a dedicated built efficient inverter genset. The TDI has a lot more moving parts and a lot more weight to throw in circles :) I would be willing to bet that is uses less fuel than a stand-by LOUD cheap unit that most people run in an outage though ;)
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    Re: battery chargers
    Brock wrote: »
    I would be willing to bet that is uses less fuel than a stand-by LOUD cheap unit that most people run in an outage though ;)

    I would imagine so. I used to have a 79 Mercedes 300SD with the 3 liter 5 cyl. turbo diesel engine, and at idle, even with the a/c running, it hardly used any fuel. Hell, even at freeway speeds I seem to remember getting pretty good mileage...25mpg or so.
  • lorelec
    lorelec Solar Expert Posts: 200 ✭✭
    Re: battery chargers

    Isn't this kind of an apples vs. oranges thing? In one case, the Honda is being loaded to near its maximum output. In the other, the TDI is being minimally loaded (newer TDI's are probably capable of near 100kW output). Of course the Honda's going to win out in efficiency. A better comparison would be a comparably sized single-cylinder diesel generator. Diesel has about 20% more BTU per gallon than gasoline and diesel engines operate at probably 15-20% better efficiency than gasoline engines. There's little doubt which one would win out then. Single-cylinder IDI diesels are bound to be dirtier than their gasoline counterparts, though. I had a Yanmar diesel on a sawmill once and had to replace it with (you guessed it) a Honda, partly because the Yanmar was just too much filth to breathe.

    Marc
  • ehorn
    ehorn Registered Users Posts: 6
    Re: battery chargers

    I am curious to see some data out of these "new" flywheel type stationary diesels (basically a modern day horizontal single piston alternative to the larger Listeroid singles and twins) with a gen sized for the 5-12kW needs. The folks here have been doing some studies with them and have some high expectations as to the reliability/efficiency and ability to tune the revs to the application need.

    From initial testing, some have reported that the stated 250 grams/KW/HR fuel consumption might be conservative.