Car went belt commando today... prelim. +10%FE

[jjackstone]

Gascort,
I was wondering which of the "cheapie" Harbor Freight panels you were considering. The lowest price ones I found were just a bit over $4/W. Those were the 15 Watt panels at $70. The prices continue up to about $8/W from there. I have been watching Craigslist lately and have seen a number of listings for one or two year old panels selling for $3/W or less. Most of them appear to be from owners who are losing their homes and don't want the banks to get the panels(or so say the ads).
This could be an option for less expensive panels. Don't forget a controller. Morningstar makes a fairly inexpensive 10A max charge contoller/regulator.
Nice project. Good luck.
JJ

[MetroMPG]

If you're using the car alternatorless regularly, you probably won't need a charge controller with a small (<= 15w) panel. (But I assume you're going to monitor voltage).

Interesting: the Metro computer doesn't seem to care about system voltage - no dummy light (not counting the alt light), even if it gets really low (like low 11v range).

However it is smart enough to shut off the DRL's when it detects the alternator not charging.

[extragoode]

The alt light is the one I meant.

[orange4boy]

Just in case you didn't know... 12.2 resting voltage is about the lowest you will want to go with anything other than a true deep cycle flooded battery. Any lower will kill the battery quick. Also you should charge it up every chance you get. Leaving a battery partly discharged will lead to sulfation.

You might want to invest in some more batteries which will allow them to last far longer especially for long trips.

I strongly encourage you to read up at Battery University if you have not done so.

Lead-acid does not lend itself to fast charging. Typical charge time is 8 to 16 hours. A periodic fully saturated charge is essential to prevent sulfation and the battery must always be stored in a charged state. Leaving the battery in a discharged condition causes sulfation and a recharge may not be possible.

Lead-acid does not like deep cycling. A full discharge causes extra strain and each cycle robs the battery of some service life.

Absorbed Glass Mat Batteries (AGM)
Cannot be stored in a discharged condition - the cell voltage should never drop below 2.10V.
Allows only a limited number of full discharge cycles - well suited for standby applications that require only occasional deep discharges.

Alternatorless driving will pay for itself as long as you treat your batteries well.

Cheers.

[orange4boy]

Reply to extragoode"

The big thing I want to know is how all you alternatorless guys keep the car from constantly complaining about the battery being low, since any thing under 13.5 sets off the dumby light? I see how oranges idea would work, but I didn't want have to carry around 3 6v bats and I question whether 2 8v bats would even maintain enough juice to keep the voltage above 13.5 for long.

Remove the bulb. 2 8V batteries in series start at 18+ volts when charged and only hit 16 when fully discharged so maintaining 13.5 isn't a problem.

Two 8 volt deep cycle golf cart batteries have about a 150 amp hour capacity each at the 20 hour rate ( most commonly quoted ) For a total of 300 AH. A consumer grade D34 yellow top has a capacity of about 55 AH.

I regularly drive about 55 miles (city) with two 12V 115 AH batteries (230 AH) and rarely drop below 12.2 resting voltage by the time I get home. (Average running amps ~ 20-30)

Common Terms

Ampere-hour or AH
The unit of electrical capacity - this tells you how much power the battery will store. Current multiplied by time in hours equals ampere-hours. A current of one amp for one hour would be one amp-hour; a current of 3 amps for 5 hours would be 15 AH. Similar to the "gallons per day" measure of water. Amp-hour ratings will vary with temperature, and with the rate of discharge. For example, a battery rated at 100 AH at the 6-hour rate would be rated at about 135 AH at the 48-hour rate. Ampere-hours (AH) designates the storage capacity of the battery. SLI batteries are not rated in AH, but in "CCA", or cold-cranking amps (marine batteries are often rated in "marine cranking amps").. Terms such as "6 hour rate" or "20 hour rate" indicate that the battery is discharged steadily over 6 or 20 hours, and the Amp-hour capacity is measured by how much it puts out before reaching 80% DOD.

[zermac]

Solar on the the roof of the car! Awsome! A couple hundred led lights over the car in the garoge to charge the battery over night and a very good volt meter, plenty of light for projects in the garoge.

[3dplane]

Originally Posted by orange4boy

Reply to extragoode"



Remove the bulb. 2 8V batteries in series start at 18+ volts when charged and only hit 16 when fully discharged so maintaining 13.5 isn't a problem.

Two 8 volt deep cycle golf cart batteries have about a 150 amp hour capacity each at the 20 hour rate ( most commonly quoted ) For a total of 300 AH. A consumer grade D34 yellow top has a capacity of about 55 AH.

I know this is from 09 but I just wanted to make a small correction: When batteries are connected in series,their capacity stays the same as their individual rating. Their voltage is adding up in series!

When connected parallel,their capacity adds up but voltage stays the same.

Example: Two 12V 50A/h batteries in series will be 24V 50A/h
The same two batteries in parallel will be 12V 100A/h.

Just to clarify and not because I'm trying to be mean! The way I read it,you were referring to a series connection! If not,my apologies!
Barna

[Andrew63]

Is 'downsizing' the alternator a possibility? If so, under what conditions? Do I need to get LEDs, reduce electrical loads, etc.

[3dplane]

Originally Posted by Andrew63

Is 'downsizing' the alternator a possibility? If so, under what conditions? Do I need to get LEDs, reduce electrical loads, etc.

Reducing electrical loads is always a good idea!

Downsizing the alternator would have to be defined a little better but the way it sounds,the answer is no. No matter how small alternator we put on there it will try to achieve the same thing as a large one: Bring that battery voltage up to the desired level. A small alternator will go full output and burn out before the battery voltage elevates to a level where the voltage regulator would allow it to reduce charging current.

Now limiting charging output could work to reduce the force needed to turn the alternator but I don't know of a simple way of doing that. Besides it would just take longer to charge at a reduced output,or never charge sufficiently if the commute is short IMHO!
Barna