Alternator v. no alternator - 10% gain @ 70 km/h

[DRW]

I can't tell you with certainty how long those batteries will run your car, but I ran my car without an alternator once relying solely on a lightweight 13 pound battery. I was watching battery volts and it went from 12.6v down to 10.9v during a 25 minute drive in daytime. I was nervous about letting the volts drop much lower because most modern cars with electronic computer controlled fuel injection will not run below a certain voltage, although I believe the lower limit is around 7 volts, which may not be good for battery life.

If possible I'd recommend mounting the batteries close to the main battery to keep the power cables short since wire length is a factor in voltage drop. See http://stealth316.com/2-wire-resistance.htm

The solar charger should put out more volts than the battery, other wise the battery might be sending power through the solar charger. Check the resistance of the solar charger in both directions to make sure it's not a closed circuit. and be sure to check it's resistance with a dark blanket covering the panel since some multimeters will blow a fuse if they're given voltage when they're in 'ohm' mode.

HTH and good luck with the project!

[benfrogg]

The problem with the solar pan appears to be that he didn't use a controller. I'll get the panel tomorrow and do some testing. Thanks for the info on testing!

I'm interested in doing this project soon. One question that I don't have answered still is, will two deep cycle batteries start the car? Are there enough cranking amps there? (especially after a long drain?)
I suppose I could put the regular battery in the back with some jumper cables just in case?
Good idea on the short cables. I think I can make a frame for the batteries behind the passenger seat. I'll be using 2 gauge wire. It should be less than 3 feet. The ground will ground to the chassis (most likely in a couple of places for good continuity).
I'm hoping for a 125 mile range without headlights. With headlights it is likely to be less than half of that.
I may have to add a third battery later. Maybe I can find another cheap or free one in my travels.
All this adds weight. That's going to effect FE some. I'll have to quantify how much that weight is affecting it.
Thanks for the info!
B

[DRW]

Originally Posted by benfrogg

I'm interested in doing this project soon. One question that I don't have answered still is, will two deep cycle batteries start the car? Are there enough cranking amps there?

Dunno, what are the specs on the battery?
Do the batteries have model numbers on them? Or at least, what are the dimensions?
Here's a good site to correlate battery size and capacity;
http://www.batteryspec.com/html/sla_battery.html

[theholycow]

FWIW I have a cheap Walmart deep cycle, which I originally bought for a trolling motor, that started my Buick 4.1L V6 just fine and now starts my wife's Isuzu 3.2L V6. However, I've heard that those cheap deep cycle batteries are just relabeled starting batteries.

[kit352]

id try to get those walmart hybred marine batteries with the starting capabilities. while not a true deep cycle they can hold a awhile. plus you get the warranty with them.
with my saturn which is barebones and barely fi i can safely go about 20 miles in the day without droping my voltage below 11v. at night its only about 5 miles. I never really played with it other than a few test runs. its on my list of things to do later. I figured about a 3% gain on fe but i didnt do any runs to back it up. id say on a newer fi car you couldnt go as long but im not sure. I did this with a regular car battery as well. I use the marine ones for my house and they didnt fit my car easily.
i believe that gains are to be had but sacrifices must be made for it to matter. no radio, a/c or blower, and no lights really. I drive highway for a good amount so i dont need to do it but you could swap in led's for the brake lights and stuff to drive on the street for the longest time.

[benfrogg]

Here's the status of my project:
After doing some research, 2 deep cycles will start the car just fine. (yet untested) One apparently has enough to start that small motor in all but the coldest conditions. (will test this week)

However, one of the issues I don't care for with EOC is that the headlights dim- significantly. I actually try to plan my EOC stop and start by when cars aren't coming at me within a 1/2 mile so it's not obvious something has changed.

So, running altenator less (or with the altenator kill switch activated) would mean dim headlights all the time. That's not good, for me.

A solution is afoot.
http://99mpg.com/mikestips/
Scroll to the bottom. This guy, Mike from CT, is a genius in my mind. What he's tested and is using in all of his vehicles as the starting battery (and only battery) is a set of two prius batteries. They are rated at 7.2vdc, 6.5AH. So, in series, they produce 14.4v on a full charge.
Even if I just got a hold of 2 of these babies, I'd have not dim headlights when EOC. So, I'm going to invest in at least two. I've found some on Ebay for cheap, that are not load tested, but are votage tested:

Those look promising. I think I may buy at least two of them soon. I need advice on this point. (keep reading)

There's also an auction for ten 1st gen prius batteries for $100 plus $10 shipping. Now these guys test out at at least 6.5v each. That tells me they are probably tired, less good for a full EV conversion.
Here:


So on to the advice. I could get just two of them from the first guy, for under $50 shipped. I have literally everything else I need for the project using the deep cycle batteries in my garage. All wiring, connectors, volt meter (c.o. dad's tool box), small solar panel, etc. I could run this system in parallel with the 14.4v battery and have the volts I need to have bright headlights at night.

OR

I could buy the 10 batteries and run all of those either with or without the deep cycles I have now. Trouble is, those batteries are tired to begin with, and have less AH than my two deep cycles.
Assuming they are relatively healthy, I should expect 6.5AH x 10 = 65AH capacity. That's at max.
I could also run all 10 AND the two deep cycles (lots-o-weight here). The 10 packs weight about 26#'s total, so no biggie there. The deep cycles, however, are 50# or so EACH.

Note in any of these scenarios, the original starting battery is deleted. (I'll likely keep it in the car for the testing phase to make sure I can start if I drain it too low). That reduces weight by one battery. So the only real weight addition will be one deep cycle and two small prius batteries.
This also means I can mount at least one of the deep cycle batteries under the hood in the existing location. Now what to do with the other? This is where the 10 prius batteries would come in handy. They could fit in multiple locations that would help to keep them cool.

This is a similar battery the deep cycle ones I have:
http://www.batteryspec.com/cgi-bin/c...ink&product=78
It is 71.5AH. So obviously I'd have greater capacity with two deep cycles than with just the big pack. But both together..... hmm.

Don't forget, lowest cost for greatest gains is the goal. I've got $0 into the mod so far.

Anybody have any solar panels they'd like to donate to the cause?

Anyway, that's all for now, looking forward to your advice.
B

[theholycow]

I've never let the headlight dimming bother me. Anyone who notices it will see that it's an old car and assume it has some kind of issues, not that you're doing something weird.

However if you want more ideas for that issue:
1. Install brighter headlights and a voltage regulator just for them that keeps them at 12v even when the rest of the car is up to 14.4.

2. Just buy two Prius batteries, not a whole pack, and only use them for the headlights.

3. This one is less likely, but how about a step-up transformer that will give you 14.4v when the rest of the car is down to 12.

4. This one is even less likely than that: A generator that runs off a wheel to make just enough power for your headlights at 14.4v. It'll reduce your EOC slightly but not much.

[DRW]

If your lights are significantly dim, what is the battery volts at that time?
Do you think the battery is going bad?
From what I've seen, a good battery will hold a higher charge after the alternator is switched off, and a battery that's going bad will have lower volts.
Also, one of the things that kills a battery is letting it sit for extended time at less than full charge. For example, if you drive the last few miles of your commute with the alternator off, then let the car sit overnight with a partial charge in the battery, that will eventually erode it's capacity.

[DRW]

Oh, another idea. The Prius, Tesla and other hybrids seem to prefer using a great number of small batteries instead of a few large batteries. I don't know the benefits of that strategy, it could be economical or it could be electrical, but it's worth looking into.

Perhaps 3 or 4 of these? http://www.batteryspec.com/cgi-bin/c...ink&product=36

[benfrogg]

HC-
Some good ideas to be had. However, I got this e-mail from Mark this morning about Prius batteries: (he's a pretty open source guy, I don't think he'll mind!)
"Hi Ben,
While the prius subpacks work well for the occasional start or short trip, I would not recommend them for several reasons as full time replacement for the lead acid.
At 14.6V they never get fully charged, or discharged so cell balancing eventually creeps in and can cause some serious issues, including cell reversals, and without a method of monitoring the cells for balancing, this will eventually happen to any dual subpack.
I use a constant current charger to keep the subpacks in balance and at a full charge.
the cells are rated at 6.5 AH, with a recommended 40% to 80% operating range so you should only use 2.7AH.
That will not provide much capacity if you are to run with no alternator, your battery powered drill has 2-3 AH batteries as a comparison.
Most small lead acid car batteries are 45 AH with the larger ones running up to over 100ah, and even with one of those you will likely only get 10-15 miles with your lights on without an alternator.
NIMH does not work well when below freezing, and Augusta,ME sees that kind of temperatures all winter.
This low temp operation is one of the reasons lead acid has been the battery of choice for car starting, as well as the fact that they like to stay fully charged.
The most serious problem I ran into was that if a cell gets reversed, it will likely fail shorted, which then reduces the pack voltage by 1.2V. This causes the 14.6V from the alternator to overcharge the rest of the cells, and at the 60A that many alternators can output, the rest of the cells rapidly get overcharged and look like this:
http://99mpg.com/blog/batterypacksex...appenstoapriu/
That was with only a 6A overcharge.
The cells vent, and in less than a minute you will have destroyed the subpacks.

I was going on a short test drive with a dual prius subpack in my silver insight last fall, and only made it 1/2 mile, when a cell shorted, and the pack had a meltdown.
Had to tow the car home. "

Anyhow, that leaves me with another idea:
Find a 2ish V golf cart battery (or more than one that = 14ish volts). That way they'd still be lead acid, deep cycle, and I could run them in series with my 12v type ones. All would be well with the world, I think, even on the charging front (not 100% of this).

Alas, I'll be carrying some extra weight around. I have noticed a HUGE difference with weight and without. 200#'s of drums can make a drive that normally nets 66 (sometimes as high as 68) or more MPG into a drive that can only achieve 58-59mpg. All of these are factors, I suppose. The set of batteries will likely add over 100#.....

For now, I'm going to research some 2v batteries and if I can get some cheap, install them just for EOC at night.

DRW-
I don't know how old the battery is. I'd guess it to be 2 years or so. I'll drop in a known good battery and see if there is a change. I haven't installed the voltmeter yet, but I'll test resting voltage later with a multi-meter.

Also, i think the smaller batteries bit is many fold- More options for total output voltage, expense of smaller batteries v larger ones?, keeping them cool (this is a biggie, more surface area is needed to keep them cool during charging/discharging), ease of the space they are going into, etc.

Anyway, that's where I'm at.
B