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Old 07-21-2010, 08:01 PM   #15
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Based on the wiring diagram and discussion about six posts ago, I'd recommend NOT mixing sizes. The discussion pointed out that even small differences in resistance will make big differences in current - hence big differences in how much the batteries are exercised - if the current is large (he used 100A, which is high charge rate and less than the maximum discharge rate.) Since the 6Cs have lower internal resistance (higher current rating) the effect of using 4 6C and 2 C4 will be that the C4 will just be supplementing the main bank of 4 6C's, perhaps adding 100 AH rather than the rated 200 AH. In my opinion, it's not worth doing. Use 6 identical batteries and follow the wiring diagram.
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Old 07-21-2010, 09:35 PM   #16
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When mixing batteries with different capacities the smaller battery will discharge first. The larger batteries at this point will feed into the smaller discharged battery reducing the capacity of the bank. When charging, the smaller battery will charge first and continue to charge. If the charger is in the bulk charging stage the voltage could be as high as 14.2-14.5 volts. This will boil the electrolyte of the smaller battery and could cause the battery to fail catastrophically. It is never a good idea to mix batteries with different capacities together in a bank.
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Old 07-21-2010, 09:41 PM   #17
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Well a call to the distributor from lifeline told me it is perfectly fine to mix 4c's with 6c's... just to strap the pair that are equal,,Another words if you have a 4c on the left you got to have a 4c on the right... The next row can be 6 c's
..Just have to match each rows ah.
When I put the big test to him and asked if they are still under warranty if mixed like this.... he said it is ok and they have done "numerous" test and conclude if used in the above manner it has no ill effect on the batteries.

They said it use to be "thought" for many years not to be appropriate but after careful study they have come to a "physical conclusion through various test that it is perfectly fine... {Again just match the pairs in ah}

Again this is the distributor talking and not me...

I sure hope he is right... how long is that Lifeline warranty???
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Old 07-21-2010, 10:11 PM   #18
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Next time you talk to the distributor ask him if he will supply you with a copy of the test results. If the company went thru the trouble of conducting the test I'm sure they wrote a test report.
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Old 07-21-2010, 10:48 PM   #19
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Originally Posted by RocketDork View Post

The solar and additional batteries is a topic of intense discussion. There are so many variables to the whole thing that its hard to really decide exactly what to do. A guy known SolarBob had some pretty good advise though. Start by knowing how much energy you USE in a day. Get a device that measures how much you use...then plan from there. The way I'm planning my system is this.

1. Measure energy used for a while, get sort of an average use pattern, with max and min use.
2. Size my battery bank for about 2 days of use without charge.
3. Size my solar panels for about 1.5 days energy use.
4. Hope I guessed right.

My thinking in the above.
Battery Bank Sizing is related to how long I boondock (2 days min, 7 days max) and the typical weather patterns where I camp. It is very important to fully charge your battery bank on a regular basis...having too much capacity makes it hard to do this...
Solar Panel Sizing is related to how much energy I can put back into the batteries. Even on a cloudy day there is still energy available, so I get some into the batteries, but not a full charge. Its rarely cloudy for long where I'm at, so I should be able to return to full charge on the next sunny day.
Sandia National Lab ran some tests on unattended solar-powered lighting using flooded-cell storage batteries and concluded that the solar panels should have more capacity than the battery so that the battery gets a full charge on the average day. So if you have a 600 AH battery bank, sized to ensure a little less than 50% depletion, you should have enough solar panels to provide, say, 60 A during the five peak hours of the average (sunny) day. That's a BIG array. We have 2 100W (i.e. 7A; the watts are measured at 17V) panels and a 400 AH battery bank, so we have to supplement the panels with a couple of hours' generator time every couple of days. Without generator supplementation, I think Solar Bob's recommendations are backwards: size the solar panels for 2 days, batteries for 1.5 (or batteries for 2, solar for more than 2.)
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Old 07-22-2010, 11:55 AM   #20
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Originally Posted by RocketDork View Post

So, you can overcharge a battery that is in parallel with others. Once the terminal voltage as determined by the existing chemistry in a specific battery is reached, you are overcharging it. If the Terminal Voltage is lower because the battery is old or of a different vintage that the rest...you can and will find that it reaches its full charge state before the others...
Good try but the VOLTAGE does not change with age.. (unless a cell shorts and then you have a bad battery)

What changes is internal resistance (Or if you like conductance (Which is 1/resistance) or the ability to pass current))

So, again, if one battery is more charged, when charging, then it will refuse additional charge till the others catch up.

And if one battery is more discharged, it will not supply more current till the others catch down.

That simple. Perfect socialist network.

The exception is at high current the older, higher resistance battery may charge/discharge slower, but as soon as the current drops. it will equalize.
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Old 07-22-2010, 12:39 PM   #21
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Good try but the VOLTAGE does not change with age.
Well, I disagree.

Age changes the Specific Gravity. SG does have a pretty strong influence on the voltage, and thereby terminal voltage.

That's my story, and I'm sticking too it! We can agree to disagree.
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Old 07-22-2010, 12:44 PM   #22
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Sandia National Lab ran some tests on unattended solar-powered lighting using flooded-cell storage batteries and concluded that the solar panels should have more capacity than the battery
Hmmm, interesting, do you have any links? I'd be interested in reading about it.

My thought was that if I had enough battery to last until the sun comes out again, and enough solar to return more than a days use of energy to the battery, that I'd eventually get back to fully charged...

I'm somewhat of a neophyte on the solar side of life, so I'm in the data gathering mode...
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Old 07-22-2010, 12:48 PM   #23
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Well a call to the distributor from lifeline told me it is perfectly fine to mix 4c's with 6c's

Again this is the distributor talking and not me...

I sure hope he is right... how long is that Lifeline warranty???
He's trying to sell you batteries...he's going to tell you whatever you want to hear that makes the sale. If you can get him to document that the warranty covers that use case, and point you to the study the company did, I'd believe what he said...otherwise, I'm still standing on the side of doubt.

Sorry for three posts in a row...
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Old 07-23-2010, 11:31 AM   #24
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This is quite the spirited thread ! .. and I really appreciate all the thought.

BOY.... I must say im a bit more confused as we go along....

I know the guy had me for 6- 4c lifeline's at anytime...So he had me for 6 anytime. With the amount of business he does, would he really sell me a "line" just to add a couple bucks...? Looks like he does high volume..

The price difference I got was not that much different from the 4c to the 6c..

I'll tell you what... Looks like Im gonna be the "TEST PILOT" here...
At my expense... { depending on how long the warranty is}

Well, I do this not exactly convinced but hopefully I can give accurate account of the experience.

With Bernie's fine help, I now have a complete Onan Equinox operators manual ! So I am now fully understanding the charging system and what is important. I still need to make sure I have navigated all the proper settings for the AGM's....
Im going to make sure my batteries have the best thick and clean cable connections. Really good thick terminal ends.
Im probably going to make a few new sets to replace some worn one's.
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Old 07-23-2010, 06:37 PM   #25
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Winding
Looking at your picture, could you rearrange your batteries and put the chassis batteries in the back (front to back, looks like you may have the width to turn them)? Then put 6-6c batteries outboard of the chassis batteries. Height i the back is your problem, not necessarily space. Just a though!!!
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Old 07-23-2010, 07:31 PM   #26
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Originally Posted by RocketDork View Post
Well, I disagree.

Age changes the Specific Gravity. SG does have a pretty strong influence on the voltage, and thereby terminal voltage.

That's my story, and I'm sticking too it! We can agree to disagree.

That we can do.. Agree to Disagree..

I will say this.. "Same, Same, Same, Same, is safe, no question there,
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Old 07-24-2010, 01:58 AM   #27
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Dork:

At the expense of picking a fight (but not to side with wa8xym), I think you have one fact incorrect......

Quote:
Properly maintained flooded cells will last just as long as AGM's, but there is a maintenance cost paid in free time...if you include that free time in the ROI calculation, you may have a different result than I do. I recognize that its different for each person...
All manufacturers will tell you this is just not true. AGMs are much sturdier, use thicker plates, are more resistant to vibration, use a better transfer of electrolyte and therefore, given equal care will significantly outlast flooded wet cells. However, the cost may or may not be justified. Does a battery that costs twice as much last twice as long? Many say the lifespan does not double, therefore the doubled price isn't worthwhile. But, the small difference in price per span more than covers the convenience. Also remember there is a cost of changing out the batteries more often, even if you do it yourself. My horror is the huge upfront cost of AGMs.

I am interested in your interest in wind. I've looked at a few windmills after talking to Solar Bill (quite a character, and often maligned). It sounds great for longer term encampments, but a good setup and plug-in system would work for shorter stays. They are a bit noisy. A guy had one about 500 feet away from me at Quartzsite and it was easily heard through closed windows.

I can't wait to see you and Franklin figure out how much solar I need. Keep up the good work!

Imagine:

As referenced in my earlier post, I do have AGMs (Lifelines) for the house, and Optimas (which are AGMs, not another type, just a brand name) for my chassis. Also..

Quote:
The same weaker batteries will reduce the combined voltage of the bank, resulting in overcharging of the better batteries or not enough charge to the weaker batteries.
...is contrary to what would actually happen. Weaker batteries will achieve full charge (for them) sooner than good batteries and would boil sooner, allowing the bank to prey on the good batteries (just as RJay mentions). That's the same theory about "one weak cell".

Franklin:

Yours is the reasoning I concluded mixing would allow the batteries to prey on each other, reducing life span.

Nick:

Quote:
Looking at your picture, could you rearrange your batteries and put the chassis batteries in the back (front to back, looks like you may have the width to turn them)? Then put 6-6c batteries outboard of the chassis batteries. Height i the back is your problem, not necessarily space. Just a though!!!
Sure! Figure out the answer to my space problem without breaking a sweat. I've been pondering this for months and along you come...... I'm just hoping they have the same footprint and are interchangeable, space-wise.
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Old 07-24-2010, 09:21 AM   #28
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Wingding- one of your starter batteries should fit under the frame, and the other should fit nicely on the new support bracket you can build between the jack & the batt compartment door (many Alpiner's have mad a shelf there).
Now if you turn the 6c's with the long way fore-aft, you should be able to assemble 2 starters & 6-6c's with sufficient head room for all. You will need new cabling (tho some or maybe all of the WRV 6V-to-12V straps will still work nicely) and new hold-downs.
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