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Topic: Solar panels and batts: a controversial point of view (Read 14 times) previous topic - next topic
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Solar panels and batts: a controversial point of view
Yahoo Message Number: 50300
Hi, Group:

Most of us already know Ed's "you need just one panel" policy. Also it is consensual in this group that the optional T-145 batts are a waste of money, since the cost difference doesn't justifies the few extra amps.

I'd like to challenge this "prejudice" against the T-145's. The standard T-105's have a 115A capacity. The T-145's have 145A. It's a 26% increase, a not so bad one. But more than that: 70% is about the max you should discharge your lead acid battery, and still have long life in them. 70% of 145A is 101.5A

Considering that, reading our messages and exchanging ideas with other members, most of us seems to be using 90A a day,(I could be wrong, it's not statistical, and would like to confirm that) no air conditioning, no shorepower. The T-145's gives us one full day, no generator, no solar panels, no vehicle engine running, with 11.5 A spare, and within a good battery depletion safety margin.
 Three, not two of the new AMSolar panels with the HPV-22 controller, will give you about 90A in an average day, so they would maintain the batts fully charged in a "on-going" way.

The extra panel weight,(installed aftermarket, because I doubt mothership will agree to sell and install the third one), plus the extra weight of T-145's, will sum 34 lbs, about half of one extra 6V T-105, which must be intalled in pairs.

I think this set-up will attend very well practically all of our group members, with a very small weight increase, no adaptations, fabrications or reduced storage area necessary.

For the real power-hungry users,I still think that a fourth panel will do better than extra batts...Finally, practically all LD's still have generators for emergencies...

Now, to consider not to have a generator (which is an idea that teases me)... it's another story, which will need a whole different line of thought and should be discussed in separate...

I'm eagerly waiting for different opinions and further discussions about these matters!

Eudoro "still in high amp mode" Lemos, Jr.
Re: Solar panels and batts: a controversial point of view
Reply #1 –
Yahoo Message Number: 50304
Quote
Most of us already know Ed's "you need just one panel" policy. Also it is consensual in this group that the optional T-145 batts are a waste of money, since the cost difference doesn't justifies the few extra amps.
Extra power aside, folks should not forget that the biggest reason for splitting real estate into more panels is to minimize shadowing problems. Few camping spots are in wide-open desert in the middle of the summer, so having your entire electrical charging system disabled by a few leaves from a nearby tree for some part of the day is likely with a single panel source. A solar panel has all the cells wired in series (daisy-chained). If one cell is in shadow, the current potential of the cells that ARE in full sun cannot pass due to high impedance with current crystalline silicon solar cell technology. If you have second or third panels that are unobstructed, they are wired in parallel to the first panel, so they can still provide their full charge current.

Steve
2004 FL
2013 Honda Fit
Re: Solar panels and batts: a controversial point of view
Reply #2 –
Yahoo Message Number: 50309
Quote
I'd like to challenge this "prejudice" against the T-145's. The standard T-105's have a 115A capacity. The T-145's have 145A. It's a 26% increase, a not so bad one. But more than that: 70% is about the max you should discharge your lead acid battery, and still have long life in them. 70% of 145A is 101.5A

Eudoro "still in high amp mode" Lemos, Jr.
I think Trojan suggests 50% as the recommended discharge floor.

For those wishing to switch to T-145's, the case is just slightly taller and the foot print about is the same. The T-105 is the better value and will doubtless be easier to find on a store shelf. I found the T-145 selling for 60 to 100% more than the T-105, so there is real value in adding an additional bank of T-105's as I did.

One more note, especially when buying batteries that may not move off the shelf so fast. When I was buying my extra T-105's, I rejected a pair that the dealer had on the floor as the voltage was low indicating they were discharged about 50%. This would not normally be that big a deal if they are in use, but on the shelf and left this way is another matter. So check the top of the battery terminal posts. Trojan uses a letter/number system to designate when the battery was made. A "E-4" would mean May '04. Look for the more recent battery and be sure both are from the same batch when buying
2.

all the best,

bumper

Not
bumper
"Yonder" '05 MB
"WLDBLU" glider trailer
Re: Solar panels and batts: a controversial point of view
Reply #3 –
Yahoo Message Number: 50315
Quote

"... I think Trojan suggests 50% as the recommended discharge
floor...."

Bumper:
 the text below was copied from the "customer care" area at the Trojan site(www.trojanbattery.com):

"Trojan's deep cycle lead acid batteries can be cycled to any percentage of their rated capacity and then be recharged. However, Trojan does recommend that you never cycle below 80% of the battery's rated capacity."

So, the 70% maximum I quoted are a little consevative (As I had to be).

Eudoro "hallellujah, ONE time in my life I was right!" Lemos, Jr.
Re: Solar panels and batts: a controversial point of view
Reply #4 –
Yahoo Message Number: 50316
Quote
Considering that, reading our messages and exchanging ideas with other members, most of us seems to be using 90A a day,(I could be wrong, it's not statistical, and would like to confirm that) no air conditioning, no shorepower. The T-145's gives us one full day, no generator, no solar panels, no vehicle engine running, with 11.5 A spare, and within a good battery depletion safety margin.
When we ordered our 2002 MB we planned on boondocking much of the time, so we ordered the T-145s and two solar panels.  I've recently added a Link-10 battery monitor to have a much better picture of what is happening with our batteries.  In the summer with the high sun and long days, the panels can easily recharge the batteries (except when we are parked under heavy tree cover).  But winter is a different story.  This past New Years at Death Valley,  we'd use about 40-50 AH per day (the furnace in the morning the biggie), but only reclaim 20-30 during the day.  Thus after 4 or 5 days, we had to run the engine to help recharge.  It amazing how quickly the charging current drops off as the battery voltage rises (whatever the charging source).
Getting that last 10-20% takes a LONG time.  So figure that your batteries are often operating between 50-80% of capacity.  I'm seriously considering replacing the old solar controller with the HPV-22 if it will fit (still trying to get actual dimensions).

Art
Art and Barbara
Settled in Atterdag Village of Solvang
2015-2022 fulltime in a 2016 Tiffin Allegro Bus 37AP
2002-2015 2002 LD MB
Art's blog
Re: Solar panels and batts: a controversial point of view
Reply #5 –
Yahoo Message Number: 50318
Quote
"..... So figure that your batteries are often operating between 50-80% of capacity.  I'm seriously considering replacing the old solar controller with the HPV-22 if it will fit (still trying to get actual dimensions)....."

Art:
Thanks for your excellent informations about your experience.

Perhaps, if we get info from other members, in a significative number, we could have enough data to improve our files and faqs.

You probably have an Heliotrope 30-S, which is 7.75" W, 4" H. The Heliotrope HPV-22 is 7,5", 4,25 H. It's so near that you'll probably adapt it without needing a small wooden "frame" to get a pro finish.

Thanks, again

Eudoro
Re: Solar panels and batts: a controversial point of view
Reply #6 –
Yahoo Message Number: 50319
".....If one cell is in shadow, the current
 
Quote
potential of the cells that ARE in full sun cannot pass due to high impedance with current crystalline silicon solar cell technology. If you have second or third panels that are unobstructed, they are wired in parallel to the first panel, so they can still provide their full charge current....."

Steve:
Thanks for the excellent info.

Eudoro "learned another one" Lemos, Jr.
Re: Solar panels and batts: a controversial point of view
Reply #7 –
Yahoo Message Number: 50320
Quote

".....But winter is a different story......"
Art:

One more reason to update your controller:

Solar panel cells produce their maximum voltage when cold. As they heat, with the sun, their voltage drops. The MPPT type controllers will give your batteries their max boost exactly when you need more: Winter mornings.

Eudoro
Re: Solar panels and batts: a controversial point of view
Reply #8 –
Yahoo Message Number: 50321
"I'd like to challenge this "prejudice" against the T-145's. The standard T-105's have a 115A capacity. The T-145's have 145A. It's a 26% increase"

Eudoro
 One small mistake. T-105s are rated at 225 amp/hours of capacity and the T-145s are rated at 260 amp/hours. This is about a 16% increase.

As bumper noted, the T-145 is 50-100% more expensive than the commonly available T-105s. They sell very few of the T-145s, when compared to the T-145. I have bought hundred of T-105s over the years but never a T-145. None of our equipment has come with T-145s, although they usually will fit.  Our vendors tell use that the T-145s are just too expensive for the value received. You just cannot beat the value of the T-105. It is the most commonly sold deep cycle battery sold.
See http://www.trojan-battery.com/voltage_2.asp The amp/hour rating is usually taken from the 20-hour column.
 Trojan now has a 6-volt AGM replacement for the T-105 but it is rated at only 180 amp/hour.
See http://www.trojan-battery.com/TrojanPartNumber_2.asp

In the boating world, we have used the 50-60% maximum daily discharge rate for years, at the recommendation of Trojan. Occasionally, a deeper discharge rate is tolerable but it will lead to a shorter life span is done too often. I feel that as you increase the solar panel capacity, you should have the ability to absorb the greater charge capability by having additional battery capacity.  Having extra battery capacity becomes even more important in the wintertime, when solar becomes ineffective and generator charging becomes a reality. A bigger battery can absorb a higher charge rate, for a longer period before the charge rates starts to drop (and increases the run time between recharging).
A rule of thumb for marine cruisers is to recharge at the 50% level and to stop charging at the 90% point (where the charge rate drops to a low level). Using this formula minimizes generator run time. This is how I approach battery charging in the winter, when the solar panels cannot keep up with daily needs. Having the Link 10 battery monitor makes this possible because I know within a few amp/hours, exactly how much capacity has been used and what is left.

Larry

More is better when it comes to solar and batteries
2001 MB
* Not to be confused with Larry W (3000 of my posts are actually from expert Larry W due to Yahoo transition mis-step)
Re: Solar panels and batts: a controversial point of view
Reply #9 –
Yahoo Message Number: 50322
"Eudoro" wrote:

Quote
...standard T-105's have a 115A capacity. The T-145's have 145A.
It's a 26% increase...
According to the Trojan Battery spec sheet at
 http://www.trojan-battery.com/productspecsguide.pdf

the values 115 and 145 are not amps, but the capacity in minutes that the batteries can provide 75 amps (when the outside temp is 80F).

The same spec sheet states that an industry-standard way to measure capacity is the level of amps the battery can provide for 20 hours.
The T-105 battery is rated at 225 amp-hours, and the T-145 at 260 amp-hours (a 15% improvement).
 Note that the battery is not fully exhausted at the end of 20 hours, but instead is drained to the level where re-charge is recommended.
That level is specified as 1.75 volts per cell for this test.
 Factoids everyone agrees on is that the T-145 is 1/2 inch taller and 10 lbs heavier than the otherwise similar T-105.

The last figure I read was that he LD factory will charge $125 to upgrade from T-105 to T-145.  Add to that the cost of a remote fluid fill kit such as the Flo-Rite Pro-Fill ($85) because the taller T-145 is difficult to service when installed in the LD's battery compartment.

So is a 15% to 25% improvement in battery life worth $205?  For someone planning to boondock regularly, I'd say yes.

--oryoki
Re: Solar panels and batts: a controversial point of view
Reply #10 –
Yahoo Message Number: 50336
Quote

"....One small mistake...."
Larry:

You are absolutely right. There are three different ways of calculating batts capacity in the same grid.
Each one gives a different measure, 18.5%, 26% and 16% difference.I got the wrong one, the wrong way, since the official measure it's the one you indicated.

It wasn't a small mistake. As a member, I can make a mistake.

As a co-moderator, not, since I have responsibilities to the group.

So, I thank you for showing the right data, and apologize to the group.
 I confirm Trojan's info about a maximum 80% discharge to maintain the battery's long life, as it is clear at their site.

Wishing you the best,

Eudoro "ego bruised" Lemos, Jr.
Re: Solar panels and batts: a controversial point of view
Reply #11 –
Yahoo Message Number: 50337
Quote
It wasn't a small mistake. As a member, I can make a mistake.

As a co-moderator, not, since I have responsibilities to the group.

Eudoro "ego bruised" Lemos, Jr.
Eudoro,

That's something that I was completely unaware of (your being co-moderator).  Maybe it's something that I missed while being gone for two weeks recently.  I always enjoy your contributions and your "middle name of the day" or aka.  Thank you now, and Judy for co-moderating this great group.  Hope you're doing well.

Tom
Re: Solar panels and batts: a controversial point of view
Reply #12 –
Yahoo Message Number: 50345
"It wasn't a small mistake. As a member, I can make a mistake.
As a co-moderator, not, since I have responsibilities to the group.
So, I thank you for showing the right data, and apologize to the group."

Eudoro

Thank you for being so dedicated to the Group but you do have the right to be wrong occasionally. I have made a lot a mistake through the years on this board...and have quickly been corrected. So no apology is needed. Your main problem was looking at battery charts that are probably unfamiliar to you; not knowing exactly which rating is commonly used.
The important thing is the gaining of knowledge and now you know more than you did

Larry   whose ego is too scarred to be brushed
2001 MB
* Not to be confused with Larry W (3000 of my posts are actually from expert Larry W due to Yahoo transition mis-step)
Re: Solar panels and batts: a controversial point of view
Reply #13 –
Yahoo Message Number: 50346
Quote
Trojan now has a 6-volt AGM replacement for the T-105 but it is rated at only 180 amp/hour.
See http://www.trojan-battery.com/TrojanPartNumber_2.asp
So one of the problems I have with AGM's is lack of quality information when doing my research. Two important factors to support AGM over flooded seem to be
1) You can discharge AGMs to a lower voltage (use more of there amp  hour capacity) without damaging them.

2) You can charge them faster.

Anybody know any sites or information to support these this? I have read about these advantages several places but am having trouble putting numbers to them. How much faster can you charge for instance.

Randy Judd
Re: Solar panels and batts: a controversial point of view
Reply #14 –
Yahoo Message Number: 50352
Quote

"Trojan's deep cycle lead acid batteries can be cycled to any percentage of their rated capacity and then be recharged. However, Trojan does recommend that you never cycle below 80% of the
battery's

Quote
rated capacity."

So, the 70% maximum I quoted are a little consevative (As I had to be).

Eudoro "hallellujah, ONE time in my life I was right!" Lemos, Jr.
Endoro,

The following is also from the Trojan site under customer care- "battery discharge". In particular, note section 1, 2 and 5. While it's true that you *can* discharge a battery down to 30%, it not being kind to the battery. Better to keep the discharge cycles more shallow. . . . bumper

"Discharging batteries is entirely a function of your particular application. However, below is list of helpful items:
1. Shallow discharges will result in a longer battery life.
2. 50% (or less) discharges are recommended.
3. 80% discharge is the maximum safe discharge.
4. Do not fully discharge flooded batteries (80% or more). This will  damage (or kill) the battery.
5. Many experts recommend operating batteries only between the 50%  to 85% of full charge range. A periodic equalization charge is a  must when using this practice.
6. Do not leave batteries deeply discharged for any length of time.
7. lead acid batteries do not develop a memory and need not be fully  discharged before recharging.
8. Batteries should be charged after each period of use.
9. Batteries that charge up but cannot support a load are most
 likely bad and should be tested. Refer to the Testing section for proper procedure."
bumper
"Yonder" '05 MB
"WLDBLU" glider trailer
Re: AGM batteries
Reply #15 –
Yahoo Message Number: 50363
Absorbed Glass Mat (AGM) batteries have several advantages over conventional flooded lead-acid batteries.

No acid worries: A conventional battery is filled with liquid acid.
In contrast, the acid in an AGM battery is absorbed in a very fine fiberglass mesh.  The liquid won't spill out even if the battery case is split open.

Rugged construction:  An AGM battery is designed to operate in environments with high levels of shock and vibration.  AGM batteries were originally designed for use in military aircraft. Life onboard an RV is easy in comparison.
 A sealed environment:  The AGM battery is sealed so no electrolye can escape.  This means the AGM battery does not need to be in a special vented compartment.  You can place the battery anywhere in the RV's living quarters if you need to.  And you don't need to perform any routine maintenance, such as checking fluid levels.  (I suppose you should clean the battery terminals occasionally.)
 Lower resistance:  The AGM battery has much lower internal resistance than a conventional battery.  This allows the battery to deliver a higher level of current  when demand is high, such as when you start up an air conditioning unit.  Lower resistance means less electrical energy is needed to charge the battery, so more of your solar panel output is translated into stored energy.  Lower resistance also means the battery heats up less when charging and discharging.
 Deeper discharge:  It's possible to regularly discharge an AGM battery more deeply than you should a conventional battery without shortening its service life.  Discharge deeper than 50% is not recommended, however.
 AGM batteries are regularly used in yachts and aircraft. So why don't RV manufacturers use AGM batteries?  They are 2 to 3 times more expensive!  Still, if you are trying to make your boondocking setup as efficient as possible, AGM should be part of your planning.

--oryoki
Replacing RV-30S with HPV-22
Reply #16 –
Yahoo Message Number: 52213
Quote
I'm seriously considering replacing the old solar controller with the HPV-22 if it will fit (still trying to get actual dimensions).

Art
Hi Art,

We need to talk more!  In January in our 2002 MB, I replaced the standard RV-30S Heliotrope solar controller with the HPV-22 when I had Discount Solar in Quartzsite add two 85-W solar panels to the original 85-w panel.  The face plate of the HPV-22 is the same size, but the controller card attachments are slightly "higher" which required carving out 1/2" or so from the top of the mounting frame in the cabinet.  Apparently the mounting holes are in a slightly different place so some additional framing wood had to be added to both sides for a firm mount. However, this was less work than it sounds, and the end result is a nice clean installation that covers the original hole exactly.  (I had planned to install the Solar Boost 2000E until I learned it does not fit the same hole and would require a cosmetic modification to cover the rest of the mounting hole.)

FYI, if you are planning to add additional panels, consider this.
The additional amperage will, of course, require a higher amp fuse (located in the converter box)in the wire from the solar controller to the battery.  The installer replaced that 10 amp fuse with a 30 amp fuse which is the capacity of the controller. While at Escapade in Imperial last week, my HPV-22 stopped charging due to an open circuit in the solar array. This weekend when I removed the panels to find the fault, I discovered that LD also installed a 10 amp fuse in the junction box under their panel. With all 3 panels in the full sun, that fuse blew, and I was out of business.  For what it is worth, Discount Solar says they do not fuse the panels as there is little chance of an over-amp condition.

Ahhh, my solar kingdom for a fuse...

Bob