LiFePO4 batteries? Solar panels?

[franco-bolli]

I have searched for, but not located a method to determine how many batteries your need Amp Hours are needed from your battery to light things up until I saw an article in Handyman Magazine this month (Sept 22)

Here is their method of calculating.
"RIGHT SIZE YOUR BATTERY BANK" 

• List all AC loads in Watts (W) in a table and calculate the total watt-hours (Wh) per day.
• Multiply that number by the days of Autonomy(DoA), that is the number of days you expect to have complete cloud cover (read very little charging). 
• Divide that number by the voltage of the system. This is the amp-hours (Ah) your battery bank should have.

This chart is an example of determining battery size

AC LOAD                  W      X            Hrs/day              = Wh/day          X         DoA     +     Total Wh

Television             132        x            2                      =   264

ventilation fans      50        x            2                      =    100

LED Lights              15         x           2                       =     30 
                                                                      Total     =  394      x            3        = 1182Wh

                             Finding the necessary Ah

                                      1182Wh / 12V   =   98.5Ah 

If 1 LiPo battery is 100Ah, it appears that it would be dead in about 3 days of this load, or whatever cut off is.

I'm not sure if this calculation takes into consideration the losses from an inverter.
I presume,  that this method could be used with strictly DC loads.

BTW, Don't shoot the messenger!!  I'm just copying the information from Handyman Magazine, Sept 22 edition page 54.

just for fun:

Airconditioner on roof of RV  (presuming 13A steady state A/C current flow at 120V)

1550W  X   4  hrs / day   = 6200Wh

6200Wh / 12V = 516.6 Ah for 1 day or more specifically a 4 hour portion of one day. 

Hope this helps someone figureout  how many batteries they will need.

------------  part 2

On the back of solar panels, should be a label that tells a tale of what you can expect from the panel.

I have one panel on the roof, rated at 157W (+/-3%)  Voc ( voltage open circuit) is 93.9V  The Vmp (Volts max power) is 75.5V  OHMS law would say 157W divided by 75.5V is 1.67A , the panel label is saying 2.08A which must be potential with no load.
During max charge on my rig, I'm seeing about 1.7A, which is todays world, ain't a whole lot of charging.

I used to work for the company that made this specific solar panel, before they went out of business in 2013, just before the big boom in solar occured. The parent company making the silicone  pulled the funding they were contribuiting and the intellectual property owner (Origin Energy in Australia) wasn't about to give the  patent information to the Chinese gov't so they closed our R&D / manufacturing down.I think this is industry standard, but I only observed the process at our manufacturing location in Wuhan, China during solar panel testing.
For those that care.... This is from memory of a process I saw a handful of times in 2013.
The completed solar panel is mounted perpendicular on a wall, a specific distance from a calibrated light source and connected to  sensitive test equipment that I think had a calibrated load bank.
The light source was "flashed" for a very short period of time, similar to a camera flash, but many times brighter than any I had seen (no pun here).   The output from the panel was analyzed and the output of the panel was determined in watts and voltage.  The data collected was used to create the label on the back of the panel, so each panel showed acutal results of the testing.  If they were below specified limits, the panel was set aside for engineering analysis.

 

[RV_]

4 minutes ago, franco-bolli said:

Hope this helps someone figure out  how many batteries they will need.

 

I bet it will help, thanks.

[Ray,IN]

As to cheap knock-offs, they are here and advertising heavily. Here is a 100A Lifepo -4 battery+20A charger advertised for $525: Ampere Time 12V 100Ah LiFePO4 Battery + 14.6V 20A Dedicated Lithium Ba

Edited August 30, 2022 by Ray,IN

[pjstough]

35 minutes ago, Ray,IN said:

As to cheap knock-offs, they are here and advertising heavily. Here is a 100A Lifepo -4 battery+20A charger advertised for $525: Ampere Time 12V 100Ah LiFePO4 Battery + 14.6V 20A Dedicated Lithium Ba

Are you saying that the Ampere Time batteries are a knock off, or did I misunderstand?

[franco-bolli]

I've been watching the prices on these and saving my pennies.

Weize 12V 100Ah LiFePO4  $399.99 12.71 x 6.49 x 8.34 inches

[oldjohnt]

Ive built and used Solar on RV's a long time and there are several  Energy Audit Methods out there which can provide a good starting point, however, in addition to whatever formula or methods you use, I have found ........You just cant predict 1) exactly how long and at what angle and intensity (based on shade and other) sun will shine on your panes and 2) your daily energy consumption (so sure have to use averages which is fine)............... PS I liked and advise the addition of a DC to DC charger for driving on cloudy days or nights........ 

THEREFORE after your energy audit ADD MORE PANELS THAN SUGGESTED if you have the available space and budget and ADD MORE BATTERIES if you have the space and budget.

 Any solar is good solar and more is better lol If possible when designing a system choose components big enough to allow room for expansion 

John T  User and lover of Solar and Lithium yayyyyyyyyyyy

[Ray,IN]

16 hours ago, pjstough said:

Are you saying that the Ampere Time batteries are a knock off, or did I misunderstand?

When compared to Battle Born and other well-estabiished brands that cost $300-$400 more for the same AH battery, IMO-yes.

Edited August 30, 2022 by Ray,IN

[pjstough]

28 minutes ago, Ray,IN said:

When compared to Battle Born and other well-estabiished brands that cost $300-$400 more for the same AH battery, IMO-yes.

I have a 300 amp hour Zooms, and we will see how it performs for a third of the cost of three 100 amp hour Battle Borns.

[Kirk W]

I went to Amazon with LiFePO4 Lithium Battery and wow! It has been several months since I last looked at them on Amazon but the number of brands and sizes have really grown. 

3 hours ago, Ray,IN said:

When compared to Battle Born and other well-estabiished brands that cost $300-$400 more for the same AH battery, IMO-yes.

I am wondering how one determines who or what is a knock-off?

Top 10 Best Lithium-ion Battery Manufacturers 2022

On the same line of thought, how did you choose what battery to buy if you have gone to LiFePO4 batteries?

Edited August 30, 2022 by Kirk W

[oldjohnt]

One of my methods to help decide WHAT BATTERY, WHAT BRAND, OR QUALITY of the many LiFePo4's out there is to peruse DIY Solar with Will Prowse on YouTube to see his test results and recommendations THEN JUDGE FOR YOURSELF. Im confident BattleBorn are good quality HOWEVER  Im NOT convinced they are TWICE AS GOOD as some other brands with the same ratings which only cost HALF as much ????  Sure, being a curious electrical engineer Ive read tons of reviews from ACTUAL USERS many who say the brand they chose is performing perfect and it may be BB or it may be so and so Ive never heard of lol

 Shop around, do your homework, read reviews, check out DIY Solar with Will Prowse MAKE THE CALL THAT SUITS YOUR NEEDS AND BUDGET. Thats what I did and chose SOK which have performed excellent. I have NO data nor could prove if they are better, worse, or the same as some other more expensive brand............ Im normally NOT into recommending and brand for fear if they are crap out its MY fault, so Im ONLY reporting mine have performed great no problems ITS YOUR CALL

 (65) DIY Solar Power with Will Prowse - YouTube

John T

[Kirk W]

2 hours ago, oldjohnt said:

Im confident BattleBorn are good quality HOWEVER  Im NOT convinced they are TWICE AS GOOD as some other brands with the same ratings which only cost HALF as much ?

The one thing that I will say for Battle Born is that so far they are the only brand that I have verified is actually made in the USA. Most of them are made in China. 

[pjstough]

28 minutes ago, Kirk W said:

The one thing that I will say for Battle Born is that so far they are the only brand that I have verified is actually made in the USA. Most of them are made in China. 

I believe the cells themselves are made in China, but the batteries are assembled in the USA.

[mptjelgin]

7 minutes ago, pjstough said:

I believe the cells themselves are made in China, but the batteries are assembled in the USA.

Correct. I don't believe that any of the cells in the 12V replacement batteries are US made.  Very likely that the cells in many of the "knock-off" batteries are coming off of exactly the same assembly lines as cells for Battle Born, Renogy, and other "name brands".  Likewise the BMS components, cases, etc. 

[Lou Schneider]

49 minutes ago, Kirk W said:

The one thing that I will say for Battle Born is that so far they are the only brand that I have verified is actually made in the USA. Most of them are made in China. 

Battle Born is also unique in that they use spiral wound cells, most of the other brands use rectangular prismatic cells.  Battle Born is assembled in the USA, but I couldn't find any info about the source of their cells.

Edited August 31, 2022 by Lou Schneider

[pjstough]

2 minutes ago, mptjelgin said:

Correct. I don't believe that any of the cells in the 12V replacement batteries are US made.  Very likely that the cells in many of the "knock-off" batteries are coming off of exactly the same assembly lines as cells for Battle Born, Renogy, and other "name brands".  Likewise the BMS components, cases, etc.

One thing that most of the more reasonably priced batteries dont have and that is a low temperature cutoff, or a heater. My battery does not have a low temp cutoff, but I dont plan on being where it is that cold that long anyway. Also, the problem is with charging cold lithiums, and not  discharging them.

 

[Chad Heiser]

There are big differences in lithium battery construction and components.  The biggest things to look for, in my experience, are cell type (cylindrical cell vs prismatic cell), BMS features (built in protections, charge/discharge rate) and warranty/customer service.

Cell type is a big factor.  Very few drop in replacement lithium batteries are built out of individual cylindrical cells.  Most of them are built with prismatic cells.  Both cell types use the same battery chemistry, but prismatic cell based batteries have four large prismatic cells inside the 12 volt battery.  If any one of those cells fails, the entire battery is now an expensive brick.  There is no way around this.  Cylindrical cell based batteries are made up of a much larger number of small cylindrical batteries (slightly larger than AA batteries) wired together to produce a 12 volt battery.  If one or even several of these cylindrical cells fail, the battery can still produce enough voltage to still function.  Obviously if enough of them fail, the battery will eventually become another expensive brick.  This, however, is less likely to cause a complete battery failure than the single point failure of a prismatic cell based battery.

Lithium battery BMS’s are not all the same.  Some are very robust and provide a lot of features.  Some are very basic and do little more than keep individual cells balanced to produce 12 volts overall.  A BMS that can’t handle large charge or discharge rates is also a red flag.  There are many batteries that have a 100, 200, or even 300 amp hour rating to store energy, but can only discharge or accept a charge at a fraction of their power rating.  When running several batteries in a battery bank, this becomes less of an issue because the overall battery bank charge/discharge rating will usually be sufficient.  When running a single battery or a small number of batteries in a bank, this could cause problems with high draw equipment like an inverter.  Temperature controls/protections are also very important for a BMS to have.  Trying to charge a lithium battery at or below freezing temperatures can kill the lithium cells and turn that battery into an expensive brick again.  Internal heating capabilities may also be important to people who have to deal with freezing temperatures on a regular basis.  Very few manufacturers offer this feature.

Warranty or customer support is also very important.  Very few “inexpensive” lithium battery companies offer decent customer support.  How do you deal with a battery warranty issue.  How do you exchange or return a bad battery? Etc., etc.

There are some other factors, but these are the big three I look at when rating or considering a lithium battery.  How long have the batteries/company been around is another consideration that can allow for more data to examine when trying to decide on a battery.

I am typically looking at higher end, high power systems that need to be supported by my battery banks so I want a battery that is high quality and has a proven track record of performance and support.

[rbertalotto]

Chad...Thank you for this post...What about "Pouch Cells".....I see this term sometimes describing a particilar Li battery.

[Kirk W]

10 hours ago, Chad Heiser said:

I am typically looking at higher end, high power systems that need to be supported by my battery banks so I want a battery that is high quality and has a proven track record of performance and support.

Thanks for that discussion of the choices. I haven't done much study of the batteries on Amazon yet but the very wide range in prices for batteries of similar specs makes it pretty obvious that there have to be major differences. Do you have an battery brand preferences to share?  Have you seen any from Amazon that are worth what they cost?

Edited August 31, 2022 by Kirk W

[rbertalotto]

Quote

 I want a battery that is high quality and has a proven track record of performance and support.

I would suggest the only brand that has been around long enough and has enough of a following to have a meaningful record of performance and support is Battle Born.......

[oldjohnt]

13 hours ago, Kirk W said:

The one thing that I will say for Battle Born is that so far they are the only brand that I have verified is actually made in the USA

I certainly LIKE that, THANKS FOR POSTING. Would you happen know if the cells they use are also USA manufactured ?? WOULD MAKE IT EVEN BETTER yayyyyyyyyyyyyyyyyy

 I think some of Will Prowses videos discuss different cell manufacturers, I will have to check that out and report back what I might find 

Nice sparky chatting with you, if ANYONE has data on who makes the cells please let us know, I fear it may only be China grrrrrrrrrrrrrrr

John T  

[mptjelgin]

4 minutes ago, oldjohnt said:

Nice sparky chatting with you, if ANYONE has data on who makes the cells please let us know, I fear it may only be China grrrrrrrrrrrrrrr

John T  

From the article linked by Kirk above:

• Top 10 Largest Lithium-ion Battery Manufacturers in the World
  • Top 1: CATL (China)
  • Top 2. LG Chem (South Korea)
  • Top 3: Panasonic Corporation (Japan)
  • Top 4. BYD Company (China)
  • Top 5. Samsung SDI (South Korea)
  • Top 6. SK Innovation (South Korea)
  • Top 7. Tesla (US)
  • Top 8. Clarios (Germany)
  • Top 9. Toshiba Corporation (Japan)
  • Top 10. Etekware Battery (China)

[oldjohnt]

Huge Thanks MP, hey that will give us plenty to digest lol.. Maybe it will answer my question of by whom and where the cells are made ??? and which if any BB uses or do they make their own ??? It will take some time and you have provided additional ammo

 John T

[folivier]

This would take some digging but I'm pretty sure BattleBorn sources the individual cells from China, tests them to get a matched set, and installs them in their own case. Probably some other manufacturers do the same but many of them are just buying complete batteries from overseas, China mainly.

[oldjohnt]

1 hour ago, folivier said:

I'm pretty sure BattleBorn sources the individual cells from China, tests them to get a matched set, and installs them in their own case

Thats DOES NOT surprise me BB or any company doesn't manufacture all its own products & components here in the good old USA grrrrrrrrrrrrrrrrrr. Its hard to find things NOT part made in China nowadays lol

 John T

 

[Randyretired]

I prefer to assemble the cells myself and add a BMS of my choice.  It is nearly impossible to find cells not made in China.   I haven't found any.  There are significant differences in the cells available and some are just scams.  Most of the cells available are batteries that don't pass the strict requirements for cars but function very well in a less demanding roll such as solar.  Some of the new cells available have been tested to maintain 80% or better capacity over 6,000 cycles. I don't have anything bad to say about Battle Born.  The batteries are proven to function well and the warranty is excellent but the price is very high.  For my use I parallel prismatic cells to build higher amp hour batteries.  I started with 200ah cells doubled to make a 400ah battery.  I have 2 of those and just added a 608ah battery using 304ah cells.  The company that provided my recent cells will match the cells for internal resistance and capacity for a little more and that made for a very well balanced battery.  I have only purchased a limited number of cells from them so I am not ready to recommend them yet.  Currently I am using JBD BMS,s.  These are often relabeled as Overkill.  However,  the balance functions struggle to keep up with higher ah batteries and my future batteries will use JK BMS's.  As you might guess the BMS's are also made in China. The US has a long way to go to compete with China on batteries.  The elements such as lithium are available here but the mining and processing plants are only in the infant stage.   Building plants to make the cells and batteries has began but I would guess these will use imported material for at least many years. At this point China is well ahead of the US and any other country.

Just edited to add I hate sending money to China and dealing directly with them is an experience. 

Edited August 31, 2022 by Randyretired