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LiFeP04 battery upgrade


Ronbo

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The DW has given me the go ahead. I have been doing a lot of reading. I have some questions.

 

The Chevy Volt and the Nissan Leaf battery cells are 3.7 volts. That is 14.8 volts for a battery pack. If I charge them at 90% (13.3 volts) would they remain at that voltage and would that be acceptable to my rig?

 

What is the difference between the LiFeP04 and the LiFeMnP04? The voltage is 3.2 per cell for both.

 

I have a Magnum 2812 and Midnight Classic 150, both are configurable for whatever I want to do.

Ron C.

2013 Dynamax Trilogy 3850 D3

2000 Kenworth T2000 Optimus Prime

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Hi Congrats!!!!!

 

I don't know the difference between the chemistries so I will leave that for someone else. Mine are LiFePO4 (calb) and are 3.6 per cell so there maybe a little difference.

 

Most of the time my batteries are between 13.3 and 13.0. I have not used them in a boondocking situation yet so they stay relatively charged. But to answer your question, yes, 13.3 would be very acceptable to your rig.

 

I charge to 13.8 but have my charher set up to go to standby;no trickle or equalization. After the charge they settle prettyquickly to 13.4. They then stayin the 13.3 and 13.2 range quite a while. My charger is set to recharge if it gets down to 12.8 but I will set that lower when boondocking. The voltages take some estimating as to what the resting rate actually is as it will show higher the actual resting voltage when charging and lower than actual resting voltage when there is a curent draw.

Dave and Lana Hasper

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I am assuming the 3.6vpc is what you are charging it at? If so that is too much for that cell. It is supposed to be 3.2volts. It should be charged to 3.5vpc and then floated at 3.34vpc. I am working on a possible presentation for the HDT rally if there is enough interest.

 

I am looking at the Starlight Solar 100ah pack for $620. I may buy 2 of those. Much more affordable than the Nissan Leaf pack plus I won't have to build my own.

 

Do you have a BMS and if so which one?

Ron C.

2013 Dynamax Trilogy 3850 D3

2000 Kenworth T2000 Optimus Prime

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No. I had to double check since I do get very confused switching between the cell voltages and pack voltages but I am charging to 13.8 pack (3.45 cell). I then let it go to standby and will rest at pack level 13.4 initially (maybe briefly 13.5).

 

Where did you get your float recommendation? I would not float them. I have not seen a recommendation to float LiFePO4. I have only seen recommendations against it (if by float you mean a float charge at that level).

 

 

I am not using them in boondocking and have been monitoring them closely to see how they react. My install really isn't finished yet. I am watching voltage levels with the Trimetric and periodically a multimeter but have the housepower bms that I will still install.

Dave and Lana Hasper

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#5 FLOAT CHARGING:
These are not lead acid batteries, not your fathers Oldsmobile, and they are not designed nor intended to be "float charged" in the typical sense. The only reason people even try to argue this point is because they are trying to save money, cut corners and adapt poorly or inadequately designed lead acid equipment to LFP technology. Not really a wise idea. Look at any of your tablets, cell phones iToys etc. and they all terminate charge when the battery is FULL. They cut back in when battery terminal voltage has fallen to a preset level, but they do not keep feeding current to a full battery.
Floating LFP is a complex subject and I will touch on this later. Bottom line is to avoid floating LFP banks if you can. Some have argued that a float voltage of 3.35VPC or lower (13.4V for a 12V bank) is not badly damaging. Remember this type of charging keeps you in the upper SOC range for long periods of time and these batteries prefer to sit at 50-60% SOC when not being used not 90%+ SOC.. Can you float at 3.35VPC or lower? Sure you can do what ever you want to, but we don't really know the long term affects other than to say it is likely going to shorten the life. Of the 80 or so white papers I have on LFP batteries not a single one of them has dealt with fractional "C" use and floating at 3.35V or lower, not one. http://www.pbase.com/mainecruising/lifepo4_on_boats

Dave and Lana Hasper

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The above quote was from Marine Compass web site that has a well known how to (kind of the Jack Mayer solar web site version of the marine LiFePO4 world) however not trickle charging is also the consensus opinion on the marine cruisers forum. http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069.html

Dave and Lana Hasper

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I have been reading the Midnight Solar forum. There are people that have had no degradation of their cells over several years. The theory is that if you float below the resting voltage, any power requirements will come from the panels and not the batteries. If the requirement is greater that the excess from the panels, then it will draw from the battery. You want to have your pack full but below 100% when the sun goes down so you can use them at night. If you just turn off the charger after absorb is done, what triggers your controller to start charging again? If you don't charge again during the day, you enter your needy period with less than optimum charge. I am still learning and want to be able to bee off the grid for a few days. Well until the DW runs out of water or fills the tanks.

 

Can you describe your system and your settings?

Ron C.

2013 Dynamax Trilogy 3850 D3

2000 Kenworth T2000 Optimus Prime

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I see. Yes, I have not thought that all the way through. I am referring only my set up with the charger, not the solar.

 

I have the magnum 3012 inverter but have been using those settings as I described in a non boondocking situation so I draw the batteries down quite slowly. If it gets down to 12.8 the charger will come out of standby and go to bulk charge.

 

As I said I have not finished my install. I have the Morningstar TS-MPPT-60 for my solar controller. I cannot remember my settings on that except that it also tops out at 13.8. Since I have been hooked to AC for now I have taken it off line (to avoid the float charge issues) except when we are on the road to prevent any issues. However, now that you make me think ahead obviously I will need to have that set up to maximize sunlight hours. Your settings do make sense tomein this context.

Dave and Lana Hasper

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We need to continue this discussion. I have a Magnum 2812 but have turned off the charger since the install. All I ever use is the solar, 1000 watts. I am topped off by 11 am every day. When I get the LiFe I will unplug to cycle them and watch what it does. I plan on installing the CleanPower Ev display (but without the display part) so I can use my tablet to monitor the system via Bluetooth. When you are ready we can talk about the setting for your charge controller. I need the info to put into my paperwork in case I actually do a presentation.

Ron C.

2013 Dynamax Trilogy 3850 D3

2000 Kenworth T2000 Optimus Prime

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Ron, you need to talk to David Dixon about the Volt cells. No one I know of has more experience with them than he does. As you know, he is working on a similar project. I'll be interested to hear how it goes. I'm about 6-12 months behind you.

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I was hoping David would comment. I may have to send him a private message. I think the 100ah 12.8 v for $610 is the way to go. It is basically turnkey ready and I only have to reset my charge controller and inverter.

Ron C.

2013 Dynamax Trilogy 3850 D3

2000 Kenworth T2000 Optimus Prime

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I bought and assembled the Starlight Solar 400AH package in January and have been pleased with it. As far as turn key, you do get the battery(s) BMS, OV & UV contactors, fuses, shunt, etc. To complete the install, you will need to have or buy the high current CB's/disconnects and build the heavy duty cables to interconnect the pieces. Larry at Starlight solar does provide a wiring diagram and some basic info and was readily available for email/phone assistance. However there are no detailed install instructions. You do need to rely on you own knowledge and experience to complete the install.

 

I have not used my system extensively yet. Only about 5 times have I used up to about 125AH, of the ~300AH usable, before solar charging.

 

I set up my Morning Star MPPT 60 controller to absorb charge at 14.3V (3.575V per cell) and 13.6V float. The 14.3V will bring the batteries into the balance mode at 3.55V/cell. I don't know it this is the best way to operate or not. It is what I am starting with and will modify down the road if necessary. I have not found a way with the Morningstar to turn off float charging. To keep from applying the float charging, I disconnect the solar charger.

 

I designed my system to be somewhat oversized. 400AH battery & 650watt solar. My usual daily boondocking power consumption is about 100-125AH and I don't foresee ever using more than ~200AH in a day. If I see cloudy days on the horizon I will limit my usage to the 100AH range. Even on cloudy days my solar should pretty much recharge the batteries at the 100AH usage level. But that is the advantage of having lithium, I don't need to get to 100% charged, pretty much ever.

Al & Sharon
2006 Winnebago Journey 36G 
2020 Chevy Colorado Toad
San Antonio, TX

http://downtheroadaroundthebend.blogspot.com/

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The DW has given me the go ahead. I have been doing a lot of reading. I have some questions.

 

The Chevy Volt and the Nissan Leaf battery cells are 3.7 volts. That is 14.8 volts for a battery pack. If I charge them at 90% (13.3 volts) would they remain at that voltage and would that be acceptable to my rig?

 

What is the difference between the LiFeP04 and the LiFeMnP04? The voltage is 3.2 per cell for both.

 

I have a Magnum 2812 and Midnight Classic 150, both are configurable for whatever I want to do.

 

Hi Ron--It looks like you're looking at a serial connection of 4 cells, and with the Volt there are actually 3 separate 15Ah cells in parallel internally (so 4S3P). 3.7V is a nominal voltage--fully charged, each cell would be at 4.2V, though consensus seems to support stopping charging at 4.0V/cell. That would make it 16V fully charged--which for most stuff on board will be just fine, but it's getting up there and may very well cause problems with some stuff. Depending on the other hardware you have, you might be better off with a 3S3P cell configuration, which would be 12.6V fully charged. The nice thing about the Volt/Leaf packs is that the chemistry makes balancing and state-of-charge monitoring easy--a voltage measurement shows state of charge, therefore you can balance at any point if needed. The downside of that is that while you're at 16V charged, you're around 12V discharged (with 10V an absolute low limit). If you want to see a voltage-vs.-SOC chart, I've posted one I generated here: http://rvnerds.com/2016/01/21/charging-a-48v-volt-battery-section/

 

As far as the inverter and charger, pay close attention to how high/low you can set the bulk charging voltage (i.e. where you'd go from constant current (bulk) to constant voltage (absorption)). I've encountered a little bit of a challenge with many of the "configurable" inverters not allowing a setting less than 13V (or 52V in 48V guise)--too high for the Volt modules in 12S configuration. Part of that is what prompted me to build my own charge controller--the lower battery voltages mean an off-the-shelf charger would stay in bulk mode and charge quickly, as long as it was shut off at the right time. Once I get some things documented a little better, I'm going to post schematics and the code for doing that--it's really simple to set up, and has been working well so far.

 

Personally, I'm not a big fan of trying to just put a new battery type into an existing system. It may be the cheapest short-term option, and may meet your needs just fine, but I think you end up with a lot of potential left on the table. I know I want to take advantage of the high charge and discharge rates to allow short generator run times and operating heavy loads like my air conditioners. In the case of the Volt batteries, a 48V (technically a 44.4V nominal system using 3.7V/cell) system is easy to set up--you can have 8x 1kWh modules without having to connect to anything other than the lugs GM has there for that purpose. Anything else and you're cutting the tabs between cells, and I certainly would have serious concern about trying to do that. I've certainly had the covers off of the modules to expose the cell tabs, but only very briefly. The amount of energy that would be released if one were to create a short circuit there would be ugly.

 

I am assuming the 3.6vpc is what you are charging it at? If so that is too much for that cell. It is supposed to be 3.2volts. It should be charged to 3.5vpc and then floated at 3.34vpc. I am working on a possible presentation for the HDT rally if there is enough interest.

 

I am looking at the Starlight Solar 100ah pack for $620. I may buy 2 of those. Much more affordable than the Nissan Leaf pack plus I won't have to build my own.

 

Do you have a BMS and if so which one?

 

As far as Leaf vs. Volt, they differ in both capacity and price by roughly a factor of 3:2. Given a choice (and I've looked at both, but only actually worked with the Volt pack), the Volt pack is a lot easier to work with. It's really simple to disconnect cables between modules and get to low voltages (for safety) quickly. From an investment standpoint, with the Leaf being electric only, you know the batteries have seen a significant number of charge/discharge cycles. The Volt on the other hand, particularly when owned in fleets, is often used with gas as its primary fuel source where the battery doesn't have to do much. There's a dealer that specializes in used Volts that looks to the lifetime fuel mileage (and looks for low numbers) to assess battery usage.

 

One thing to keep in mind with most of the BMS systems out there is that they're not designed to handle the higher voltages from a lead acid charger indefinitely. They shunt across individual cells to prevent overcharging at the cell level, but once all cells are charged, you still need to make sure the charger isn't trying to charge. You'll be generating heat, and the extent to which that can be tolerated likely varies based on the BMS design.

 

I have been reading the Midnight Solar forum. There are people that have had no degradation of their cells over several years. The theory is that if you float below the resting voltage, any power requirements will come from the panels and not the batteries. If the requirement is greater that the excess from the panels, then it will draw from the battery. You want to have your pack full but below 100% when the sun goes down so you can use them at night. If you just turn off the charger after absorb is done, what triggers your controller to start charging again? If you don't charge again during the day, you enter your needy period with less than optimum charge. I am still learning and want to be able to bee off the grid for a few days. Well until the DW runs out of water or fills the tanks.

 

Can you describe your system and your settings?

 

 

I see. Yes, I have not thought that all the way through. I am referring only my set up with the charger, not the solar.

 

I have the magnum 3012 inverter but have been using those settings as I described in a non boondocking situation so I draw the batteries down quite slowly. If it gets down to 12.8 the charger will come out of standby and go to bulk charge.

 

As I said I have not finished my install. I have the Morningstar TS-MPPT-60 for my solar controller. I cannot remember my settings on that except that it also tops out at 13.8. Since I have been hooked to AC for now I have taken it off line (to avoid the float charge issues) except when we are on the road to prevent any issues. However, now that you make me think ahead obviously I will need to have that set up to maximize sunlight hours. Your settings do make sense tomein this context.

 

My approach for dealing with different charging methods is to bring all charging sources to the battery pack, and disconnect them via relays controlled by the battery controller when the battery is charged. In conjunction with another project I've been working on for about a year, I'll be controlling the converter/charger based on a daily solar forecast (obviously with some logic to accommodate errors in the forecast). Given the high charging rates that a Li-ion battery can tolerate, I'll then be able to use basic off-the-shelf charging equipment (i.e. not configuring special charge profiles), and let the controller shut things off when done.

 

 

Ron, you need to talk to David Dixon about the Volt cells. No one I know of has more experience with them than he does. As you know, he is working on a similar project. I'll be interested to hear how it goes. I'm about 6-12 months behind you.

 

Jack, that's a little scary! Actually, I've been really pleased with how things have been working so far. If things will dry out here enough that I can get under my rig to move some cabling (and I can find the time), I plan to fully remove the remaining 12V stuff in 2 of the bays under my rig. I'm still keeping the main 12V distribution panel, which will have a buck converter co-located to step down from 48V for all of the little stuff, but I'm going to move the battery cables for starting the generator to the chassis battery bank--which always seemed like where they should have been connected to begin with: more cranking amps, and they'd be charged so that you could start the generator easily to charge the house bank. As part of that, I'll also have a boost converter to allow the alternator to charge the lithium bank--which is a convenient way to limit the load the alternator sees.

 

I'm running out of time to get it all done before heading to Louisville (and have a lot to get done to have things ready for that), but it'll be working in some form or another. The 6 lead acid batteries still limping along are pretty well worthless at this point, and I'm not spending any money on them.

45' 2004 Showhauler -- VNL300, ISX, FreedomLine -- RVnerds.com -- where I've started to write about what I'm up to

Headlight and Fog Light Upgrades http://deepspacelighting.com

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Al, change your float voltage to 13.36. That is 3.34vpc and is lower that the resting volts of the cells. At this level the float doesn't matter. If you then use some stored power and the voltage drops, it will drop out of float and then will recharge appropriately.

Ron C.

2013 Dynamax Trilogy 3850 D3

2000 Kenworth T2000 Optimus Prime

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I'll toss my praise of Larry and Debbie at Starlight Solar. Good people, good products, good support, and willing to work with you along say a learning curve:)!

 

I visited Starlight Solar yesterday, and Larry worked with MidNite to get our Classic 150 software upgraded to talk with a recently added Whiz Bang Jr. I also had him review our full solar install, as a second set of much more experienced eyes then I have. While I hope to get another 5 + years out of our existing Lifeline's, Larry also helped me look over our battery bay for future upgrades to a lithium bank. As mentioned, they're both good people, and I found Larry to be a straight shooter:)!

 

Also, might be of interest to read and see the pictures, is Nina's and Paul's new system. (Believe I have seen this posted elsewhere too:)!).

 

http://wheelingit.us/2016/03/06/the-big-beastly-solarbattery-upgrade-part-iii-installation/

 

This link is the the third in her series...

 

Really enjoy reading posts like this, as I get to self educate along the way:)!

 

Best to all,

Smitty

Be safe, have fun,

Smitty

04 CC Allure "RooII" - Our "E" ride for life!

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Al, change your float voltage to 13.36. That is 3.34vpc and is lower that the resting volts of the cells. At this level the float doesn't matter. If you then use some stored power and the voltage drops, it will drop out of float and then will recharge appropriately.

Good suggestion. I'll reconfigure my voltages.

 

Thanks

Al & Sharon
2006 Winnebago Journey 36G 
2020 Chevy Colorado Toad
San Antonio, TX

http://downtheroadaroundthebend.blogspot.com/

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Watch your SOC on your battery. You don't necessarily want it at 100%. I am going to shoot for 90-95%. If you notice the SOC drifting up while on float, lower it just a bit.

Ron C.

2013 Dynamax Trilogy 3850 D3

2000 Kenworth T2000 Optimus Prime

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I purchased the 300 ah battery with BMS from Sarlight Solar. I received the BMS today. I will pick up the actual batteries in 3 weeks when I am in Pheonix. I decided to go with a prebuilt system instead of building one myself. If I had ordered all the parts to assemble myself I would not have saved anything. Now I have the support. I had thought about a Chevy Volt battery pack but the initial battery would have been about what I paid for my whole system, and that is befor I start putting everything together. I also would have had a system that was at a higher voltage than I was comfortable running for all my 12 volt item long term. When I do the complete install, I will post pictures. Is anyone interested in purchasing my 6 volt batteries with battery watering system. I have 4 of them. I have had them 2 years and they have never discharged lower than 80%. I am asking $200 for them. You have to pick up. If interested I am in Sacramento right now. Going to Pheonix in April, then Albuquerque, Plainview tx and then Houston tx.

Ron C.

2013 Dynamax Trilogy 3850 D3

2000 Kenworth T2000 Optimus Prime

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