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3 tons

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Posted: 06/29/22 10:39am Link  |  Quote  |  Print  |  Notify Moderator

I have a 100a pass-thru charger and a PD 9245 - the highest combined amperage I ever witnessed is 82a (usually a bit lower as it tapers down), this feeding into 400a/h of LFP (cylindrical cells = air gaps), mfg’s ‘C’ rate is 1.0, but I can’t even get close…With just the lowly PD, I can’t hardly imagine exceeding most other mfg’s C rate…

3 tons

3 tons

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Posted: 06/29/22 10:52am Link  |  Quote  |  Print  |  Notify Moderator

This, from SolaCity:

Storing Lithium-Ion Batteries
The very low self-discharge rate makes it easy to store LFP batteries, even for longer periods. It is no problem to put a lithium-ion battery away for a year, just make sure there is some charge in it before placing it in storage. Something between 50% – 60% is ideal, that will give the battery a very long time before self-discharge brings the Voltage close to the danger point.

3 tons

time2roll

Southern California

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Posted: 06/29/22 10:58am Link  |  Quote  |  Print  |  Notify Moderator

3 tons wrote:

I have a 100a pass-thru charger and a PD 9245 - the highest combined amperage I ever witnessed is 82a (usually a bit lower as it tapers down), this feeding into 400a/h of LFP (cylindrical cells = air gaps), mfg’s ‘C’ rate is 1.0, but I can’t even get close…With just the lowly PD, I can’t hardly imagine exceeding most other mfg’s C rate…

3 tons
Would seem like a charger issue or the wiring is inadequate more than a battery limitation.


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Itinerant1

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Posted: 06/29/22 11:17am Link  |  Quote  |  Print  |  Notify Moderator

time2roll wrote:

3 tons wrote:

I have a 100a pass-thru charger and a PD 9245 - the highest combined amperage I ever witnessed is 82a (usually a bit lower as it tapers down), this feeding into 400a/h of LFP (cylindrical cells = air gaps), mfg’s ‘C’ rate is 1.0, but I can’t even get close…With just the lowly PD, I can’t hardly imagine exceeding most other mfg’s C rate…

3 tons
Would seem like a charger issue or the wiring is inadequate more than a battery limitation.


I agree.

I know if I had to combine my solar and Magnum charger it would max around 175a charging (with good sun) and have seen 165a when running the generator one time to see what it would do combined. Makes for some quick charging. [emoticon]

As far as charging I can feed the batteries 100a (.2c) my with the eu2200i till 98% SOC when absorbs kicks in for 6 minutes and tapers to 99% SOC.

I mentioned this in previous post that I could just about put a stop watch to the minute for how long it takes to use the generator to charge batteries to full if need be.


12v 500ah, 20 cells_ 4s5p (GBS LFMP battery system). 8 CTI 160 watt panels (1,280 watts)2s4p,Panels mounted flat. Magnum PT100 SCC, Magnum 3012 hybrid inverter, ME-ARC 50. Installed 4/2016 been on 24/7/365, daily 35-45% DOD 2,000+ partial cycles.

3 tons

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Posted: 06/29/22 11:20am Link  |  Quote  |  Print  |  Notify Moderator

time2roll wrote:

3 tons wrote:

I have a 100a pass-thru charger and a PD 9245 - the highest combined amperage I ever witnessed is 82a (usually a bit lower as it tapers down), this feeding into 400a/h of LFP (cylindrical cells = air gaps), mfg’s ‘C’ rate is 1.0, but I can’t even get close…With just the lowly PD, I can’t hardly imagine exceeding most other mfg’s C rate…

3 tons
Would seem like a charger issue or the wiring is inadequate more than a battery limitation.


I’m running 0004 / 3’ cabling with crimped, silver soldered lugs…I think it has to do with at what SOC point I begin the charge, but it’s pretty much inconsequential to me since I mostly use solar and ‘play’ somewheres in the 60-80 % SOC range…No doubt, internal resistance plays a role…

3 tons

jaycocreek

Idaho

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Posted: 06/30/22 09:46am Link  |  Quote  |  Print  |  Notify Moderator

I have been using lifepo4 for just a year using them daily running compressor refers and TC stuff,watching numbers out of bord-om and constantly reading about them..I find it interesting that there is no number or numbers agreed on by the mass of users..

You have Will Prowse saying charge them to 100% and use them down to 0% because calendar aging will get them before the cycle count does..Then the masses on his forum argue over the best numbers for the least stress on the cells..

I have picked out a few of the most intelligent opinions(IMHO) on LFP settings from mostly DIY solar forums and saved them by there names to my phone and Victron app library setting to try for my uses..A couple/few of them post here..Example in my library MikeF/Steve/Time2 etc..They all work great but I haven't came up with a final setting for my use yet..

Everyone knows each setup is different and each person has to find his golden numbers that work best for his style of use and charging..In my case with an older TC,I just bypassed the old converter and use 100% solar and a 20 amp LFP charger for gen time if needed with my two 100ah batteries in parallel..

Most people agree with this from solacity though(I think)
Solacity wrote:

To sum up, for long and happy LFP battery life, in order of importance, you should be mindful of the following:
Keep the battery temperature under 45 Centigrade (under 30C if possible) – This is by far the most important!!

Keep charge and discharge currents under 0.5C (0.2C preferred)

Keep battery temperature above 0 Centigrade when discharging if possible – This, and everything below, is nowhere near as important as the first two

Do not cycle below 10% – 15% SOC unless you really need to

Do not float the battery at 100% SOC if possible

Do not charge to 100% SOC if you do not need it



Lifepo4-380ah/Lithium NMC-140ah/Solar-400 watts/Wagan & Giandel PSW/Engel & Iceco 3-1 compressor fridge freezer/5K Window AC/Honda 2K

time2roll

Southern California

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Posted: 06/30/22 10:30am Link  |  Quote  |  Print  |  Notify Moderator

My issue with going to zero % is that there is a hard cut off and all goes dark. The 10%-20% buffer is for convenience of timing the next charge cycle if needed. Going to 100% discharge is not an issue as much as going 101% at a bad time to charge.

BFL13

Victoria, BC

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Posted: 06/30/22 11:06am Link  |  Quote  |  Print  |  Notify Moderator

Some graphs here of interest. Scroll down. One has the Absorption SOCs for some lower C rates.

These guys seem to have a clue, lots of interesting (IMO) posts on some of the things being discussed here.

https://forum.solar-electric.com/discuss........g-lfp-lifepo4-batteries-to-90-soc-or-not


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S Davis

Western WA

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Posted: 06/30/22 02:35pm Link  |  Quote  |  Print  |  Notify Moderator

My EVE LF280N cells are rated at 3500 cycles from full charge to 2.5 volt cut off and that is at 1.C in a compression fixture. I am not to worried about charging them up to 100% SOC and using the full capacity. From what I understand if you draw your battery down 20% and then charge it back to 100% that is only 20% of a battery cycle.

At 3500 cycles I think for most users they will age out before cycling out, I think there are many more factors that will affect cell life more than using the manufacturer stated capacity.
[image]

* This post was edited 06/30/22 02:43pm by S Davis *

Cptnvideo

Arizona - most of the time

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Posted: 06/30/22 03:40pm Link  |  Quote  |  Print  |  Notify Moderator

I'm happy with what I do but I'm not saying it is the correct thing to do. The charger part of my 3kw inverter/charger is turned off and the converter that came with my 5th wheel is unplugged. So battery charging (whether plugged in or not) is only done by the solar panels.
I bulk charge to 14.2V, then absorb for 15 minutes, then float at 13.6V.


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1600 watts solar, 3kw inverter/charger, 3 206AH LiFePo4 batteries

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