LifePo4 Charge Performance

pianotuna wrote:
Steve,

I find some of your statements misleading.

1. not all li can discharge at high rates. When they are BARE without bms it is true--but at least some BMS designs limit discharge rates to 1C

2. SiO2 can be taken to 0 volts--so the capacity is 1C, but you do loose cycles.

3. SiO2 can be charged at 27 amps. There is no bms to protect the battery--that is on the shoulders of the owner.

4. LiFePo4 can only be taken to 20% state of charge. The makers get around that by building a 120 amp-hour battery and using the BMS to limit it to 100 amp-hours. As with most batteries going deeper costs cycle life.

I think pouch cells are a bit riskier than the approach that Tesla and other makers are using. One poor pouch may dramatically reduce the entire capacity.

I believe LiFePo4 are GREAT, but only if there is zero cold weather use. If there is--then the MUCH more expensive lithium titinate chemistry needs to be used.

It is at this moment -22 F where I am located. Last night was -35 f.

1, Most BMS limit to 1C but thats charging rate not discharge, C1 would be discharge ;) but if you have a 560AH bank which is two 12V batterys build with 280ah cells that gives you a discharge of 560Amps .. i would call that high. even if you have a store bought one that is only 100ah and discharge 100amps out of it for the size of battery that is a pretty high discharge, two of thoes gives you 200 amp potential and so on. do any ove these other batteries we are talking about have over a c1 discharge rate?

2, all my stuff above was taken at the design to not harm the battery in any way, thats why sio2 is concidered 100 to 20, if we are going to start saying we can take it down to 0 with a little bit of dammage then we have to say for GC batteries we can take them from 100 to 20% instead of 50% as it only reduces the life a little , or Li from 100-0 and get 130ah out of the battery instead of 100 as it only affects it a tiny bit. this is the part of comparing oarnges to apples or apples to apples I was talking about. using an even playing field that maximizes the life of each battery. it doesnt mattery how many battery cells they use to build a 100ah battery , what is important is the advertised capacity and if you get that. to me building a safty factor into a battery is just a little bonus.

3, so I have discovered I thought there would be aceptance rate throttling with Si02 like there is with Lead acid, that is a huge down side for Sio2 if thats the case, but still can work for people.

4, I beieve that is exactly what I said..........

no body uses pouch cells they are the worst lol, battle born uses a 26650 battery in there set up, these are probably one of the better cells to use but it turnes DIY into a complicated and more expensive affair. another good one is the prismatic cell, this is what DIY is mostly. traditionaly they were used in high voltage high capacity power storage like solar battery back ups for comunication and such and some companies are using these to build batteries also. less soldering, less conections and so on. in fact this type of cell is becoming so populare due to the ease that Battle born has made a propaganda video trying to make them seam inferior which like a lot of posts on here they take select info and use a mix of names to make people thing that prismatic cells are the same as pouch cells or that all prismatic cells are made of plastic (thoes are the first generation)

as for the other style batteries that tesla and battle borm use. one bad battery in the series knocks out a whole bank so same idea, just a lot harder to find the bad battery when your looking through 100's instead of 4 haha.. thats why people get parts of tesla packs for there rv's in the states a lot as one section goes bad and they just replace the whole battery. then a company buys the old one for cheep, pulls it apart and sells off the good sections.

cold weather use to a point isnt an issue as I have tried to explain also. for your self who uses the rv as a acomadation for a bisness purpose yes it is an issue , but for 99.9% of the people will never go camping when it is -20 or colder. if you do camp in that -20 to 0C range the only thing you have to do is make sure the batteries are in a space that is heated by the furnace. they can discharge to -20C and once there warm if you have solar they will charge like normal.

now in your case as I have said when you show up some where at -30 or -40 then ya Sio2 will be better for you and the best part is you can write off the expensive cost.

so I dont see anything that I have said as misleading. I didnt know it was a user controld low amp aceptance rate into the Sio2, but I just learnd that this morning and I find it funny that info wasnt more accesable on there website.