LiFePO4 battery build

[StirCrazy]

I got my new cells in today and I am going to start putting them together after I sort out whether I am getting a new cell or not, as one has some slight damage. It is probably fine to use but between shipping and duty charges I paid quite a bit for this set of cells so if they offer to send a new cell, I'll take it.

so, the cells I got for this build are EVEv304AH grade A cells. so, when I do get it together and do a capacity test, I am expecting more than 304 and possibly up to 320AH.

here is how they were packed


here is the damage on one of the cells


length


height


width



Anyway, what I want to know is if there is interest in me doing a thread on this build. People that have already built batteries probably wouldn't be interested much but it is more the people that are sitting on the fence about building their own. Also, I would want people who have done builds before to have input on how I make a case or whatever else. my last one wasn't in a case or compressed.

[StirCrazy]

pianotuna wrote:
Stir, the 875 amp-hours were brand new flooded jars. When they died I realized I didn't much laying in the snow to top them up. Li back then were an arm and a leg and your first born son. When I found out the temperature limitations I looked for an alternative chemistry. I found Lithium Titinate--but they were totally beyond my budget (about 4 times the cost of Battle born).

I live on a limited budget. I decided to try the telcom jars, which, similar to LiFePo4 have a higher voltage. (not as high as li, though).

I apologize if I misinterpreted your bms situation. It appear to me that you planned on not having one in the new bank.

no that was just to clear up the misconception that you need a BMS, frankly I think you would be silly to run without one as it takes all the work away from you, but in my situation with almost 10X the daily capacity I use I could very easily get away without one. but no, I already have a JBD BMS... but now I have found a new one that I may just order has it has 2 amps active balancing built in instead of the .1A passive balancing I have in the JBD

[StirCrazy]

pianotuna wrote:
stir I've provided the link to proper li management many times.

ScottG nice includes not using them at -34 F. I can't change the climate where I live.

I think Li are wonderful when they are suited to the climate.

no, a lot of the stuff you have posted is sales propaganda which is from a company that gets their main sales from different types of batteries, everything I post is from the manufacture of the actual cells. the new generation of cells I have are usable to -35C for discharge so if you're willing to move them to a conditioned space there is no reason you couldn't use them.

[time2roll]

Cells look fine. JBD is great. Enjoy the new found freedom with lithium.
I recommend an active balancer over doing an initial parallel top balance.

I have 16 similar grade B cells and they work perfectly. Although I would have preferred your terminals if they were available at the time.

[pianotuna]

Stir, the 875 amp-hours were brand new flooded jars. When they died I realized I didn't much enjoy laying in the snow to top them up. Li back then were an arm and a leg and your first born son. When I found out the temperature limitations I looked for an alternative chemistry. I found Lithium Titinate--but they were totally beyond my budget (about 4 times the cost of Battle born).

I live on a limited budget. I decided to try the telcom jars, which, similar to LiFePo4 have a higher voltage. (not as high as li, though).

I apologize if I misinterpreted your bms situation. It appear to me that you planned on not having one in the new bank.

[dedmiston]

StirCrazy - Please feel free to disagree with pianotuna, but you must disagree without being disagreeable. Keep it kind and respectful please.

[ScottG]

pianotuna wrote:

ScottG nice includes not using them at -34 F. I can't change the climate where I live.

I think Li are wonderful when they are suited to the climate.

Exactly - the right tool for the job.
I'm lucky here in W. Washington in that we never see those kinds of temps. Plus, mine will be inside the RV where it never drops below freezing even during storage.

Of course, there's always heated Lipo's for those in marginal area's (not your case).

Scott

[pianotuna]

stir I've provided the link to proper li management many times.

ScottG nice includes not using them at -34 F. I can't change the climate where I live.

I think Li are wonderful when they are suited to the climate.

[ScottG]

Given the way RV'rs will use lithium batteries, there's just no reason to worry about being nice to them (the batteries that is. We should always be nice to RV'rs..).

[StirCrazy]

pianotuna wrote:
Once every 30 cycles do a full recharge. The rest of the time charge to 85%. Try not to go below 20%. (40% would be even better for cycle life).

The best way is to have a bms. Sure, it costs more--but no battery is cheap. So why not do it the best possible way?

900 amp-hours is a respectable bank. I got to 875 in 2012.

Where are you getting every 30 cycles from and do you even know why you charge to 100%, or for that matter do you even halve to? yes, lowering the actual amount of discharge you use will increase life but there are other ways to do it without losing capacity also. for example, uncompressed my cells have a cycle life of 4000 cycles at 100% discharge. do if I do that twice every weekend so 104 cycles per year, which will last me 38 years. by compressing them properly that will add another 1800 cycles to that 4000. but having said that the compression has the biggest effect in the first few cycles where it acts to squeeze out any air bubbles that are trapped in the cell during manufacturing, so I'll probably just compress them while I do my capacity testing and do 4 or 5 cycles of the battery.

I already stated that I did have a BMS which makes me wonder do you even read the posts or just start spouting out after reading the first two lines?

There is also a difference between your 875 of AGM which gets you about 437 of usable AH if you want them to last, probably less than that as you said they were used telecom jars which means they probably have already lost capacity. I will have 900AH which I can use 100% of if I like and they will outlast me.

I will not be discharging 100%, I build my batteries to have between 5 and 10 days capacity if the solar breaks so normally I'll only discharge 10 to 20% and yes, I will be setting 90% as the top of this battery in the camper, but I won't be charging it to 100% ever, aside from the first few cycle tests. After that I will be adjusting the parameters to make 90% act as 100% so it will balance every time it gets to 90%.


Admin's Edit: Removed some of the vitriol towards Pianotuna.

[pianotuna]

Once every 30 cycles do a full recharge. The rest of the time charge to 85%. Try not to go below 20%. (40% would be even better for cycle life).

The best way is to have a bms. Sure, it costs more--but no battery is cheap. So why not do it the best possible way?

900 amp-hours is a respectable bank. I got to 875 in 2012.

[StirCrazy]

Tom_M wrote:
You will have to add a BMS to the build.

Just wanted to discuss this point also. no you don't need a BMS, but for the way we use them in a rv I would agree and highly recommend that you use one. Before there were quality BMS or BMS that would handle a large number of cells, you used other things to control your shutoffs and didn't have things like low temp cut off unless you used a thermometer with an alarm.

The major difference is how you balance them though, with a BMS you top balance so you can get the maximum charge into the pack. If you're just running raw cells you bottom balance, so all the cells reach their lowest state at the same time, without one cell going too low giving you a more predictable power floor. With a BMS this is controlled as it will shut down the batterie if any cell drops below the min setting so you don't need to top balance. Also, without a BMS you are normaly manually charging so you would be monitoring the cell voltage with a multimeter to get them to the point you want them.

So, it is not necessary and lots of people don't use them, but they are a good send for automation all the stuff you would have to do manually. I don't see not having one as a good fit for a rv type situation theough.

[StirCrazy]

pianotuna wrote:
I would certainly ask for a replacement on grade A cells.

What bms will you use or will you 'roll your own'?

Costing would be of interest for sure.

na Im not that ambitious to make my own BMS I got the same one I used in the camper build thinking I could parallel the batteries if I had to, but the camper is only 280 AH so that might have to be changed. ideally, I want to build two batteries for the 5th wheel and have the capability to add the camper one also to give me 900AH in there for them long family vacations where you want to run the beer fridge and the Margaritaville 😉

[StirCrazy]

Tom_M wrote:
I'd be interested in what your total cost will be. You will have to add a BMS to the build. Last year I purchased a FEENCE 100AH LiFePo4 "drop-in" battery which has a built in BMS for $300 from Amazon. Today it is selling for $179 - $10 coupon + $40 delivery, total $209.
Here's a link to Amazon:
https://www.amazon.com/LiFePO4-Battery-Rechargeable-Batteries-Trolling/dp/B0CJTWDRZR/ref=sr_1_5?crid...

Here's a link to a YouTube video:

https://www.youtube.com/watch?v=VsBtAroiLto

I'll have to figure out the US pricing here, hang on..

so, the cells were 134.00us each, so 536.US. my BMS was about 80.00US it's a 150 amp JBD smart BMS with Uart and Bluetooth (same one I used in the camper). I have had the BMS and a 23 bucks active balancer that I haven't decided if I am going to use. for quite a while now, I got scammed on an original order of cells so I went to an American distributer and paid a bit more than the original order was

ya the cheapest we can find drop ins in Canada is about 450 plus tax and shipping for drop in's but, I would go this way anyways as it is the same power as three 100amps but smaller and probably a bit lighter also.

[pianotuna]

I would certainly ask for a replacement on grade A cells.

What bms will you use or will you 'roll your own'?

Costing would be of interest for sure.

[Housted]

Tom_M wrote:
I'd be interested in what your total cost will be. You will have to add a BMS to the build.

X2

Housted