LTO battery

[Grapes2wine]

Tried a search for an existing thread but didn't find one, my apologies if it already exists. I am doing two projects, so far, one is an RV capable of long term boondocking and the other is a grid-tied system for a good friend.
While researching the battery banks for both, I came across this relatively new technology. Loved all the pros; no fire hazard, no off gassing, reasonable charge density per kg or cc, and importantly up here low temp charge/discharge and of course many, many cycles. Which brings up my confusion. The specs are all over the map....... even from the same manufacturer. Not just cycles but cold temperature capability.
I am also sufficiently confused I can't even figure out how much capacity I need....... the plan is 4-6 245w 60 cell panels 24V on the RV and 20 of the same panels 48V on the house. That's the limit of roof space and with the low cost of these used panels, thanks Will, it only makes sense to use the panels as the limiting factor.............I think. From what I understand another advantage of the LTO battery is its no problem adding on more capacity should the need or budget require/allow it.
OK folks come out with your guns a blazin', I'm all ears. P.S. just watched Will's video on the battery cost comparison so until the new C6 batteries have some time under their belt its either LTO or LiFePo4 as I see it.

 

[svetz]

LiFePO4 and LTO are both safe, LTO has enough cycles for a lifetime and usually a price to match.

As long as it's safe, it's not a matter of chemisty for most people; it's about economics. There's an example here: http://www.diysolarforum.com/index.php?threads/battery-faq.200/post-5082 for how to compare batteries of different chemistries.

 

[Craig]

Im experimenting with LTO batteries so far I like them but have not capacity tested them yet 100% I'm using 12 batteries which gives me a low voltage of 1.6v per cell and high of 2.8v per cell with a total range of 19.2 volts to 33.6 my plan is to cycle them them fro 20 Volts to 33 volts from my testing so far that high end of the charge does not yield that much energy. Currently my inverter works from 33 volts down to 21.4 volts but I have found one or two with a range of 18.1 to 34 volts so they should be perfect. Im just want to do some more testing before I shell out 1500 on the inverter. Most other inverters dont have a range optimal for LTO batteries.

Im working on a testing rig to get full DOD out of batteries and I will report my results hopefully with a full energy per Mv drop in voltage. If i test these and they get close to 40 AH I will use these batteries in my systems. I want to use them because of the high C rate and numbers of cycles possible. Plus I just like trying different things.

 

[Craig]

the price is about 20% higher than LIfePO4 but they last conservatively 5 times as long

 

[Grapes2wine]

Thanks Svetz and Craig for your input. I'll be curious to hear about the further results of your tests. Of course cycle life will be tough to measure with such a potential.

 

[Grapes2wine]

I have put requirements off in an RFQ to one of the off shore manufacturers of both the cells and battery packs with balancer/bms included. It will be interesting to see what he/she comes back with. Then I'll ask about the warranty on both the cells and the BMS trying to heed some knowledge gained in other threads.

 

[Craig]

I have put requirements off in an RFQ to one of the off shore manufacturers of both the cells and battery packs with balancer/bms included. It will be interesting to see what he/she comes back with. Then I'll ask about the warranty on both the cells and the BMS trying to heed some knowledge gained in other threads.

Yes i'm working with a supplier as well I'm looking for guarantees if I test batteries and they are not up to spec. Im not that worried about balance in LTO so far Ive tried to mess up balance and they seem to end up fine.

 

[Grapes2wine]

I've read that elsewhere as well....... this manufacturer seems to have the two functions together on the board, probably cost more to delete the balance function. I always try and give suppliers an opportunity to improve on my specs with an off the shelf option that is usually either less expensive or similar in price with more functionality. I have outsmarted myself a few times insisting on only a certain specification and add-ons. I'll let you know what they come back with.

 

[Craig]

so from the info Im getting there is a significant difference between the 30Ah cells and 40Ah cells 30Ah cells are rated at 27ah and 40 are rated at 41ah. plus 30 ah are 20k cycles and 40ah are 30k cycles just what the vendors are telling me.

Ive been looking into the round ones. does anybody have any thoughts on the prismatic LTO?

 

[thedodgersonline]

Im working on a testing rig to get full DOD out of batteries and I will report my results hopefully with a full energy per Mv drop in voltage. If i test these and they get close to 40 AH I will use these batteries in my systems. I want to use them because of the high C rate and numbers of cycles possible. Plus I just like trying different things.

Hi Craig
I would be extremely interested in your testing setup as I am about to pull the trigger on some LTO cells (66160 40aH) but would like to test them to see how they go. If you could put up some schematics / equipment list / pictures / videos ...anything PLEASE.
Thanks in Anticipation.

 

[thedodgersonline]

so from the info Im getting there is a significant difference between the 30Ah cells and 40Ah cells 30Ah cells are rated at 27ah and 40 are rated at 41ah. plus 30 ah are 20k cycles and 40ah are 30k cycles just what the vendors are telling me.

Ive been looking into the round ones. does anybody have any thoughts on the prismatic LTO?

Hi Craig

They cycles quoted seem to range from 15000 to 30000 but I have been mainly focusing on Yinlong batteries. No specif reason just trying to get some commonality. Also the warranty offered seems to fluctuate between 18 months and 36 months.
The best price I have got from AliBaba is USD27 for the 40aH Grade A cells. Prices seem to be all over the place as well but I have never had a problem with the AliBaba buyer protection.

Regards

 

[Craig]

Hi Craig

They cycles quoted seem to range from 15000 to 30000 but I have been mainly focusing on Yinlong batteries. No specif reason just trying to get some commonality. Also the warranty offered seems to fluctuate between 18 months and 36 months.
The best price I have got from AliBaba is USD27 for the 40aH Grade A cells. Prices seem to be all over the place as well but I have never had a problem with the AliBaba buyer protection.

Regards

Yes I get about the same price at a low if 15k cycles that means they last 40 years assuming 1 cycle per day. I currently have quite a few I'm making a test rig for to check capacity.

 

[Craig]

Test rig nearly completed gonna add more resistors to reach 40 amp draw

 

[Craig]

The black box in the middle reports amps to raspberry pi which logs the current every 10 seconds and keeps a tally of usage. The relays at top turn on to start discharge then turn off at the 1.6 Volt cutoff voltage. the meter in the middle is just so I can compare raspberry read current with something else.

 

[Craig]

Even at $50.00 per cell 18 cells would give you 120 AH at 12v for 900 dollars very compareable to Battle Born with minimal cold weather issues plus more cycle life,

 

[Craig]

Tested my first 40Ah cell it came up to exactly 35.075 Ah This was at around a .625 C rate.

Gonna test some more at a .25 C rate to see what happens.

 

[Picasso]

did you get a chance to check the weight of your 40Ah cell?

 

[thedodgersonline]

Tested my first 40Ah cell it came up to exactly 35.075 Ah This was at around a .625 C rate.

Gonna test some more at a .25 C rate to see what happens.

Hi Craig
Did you get these via Ali - if so you can make a claim and get your money back..
Regards

 

[Craig]

Battery ID 124-2

Received Voltage 2.2 #voltage tested out of box

Charged To Voltage 2.81 # what I charged to before testing

12 Hour Sink Voltage 2.6 # voltage after battery rested about 12 hours

Test Start Time Fri Dec 6 06:49:35 2019

Pre discharge Volts 2.6 # voltage when hooked to test system before discharge


# Ah each of these is a voltage level and amps produced at that level
2.4 1.54 Ah
2.3 3.86 Ah
2.2 4.04 Ah
2.1 6.68 Ah
2.0 11.1 Ah
1.9 4.73 Ah
1.8 0.72 Ah
1.7 0.26 Ah
1.6 0.12 Ah

Test Total AH 33.07






so this is my test profile.

I have contacted China and they are looking in to it.

I charged cell to 2.8 volts
let settle for 12 or so hours
tested voltage again it was down to 2.6
hooked up to 25-30 amp load
discharged to 1.6 volts recording output amps and volts every 15 seconds.

 

[thedodgersonline]

Hi
Any update on these batteries?
Regards