Lithium titanate

#1

Charging central.

12 15ah packs being discharged.

4volt 1,000ah pack connected to my welder. Only thing I have big enough to charge this one.

As the others, completely doa. :frowning:

The pouch cells are delivering >10ah and still going.:slight_smile:

Important ones are the 3 X 24v 60ah batteries. Two are charged. Waiting for the last one. Then I’ll do a discharge test.

Extremely time consuming to evaluate unknown batteries.

These deliver most of there energy at 2v/cell.

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#2

Up to 30ah discharge and still going on the 24v 60ah batteries.

They measure 12" X 11" X 6" each.

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#3

50ah and turned it off for the night.
Looks like they may be useful if I can get more.

Large voltage swing.
72v pack from 84v to 45v.
Most power between 72 and 54. Great for a 48v car.

Gem might want more.

Just not going to have the time to get individual pouches tested.
There are about 30 60ah cells. Most marked scrap or seconds.
If there was a way to get them to someone. I’d pass them along.

Anyone up north?

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#4

All 3 in series discharged 63.5ah.:clap2:

These 60ah 24v packs are the most useful of the samples.

I will get a pallet of them if available.

If I get a few more, I’ll test 4 X 10s batteries in Gem.
40 cells charged to 2.3 should give good range and performance.

Gems will operate over an 18 volt range.
2.3v down to 1.9v should work.

Titanate batteries can be charged in 10 minutes. Tolerate lots of charge/discharge abuse.
Some batteries that were down to .5 volts are coming back from the dead.:eek:

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#5

Inadvertently charged a few cells over recommended 2.8 volts.

To 4 volts.:eek:

Swelled up. No heat or fire.:o

Actually still works fine. I don’t know what would happen if confined in a pack.

This mistake is a wake up call. Time to make some 2.8v chargers.

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#6

As I’m expecting more 24v 60ah batteries soon, researching a charging solution.
10 cell octopus. 10 X 2.75v 10a smart chargers.
Access thru factory bms port.

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#7

You get a CHARGE out of doing this don’t cha?

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#8

Guess you have me pegged. I do like wires!

Have these two charged and delivered to my brother for his 48v ParCar truck.

Should know shortly how they work out.

Have to come up with a better charging solution.:confused::confused:

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#9

Got 5 pallets in last week.

360ah 4.6v batteries 10pcs
60ah 24v batteries 20pcs left
12v 20ah packs
18v 20ah packs

20ah pouches
60ah pouches

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#10

Awesome! :smiley:

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#11

Did a 36v scooter project today.
18s 12ah pouches.
Back to back 9 high stack.

Rivet tabs together.
1/8" paper punch
SS brush
Oxide inhibiter
Silicon self fusing pad under each folded tab
Kapton tape
BMS wire to a rivet in each connection
10awg eyelet and rivet B+ & B-

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#12

Lots of these pouches left.

If a brave soul wants to try an 36s 60ah Gem project.:eek:
This would be a huge, but fun undertaking.:slight_smile:

1/2 price to first member to save me the work of doing it myself.
My cars are lithium, now.

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#13

Any updates on the real world performance of your Lithium upgrades?

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#14

I’m in the process of upgrading the electric go-kart I built last summer to a beefier motor and using some salvage-but-in-good-condition battery modules (each module is a 12S pack of 20Ah Lithium Titanate cells). I have six such modules so combining them in two parallel strings of three modules would give me a 36S2P arrangement allowing for a nominal 72v (92.5-ish open circuit at full charge down to 54v when it is close to empty) with a 40Ah capacity.

This is, I realize, vast overkill for a go-kart as it would give me a full hour of pedal-to-the-metal operation up a fairly steep hill so I may just use one string and reserve the other for a different project.

My question is this: does anyone have a recommendation for a 36S Lithium Titanate charger? Each 12S module has a monitoring board that reports the cell voltage of each individual cell over CAN every few milliseconds (along with some other data I have yet to decide). The board in each module clearly contains the balancing circuit but short of deliberately unbalancing a pack to see what it does I can’t be sure whether each pack autonomously balances when being charged or if it merely reports status up to the donor wreck’s main computer and the main computer sends it back messages telling it which balancing action to take on which cell and when.

The upshot is that even if they don’t auto balance I can at least take control by programming a microcontroller to watch the CAN output and shut the charger down when the first cell reaches full charge (and, of course, tell me which one so I can bleed some charge off it and the finish charging the rest) so I don’t strictly need a balancing charger nor do I need one that’s capable of quick charging them (a 10A or 20A charger for 36S would meet my needs quite well). Any recommendations?

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#15

Depending on your budget a c10325 charger will charge any chem from 12v to 102v @1500 watts. ~15amps.
$350
A 72v delta-q is 1200 watts. ~12a.

You can add discrete balancing boards. A common one shunts @ 2.7 volts to bring voltage to 2.65v.
Nicest one that I found does 6s per board. 6 leads show which shunts are active.

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