LTO Lithium Titanium Oxide (Titanate) Battery 30S (now 32S)- Seeking the Ultimate Commuter Battery

[Sunder]

I made some high current analog balencer pcs. I can send you one next time something goes your way.
As I recall 6s and 12s.

Can you explain what these are and how they work?

I am still experimenting with some ways to balance LTO on a monster (55S) pack.

Thanks,

 

[Inwo]

They are simple LM-741 shunt reg driving TO-220 pnp with resistor or lamp load.
10t pot adjust.
Some versions had centering resistors on the pot.
Have to look if I have any boards left. I was selling them for a while.
The ones with lamps and heat sinks have to much time in them to part with.
Any bare boards I will never use.

 

[Inwo]

Why I stopped using mine for LTO
This particular board is aggressive, cheap, and scale-able.

Wouldn't need the monitor, but they're cheap too.
Heat sink is a must. This is minimum. Just happen to have a box of these properly drilled al bars.



ps.
Led activity lights on board are sweet!
Not XH plugs so I piggy backed xh on top.

 

[Inwo]

8-24s bt bms lcd wiring.

Rather than start over...............

https://community.electricforum.com/t/8-24s-bluetooth-bms-thread/13711

 

[ElectricGod]

Why I stopped using mine for LTO
This particular board is aggressive, cheap, and scale-able.

Wouldn't need the monitor, but they're cheap too.
Heat sink is a must. This is minimum. Just happen to have a box of these properly drilled al bars.

MVC-003F.JPGMVC-004F.JPG

ps.
Led activity lights on board are sweet!
Not XH plugs so I piggy backed xh on top.

This is the option I'll probably go with if the 7S modular BMS doesn't work out. Smart, programmable, LCD and possibly BT and app is a better option.

 

[wiredsim]

What is the consensus on the need for balancers? I just built a 12S pack out of the 11AH LTO cells and my first charge was concerning as three of the cells only charged to 2.5 volts while the others charged to 2.8. I didn't have the final connections in place, so I am withholding judgement. I am spot charging each of those cells to 2.8 and will go from there.

Also, for charging I am considering purchasing one of these:

https://www.ebay.com/itm/1500W-30A-DC-DC-Boost-Converter-10-60V-to-12-90V-Step-Up-Power-Supply-Module/172739238019

In conjunction with two 12V server supplies I have isolated and put in serial. The limit will be the step up module, but this should allow me to charge at 20 amps versus getting a Meanwell S-350 knock-off and charging at ~8 amps. What rate do you typically charge at?

Thanks!

 

[parabellum]

Also, for charging I am considering purchasing one of these:

https://www.ebay.com/itm/1500W-30A-DC-D ... 2739238019

In conjunction with two 12V server supplies I have isolated and put in serial. The limit will be the step up module, but this should allow me to charge at 20 amps versus getting a Meanwell S-350 knock-off and charging at ~8 amps. What rate do you typically charge at?

You know that Input V must be lower then Output V to control charging current with this boost converter?
In event where input>output, converter will work like diode and pass all current available. If you plan deep discharge the battery, you should consider paralleling those supplies or regulate the voltage below LVC of your battery.

 

[ElectricGod]

What is the consensus on the need for balancers? I just built a 12S pack out of the 11AH LTO cells and my first charge was concerning as three of the cells only charged to 2.5 volts while the others charged to 2.8. I didn't have the final connections in place, so I am withholding judgement. I am spot charging each of those cells to 2.8 and will go from there.

Also, for charging I am considering purchasing one of these:

https://www.ebay.com/itm/1500W-30A-DC-DC-Boost-Converter-10-60V-to-12-90V-Step-Up-Power-Supply-Module/172739238019

In conjunction with two 12V server supplies I have isolated and put in serial. The limit will be the step up module, but this should allow me to charge at 20 amps versus getting a Meanwell S-350 knock-off and charging at ~8 amps. What rate do you typically charge at?

Thanks!

1500 watts is a bit of an exaggeration too. I have several of these exact boost converters. I used them to make this charger at 82 volts out. I get just short of 9 amps max before they shut down. That's with 2 of them in parallel and they get hot, hence the fans. That's about 800 watts for 2 of them, not 1500 watts each. They do better at delivering current, the closer you are to 1:1. I was powering the converters from a meanwell 24 volt, 25 amp PSU. I built 2 of these and one is still being used after 2 years. The other, I took apart and reused the PSU to build a legit charger at 82 volts out of 4 SE-600-24 PSU's. It cost a lot more, but I can charge at 25 amps or 2050 watts continuous too.

Regarding balancing...if all cells were created equal, there would be very little need for balancing. As we all know, that's not true and cell resistances change, capacities change and so on...aka...the need for balancing. I'm lazy. I want my packs to stay balanced and for me to not have to think about it. As a result, I want an option that is automatic and self managing. That pretty much means a BMS or some kind of balancing board. I also don't want to have to open up the battery bay to manually check balance status and that means some kind of LCD or app on my phone so I can quickly see status.

Regarding charging amps, what's the packs capability for taking current? I bet no charger option you have will come close to the capability of the pack to take in current. AS a result, build your charger to max out whatever you can afford to pay. Why wait 8 hours to charge when you can do the exact same thing in 1 hour?

 

[wiredsim]

Also, for charging I am considering purchasing one of these:

https://www.ebay.com/itm/1500W-30A-DC-D ... 2739238019

In conjunction with two 12V server supplies I have isolated and put in serial. The limit will be the step up module, but this should allow me to charge at 20 amps versus getting a Meanwell S-350 knock-off and charging at ~8 amps. What rate do you typically charge at?

You know that Input V must be lower then Output V to control charging current with this boost converter?
In event where input>output, converter will work like diode and pass all current available. If you plan deep discharge the battery, you should consider paralleling those supplies or regulate the voltage below LVC of your battery.

That is a really good point, I may have to consider switching between 12v to 24v input for starting versus kicking into the full output. The problem is, (as ElectricGod points out) the smaller the difference between input and output voltage the higher the total output of those boost converters. The "1500w" units are supposedly good for 30amp input x input voltage. So at 12 volt input it would be only capable of 360 watts, bumping up to 24 volts would supposedly allow for 720 watts or something like 25 amps at nominal charge rate over the CC/CV curve. Considering these are 11Ah cells, 20/25 amps is plenty good for me at this point, should be around a 50-60 minute charge. I have a "600w" version of these right now, and honestly I may just stay with that. I'm using this pack with a used Neuton mower (formerly SLA powered with two x 10ah 12v AGM batteries) and it's got some real power now, I hadn't mowed yet and with the recent heat I was basically mowing down a hay field. One charge powered through the whole back yard with no problems, I just finished the last section as I got down to a 2.0/2.05 volt per cell range. So normal mowing this battery should easily handle the whole yard, so recharge time doesn't matter as much anymore. Actually the 30amp breaker kept popping when it would bog down with grass, but again normally that shouldn't be an issue. I didn't mind the 5 minute breaks in the 94 degree weather anyway.

The biggest problem I have is I need to make this easy to use from a battery connection and recharging standpoint so no one has the excuse that it is too complicated to use and shirk their mowing responsibilities. I have new found appreciation for all the work the power tool companies put in to making these things dummy proof.

 

[ElectricGod]

The biggest problem I have is I need to make this easy to use from a battery connection and recharging standpoint so no one has the excuse that it is too complicated to use and shirk their mowing responsibilities. I have new found appreciation for all the work the power tool companies put in to making these things dummy proof.

Most power tools do balancing in the pack or they have many small connectors to balance in the charger. The packs are not complex...5 or 6S at most so this is very simple to do. when you get into many more cells, then balancing gets lots more complicated. If you look at a lot of 40 volt chordless tools, they will use 2 batteries so that balance charging stays simple.

you can stay easy and fool proof if you use an onboard balancing system that no one but you has to think about. If all your family has to do is plug in to charge, they will see your electric mower as easy to use.

 

[wiredsim]

Why I stopped using mine for LTO
This particular board is aggressive, cheap, and scale-able.

What do you think of this board for a 12s pack?

https://www.ebay.com/itm/MaxWell-12-string-2-7V3000F-super-capacitor-protection-board-32V-250F/132328436142?hash=item1ecf63b1ae:gnUAAOSwy69Zueyw

 

[Inwo]

Should be fine for a low cost dissipative top balancer.

If you have a larger budget, look at these active energy transfer boards.
Available for any cell count or chemistry. 60v limit per section.
1 triple board can do 24s lto.
>4a balance current transfer.
No setup or adjustment.
Switch to turn it of if you want.


16s stocked. I can post in for sale section.

 

[SamRich]

MAIDEN VOYAGE TODAY
Finally got it painted.
8 miles to work went smoothly.
Bike is pretty heavy but well balanced.

I used 4.5 Ah, which is a bit more than expected. My 35H Edge motor usually consumes 3.2-4 Ah, but I think the Voltage is generally higher on the Multistar 20S 10ah (~80V) setup than this LTO battery (70V), which might explain a ~10% increase in Ah.

80 V*4 Ah ~ 70 V*4.5 Ah ~320 Wh.

The motor/controller efficiency might be a bit different too.

The battery is too big to remove so I need to bring the whole bike into my office to charge it...no big deal. Just draws people attention and got a few questions/compliments on the bike

Still need to lace matching from rim/tire

 

[lwik]

To funny. I have not been on for months since I moved for my new job and adjusting to my new area. I thought I would log on to see if you had any specs on your build Sam and see how the LTO's were working out and you posted your very first results today! Hopefully by the end of summer I will have the time to start an LTO set up for my rig. I'm glad more people are starting to try LTO's out!

How fast are you charging the batteries at work? I know LTO's can handle a faster charge then L-Ion.

Good to see some results finally!

-Lars

 

[SamRich]

How fast are you charging the batteries at work? I know LTO's can handle a faster charge then L-Ion.
-Lars

Yeah definitely a long build...much longer than usual due to unforeseen events that are now resolved.
Good luck with yours! Looking forward to seeing updates.

I charge at 2.7A but looking to build 10A charger.

 

[lwik]

I was looking that the Chargery.com 1500w 24s charger. I am still on the fence of getting the batteries from Inwo, they are a good deal but I also have been talking to a company in that will have the 20AH ones that some how are pretty light for LTO's at 515g per battery.
https://www.alibaba.com/product-detail/2016-New-Product-High-Quality-2_60508999835.html

They also said that they can get /create versions that have a screw thread on top for easy connection so I don't have to spot weld them together. I would need 21 of these batteries to reach the battery voltage. It's still a ways away though and I will probably speak more with Inwo since he can get the charger and things and is pretty smart about this stuff from our conversations.

Please keep posting updates on your experiences with the LTO's

-Lars

 

[ElectricGod]

How fast are you charging the batteries at work? I know LTO's can handle a faster charge then L-Ion.
-Lars

Yeah definitely a long build...much longer than usual due to unforeseen events that are now resolved.
Good luck with yours! Looking forward to seeing updates.

I charge at 2.7A but looking to build 10A charger.

2 things...
1. Can you fix your previous post. None of your pictures work.
2. If you can live with 20 volt increments, Lenovo 170 watt laptop PSU's are a great option for about 10 amps.

Here's an 82 volt charger I made out of them. The AC inputs are all in parallel and the DC outputs are in series. These PSU's are super cheap on ebay...about $16 each. The outputs are fully isolated, over current and over heating protected. I've never tried connecting one backwards, but it wouldn't surprise me if they were reverse polarity protected as well. I've used this charger many times....very reliable and cheap.

 

[SamRich]

2 things...
1. Can you fix your previous post. None of your pictures work.
2. If you can live with 20 volt increments, Lenovo 170 watt laptop PSU's are a great option for about 10 amps.

Here's an 82 volt charger I made out of them. The AC inputs are all in parallel and the DC outputs are in series. These PSU's are super cheap on ebay...about $16 each. The outputs are fully isolated, over current and over heating protected. I've never tried connecting one backwards, but it wouldn't surprise me if they were reverse polarity protected as well. I've used this charger many times....very reliable and cheap.

Thanks for the heads up. Must not have made those pics public.

Yeah that's not bad idea - could probably source a few with different voltage to get the right sum.
I did find a 11A 70-90V adjustable power supply for ~$100 that should work nicely.

 

[wiredsim]

In regards to balancing, what I find is that after a couple rounds charging my cells without balancing they can be off by up to .15 volts. I charged to 33.8 and the higher cell was 2.9 and the lowest was 2.75. However after using them for a short period of time, maybe 15-20% of capacity, they are all exactly balanced within .01 volt. Seems like the "top balance" reveals some difference in holding capacity in the 2.7-2.9 volt range, but that seems to burn off very quickly with no significant energy within that voltage range. That matches other analysis of LTO cells I have seen showing the majority of capacity in the 2.0 to 2.6 voltage range

 

[ElectricGod]

In regards to balancing, what I find is that after a couple rounds charging my cells without balancing they can be off by up to .15 volts. I charged to 33.8 and the higher cell was 2.9 and the lowest was 2.75. However after using them for a short period of time, maybe 15-20% of capacity, they are all exactly balanced within .01 volt. Seems like the "top balance" reveals some difference in holding capacity in the 2.7-2.9 volt range, but that seems to burn off very quickly with no significant energy within that voltage range. That matches other analysis of LTO cells I have seen showing the majority of capacity in the 2.0 to 2.6 voltage range

LTO is way more tolerant to over voltage than other lithium options. Still...I'd want to make sure I don't repeatedly over charge cells.

 

[SamRich]

Got a new Charger for the LTO bike.

States 10 Amps but looks closer to 13!
https://www.ebay.com/itm/84V-10A-Li...ion-Ebike-Power-XLR-Plug-Stealth/332658726743

Screenshot from BT BMS while charging.

So Charging at nearly 1kW!

This battery feels more like a hybrid between LIPO and Super caps. I can put enough charge for my 9 mile commute in about 20 mins!

The charger is big but not too heavy. I could easily carry the 1kW charger on the bike for fast charges if I needed more range.

I had to change the power AC cord for the charger though... It had tiny wires, like 18Ga and was getting uncomfortably hot. I used 14Ga and now it stays cool. The DC side has 2X 14 or 16Ga wires for each poles so that was properly spec'd. They basically took two 42V chargers and stacked them in series to get 84V.

So far really happy with the motor/battery setup. It pushes 100A @ 70V no problem

Based on CA, the battery has internal resistance of 55 mOhms so for 30S that's a bit less than 2 mOhms per cell - matches the specs.

I'll be interested to see how quickly (or slowly) it increases...stay tuned...I'll update after each 100 Cycles.

 

[ElectricGod]

I hope that thing works out for you. Personally, I swear by Meanwell PSU's...they are pretty much the best thing around.

 

[ElectricGod]

I haven't figured out how to program this yet, but it will handle LTO, LIFE or LION/LIPO. This is 5 boards or 35S stack. You can stack them 16 tall or 112S. I think realistically they will balance at about .5 amps despite the sales page and docs saying "up to 1.2 amps". Obviously, this in LIPO. By default from the factory it is set up for LION so that works for this 32S pack too. Once I figure out how to program it, I'll give it a try on a 48S LTO pack.

I did a post over here that goes into more depth.
https://endless-sphere.com/forums/viewtopic.php?f=14&t=88676&p=1390216#p1390216

 

[SamRich]

I did a post over here that goes into more depth.
https://endless-sphere.com/forums/viewtopic.php?f=14&t=88676&p=1390216#p1390216

Thanks for sharing. The fact that you can use the existing balance cables means you can easily swap out subpacks or increase capacity (S) based on need without re-soldering- very useful option.

 

[ElectricGod]

I did a post over here that goes into more depth.
https://endless-sphere.com/forums/viewtopic.php?f=14&t=88676&p=1390216#p1390216

Thanks for sharing. The fact that you can use the existing balance cables means you can easily swap out subpacks or increase capacity (S) based on need without re-soldering- very useful option.

It also leaves the LIPO packs unmodded. Otherwise I'd be talking them apart to put in the balance wires directly to the cells. This is much easier.

This might interest you... it's 3 20S LIPO packs in parallel. I made a hydra cable that takes a single 5S balance connection and makes it into 4 balance connections. The 4th connector allowed me to put a cell log on the extra connector. I ran for a couple of years on these cables all feeding into a single BMS. I could easily do the same with multiple 32S LIPO packs with this balance board set up.