PINNED - Lithium battery conversion/info

[expresso]

i listen to what you smart guys say here - if the Cells can do 150A steady - which we dont want of course - if its only pulling about 34A Max for very short times - the 15ah cells - 105ah pack should be fine for many years ?

its not being stressed too much - this is what i understand - is that correct ?


when not being stressed just riding around flat mostly etc, - its even less draw -

[steves1977uk]

It's about 5 to 8 amps on flat smooth surfaces and 120 amps on thick carpets/grass/mud etc...

Steve

[Burgerman]

It's about 5 to 8 amps on flat smooth surfaces and 120 amps on thick carpets/grass/mud etc...

Steve

Per motor.

its not being stressed too much - this is what i understand - is that correct ?

Correct, thats why it was important to maximize capacity, and minimize going too high or too low with volts.

[expresso]

another good reason for me to do an ADD ON for the full pack chair and just leave it connected - the hardest part would be for me to just find a plastic container to sit in and in a Back Pack -

[expresso]

Opps - stupid me - i did forget one thing - i cant leave the ADD ON connected to the full pack and charge all together - i need to charge them separate - what was i thinking - i got excited for a moment - that would be a pain to do each day or when ever charging - i may hold off on that plan now - unless my friend wants my 36ah pack - i can offer it much less than starting from scratch for him and its already made and ready - hardly used also - 3 months max -

[Burgerman]

You can if you make a short Y lead and plug both in.

This guy is doing 10 at once... https://www.youtube.com/watch?v=WY194Md6KNg

[expresso]

You can if you make a short Y lead and plug both in.

i cant vision this - i need more info please - - so i can picture what your saying - - the balancing part is the what i didnt think of before - unless i make the cable connection to the chair in two parts - which i can disconnect from the pack end easier - and charge the pack alone then reconnect it to the cable from the chair end -

i didnt want to disconnect the SB50 each time - i can make that cable SB50 leave it on the chair end - other end XT 90 - its easier to disconnect the XT 90 from higher up in the back pack - then charge the ADD ON alone - when all done just reconnect the XT 90 end again -

more wiring this way and instead of one cable to chair - its broken up in two parts - would still work - unless theres a better simpler way for me ?

[Gnomatic]

expresso, reading more of BM's links and posts, the 150A figure for those cells is a burst rate, not continuous. From Headway Headquarters

This Headway 40152S 15Ah certified cell has a continuous discharge rate of 3C, and maximum pulse of up to 10C

So this means that the continuous discharge rate of the cells in your pack(same ones I'm planning to use) is rated 45A.(3C x 15Ah = 45A) But the max you're drawing out of your cells when climbing a curb or something strenuous is 34.29A. In that scenario each cell is getting discharged at a rate of 2.29C (2.29C x 15Ah = 34.29A) And that is just for a very short amount of time.

For the vast majority of your drive time you've been cruising along only pulling ~16A continuous off your pack. Lets just call it 20A off the pack typically in your use to build a bit of headroom into the figure. 20A div by 105Ah = .19C. These cells are rated at 1500 cycles with a 100% depth of discharge, or 2000 cycles at 80% DOD. At a 1C discharge rate. Typically, you're only discharging your cells at only .19C!

Long story short: The cells in your 105Ah pack should last a LONG TIME.

(BM or anyone else feel free to correct me if I've got any of the above wrong, I'm still getting my mind wrapped around all this before embarking on building my own pack)

[expresso]

Ok - i feel better now maybe not in rush to make another Pack unless my friend takes my 36ah pack - then i make another one to replace that -

i will leave the ADD ON with the Lead chair indoor only in a year or so - once i get a new chair - this way i wont even have to charge that one for a week or two per charge - will be last chair with Lead -

[expresso]

i guess its confusing since the specs on the EV site - says 150A

http://www.evassemble.com/index.php?mai ... cts_id=175

dosnt mention pulse etc, - says continuable

its fine either way - with the way you put it in the last post - i am fine with that - .19C less than 1/4 of 1C is 90% of the time i would think or 80% - hills etc, are short overall
even if i do many hills in a ride - cant be more than a dozen - depends what is considered a real hill etc,

since i been riding much more and alot of distance - i do run into many more hills - i can say at least 80% is flat normal ground - never counted how many hills or steep inclines i do on these rides -

[Burgerman]

Dont worry your battery is fine! You will wear out before it does.

[Gnomatic]

i guess its confusing since the specs on the EV site - says 150A

http://www.evassemble.com/index.php?mai ... cts_id=175

dosnt mention pulse etc, - says continuable
-

Yeah, there's conflicting info on this. In this case, best to take the conservative approach, especially since BM does.

You should be fine with your pack.

[expresso]

You can if you make a short Y lead and plug both in.

This guy is doing 10 at once... https://www.youtube.com/watch?v=WY194Md6KNg

no matter how i think about it - it would mean i have to remove the full pack from the chair and do some kind of rewiring for the charge balance wiring on the battery ?

i dont want to remove the pack at all unless i really really have to - i think i did a better job packing it up and sealing it better this time - after adding the breaker -

its in there connected - and not moving -

but i like to understand how to do it - for the future next full pack i do - i can maybe build it in a way that i can make use of a ADD ON with out unplugging it charge -

i got confused since the lead chair with ADD on i charge it all at once -

[shirley_hkg]

Rewiring of your big pack is unnecessary .

Each of your add-on pack should have two D-sub connectors , one female and one male .

Then you can do endless count parallel charging .

[Burgerman]

Or make just one Y shaped charging cable.

[expresso]

Rewiring of your big pack is unnecessary .

Each of your add-on pack should have two D-sub connectors , one female and one male .

Then you can do endless count parallel charging .

Ok from what i understand from this is - on the ADD ON pack - make two charging cables with D sub - balance wires etc. one of them would be Male end - another Female end -

i then connect the Female D Sub from the ADD ON to the Chair Dsub charge cable is there already connected to the Chair pack -

leaves me the Male Dsub charge cable which goes to the PL 8 charger -

then i would just charge as i do now - same preset and it would charge the whole chair and ADD ON - as one large Pack and balance it all the same way i am doing now ?

is that correct ?

in this case - i wont have to touch my chair pack or do anything to the chair - its all done on the ADD ON pack - ?

the only issue if this is correct is having to make a long enough cable from the ADD ON to the Chair so i can use the seat lift all the way up -

i can vision this way - if its correct

[Burgerman]

Yes apart from the termination mA setting will need increasing a little. So save a new preset. Then you have one for 105Ah and another for whatever size both combined are.

[expresso]

Yes apart from the termination mA setting will need increasing a little. So save a new preset. Then you have one for 105Ah and another for whatever size both combined are.

Ok very good then - i can see doing this - gives me options - if i do it - the ADD On would be 15ah cells - 3 Rows - 45ah - total would be 150Ah when all said and done -

Is this what you meant when you said - Make a Y cable ? or did you have something in mind ?

i will have to see how i can make a long enough charge cable going from the Dsub to the ADD On - i may have to extend the balance wires - its interesting to see how it works out this way -

[Burgerman]

Yes. I had Y cable in mind!


https://www.google.com/search?q=y+cable ... 80&bih=579


Like this with your SubD connectors...

[expresso]

yes - i think it would be easier for me to make Two sets instead of trying to make the Y cable that way - that would be nice - since its really like one cable instead of two - but then i have to splice and solder all the power and balance wires -

they wont fit on ONE sub D connector -

i would make one Sub D long enough to connect to the chair when fully lifted up - and the other sub D cable on other side of the pack just for charging the way i have it now - the Pack would have two complete Sub D - balance wires etc, on each side of the pack - and one side will have the power cables also going to the SB50 on the chair for the ADD on to connect -


just curious - since there will be two sets of cables connected to the pack instead of just one - when in use - does it take power from both ends ? how does it know where to take power from the ADD ON ?

[Burgerman]

Not sure what you mean. In every case, driving or parked, the fullest battery charges the empty one if both are the same lithium chemistry.

So if your chair takes some from the main pack, the add on then is connected to a battery with a lower voltage. So some electrons go off to restore the balance!

[expresso]

Let me see if i can explain what i am thinking -

the way it is now - the ADD ON is connected to the Chair with a SB50 which is connected to the main pack in the chair -

when in use this way - that cable is like an extension to the main pack right - now when in use - it will discharge from that cable flowing back and forth charging and discharging


NOW i will have another cable Sub D going to the chair also - on top of the extension cable to connect both packs -

when in use this way - both those cables would be connected to the main pack - does it discharge from both those cables ? i am sure i am wrong how i am thinking -

or does it just discharge what it needs as needed and gets split between both the cables coming from the ADD ON to the chair - ? thats the only thing i can think of that makes sense to me

[expresso]

OH - wait i just though of something -

if i did do this - i wont have to connect both ends to the chair - just one SubD cable going to the Chair SubD and thats it - i wont have to Connect the cable to the SB50 cable thats on the chair now which is used to connect the ADD ON pack

but in that case - the wiring would be 12AWG wires for power -

the wiring i have on the cable SB50 from the chair to connect the ADD ON now is 10AWG -

would that be a problem if i used just the one Sub D cable from the pack to the chair with 12AWG ?

[Burgerman]

the wiring i have on the cable SB50 from the chair to connect the ADD ON now is 10AWG -

Leave it then.

The amps will half to each battery so a bit high maybe, but you could just use the subD connectors. And see...

[expresso]

if using just the Sub D with 12 AWG to connect the ADD ON to the full pack -

if this way is good enough - i wont have to make another cable to connect to the chair SB50 end - One less cable on the ADD ON -

but how would know if 12AWG is good enough ?

[Burgerman]

Try it.

[expresso]

Try it.

i will - nothing to loose - once i get some items in order and think about it - before ordering the cells - i want to find a back pack - that can hold it nicely -


When i do try it with the Sub D alone - how would i know if its OK or Good enough with 12 awg ? what would i notice or see on the charging graph etc, to tell me if its OK or its too thin - not looking to burn it up when in use

when you say try it - i get that - and it will work if i used it - just the 12 awg - you think thats thick enough to handle - the breaker i added wont have any effect on that cable i dont think -

[Burgerman]

If it gets hot...

[expresso]

If it gets hot...

Right - but i would be in the chair riding most likely alone - i wont know if its getting hot or not or whats hot enough more or less -


lets say - i added the other cable also going to the chair on the other side with the SB50 end - then i have two sides with cables connected to the pack and ADD ON -

would that be safer then ? that was my original question - if having both cables connected - which cable is being used - i would think they both would be in use - and how does that work then - ? both in use - does that mean its splitting the needs between both cables ?

one cable would then be 12 awg and the other 10awg -

[Burgerman]

You are getting all complicated and overthinking again. You are going to have wires everywhere!