80Ah ADD ON build

[expresso]

yes thanks - ex goose - will look for one to purchase - the width is about 2 inches long and 1 1/2 wide - to me it looks thin - i will use the shorter headway screws i have plenty of - i will double up anyway - nothing to loose - i have plenty of them and it can help to fill the gap - i will use lockwashers i have with the headways also - instead of getting different ones - i can add in the small flat washer also - after that i cant see it not working.

the ends with the cables should be fine - the rest without i need to fill the gap good - i ordered a hole puncher to see if i can get them to fit once i wrap them first and add sheet in between.

finished Cell 5 yesterday and looks about the same as the others - close to 75ah returned - if BM says you return less than you actually have - then it should work out to be very close to 80ah at 2.9v -

[expresso]

https://smile.amazon.com/Electronic-Mea ... al+caliper

would this work - be good enough ?

[LROBBINS]

I've been using one like that almost daily for at least 10 years now. The only shortcoming is that the button cells don't last long with this heavy use. Once I got fed up with that, I soldered in a couple wires to connect an AA battery (taped to the caliper) which lasts a loooong time compared to the button.

[flagman1776]

I used to use dial calipers but went digital with a selection of plastic & Stainless Steel from Harbor Freight. Always one within reach. More accurate than the user.
Yes, your Amazon selection is adequate, too.

*** In my use, I haven't replaced a battery yet.

[Burgerman]

finished Cell 5 yesterday and looks about the same as the others - close to 75ah returned - if BM says you return less than you actually have - then it should work out to be very close to 80ah at 2.9v

If you take OUT 50Ah out will put back 52 or 54Ah. Depending on charge settings or cell resistance etc.

You need to measure it the other way, on discharge.

[expresso]

Ok thanks. I will do a full discharge when I make the pack. I was thinking of doing. Each cell.but don't see the need a lot more time. We

[expresso]

they all seem so far about the same - again i lost most of my graph while i left it charging and went out - when i got home the PL 8 software was closed - was still charging fine - i reopened it to keep recording but didnt show a good graph - on Cell 5 - Cell 6 is good and Cell 7 should be finished in a few hours

one more to go - waiting on some supplies - silicone sheets etc, - then i can start to wrap - i may just get 75ah out of them when doing the full discharge - i should at least get 75ah - based on what i am getting on recharging - but i wont go past 2.9v - they say 2.5v cutoff and no lower than 2v for protection.

could it be that these Cells can do 2.5v Safely and not below 2v with out damage - thats how the specs show and say.

[expresso]

some cells i found say in the specs as 3v cutoff - that means even going down to 2.9V would be too low - in those cases i would think you dont want to go below 3.2v - you have to read the specs and use Cells which at least show a 2.5v cutoff limit i would think - and most do - but some rare Cells i seen 3v cutoff

[expresso]

cell 7

[Burgerman]

Cells with 3v lower limit are lithium ion.

[expresso]

Cells with 3v lower limit are lithium ion.

Ok its always good to double check the specs of what kind of Chemistry the Cells are - they get mixed in there and sometimes i have noticed they call them different names - and somewhere in the specs you see LIfePO4 - or 3.2v - and then you see lithium ion etc, - it can be tricky - you have to make sure you are buying LIfePO4 3.2V -

i will be on the look out now if i see a cutoff Volt of 3V - to see what chemistry they show - you really never know the truth 100% with this stuff unless buying Headways i think - i just hope they are good once built as a pack - on my last Cell today - waiting for silicone sheets etc, - will start to fireproof wrap each cell first in the meantime -

[Burgerman]

Actually you need to look at charge voltage.

4.2VPC is either Lithium Polymer firebomb hobby type cells, or may be lithium ion cobalt laptop type cells and in both cases very short lifespan.
4.1VPC is lithium ion cobalt type as above, but with less capacity and much longer service life and as used by Tesla etc. SAME CELLS different way of using them. Charging to .1v less means 2 or 3x the service life and 20% less capacity on these cells. As such my laptops advanced BMS allows me to charge and balance at 80% charged, maximum. Its battery is as new 2 years on.
3.65VPC is LiFePO4 with too high charge point because they get less problem balancing with a typical useless BMS... Shortens life slightly.
3.60VPC is LiFePO4 with a safer charge voltage. Requires a proper balancer or charger that can balance.
3.55, 3.50VPC as above, slower to charge, slightly, longer life slightly... In the case of a LiFePO4 cell all these charge voltages mean its 99 to 100% charged. It only changes cycle life and the ease of balance and the CV time.

Expresso's head explodes...

[expresso]

i dont bother with things that dont affect me at the moment - so if i am dealing with LifePO4 which is what we want only - i look for 3.2v as a guide - but i always read all of it - specs and re read - it can be tricky and then if they say different specs on top and bottom of the same page - then you have to double check again and ask to be sure it really is 3.2V Life

its easy to make a mistake - Last Cell is done - now i will start on wrapping them - and then wait for the silicone sheets to arrive next week - to add them - and then check the connectors

[Gnomatic]

Looks like you got a solid group of cells, expresso. Pretty consistent. You are going to set the Ah record for an add-on pack.

[Scooterman]

Looks like you got a solid group of cells, expresso. Pretty consistent. You are going to set the Ah record for an add-on pack.

I second that Expresso

Also thank you for posting the charging graphs, they'e really informative.

I was doing some reading about bogus claims/specs on some chinese cells. And how some cells are manufactured in backstreet workshops but sold through flashy websites. It got me thinking it's probably a bit like counterfeit pharmaceuticals made in India but sold through professional looking websites. Some of the counterfeit manufacturers drugs can be good quality, but others rubbish (even dangerous) quality.

[Burgerman]

Well the PL8 can determine EXACTLY what you got. Because while it can measure and graph what you put back, that isnt an accurate way to determine capacity. Some is wasted as heat through resistance, cables etc. And recharging efficiency varies among cells. And chemistries. Lead is terrible. Lithium generally almost 95% efficient. But with lead you might put back 1.3 times as much as you can get out.

But the PL8 can ACCURATELY discharge a lead battery, graph it, Volts V time, Ah V time, Etc. So you can FULLY but safely set it to discharge a full cell, to a specified safe voltage, and measure EXACT capacity you got from it. So you can see if you are getting what was claimed, or not.

[expresso]

I will test it doing a full discharge once its all done - when all done - will leave connected alone for a night - let them all blend it a bit - then full recharge - then discharge to 2.9V - it should be close to 80ah i think -

i could have even used a 100ah Cell to make this ADD ON - but they were thicker - same size more or less just thicker - and my goal this time around was to make them fit in the plastic shoe box i use with out having to cut to extend it like i had to do with all my previous ADD ONs - headways included - actually those were the longest of them -

this Cell size is 29mm thick - so i can wrap it - add sheet of silicone - and still fit nicely padded around the edges etc, - only thing i have to figure out in the end is the cover - since they are taller than all my other cells - i cant just close the cover on it - i need about 2 inches to give it some room after i add wiring etc, .

when i get there - i see how i will handle it - i think its easier to deal with the cover than extending the whole thing for more width - but it can be done with a 100ah ADD ON also - that would be wild just to say you have a 100ah ADD ON when most chairs dont have that inside - on any other chair this ADD ON would i am pretty sure can give you a solid 40 miles - with Lead and 80ah ADD ON - on most chairs - i am hoping to get 40 miles on the bounder - 180ah total i would have never though i would have 180ah pack 3 years ago when i started - its addictive -

[expresso]

Looks like you got a solid group of cells, expresso. Pretty consistent. You are going to set the Ah record for an add-on pack.

i think so for real - Shipping wise was very fast - had these in two weeks delivered - - costs all included - customs or import tax etc, nothing - i dont want to count my chickens just yet - but so far cant complain - if they turn out good - it was a good deal i say.

[expresso]

Looks like you got a solid group of cells, expresso. Pretty consistent. You are going to set the Ah record for an add-on pack.

I second that Expresso

Also thank you for posting the charging graphs, they'e really informative.

I was doing some reading about bogus claims/specs on some chinese cells. And how some cells are manufactured in backstreet workshops but sold through flashy websites. It got me thinking it's probably a bit like counterfeit pharmaceuticals made in India but sold through professional looking websites. Some of the counterfeit manufacturers drugs can be good quality, but others rubbish (even dangerous) quality.

thanks - well hard to know for sure what you get - i hope they are good now and for the long run - no way of knowing - all websites look great - and dealing with over seas - i dont see any other choice - nothing here in the States - even if they were - they would cost double - so we will still deal with China

[Scooterman]

https://www.aliexpress.com/item/4pcs-High-power-system-4s-3-2v-100Ah-lifepo4-battery-cell-12V-14-6v-pack-for/32839723292.html?spm=a2g0s.8937460.0.0.1dd02e0equa0uT

same size at 100ah Cell -

I did googled the name of the manufacturer. This guy bought from same man'.

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

NB: make sure to also read the video blurb.

[expresso]

yeah i cant say if mines will be great long run or even short run - i will see - my first order for the 60ah Cells turned out OK but for one weak Cell - i was having an issue getting them to replace it - so i just stopped payment with PayPal - they agreed with me and wanted to refund me everything but i had to return them all - of course i didnt want to do that - and it would cost me to return - i never even considered that - after about 2 months of them not getting paid - they were begging me to release the money and sent me a replacement cell which i need to replace on the 60ah pack - this winter

so do i really trust them - NO - not much i can do - you take a chance - i am not experinced at buying from China or this way at all - Headways i never worried about it - but with these kind and so many all over the place - you ready never know for sure - they do make custom cells so may not be a Brand new Shell on the outside but i want to hope at least on the inside are New since i have asked a dozen times at least that i only want New Cells etc,

like they really care what i say - once its sold - thats it - but again i used Paypal so i have 90 days to open a dispute - which is why i start to work on them and want to get it built within a month at least to test and discharge etc, - not rushing but within a month i have it done and tested as a pack - cross my fingers that i dont have an issue with it.

[expresso]

https://www.lifepo4-batteries.com/sale- ... f-car.html

i tried this site first - they look Brand New in the pictures at least - they sound great - even costs were about the same more or less - BUT they didnt have the 80ah Cell they show on there site - and dont remove it either - they tried to offer me a different Cell - Size and Ah were different - so i moved on -

now if i were doing a Full Chair - this Cells above i would have used - but i was looking for a 80ah Cell more or less but the Size had to match and most were at least 36mm thick - i wanted thinner this time for this ADD ON for a few reasons. or else i would have gotten them from the above site -

i tried other places and same thing - that 80ah Cell they show isnt there no more - at least at the time i was asking for it - if they come back in stock - which i dont think so - it sounded as if they are made and then sold out - and then not made again - dosnt seem they will always have them if needed down the line.

which you have to think about also - what if you needed a extra Cell in a few years from now - the chances are we may not even be able to get the same Cell. this is just the feeling i am getting - i could be wrong. - if they lasted 5 years working as an ADD ON - at least 5 years - then you can say Ok it was worth it - you hope for more than 5 years - but take what you can get

[expresso]

Ok i finally got a digital Caliper and i love it already came with an extra battery also -

this is the connectors i have to use - you cant see the readout from the pictures but the thickness is about 0.3mm

20mm width and 40mm long -

can one of these handle the job alone ? just to know - but i will use two anything to fill the gap

[expresso]

2 more

its about 46.8 mm the length -

[snaker]

Mine are 2mm thick

[Burgerman]

0.3 x 20mm wide is the same as a 6mm sq mm wire.

Which is what I would likely use for an addon anyway. But if you can use 2 for each, then do so. Since 6mm2 is good for only 60A.

[Scooterman]

thanks - well hard to know for sure what you get - i hope they are good now and for the long run - no way of knowing - all websites look great - and dealing with over seas - i dont see any other choice - nothing here in the States - even if they were - they would cost double - so we will still deal with China

I hope so too expresso

And I agree with you regarding buying from china being the only really viable option. There are no lifepo4 sellers, the nearest I've found is GWL in chezchovacia and they're almost twice the price for half the Ah as buying cells direct from china. And GWL cells are chinese anyway.

Also looking at the these two graphs I can't see the price of lithium coming down anytime soon.

lithium

lead

I found these, big bang for small bucks. https://www.alibaba.com/product-detail/ ... 3f51SLoEsV

But if I understand the spec right they are only 1C rated?

[Scooterman]

The is Eve technologies production line.

Very impressive

https://www.youtube.com/watch?v=xdl5a2iyPYU

[Scooterman]

BM - 16 of these will fit in your salsa: 200Ah for $1,000 + shipping & taxes.

https://www.alibaba.com/product-detail/ ... c740bewjXx

You'll be able to go to the moon and back

[Burgerman]

We saw those before. Was waiting to see if anyone has tested them. But I like round numbers.