Transmission1

anyone using these ??
its something I got into through my brother building E Bikes and the battery technology behind it
last week I built a 4s x 5p cell for a busker amp with a BMS (battery management system) that has
14.4 Max 3.2 Nominal and 12v cut off with an Ah rating of 11Ah but it would be very easy to up the Ah to well over 30+Ah using a stack of 3

just a thought as normally we work on 36 & 48 volt packs
I'd be happy to tell folk how to do it and you can use recycled laptop battery's to save on cost
you just have to be handy with a soldering iron or have a spot welder (I have both)

I dabble with 18650's in a small way. I now build my own boosters/regulaters and converters as the cheap Chinese stuff is generally crap.

oldpink wrote: ↑24 Jan 2019, 23:49 anyone using these ??
its something I got into through my brother building E Bikes and the battery technology behind it
last week I built a 4s x 5p cell for a busker amp with a BMS (battery management system) that has
14.4 Max 3.2 Nominal and 12v cut off with an Ah rating of 11Ah but it would be very easy to up the Ah to well over 30+Ah using a stack of 3

just a thought as normally we work on 36 & 48 volt packs
I'd be happy to tell folk how to do it and you can use recycled laptop battery's to save on cost
you just have to be handy with a soldering iron or have a spot welder (I have both)

With the BMS voltages you present here, the cell chemistry should be LiFePO4. I've never heard of laptop batteries using LiFePO4; they're usually LiCoO2. LiFe cells has a nominal voltage of 3,2 to 3,3 Volt/cell, max. charge 3,6 Volt, while LiCo cells has 3,7 Volt/cell, max. charge 4.2 Volt.

If you are using a LiFe BMS on LiCo cells, you will never see more than 15-20% of the rated capacity of the LiCo cells... (The other way around (LiCo BMS on LiFe cells), will probably ruin the cells...)

If you want to make a "12 Volt battery" out of 3,7 Volt laptop cells, your best bet would be 3 in series. That would give you 12.6 Volt fully charged, and 9 Volt empty. 4 in series would give 16.8 Volt fully charged, and 12.0 Volt empty - a bit too high for most 12 Volt equipment.

Earlier battery packs for e-bikes used LiCo, or LiMn cells at nom. 3.7 Volt, but most packs today uses LiFe cells (at 3.3 Volt), since they are much safer and last longer, so it's probably LiFe cells you have used (i hope ), and they are excellent to build direct replacement 12 volt batteries with.

the Bike batteries (and the busker amp) are built using 18650 Samsung cells
I only mentioned laptop cells as the can be used / recycled

https://www.youtube.com/watch?v=nDoQoVA0hAc might be worth a watch

some of his vids are interesting

for our top bike batteries we use Samsung or LG 3.7v - 3.5 AH cells in series & parallel to give up to 10.5, 14 or 17.5 packs at 36v
we also do 48v that we can take to even higher Ah but we hit problems with the law as these are only for off road bikes as we use 500 - 1000w hubs to build the bikes
legally you can have 250w drive and has to be peddle assisted and restricted to 15mph to comply with the 2016 laws on E Bikes
we have a test bike with a mid drive that can get over 40mph using the bikes gears but tricky to use until you get used to changing the gears while powered

I'm planning to build myself a new bike for the summer like this orange one with a 1000w front hub and 48v - 17.5 or higher battery if I can 3D print a case to hold it

working with some new software as I have a 3d printer incoming on Tues for some R%D been a while since I done any CAD but after only a few hours I have managed to get the basics to get to this stage, this is a prototype battery holder for a 36V 17.5 Ah upgrade for my current bike
I have cut away as much as I dare from Mk1 to reduce the weight in Mk2 as every gram helps
and channels cut to run the BMS cables, the BMS will be mounted on a snap on 3d printed base as seen in a test in the mock up here in a smaller test battery

test battery is for as custom motorbike that only requires starting the bike as per the customers spec's to see if it works
the design I'm working on is take my bike up from 14 - 17,5 Ah adding 50% to my range in the process
it will also have a standard USB connector to charge or power mobiles so great for camping trips in the summer as well

Awesome stuff old pink! I’m putting together a 3s 18650 bank of cells for portable 2m use with a trio tr2300 and small 10w amplifier. I also have a portable 11m setup in mind. Thinking a homebrew coax gainmaster on a portable 10m pole. I enjoy pedestrian portable

Adding to this long thread...

I bought a "Zippy" 8.4Ah lithium-iron-phosphate from Hobbyking. It puts out 13.2V and powers a 100W radio on Rx/Tx for several hours. Some connectors and a charger do bring the cost to near £80 though. Far better than a lead-acid battery and easier than stacking 18650's.

-Rob