I started with cheap eZip eBikes.
Being sadly disappointed with oem battery performance-capacity-endurance I decided to "play" ...
Too many pictures to fit in one post, so supplied links.
36V 11Ah SLA test
36V 11Ah SLA Toolbox
Speed, or range, pushed 150% ... not both at once tho.
24V 7Ah Nimh too small for 450w motor so ...
Doubled it up. worked great till accidental short detensioned the springs.
Now I always build in a fuse.
24V 14Ah Nimh
Weak point is the light duty springs.
Recommend spring contact points "enarmored" by covering and running tinned copper braid between cells, and ensuring good contact with dielectric grease.
37V 10.4Ah Li-ion My first Li-ion build.
Proved too small for 675w motor 35A controller.
Made using recycled laptop battery cells.
37V 20.8Ah Li-ion 2008 vintage build.
Still use on my Winter eBike.
Li-ion vs SLA
37V 20.8Ah Li-ion #
25.9V 31.2Ah Li-ion 2009 vintage build.
Used till 2011 - relegated to reserve status or doubled range for trips.
eZips are designed to carry 2 packs.
25.9V 31.2Ah Li-ion 2011 build.
Made use of recycled eZip RMD battery cases.
37V 26Ah 1kWh Lipo Lico
Prototype: 120 - 2160mAh cells 10s12p.
37V 26Ah 1kWh Lipo Lico
Used tinned copper braid as flexible - durable conduction media.
Laid in a 7/16" layer of waferboard as stable-protective base.
Several of the builds are packaged in insulated bags.
Or at least are padded with closed cell polystyrene or foam.
Packs exhibit markedly reduced performance when cold!
The recycled Li-ion and lipo builds are constructed from laptop technology cells, of a Lithium Cobalt formulation, about 2x the energy density of LiFePO4 ... but designed with a low "C" rate.
Built to expend at .33 to .5C a maximum 1C surge is recommended.
30Ah pack recommended for a 10 - 15A continuous output, surges above 30A for brief periods only.
Still ... 30Ah pack is the size of a 15Ah LiFePO4 or a 6Ah SLA ...
Laptop Lipo 25.9V 26Ah
Going strong after hundreds of cycles.
I did include balance connectors with all Li builds.
After proven reliable, I typically "bulk charge" and occasionally "balance charge".
I did re-design MeanWell power supplies as rapid Bulk chargers.
25.9V 22.8Ah RC lipo
37V 17.1Ah RC Lipo
Got tired of crappy cordless tool batteries
14.4V 1.2Ah Nicd > 14.8V 5.2Ah Li-ion
7s 25.9V 5A charger build
I modified MeanWell power supplies as bulk chargers.
Extended voltage range
Variable current adjustment
Modifications required for running "in Series"
Built in volt meter is nice.
Quick add, in line, amp meter handy for monitoring charge rate.
I "modularized" for maximum adaptability.
2x = 7s 25.9V 10A build
28.9V??? Yes battery capacity mapping showed efficient battery usage to be at a lower peak charge. A "full" 4.2V per cell charge added needless damage for minimal capacity increase!
Every "type" cell has a different voltage range of maximum and most efficient energy storage.
I have mapped several types but mostly the ones I've recycled.