<p>HR000000000<br />
H Hybrid: Denotes some prepurchased or hard to find components<br />
R Robotics: suitable for robots</p>
<p>buy: 4s 40A BMS<br />
<a href="https://www.aliexpress.com/item/4000025857655.html"
class="uri">https://www.aliexpress.com/item/4000025857655.html</a>
(can't specifically vouch for this vendor, just chose the first that
came up)<br />
make sure to choose 4s and balance</p>
<ol type="1">
<li><p>find or buy materials: duct or gorilla tape, trashed computer dvd
or cd drive, 20 18650 cells, molex connectors(you can also use barrel
jacks or whatever you want to transfer power), wire and maybe 'tab wire'
<a href="https://nl.aliexpress.com/item/32650006768.html"
class="uri">https://nl.aliexpress.com/item/32650006768.html</a></p></li>
<li><p>solder everything together as per schematic and pictures (there
is theoretically a danger in soldering cells, but I have never had a
problem. Have a pair of pliers and a nearby window handy to throw them
out of if anything goes wrong)</p></li>
<li><p>wrap in cardboard and tape as per pictures</p></li>
<li><p>add the cd/dvd drive lids(if you taped well you won't short
anything and burn your house down</p></li>
<li><p>tape dvd lids to battery</p></li>
</ol>
<p>Getting into the battery for maintenance just requires a utility
knife.</p>
<p>Watt Hour does a great job describing the 3s BMS, which is very
similar to the 4s used in my case: <a
href="https://yewtu.be/watch?v=QNENyu97w2A"
class="uri">https://yewtu.be/watch?v=QNENyu97w2A</a></p>
<p><em>Battery Schematic</em><br />
<a
href="https://hackerpublicradio.org/eps/hpr3816/0_4s5batteryschematic.jpg"><img
src="https://hackerpublicradio.org/eps/hpr3816/0_4s5batteryschematic_thumbnail.jpg"
alt="Battery Schematic" /></a> <br/><small><small><em>Click the
thumbnail to see the full-sized image</em></small></small></p>
<p><em>Cut through tape to reveal battery</em><br />
<a
href="https://hackerpublicradio.org/eps/hpr3816/1_cutthroughtapetorevealbattery.jpg"><img
src="https://hackerpublicradio.org/eps/hpr3816/1_cutthroughtapetorevealbattery_thumbnail.jpg"
alt="Cut through tape to reveal battery" /></a>
<br/><small><small><em>Click the thumbnail to see the full-sized
image</em></small></small></p>
<p><em>Flat metal holds cells together</em><br />
<a
href="https://hackerpublicradio.org/eps/hpr3816/2_flatmetalforSolarCellsHoldscellstogether.jpg"><img
src="https://hackerpublicradio.org/eps/hpr3816/2_flatmetalforSolarCellsHoldscellstogether_thumbnail.jpg"
alt="Flat metal holds cells together" /></a>
<br/><small><small><em>Click the thumbnail to see the full-sized
image</em></small></small></p>
<p><em>Detail of 4.2v</em><br />
<a
href="https://hackerpublicradio.org/eps/hpr3816/3_detailof4.2v.jpg"><img
src="https://hackerpublicradio.org/eps/hpr3816/3_detailof4.2v_thumbnail.2v.jpg"
alt="Detail of 4.2v" /></a> <br/><small><small><em>Click the thumbnail
to see the full-sized image</em></small></small></p>
<p><em>Only have to desolder one side</em><br />
<a
href="https://hackerpublicradio.org/eps/hpr3816/4_onlyhavetodesolderoneside.jpg"><img
src="https://hackerpublicradio.org/eps/hpr3816/4_onlyhavetodesolderoneside_thumbnail.jpg"
alt="Only have to desolder one side" /></a> <br/><small><small><em>Click
the thumbnail to see the full-sized image</em></small></small></p>
<p><em>New cells in</em><br />
<a
href="https://hackerpublicradio.org/eps/hpr3816/5_newcellsin.jpg"><img
src="https://hackerpublicradio.org/eps/hpr3816/5_newcellsin_thumbnail.jpg"
alt="New cells in" /></a> <br/><small><small><em>Click the thumbnail to
see the full-sized image</em></small></small></p>
<p><em>Make sure there is thick tape covering battery</em><br />
<a
href="https://hackerpublicradio.org/eps/hpr3816/5.5_makesure_there_is_thick_tapecoveringbattery.jpg"><img
src="https://hackerpublicradio.org/eps/hpr3816/5.5_makesure_there_is_thick_tapecoveringbattery_thumbnail.5_makesure_there_is_thick_tapecoveringbattery.jpg"
alt="Make sure there is thick tape covering battery" /></a>
<br/><small><small><em>Click the thumbnail to see the full-sized
image</em></small></small></p>
<p><em>DVD drive case for stability</em><br />
<a
href="https://hackerpublicradio.org/eps/hpr3816/6_dvddrivecaseforstability.jpg"><img
src="https://hackerpublicradio.org/eps/hpr3816/6_dvddrivecaseforstability_thumbnail.jpg"
alt="DVD drive case for stability" /></a> <br/><small><small><em>Click
the thumbnail to see the full-sized image</em></small></small></p>
<p><em>Tape the DVE case to battery</em><br />
<a
href="https://hackerpublicradio.org/eps/hpr3816/7_Tapethe_dvdcasetobattery_ChargeboardisbehindtheCardboardTaped_FlapAbove.jpg"><img
src="https://hackerpublicradio.org/eps/hpr3816/7_Tapethe_dvdcasetobattery_ChargeboardisbehindtheCardboardTaped_FlapAbove_thumbnail.jpg"
alt="Tape the DVE case to battery" /></a> <br/><small><small><em>Click
the thumbnail to see the full-sized image</em></small></small></p>
<p><em>Charge board with Molex connector</em><br />
<a
href="https://hackerpublicradio.org/eps/hpr3816/8_chargeboardwithmolexconn.jpg"><img
src="https://hackerpublicradio.org/eps/hpr3816/8_chargeboardwithmolexconn_thumbnail.jpg"
alt="Charge board with Molex connector" /></a>
<br/><small><small><em>Click the thumbnail to see the full-sized
image</em></small></small></p>
<p><em>Outdoors 1</em><br />
<a href="https://hackerpublicradio.org/eps/hpr3816/9_outdoors1.jpg"><img
src="https://hackerpublicradio.org/eps/hpr3816/9_outdoors1_thumbnail.jpg"
alt="Outdoors 1" /></a> <br/><small><small><em>Click the thumbnail to
see the full-sized image</em></small></small></p>
<p><em>Outdoors 2</em><br />
<a
href="https://hackerpublicradio.org/eps/hpr3816/9.5_outdoors2.jpg"><img
src="https://hackerpublicradio.org/eps/hpr3816/9.5_outdoors2_thumbnail.5_outdoors2.jpg"
alt="Outdoors 2" /></a> <br/><small><small><em>Click the thumbnail to
see the full-sized image</em></small></small></p>
