.h Ni-C Notes Bookbinder NI-CD NOTES I'v ha PX- fo almos year now I tha time largel becaus I'v ha som troubl wit them I'v learne quit bi abou th Ni-C batterie tha powe thi compute an it portabl peripherals Followin i summar o wha I'v bee abl t glean fro readin an fro observation abou Ni-C batterie i genera an abou ho the ar handle withi th PX- i particular. Th PX-8' Batteries ..@1The PX-8's Batteries Th PX- mai uni contain tw rechargeabl batteries Th mai battery supplie powe whe yo ar usin th uni an i recharge wit a A adapte tha provides abou volt DC Thi batter i rate a 110 mA a nomina 4. volts Th backu battery supplie powe whe th uni i switche of o turn itsel off Thi backu powe keep dat an program store i th PX-8' mai memor intact Th backu batter i rate a 9 mAH als a nomina 4. volts T insur tha th backu batter i alway i full charge stat whe i i needed i i recharge i on o tw ways eithe b th A adapte or i th PX- i o bu th adapte i no connected b th circuitr tha power th LC screen Th Batterie o Som PX- Peripherals ..@1The Batteries of Some PX-8 Peripherals PF-1 Battery ..@2PF-10 Battery Lik th PX- mai battery th PF-1 dis driv batter i rate a 4. volts 110 mAH I, too, appear t b buil fro fou rechargeabl sub- batteries Th PF-1 als ha backu battery sai t b goo fo abou 1 minute o operatio afte th mai batter run down Thi batter look identica t th batter o th mai PX- board I i soldere t th PF-10' mai printe circui board. RA Dis and Multi-Unit Battery ..@2RAM Disk and Multi-Unit Battery Th RA dis batter i rate a 4. volts 45 mAH I i buil fro fou 'AA siz cells CX-20 Mode Battery ..@2CX-20 Modem Battery Th externa mode batter i identica t th RA dis battery excep tha i use slightl differen connector. .pa Genera Characteristic o Ni-C Batteries ..@1General Characteristics of Ni-Cd Batteries Ni-C batterie com i variet o basi types Thes include: Resealabl Vente an One-sho Vented Whe sufficientl overcharge o over-discharged Ni-C batterie ca buil u enoug interna pressur t caus ven t open Thi release th pressur an prevent a explosion bu i als release som o th battery' electrolyte Som Ni-C batterie ar buil wit one-sho vents thes vents onc open d no reseal an th batter eventuall drie out Man moder Ni-C batterie ar buil wit vent tha wil resea onc th situatio creatin th exces pressur ha bee corrected Thes batterie ma b somewha reduce i capacit onc the hav vente (a i lead-aci batter tha ha bee allowe t ru lo o acid) bu the will i man cases stil b usabl fo quit while Cell tha hav vente wil hav whit crystal growin nea th positiv contac o wil show other obvious signs of leakage. Norma Charg an Fas Charge Som Ni-C batterie ca onl b recharge a rat les tha o equa t th so-calle "1 hou rate, whic i one-tent th rate ampere-hou capacit o th batter (C/10) Fo example th 1 hour rat fo th 110 mA PX- mai batter i 11 mA Du t inefficiencie i th chargin process th batter mus b recharge a thi rat fo 1 t 1 hour t achiev ful charge Othe batterie ar designe t b abl t withstan charg rat equa t one-fourt thei rate capacit (C/4) Thes batterie ar capabl o sustainin repeate "fas charges withou damage Th batterie use i th PX- appea t b o th "fas charge variety sinc the ar intende t withstan charg rat greate tha C/1 withou shortenin thei life. Normal Capacit an Hig Capacity Norma capacit Ni-C batterie wil continuousl operat devic fo approximatel th sam perio o time o on charge a ordinar dr cells High-capacit batterie wil operat th sam devic fo longe perio o time (Fo example th Radi Shac high-capacit 'C cell hav almos twic th capacit o th standar Ni-C 'C cell an th high- capacit 'D cell hav nearl fou time th capacit o standar Ni-C 'D cells.) Ho Ni-Cd Batterie Ca B Damaged ..@1How Ni-Cd Batteries Can Be Damaged Ni-C batterie ca b damage b imprope us (ove-dischargin o dischargin to quickly o b imprope rechargin (ovechargin o chargin to quickly) Overl dischargin Ni-C batter ca caus th weake cell t b reverse-charge b th stronge cells Thi ca permanentl damag the b causin the t vent (I general n cel i Ni-C batter shoul b permitte t fal belo 1. volts. Overchargin Ni-Cd a rat u t one-tent th ratin o th batter ma temporaril weake them bu th damag ca ofte b mostl reversed a describe below O th othe hand overchargin a to grea rate a wella dischargin a rat greate tha C/2 ca caus Ni-Cd' t overheat Overheatin ca lea t ventin o ca caus interna short t develop (Interna short ca sometime b repaire b burnin the ou usin th technique described below.) Ni-C batterie ar als subjec t "memory effect Thi ca happe afte th batterie hav bee subjecte t repeated identica partia discharge/ful recharg cycles batter wit thi proble wil appea t b discharge whe i "remembers th poin i it discharg cycl a whic i i usuall recharged Thi effect too ca b reverse an th batter restore t nearl ful capacity. Ho th PX- Charge Batteries ..@1Ho th PX- Charge Batteries Mai Battery ..@2Mai Battery Th mai batter i recharge b 6- vol D powe sourc connecte t th "ADAPTOR plu o th bac o th PX-8 diod i th PX- charg circui i intende t protec th batter fro dischargin i th powe suppl connecte t th compute fall belo th batter voltage an t protec th compute fro damag du t revers polarit powe supplie o shor circuitin th powe suppl connector Th circuitr als contain Zene diod whic wil shun moderat overvoltag (thoug wouldn' g ou o m wa t tes an o thi protection sinc it too i capabl o bein damaged) Th compute i designe t recharg th batterie a moderatel fas rat (150-200mA fo eigh o eleve hours dependin o whethe th compute i turne of o on respectively whe th charg cycl begins Afte that charg drop t trickl charg o abou 4 mA Thi i intende t allo yo t recharg th compute fairl quickl an kee i i charge state whil a th sam tim avoidin overchargin th batterie i th charge i lef connected Unfortunately i yo ar no carefu abou ho yo recharg th batteries th circuitr tha i intende t protec agains overcharg ca wor agains you Th manua supplie wit th PX- doe no adequatel war agains this. Here' th problem Th PX- recharg i monitore b circuitr intende t protec agains overcharge I doe s b detectin whe externa powe i supplie t th uni an a tha tim initiatin it o 11-hou charg cycle I doe s regardless o th curren stat o charg o th battery Thi mean tha i th batter i partiall charge whe th powe suppl i attached i wil b overcharge fo som portio o th nex eigh o eleve hours an i wil b overcharge a th full charg rate Repeate overcharge o thi sor wil eventuall damag th batteries Althoug moder Ni-C batterie ca "take continuou chargin a th C1 rat (1/10t thei curren rating withou sufferin permanen damage th PX- charg rat considerabl exceed this Therefore yo shoul no recharg you PX- unles th batter voltag ha droppe belo abou volts (Th PX- wil switc fro trickl charg t ful charg b itself i th voltag drop belo volt whil trickl charg i i effect. I yo d nee t recharg befor thi ha occurred yo wil b doin you compute favo i yo d no leav th charge connecte fo th ful 8-hou period o i yo tak th tim t ru th batter dow b usin th seria por o tap drive Sinc th charg rat i booste t ful eac tim th powe suppl i connecte t th rea o th computer yo shoul als not disconnec an reconnec th adapte onc a charg cycl ha begun Eac reconnectio begin anothe ful charg cycle. Backu Battery ..@2Backup Battery Th backu batter i designe t alway b a pea charg whil th PX- i on s tha i ca tak ove whe th mai batter need t b charged I th A adapte i connected th backu batter i recharge i th sam fashio a th mai batter (ful charge/trickl charge) I th adapte i no connecte an th compute i turne on th backu batter i recharge throug th internal powe suppl t th LC screen RA Dis Battery ..@2RAM Disk Battery Th RA dis o Multi-uni batter i recharge i manne simila t th mai battery an i subjec t th sam ful charge/trickl charg cycle I ca onl b charge whe th RA dis i connecte t th PX-8 sinc i does not have a separate external power supply connection. PF-1 o External Mode Battery ..@2PF-10 or External Modem Battery Th PF-1 an CX-2 externa mode d no see t hav overcharg protectio circuitry Thei batterie ca b damage b bein continuousl connecte t charge ( ca sa fro persona experienc tha th PX-1 batterie wil overhea i the ar connecte to long) I th batterie hav no leake du t overcharge mos o th apparen damag ca b reverse b cyclin th batterie throug on o mor charge/discharg cycles I the hav leaked the shoul b replaced Thi ca b don b orderin batter pac fro a EPSO supplier o muc mor cheapl b purchasin th appropriat replacemen cell (fro a electronic supplie o fro Radi Shack an buildin ne batter pac fro th origina one a describe elsewhere i thi article. Ho t Squeez Littl Mor Powe Ou o PX- Batteries ..@1Ho t Squeez Littl Mor Powe Ou o PX- Batteries Yo ca us th techniqu recommende fo restartin th PX- afte yo hav change th batter t ge fe minute mor lif ou o discharge PX- batter -- enoug t finis mos low-powe operations I th uni ha turne itsel of becaus th batter go to low tur th powe switc t "off an le i si fo fe minutes Whil holdin dow th rese button tur th uni o an releas th rese button Th PX- wil probabl com on an i wil functio fo anothe fiv o te minutes. PX- Ni-C DO' an DON'T's ..@1PX-8 Ni-Cd DO's and DON'Ts Don' shor ou th battery D b carefu whe yo remov o replac th batter fro th PX-8. o Don' overcharge Thi wil happe i yo attac th charge fo th ful hour whe th batter i no full discharged Wai fo th "CHARG BATTERY messge o us batter monito progra lik px.com battery.com o pxuti an don' recharg unti th batter i nea th cutof poin (4. o 4. volts). o D le th batter rundow completel befor yo recharge Don' partiall discharg an the full recharge Thi ca produc th so- calle "memor effect. Th memor effect whic ca occu afte repeated nearl identica partia discharge/ful recharg cycles cause th batter t appea discharge a th poin th prematur recharg cycle previousl began therefor givin shorte servic tha i should. Ho Damage Ni-C Batterie Ca B Restored ..@1Ho Damage Ni-C Batterie Ca B Restored Yo ca restor wea batter i i ha no becom physicall damage (interna shor o leakag o electrolyte) Usually al yo hav t d i repeatedl pu th batter throug ful discharge/ful recharg cycles preferabl bringin th termina voltag dow t 4. volt (bu no lower! fo 4. vol battery T restor th PX- batterie, tr full dischargin an the rechargin th compute fe times I thi doesn' improv thing sufficiently tr bringin th batter dow belo th 4. volt a whic th PX- normall cut out Yo ca d thi b firs lettin th compute ru th batterie down the disconnectin th batter an insertin th end o 10 o 22 oh resisto i th connecto tha normall plug int th PX-8 Monito th batter voltag wit voltmeter clipped to the resistor leads. A last-ditc effort yo ca tr t restor batterie tha hav on o mor shorte cell b joltin the wit shor burs o exces charge Thi charg burn throug smal shor circuit withi th cel itself Yo ca suppl thi charg b buildin an applyin th circui belo (fro Hands-O Electronics Jun '87) __ 25 + __/\__ blast button vdc o---////-------+----o o-----+------------o to voltmeter plus 150 ohm | | 1 watt | o blast | resistor | / | blast/charge | / | switch +----/ o-----+ | charge | | | | + | + 10,000 mf ----- ----- capacitor ----- --- cell to be blasted (or more) | | | | | | 25 - | | vdc o--------------+---------------+-----------o to voltmeter minus Th ide i t leav th switc o "blast an le th capacito charge the hi th blas butto fe times waitin fe second betwee eac hit The switc t "charge an watc th voltmeter i yo hav succeede i repairin th damag t th battery th batter voltag wil rise I not yo ma a wel repea th proces coupl o times the pu th batter throug norma charge/discharg cycl an se wha happens hav als accomplishe th sam thin b momentarily shortin a dea cel o batter acros si vol powe supply thoug can' guarante th safet o thi procedure I an event batterie brough bac t lif wit thi metho ar no likel t las a lon a batterie tha hav no bee damaged an yo ar probabl bette of replacin them. Replacements for PX-8 Batteries ..@1Replacements for PX-8 Batteries Th mai batter i eas t replac whe i wear ou (tha is wil n longe hol charg fo reasonabl perio o time) I i buil fro fou 1. vol sub- cells replacemen pac i availabl fro Epson bu on ca als b constructe muc mor cheapl fro tabbe sub- cell availabl fro Radi Shac an othe electronic suppliers O th othe hand th backu batter i soldere t th mai circui boar o th PX- an woul b difficul fo PX- owne t replace eve i substitut coul b found. replacemen batter pac fo th PF-1 i availabl fro Epson Th PF- 1 i als designe t ru of ordinar 'C batteries wit simpl modification describe below yo ca enabl i t us an t recharg commonl availabl standar o heav dut Ni-C 'C cells (Th heav dut batterie provid almos twic a muc powe a th factor batteries.) Th batter fo wedg (RA dis o Multi-unit ca b replace easil b removin th retainin screw o th RA dis unit unpluggin th batter pack an replacin defectiv o wor ou cell wit tabbe 'AA cell availabl fro Radi Shac o othe suppliers Th CX-2 mode batter pac i similarl constructe an ca b repaire i th sam way. Modifyin th PF-1 t tak High-Capacit Batteries ..@1Modifying the PF-10 to take High-Capacity Batteries Th followin i adapte fro descriptio b Joh Cooper I describe ho t modif PF-1 dis driv t us Radi Shac 1.8A 'C Ni-C batterie (Radi Shac par #23-141) hav performe th sam modification followin hi directions. Th projec require fou batteries Th modificatio enable th PF-1 t recharg thes o othe rechargabl batterie a wel a th origina batter pack Note however tha yo shoul not operat th PF-1 wit th charge attache whe yo ar usin ordinary disposabl batterie afte yo mak thi modificatio t th PF-10. 1. Set the PF-10 on a flat surface with the back of the unit facing you. 2. Remov th singl scre betwee th Seria plu an th Adapte plug. 3. Tur th uni o it bac an remov th batter cove an batter pack. 4. Remov bot o th mos rearwar PF-1 cas screws Slid th plasti batter carrie an rea cove combine ou t th rear 5. Carefull disconnec th plu connectin th batter carrie t th mai printe circui board. 6. Tur th batter carrie ove s yo ca se th smal printe circui board Pr th boar u littl t fre th wires the de-solde th whit wir fro thi circui board Stor th wir unde th tap tha dresse th plu wire o th carrier. 7. Connec th now-empt pa wher th whit wir wa t th re wir pad an then t th brow wir pad 8. Reassemble Mak sur yo plu th batter carrie wire int th mai PC th sam wa the cam off an don' forge th ON/OF switc cover littl organizin o th wirin harnes ma b necessar t kee i clea o th Seria cabl sockets. .pa Th PF-1 shoul ru abou twic a lon betwee charge (thoug i wil als tak abou twic a lon t recharge) Th ne batterie shoul als b muc les succeptibl t damag fro overcharge sinc th charg rat o th charge tha come wit th PF-1 charge th ne batterie a les tha th C/1 rate for these cells. David Bookbinder West Medford, MA October 10, 1987