Low energy Input, mass hydrogen output methods in use.

[AntDavison]

[btrautman]

[jjbeamish]

[AntDavison]

[AntDavison]

[thrival]

[DavidCrow]

[B0rriska]

[BEMET]

[jjbeamish]

[geotrouvetout]

[jjbeamish]

[thrival]

[AntDavison]

from Linden&Reddy "Handbook of Batteries" 3rdEdition(2002)McGrawHill chapter.25 isbn.0-07-135978-8

on Edison/IronNickel batteries

25.1 ... GENERAL CHARACTERISTICS ... Its limitations are low power density, poor low-temperature perfomance, poor charge retention, and gas evolution on stand ...

25.2 ... disadvantages : high self-discharge, hydrogen evolution on charge and discharge ...

25.6 ... ELECTROLYTE ... Shortly after initiation, hydrogen evolution begins on the iron electrode. The considerable hydrogen evolution on charge presumably helps counteract iron passivation in the alkaline solution ...

25.7 ... VOLTAGE ... The battery's open circuit voltage is 1.4v; its nominal voltage is 1.2v. On charge, at rates most commonly used, the maximum voltage is 1.7 to 1.8v

25.8 ... DISCHARGE CHARACTERISTICS . The nickel-iron battery may be discharged at any current rate it can deliver, but discharge should not be continued beyond the point where the battery nears exhaustion ...

25.10 ... CHARGING ... As long the charging current does not produce either excessive gassing (spray out of the vent cap) or temperature rise (above 45°C), any current can be used. Excessive gassing will require more frequent addition of water. If the cell voltage is limited to 1.7v, these conditions should not be a consideration ... Typical charging curves are shown in Fig.25.9
[Figure plots Voltage v. Time, showing four curves 1.5, 1.533, 1.566 & 1.6v rising repectively to 1.74v over 8.5hours (15A/100Ah), 1.76v over 6.33hours (20A/100Ah), 1.75v over 5.5hours (25A/100Ah) & 1.79v over 4.25hours (30A/100Ah)] ...
25.11 ... The charging circuit should contain a current limiting device to avoid thermal runaway on charge ...

25.13 ... SPECIAL HANDLING ... The battery should be operated in a well-ventilated area to prevent accumulation of hydrogen. Under certain circumstances, hydrogen can be ignited by a spark to cause explosion with resulting fire. In multicell batteries the usual precautions in dealing with high voltages should be taken.
If the battery is to be out of service for more than a month, it should be short-circuited, then left in that condition for the storage period. Filing caps must be kept closed. If this procedure is not followed, several cycles are required to restore the capacity upon reactivation.
Constant-voltage charging is not recommended for conventional nickel-iron batteries. It may lead to a thermal runaway condition which results in dangerous conditions which can severly damage the battery. When the battery nears full charge, the gassing reactions produce heat and temperature rises, lowering the internal resistance and the cell EMF. Accordingly, the charge current increases under constant-voltage charge. This increased current further increases the temperature, and a vicious cycle is started. A modified voltage charging with current limiting is, however, acceptable.

[zendog]

what a bunch of great information form Alaskastar, Thrival, Bemet, Antdavison, Orange, geotrouvetout and of course the rest too.

Ok so, this Edison Battery? - sounds lke it was well known for "gassing off" hydrogen. Will nickel as positive plates and iron as the negative in a solution of potassium hydroxide do for our project? continuous cycles of charging and then dead-shorting to discharge it - building into the design large surface area electrodes (alaskastars oft mentioned "suitcase sized" cell
Wonder if high quality stainless steel and iron can work as the electrodes?