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I need a battery to act as capacitor for a small generator (~7V peak) which does not produce smooth DC. Normal capacitors are unable to deal with ~0.2 second dead time when load is attached, lithium batteries will not be happy in those harsh conditions.

I am unable to find lead acid batteries of 6-8V that fit my setup but have many dead batteries of perfect size. I took one apart and found that the positive plate had turned into dust.

Just for fun, I put two negative plates side by side separated by paper and poured on some dilute sulfuric acid. The battery appeared to work fine and it can produce decent current for its size.

I am unable to find much information online about battery chemistry as to why lead dioxide is used for positive and if only lead from negative plates can work fine as battery. Should I build my battery without lead dioxide plates? Will it work?

Any way to determine nominal, charge and discharge voltage of a lead acid cell you just made?

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    \$\begingroup\$ The only time I've seen people attempt this sort of thing is in YT videos from South Asia (Pakistan, mostly, and large truck batteries). You can buy new plates on Indiamart etc. inexpensively. Here is an explanation of the manufacturing process of flooded lead-acid batteries. \$\endgroup\$ Commented May 26, 2022 at 18:22
  • \$\begingroup\$ I am from Pakistan and they do make batteries in my city too, I can have it made by them but I wanna learn, doubt they will be able to explain the chemistry and dos/don'ts to me @SpehroPefhany \$\endgroup\$
    – asim
    Commented May 26, 2022 at 18:30
  • \$\begingroup\$ Be careful in your handling of lead and lead oxide. They are toxic and the effects of repeated exposures are cumulative. \$\endgroup\$ Commented May 26, 2022 at 21:01
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    \$\begingroup\$ thanks, I use gloves and avoid powder dust, already scared of lead poisoning @MathKeepsMeBusy \$\endgroup\$
    – asim
    Commented May 26, 2022 at 21:09
  • \$\begingroup\$ What is the current expected? What is the commutation frequency you intend to smooth it out, using the battery? Is this generator a single-phase or 3-phase? To be considered: (1) Depending of the current level, a assuming V_peak < 8.4V, you could use 2 Li-ion cells in series. (2) But if you really prefer the L.A. battery type, then 3-cells can reach 7.0V at 100% charged state; gassing may happen for extended use at 7.0V, so distilled water being replenished will be a “must have”. (3) 4-cells would operate in an insufficient voltage level, so this configuration is not good for you. \$\endgroup\$
    – EJE
    Commented May 27, 2022 at 5:02

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Make a Planté type battery. Only lead sheets on both sides but needs "forming" by charging and discharging 40 times inverting polarity before being used to store power. Check this site: https://www.fieldlines.com/index.php?topic=150445.0

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