This is a follow up question based on this.

I have an ebike which uses lead acid battery, my question is do I need to fully drain it before charging it again?

How about when the battery is newly bought, any changes in charging it?


closed as off-topic by Leon Heller, PeterJ, Daniel Grillo, Nick Alexeev Aug 4 '15 at 3:20

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – Leon Heller, PeterJ, Daniel Grillo, Nick Alexeev
If this question can be reworded to fit the rules in the help center, please edit the question.

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    \$\begingroup\$ This has become a hot question so for the wallies coming in from other SE sites: NOT a Lithium battery! Lead acid batteries are (almost) exclusively car batteries. \$\endgroup\$ – Alec Teal Aug 1 '15 at 12:10
  • \$\begingroup\$ @AlecTeal, if by "(almost)" you were included Remote Area Power Systems, telecoms repeater/cell sites, telephone exchanges, batteries for UPSs that power everything from a PC to a building, and massive megawatt-scale grid-connected batteries for doing frequency regulation & peak shaving, sure, "almost". \$\endgroup\$ – Techydude Aug 2 '15 at 7:29
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    \$\begingroup\$ Lead acid batteries are shipped charged. Wholesalers of reputable manufacturers are tasked with topping up batteries that have been held in stock for some number of months to make sure they are not damaged and to make sure the end customer gets a charged battery to install. \$\endgroup\$ – KalleMP Aug 2 '15 at 17:44
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    \$\begingroup\$ @Techydude it was more to stop someone coming in and thinking "I've been using my phone battery all wrong", don't worry though, I'm sure you'll find someone who appreciates your pedantry one day. \$\endgroup\$ – Alec Teal Aug 2 '15 at 18:37
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    \$\begingroup\$ @AlecTeal I have appreciation for such pedantry. Let's take it further and recognize that starter and deep cycle lead-acid batteries are not the same (although neither need to be completely discharged before re-charging). \$\endgroup\$ – Nick Alexeev Aug 4 '15 at 3:19

No, you should NOT fully discharge a Lead-Acid battery.

The normal reason for wanting to fully discharge a battery is because some batteries have a so-called "memory effect" - old NiCd cells are notorious for this.

But Lead-Acid does NOT suffer from this effect.

In addition, you can cause permanent damage to some of the individual cells within the battery if the battery is discharged too deeply - the polarity of the weaker cells can actually reverse polarity. This causes permanent damage to those cells.

Depending on which exact Lead-Acid battery you have, end of life discharge voltage for a nominal 12 Vdc battery (6 cells) ranges from 10.5 Vdc to 11.5 Vdc. The manufacturer of your particular battery will specify what the minimum allowable voltage is.

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    \$\begingroup\$ A lead acid battery life is longest when held at full charge without over-charging, this is a delicate act that professional float chargers attempt. Total draining will always reduce the life. \$\endgroup\$ – KalleMP Aug 1 '15 at 9:23
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    \$\begingroup\$ @KalleMP, so by charging it frequently and making sure that it is always full charge but not overcharge will result in long life? \$\endgroup\$ – Cary Bondoc Aug 3 '15 at 0:10
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    \$\begingroup\$ @CaryBondoc Yes, the best is an accurate float charger to maintain the full level if a standby system, if used in a power application then recharging immediately after use is the best. \$\endgroup\$ – KalleMP Aug 3 '15 at 13:19
  • \$\begingroup\$ Does lead acid battery have charge count? Someone said that lead acid batteries can be charge for specific amounts only. \$\endgroup\$ – Cary Bondoc Mar 9 '16 at 1:09

Batteries as a rule should not go below a certain safety level. If you drain a battery below a drastic level it needs a lot of current or amperes to kick it back to life. This would mean drawingin a lot of current from the charger and it could be an adaptor or such equipment which is never good.

Most professionaly designed equipment has a battery overvoltage and overdischarge protection circuit. Ricoh and Sieko Instruments make dedicated ASICs for such applications. You can look at Seiko Instruments S8204 chipset for more application information.

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    \$\begingroup\$ Your answer is not directly relevant to lead acid batteries which behave differently to Lithium Ion batteries and have a different set of issues to deal with. \$\endgroup\$ – KalleMP Aug 1 '15 at 9:05
  • \$\begingroup\$ i merely pointed out the need for such a circuit and provision. \$\endgroup\$ – Board-Man Aug 1 '15 at 9:11
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    \$\begingroup\$ I did not down vote your answer because it has some value but I added the comment because OP was facing specific issues with their Lead-acid system and Ni-Cd memory effect warnings. \$\endgroup\$ – KalleMP Aug 1 '15 at 9:26

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