Author Topic: charging lead acid batteries  (Read 158 times)
HomeBrewLamps
Hero Member
*****
Offline

Gender: Male
Posts: 1465
View Gallery


SodiumVapor 105843202020668111118 UCpGClK_9OH8N4QkD1fp-jNw majorpayne1226
charging lead acid batteries « on: September 03, 2019, 10:20:29 AM » Author: HomeBrewLamps
Could this charger be used to charge this lead acid? If the addition of a resistor or some other passive component is necessary than that can be done. I do not posses a proper lead acid charger for SLA's

The battery in question is a 6 Volt 3AH Lead acid battery

This is going to be used to power my bike headlights when the generator isn't spinning.

The charger is a NiMH/NiCD 7.2 to 12V battery charger with a selector switch for charge current choices of 0.9 amps to 1.8 amps and a maximum output voltage of 16 volts.


Also on a side note is there a simple circuit that I could use to charge the battery off the bicycle dynamo itself? This would eliminate the need for an external charger but the idea of building a complicated charging circuit is rather daunting. The dynamo outputs 6 volt AC so a rectifier would be necessary.
« Last Edit: September 03, 2019, 10:30:06 AM by HomeBrewLamps » Logged

~Owen

Mercury Vapor LampHigh Pressure Sodium Scavenger, Urban Explorer, Lighting Enthusiast and Creator of homebrewlamps Cool High Pressure SodiumMercury Vapor Lamp

Medved
Hero Member
*****
Offline

Gender: Male
Posts: 4254
View Gallery

Re: charging lead acid batteries « Reply #1 on: September 03, 2019, 03:23:03 PM » Author: Medved
For an emergency chargkng (you are stuck with an empty battery and no other charger) maybe, make sure the current does not exceed the CA/10 (so 0.3A for your 3Ah battery, so you will need some 12V/5W ballast lamp) and observe the time (do not exceed the rated capacity).
Otherwise look for some dedicated charger (it could be a simple voltage control add-on extension for your present charger), otherwise you will kill the battery soon.

For any lead acid you need a voltage regulation, the current is not that much critical (basically limitting to a level safe for the charger).
For a long term maintenance (or when you dont care about the charging time becoming one day) charging you need 6.9V, for fast charge (to limit it to few hours) the recommended level is full blastcurrent till the voltage reaches 7.2V, then maintain that till the current drops to about CA/20 till CA/10 (it is not that much critical), then switch over to the 6.9V or shut down (and declare fully charged on the signal lamps).

NiCd/NiMh needs control based on either charge (time and current;the slow ones), or temprature rise detection (either directly, or indirectly via dV/dt or so), or cell temperature compensated voltage control (usable only within embedded systems, so never with such charger).
Logged

No more selfballasted c***

HomeBrewLamps
Hero Member
*****
Offline

Gender: Male
Posts: 1465
View Gallery


SodiumVapor 105843202020668111118 UCpGClK_9OH8N4QkD1fp-jNw majorpayne1226
Re: charging lead acid batteries « Reply #2 on: September 07, 2019, 11:07:38 PM » Author: HomeBrewLamps
Alright. Thank you for the information. Always enjoy reading your in depth answers.
Logged

~Owen

Mercury Vapor LampHigh Pressure Sodium Scavenger, Urban Explorer, Lighting Enthusiast and Creator of homebrewlamps Cool High Pressure SodiumMercury Vapor Lamp

Medved
Hero Member
*****
Offline

Gender: Male
Posts: 4254
View Gallery

Re: charging lead acid batteries « Reply #3 on: September 08, 2019, 11:19:43 PM » Author: Medved
By the way quite some time ago I've published the circuit Im using. It is designed for an old style mains transformer based 12V 0.5A wall wart (so the input undervoltage rollback circuit around Q1, with 1A and above power source you wont need that) and 4Ah 6V torch battery (so values should fit your use).
« Last Edit: September 09, 2019, 01:01:26 AM by Medved » Logged

No more selfballasted c***

funkybulb
Hero Member
*****
Offline

Gender: Male
Posts: 645
View Gallery


Re: charging lead acid batteries « Reply #4 on: September 13, 2019, 01:56:51 AM » Author: funkybulb
harbor Freight tools sell a small smart charger
for this application.   and radio shack at one point
sold a lead acid SLA charger for 6 volt lead acid
lantern battery.  i would try Acadamy sporting good
store also  as they sell such battery for camping lanterns
and deer feeders . 

 I wont recommend  Lead acid  for this application
  cause  u can ruin them on deep discharges 

  NIMH would be a better application as u can
 build a 5 cell 6 volt battery pack with 3 AH AA
 cells and it take far more cycles and deeper discharge


 Only reason I use them for lighting is emergency lighting and I use a Low voltage drop out regulator.
 
 
   
Logged

No LED gadgets, spins too slowly.  Gotta  love preheat and MV. let the lights keep my meter spinning.

Medved
Hero Member
*****
Offline

Gender: Male
Posts: 4254
View Gallery

Re: charging lead acid batteries « Reply #5 on: September 13, 2019, 03:04:01 AM » Author: Medved
 

 I wont recommend  Lead acid  for this application
  cause  u can ruin them on deep discharges 

  NIMH would be a better application as u can
 build a 5 cell 6 volt battery pack with 3 AH AA
 cells and it take far more cycles and deeper discharge


 Only reason I use them for lighting is emergency lighting and I use a Low voltage drop out regulator.

   

The deep discharge is not hurting that much (compare to other chemistries), if it is for short time only. It is even more robust against over discharge than NiMh and if kept on float voltage charger, it remains ready all the time without degrading like LiIons use to do (so ideal for something resting on a maintenance charger occassionally pulled for iuse and returned back). Up to now, the lead acid (in any form) is still the most robust technology (temperature range, discharge currents, short term complete discharge,...), when kept charged during normal storage. Plus they still offer the lowest cost per Wh...

Personally I would stay away from the 3Ah or higher capacity HR6 (aka "AA" size NiMh), they have no reserve at all for any abnormal operation (overcharge, over discharge), yielding to premature aging (demonstrating as increase of internal impedance).
Better to use the 2Ah "ReadyToUse" types (Eneloop,...; very cheap sold as Ikea Ladda). Even when on paper the capacity seems to be not that high, these tend to maintain it really with very wide range of loads, unlike the "standards", which tend to loose it after few cycles at elevated current.
An undervoltage (underdischarge) protection is a must with these, otherwise the cycle life will drop significantly due to electrode corrosion (accelerates when cell voltage drops below about 0.9V).

LiIons dont like to be stored fully charged (their degradation accelerates at voltages above 3.9V), but unlike others they do not wear on charge/discharge cycles at all, so they are perfect for just permanent cycling use (discharged by working with the machine, recharged, then discharged again and over and over). Dont think that fits the application. But today seems to be the second cheapest per Wh, but need precission voltage charger and active protection circuit for safe operation. But all that electronic is readily available for cheap, so still seems to me as the cheap way for a 10Wh range (that is the single 18650) battery.
Logged

No more selfballasted c***

Print 
© 2005-2019 Lighting-Gallery.net | Powered by SMF 1.1.21 | SMF © 2015, Simple Machines