Questions tagged [lead-acid]

A type of very common chemistry system used batteries using lead and sulfuric acid. fully charged it will have a voltage of 13.8 V. These batteries are used in automotive and robotics environments.

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1answer
232 views

Understanding C20 value of lead battery for a low power circuit

I've developed a simple circuit using a Photon to send data to my database. It has to be a portable device and because of this I looked into lead batteries. My circuit runs on 5V and draws a maximum ...
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1answer
306 views

What is the actual capacity & charging current of a given deep cycle lead acid battery?

Firstly let me say that this is with a view to using a lead acid battery for backup purposes in case of power outage (mains power, a few lightbulbs but with daily outages lasting a few hours) So let'...
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101 views

Why does my 12V SLA Battery behave strangely when charged by simple LM317 circuit?

I'm currently working on a DIY alarm circuit and I have need of a charge controller for a 12V SLA battery. I picked up a XH-M603 charge controller (https://www.banggood.com/XH-M603-DC-12-24V-Charging-...
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45 views

Lead-acid battery Polarity Swap

I’ve seen people ask how to discharge a lead-acid battery, which is easy enough. I have a lead-acid battery that I must have connected to my on-board boat charger backwards. It must have been very ...
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1answer
47 views

Charging 4 x 12V lead acid battery with solar in series or parallel?

I have a small electric vehicle that currently uses 4 x 12V 8Ah SLA batteries wired in series as its 48V battery packs. I have 2 of these packs. In order to charge the batteries, I unplug all of them,...
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55 views

How does the charging curve of a deep-cycle lead-acid battery change as it degrades?

I am designing a circuit inside a UPS that periodically tests how long the battery can power the load. It does this by breifly disconnecting the power from the UPS and extrapolating from the measured ...
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28 views

Float charging current for AGM battery?

I have a no-name 2-stage trickle/float charger I bought "surplus" and I'm trying to decide whether to throw it out or not. It trickle charges a 35 Ah AGM battery up to 14.4V at 500 mA, then drops to ...
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56 views

Can Lead Acid and Lipo batteries be connected together to achieve higher resulting current?

I have a lead acid battery setup which has 3x12V 12Ah batteries connected in series resulting in 36V 12Ah output. I also have 3 LIPO batteries (1x11.1V 3300mAh, 1x11.1V 3000mAh and 1x12.6V 4500mAh). ...
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2answers
8k views

Can the terminal voltage of a lead acid battery be reversed?

I recently acquired a used riding mower. I figured it was dead, so hooked it up to a trickle charge overnight. Next morning, still totally dead. I stuck my voltmeter on it, and measured -11.8V. Check ...
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3answers
796 views

How to Choose a Lead Acid Battery Charger?

It has been suggested that you can charge sealed lead acid batteries with a normal power supply. On the other hand, chargers are available for purchase, but cost almost $100. Is there a reason to go ...
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58 views

Is it possible to fully charge a 12V lead-acid traction battery using a car battery charger?

I got a 45Ah 12V traction battery for my experiments and I was assuming that I can recharge it using a normal car battery charger (the main difference between 12V car starting battery and 12V lead-...
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35k views

Lead acid battery boiling during charging: this is bad, right?

I'm an electrical engineer who could use some help understanding lead acid batteries. I recently bought an old motorcycle and charged the battery on my trusty automotive style battery charger after ...
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1answer
70 views

What are the covers behind the terminals for in lead-acid batteries?

Some lead-acid batteries have two extra covers behind the terminals (See the images below). I understand that the 6 holes in the row in front of the terminals are used to water the cells. But what is ...
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1answer
125 views

Battery Disconnect Switch

I'm an Electrical Engineering student still new to power systems. I'm working on a project that uses a 24V and 200Ah battery bank made up of 4 AGM lead acid batteries. The batteries are supplying four ...
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2answers
61 views

Lead-acid battery charging fixed current stage specification

This post doesn't question the charging process or its theory. I seek to understand how to read the battery manufacturer's requirement of fixed current stage. They prescribe a current to be held at ...
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1answer
176 views

Does mobile charger and buck converter have any basic difference?

I have a 2 cell(4.2V)/12Ah deep cycle flooded lead acid battery that i usually charge by 5V/2A smartphone charger. By using this charger it takes 200mA current for charging. Today i got my CC/CV buck ...
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4answers
11k views

Why are Li-Ion battery so much safer than lead-acid?

Recently I asked how to charge a (lead-acid) car battery at home and looks like the answer is very dangerous, don't do it unless you really really have to. Meanwhile people charge Li-Ion batteries of ...
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67 views

MPPT lead acid over voltage

As I understand it, an MPPT algorithm adjusts the charging voltage until it finds the point where maximum power is delivered into the battery. If a 12V lead-acid battery is used, is there an upper ...
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1answer
732 views

Many questions about charging a lead acid battery

Well, I have a 12V 9AH SLA Battery, and I use a 7815 + a diode in series to charge it, (I really wanted to build a charger using the L200 or the LM317 but I couldn't find any of those in my city). So, ...
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2answers
68 views

Lead acid battery increasing current under constant voltage

I've found an old lead-acid battery and decided to check if it still is in a decent condition. I've opened all rubber caps and checked that the water level was still OK. It measured 10.5 V before I ...
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92 views

Will a 4 Ah 12 V battery be fine for a 2 A 12 V diaphragm pump + a Raspberry Pi?

I've got a 4 Ah 12 V lead acid battery which currently runs a Raspberry PI. I'd like to connect a diaphragm pump to this battery as well. The pump has a max. rating of 2 A. Assuming a fully charged ...
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285 views

Powering a 5v raspberry pi, a 12v motor and a 24v motor using 2 batteries charged with a solar panel

I want to control a 250W 24v motor, as well as a 12v 1W motor using a raspberry pi. It needs to all be powered by 2 lead acid batteries which are being charged when not in use. My plan is to use two ...
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2answers
581 views

What is the lowest voltage a 12V lead-acid battery in a car could be?

I'm trying to design a product that is powered from the 12V rail inside the car. In normal driving (engine running, electronics on etc.), what would be the minimum voltage of a low battery? Reading ...
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1answer
75 views

DIY Lead Acid powered USB-C power adapter [closed]

I recently found a great appreciation for the long battery life of my newly acquired mac book pro and was thinking how I can scale that up even more (since I travel and work on site a lot), by ...
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1answer
38 views

CSB batteries Constant Current Discharge Characteristics

I'm comparing batteries for use in UPSes and during my tests I was consulting the datasheets of 2 manufacturers. The datasheet from SunLight is crystal clear but CSB's datasheet is using terminology ...
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197 views

Parallel connection of old and new gel batteries [closed]

I have a battery system shown in the picture, 6 parallel branches of 4 batteries connected in series. The first 3 consist of old batteries which are 2 years old, the fourth branch consists of 1.5-...
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2answers
168 views

Reserve Capacity Testing On Lead-Acid Car Battery

All car batteries have Reserve Capacity ratings instead of Ah ratings for deep-cycle batteries. Using this data to test the health of the car battery a good way to estimate life left? Let say I have ...
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3answers
2k views

To pulse or not to pulse

It is accepted practice to maintain lead acid batteries at a float voltage of roughly 2.3 Volts per cell. The precise value depends on battery type and battery chemistry and ambient temperature. We ...
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9 views

Battery Discharging and Effect on Lifespan

I have noticed that some times during the day when my solar system panel is shaded it starts using the battery bank power (a few ampers) for a few seconds and then recharges the battery after the ...
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3answers
57k views

What is a safe max. discharge rate for a 12V lead acid battery?

I've got a 12V 2.4Ah lead acid battery which I plan to connect a water pump to. I've looked at various pumps, but the one I'm most interested in draws 2.2A. I'm not so interested in how long the ...
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7answers
14k views

Why are lead-acid batteries preferable for submarines?

According to Wikipedia article lead-acid batteries are used for running submarines propulsion engines. Submarines are used by the military and the military can afford very expensive toys. Lead-acid ...
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1answer
264 views

Voltage drop on batteries when connected to ups/inverter

I have recently installed a solar system and trying to understand the voltages of batteries when they are being charged and when they are providing power to load. Here is what I observed: I have 2 ...
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4answers
15k views

What can be the consequences of charging a lead-acid battery with an excessive voltage?

In my field-operating device I use a simple PWM step-down to charge a 6V 3.9Ah lead-acid battery from a 5W solar cell with a voltage of 7.2V. Unfortunately the DC regulator got damaged today and the ...
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1answer
71 views

What is 'DOC' in terms for Depth of Discharge for SLA batteries?

I'm trying to understand the spec of a SLA battery. There's a chart which is titled "Cycle Life in Relation to Depth of Discharge": Can I ask what 'DOC' stands for and the chart is read? How come ...
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8answers
77k views

How bad is it to undervoltage a 12-volt lead-acid battery?

I had a heated discussion with a few colleagues today revolving around how low of a voltage was alright for 12 volt lead-acid battery; they were in the opinion that the low voltage warning buzzer and ...
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167 views

Which AGM battery terminals should be used when wiring 3 or more batteries in parallel?

With a 12V AGM battery bank of 3 or more batteries wired in parallel, is charge able to be drawn by attaching to any random positive and negative terminal across the battery bank? Is it optimal to ...
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2answers
238 views

What is the effective equivalent battery capacity between Lithium Ion and Sealed Lead Acid batteries? [closed]

I was told by a battery salesperson that a Lithium Ion 100Ah battery is equivalent to a 260Ah lead acid battery bank. Is this correct? I understand that lead acid batteries should only be discharged ...
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2answers
60 views

ADC conditioning for Lead-Acid monitoring? [duplicate]

I want to monitor a 12V lead-acid battery using an ADS1110 ADC. This ADC has a reference voltage of 2.048V. Thus, I (think) need to condition my input from, say a 10V-15V level range to 2 volts (0.4 ...
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2answers
70 views

Substitute 12v Lead Acid Battery with Nominal 10.8v Lithium Ion Battery?

I am looking to replace an existing 12v Lead Acid battery configuration (two 7.5Ah batteries in parallel) for an old practice tennis ball machine. The machine consists of 12v dc motors and sensors to ...
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42 views

Do I need a cut off circuit for my battery

Do I really need an auto cut off circuit for my battery when my charger only outputs 13V and 1A at max. The battery I want to charge is a 12V 7Ah Sealed Lead Acid. I heard that the cut off for lead ...
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73 views

trickle charge backup battery

I would like to know if the schematic below would work to keep a 12V SLA battery at or close to float voltage to be used as a backup battery? R1 will limit the charge current to the battery, but am I ...
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175 views

Lead acid battery charging current dosent become zero

Here I am charging a 6V 4.5Ah lead acid battery by using a 8V-10V LM317 input supply for the circuit. I'm using the BD139 transistor to cut off and a 6.8V zener diode. As the battery voltage reaches ...
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17 views

Using SLA in place of LFP to test an LFP charging device

I'm testing a solar charge controller for LiFePO4 that uses absorption and float stages. By design, power-on initiates the absorption stage, and a timer terminates absorption and initiates the float ...
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2answers
78 views

Sealed lead-acid battery UPS indoor?

I bought a BX700UI APC UPS for my linux arm server setup (40 watts) to protect it from power cut. - I have the server in the bedroom is it dangerous to have such an Ups in a small bedroom? - Thinking ...
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1answer
53 views

charging 12v lead acid battery with OEM charger [closed]

I have an ExpertPower 12V 7 Amp EXP1270 Rechargeable Lead Acid Battery (link on Amazon here) and would like to safely charge it. Do you think this charger (Battery Tender 021-0123 -- link here) is an ...
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1answer
12k views

Charging Lead Acid Battery from dynamo

I want to build a Lead acid battery charger. for that I want to use a small IC engine coupled to a dynamo and the dynamo I got is rated at 12V, 35A and I want to charge 12V 7.5 Ah Lead Acid battery. ...
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2answers
4k views

pulse charging lead acid battries effects and side effects

I am developing a solar charger which charges lead acid batteries.I would like to clear a few of doubts on this issue. I am using IR2110 gate driver for driving 2 n-channel mosfets in an half bridge ...
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2answers
2k views

How much current can lead acid batteries safely supply?

I have a motor I wish to drive with an 18V lead acid battery. The motor can draw quite a lot of current when stalling and I am worried of overdischarging the lead acid battery. Unlike LiPo batteries ...
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1answer
984 views

Mixing Lead acid and Lithium ion in series, after charging them separately

Can I connect a Lithium ion battery battery pack with a Lead acid battery bank; in series. I will charge both separately cells strings separately (not to mix the chemistries) before putting them in ...
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1answer
29 views

Designing an effective extensible solar cell + car battery setup [closed]

I've got a cabin that I visit on weekends and because I need to charge my computer and tools there, I decided to bring an old car battery and bought a solar panel to charge it. Right now I use a cheap ...