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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3answers
78 views

Robust low battery cutoff

I am building a 5V DC charger for an offroad motorbike. The main goal is to use this to charge/power a mobile device/phone/tablet whilst travelling/camping. If space allows maybe also a GPS tracker ...
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1answer
68 views

Can de-ionized water be used instead of distilled water to prepare lead acid battery electrolyte?

I have a couple of Yuasa and Power Sonic conventional lead-acid bike batteries that I recently purchased for a very good bargain price from a seller. They are new and never used. But unfortunately, ...
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90 views

How to check with a simple multimeter whether an old lead-acid battery and its charger are still working?

I have an old (ca. 10 years old) 6V lead-acid battery and a mains charger for it and I know the combination worked years ago. Now I tried to recharge the battery and the charger's LED turns on ...
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63 views

Why doesn't current fall to zero after unplugging the charger? [closed]

I use an automatic charger to charge my lead acid battery. After the battery is fully charged, it shifts to maintain mode, where the charging current reduces to as low as 13mA. I noticed that even ...
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1answer
60 views

Help understanding RV/Marine battery chargers

I am trying to understand how modern 3-stage marine/RV lead-acid battery charge systems work. It's very common to wire a charger in parallel with both the battery bank and the "house" power. This ...
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1answer
31 views

Circuit Charging Sealed Lead-Acid Battery (NP1270M)

I have a project (remote gate opener...) I have made good progress but its the first time I have built a charging circuit so I have some questions I need help with. The battery I am using is a sealed ...
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2answers
87 views

What is the Ah to voltage relationship of a 12 V lead acid battery?

I've a DC motor (brushed) that is driven by a set of 12 Ah 12 V lead-acid batteries. When motor stops moving, I assume that all the current (at least most of it) in the batteries is drained. However, ...
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1answer
27 views

Do I choose a series or parallel battery set up to power a fish finder?

I plan on running a Garmin UHD 73SV fish finder off two 12V 7A lead acid batteries for a kayak. The unit pulls 1.25Ah. So if I run them in parallel I will have 12v 14A with a run time of about 11.2 ...
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0answers
66 views

Connecting multiple chargers to a lead acid battery

I have a scenario where I want to connect an external battery charger to an alarm system's battery to keep it charged fully despite our country's frequent rolling blackouts. The battery is a larger ...
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1answer
50 views

Choosing a resistor for balancing lead acid batteries

I have a solar-panel-and-battery kit with a built-in inverter and what not built into the battery box. (Goal Zero Yeti 400) The battery box has Anderson Powerpole connectors for chaining it to ...
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56 views

Limit current when charging a battery?

So I am trying to charge a 12V 1.3Ah lead-acid battery(actually they are two 6V batteries in series). Now I have a power supply which says 12V 500mA but actually outputs more like 21V.. No idea why.. ...
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2answers
64 views

Charging a big battery with small solar panels very very slowly

I have a 6V, .7amp solar panel that typically puts out 2-5V under normal conditions. I would like to charge a 12V 5 amp hr lead acid battery over a few days to weeks. The device that I want to ...
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1answer
74 views

On the possibility of lead acid battery recoverability [duplicate]

I have a 6 V 4.5 Ah lead acid battery which I did not charge for the last 6 months. Now the battery voltage fell to 3 volts and then I charged it for 24 hours at 50 mA. Now when I measure the voltage ...
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1answer
48 views

Lead-acid battery charger, specific circuit, 3~4.5 Amps, doubts + recommendations

I want to build a lead-acid battery charger which can reach an average charge current of 3 to 4.5A, and start with a prototype. The charger needs to be supplied by the mains, up to 250VAC, for example....
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1answer
40 views

Confused about battery rating specifications [duplicate]

I'm confused about how to understand battery capacity by its ratings. I though I understood Amp-Hours, as a nominal rating where they usually specified a period of time where that rating was ...
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1answer
86 views

Why do lead-acid batteries perform better than Li-ion with substantially more ampere hour?

I've been using a 36V motor that draws ~13A current at peak. I initally used a set of three lead-acid (12V 12A) batteries in series to power the motor. They had sufficient power to easily take a ...
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1answer
63 views

Can lithium batteries and lead acid batteries be used together? [closed]

If I have the two batteries with same voltage but different capacity, can lithium batteries (the lfp battery like this type) and lead-acid batteries be used together?
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1answer
76 views

Is there a minimum for charging current for lead acid battery?

I've recently bought a 9 V, 3 W solar panel that I wanted to use to make a small project in my balcony, then I bought a 6 V, 4000 mAh sealed lead acid battery, I want the solar panel to always charge ...
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1answer
177 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
73 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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1answer
92 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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1answer
315 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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1answer
93 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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0answers
90 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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1answer
72 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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2answers
67 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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2answers
112 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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102 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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2answers
2k 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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2answers
91 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
145 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
253 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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2answers
581 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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1answer
413 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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1answer
199 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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1answer
340 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
419 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
61 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
133 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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151 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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20 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
144 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
58 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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2answers
3k 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
2k 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
30 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 ...
3
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0answers
309 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-...
3
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3answers
517 views

Car battery (lead acid) discharges much, much faster than it charges?

Let's assume a lead acid car battery (12V, 50Ah, 250A output). According to BatteryUniversity article BU-403: The charge time is 12–16 hours and up to 36–48 hours for large stationary batteries. ...
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2answers
191 views

Charging a lead acid battery with a lower bulk voltage

Will a lead-acid battery completely charge when using a bulk voltage below the one indicated on the specs sheets for it, even if it takes longer? In my case the battery is in a place with temperature ...
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2answers
161 views

Is my 12v lead acid battery 100% dead?

so I got a ups with a 12v lead acid battery that was constantly on so the water inside the cells has disappeared, initially the reading voltage was 0.3v, and when I added distilled water it generally ...

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