New answers tagged batteries
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Can relay source and switching source be the same?
Yes.
Any particular reason you are switching ground instead of +12 V?
No reason in particular. Is there a downside to one way or the other?
No problem, should a source terminal not be grounded (either +ve or -ve e.g. as in an automobile).
Should a source terminal be grounded, switching the ungrounded side ...
1
The pushbutton only needs to drive current to relay coil to actuate it. That might be in the order of 0.1A. The relay contacts are the ones that need to handle the 80A load. So of course you can use the same 12V supply to drive a 12V relay coil.
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It looks like someone has to answer. I assume you understand the circuitry:
The bottom DW01A detects the voltage drop on R004||R004, that is current sensing resistors.
Each DW01 detects OC and OD, sends signal down the string of 1Mohm-s to cut off the switching FETs.
HY2123 turns on the bleeding resistors at a set voltage.
Is there any way to make this ...
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The first 4 digits of the designation “18650” indicate the physical dimensions.
18650 can contain many different Chemistry, that decides the voltage.
3.7V is nominal voltage for Li-polymer, and 3.6V is for Li-ion, according to this website.
Your battery cell is Li-ion. Please be careful using it without protection circuitry. Keep it far away from other ...
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While yes this could work, it's a very poor solution.
As the battery gets drained, it's voltage will go down, which means a higher load is needed to keep the same output voltage and current. Efficiency will drop at the battery and at the converter.
Is the 36V battery able to produce atleast 22 Amps? Or higher as the voltage drops, ~25A at 32V? Assuming the ...
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The Tesla battery fuse system provides protection against thermal runaway that is not available in prismatic slab/brick configurations such as in the Chevrolet Bolt.
A prismatic slab can be considered to be like a cylinder cell except unwrapped into a flat plate, with a single Tesla cell representing perhaps 1/20th to 1/40th of the stored capacity of the ...
1
The small PCB in some lithium ion cells is a battery protection circuit.
LiIon cells should not be charged to 5V. It will damage them, and they may even catch fire. The maximum a cell should be charged to is about 4.2V.
The protection curcuit will usually also switch the cell off when it is nearly flat. This also protects the cell from damage.
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Below is a simple simulation of using ideal diode rectifier that has 30mV voltage drop. When the aux bank is drained, it will take all the current.
Connecting together aux. bank with a start battery could boil your start battery - only the voltage difference and internal resistance would limit the current.
simulate this circuit – Schematic created ...
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You could try this - most op-amps are not well-suited to driving speaker loads directly, though some may be okay driving headphone loads.
In order to minimize the shutdown current you also likely need to drive the PWM output to 0V or the internal circuitry of the op-amp may draw current from the output, perhaps partially powering up.
As shown you’ll lose a ...
6
Does the schematic make sense and am I hooking things the proper way?
Do it like this: -
You wouldn't use an NPN emitter follower to do this; use a PNP common-emitter circuit. I wouldn't recommend trying to switch the 0 volts to the amplifier with an NPN either if your amplifier is driving a loudspeaker.
Is a pin's output stable enough to drive a op-amp ...
1
Use a SEPIC converter, connect at the highest voltage point below its maximum rated input voltage. Be sure to take into consideration the maximum voltage during charging. My preference would be at the 12 to 24V point. Reason it appears there are engines involved in the systems and when the starter(s) kick in battery voltage can drop quite a lot especially if ...
1
I found the article having deficiencies and looking to find more
"accurate" and scientifically minded studies on batteries charging /
discharging effects / performances (that study disclosed sample size
for only one of 6 figures/tables/results, no peer-review, it is not a
journal publication).
Plenty of scientific papers can be found on the Net ...
0
You should try checking out LifePO4 batteries as an alternative solution. They have a nominal voltage of around 3.2V, so having 2 in series is 6.4V, which is really close to what your camera needs. You will require a (tiny) BMS circuit on it though since discharging them below its recommended minimum voltage will permanently damage it.
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You could disassemble one, and use the cells individually to power some "joule thief" kind of contraption.
Novice friendly video by Big Clive
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At an average of 1.33V /cell they still have about <20% SoC or juice left.
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As you say, when the battery voltages are different, yes, current will flow and the circuit can be said to "work".
HOWEVER be aware that current flowing into the lower voltage battery will charge it. So, this circuit (whatever else it does) is a battery charger.
Now if that's what you intended ... great.
However, if the lower voltage battery is not ...
3
Note Amperehours (Ah) is a unit of capacity and not current ; when multiplied with Volts the result is Watthours which is a unit of energy and not power.
12V lead acid battery is built with 6x 2V cells in series.
You'd use individual cells if...
you need a different voltage than 12V, that requires a number of cells in series that is not a multiple of 6
...
1
Those 2V 200Ah are different technology, they have thicker plates. They also have more cycles, they are made for professional use. You will hardly get them on free market, the company will give the guarantee only if proper mounted (by them). They are not filled with acid, it is poured in-situ, they are expensive.
On the other hand you have a consumer battery ...
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If the 2C cells are as well matched (unlikely) as the 12V cell , the it is the same, otherwise without an active Charge balancer, the weakest cell will age the fastest with runaway over/under charge with much lower MTBF.
If they are matched same or better, then it is the same energy storage.
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The simple answer is that current only flows if there is a potential difference. So positive to positive may only be a relative measurement if one is "more positive" than the other.
BTW, this simplification excludes superconductors.
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It's about peak power draw.
Over in the DIY stack we talk all the time about a large battery/solar system vs a generator. If you want to run dryer and water heater at the same time (10,000W between them), a 5000W generator cannot carry that load. But if the house has a battery system like a PowerWall capable of sustaining those loads for an hour or two, ...
0
It looks like this is a 3.7V battery, and the board in question looks like a Blue Pill (I think). Voltage wise, you can connect the LiPo battery to the 5V rail to power the device. Please note as the battery voltage gets lower, you'll eventually lose your 3.3V output on the Linear Regulator on the board due to the Linear Regulator dropout voltage. Also, don'...
1
TL;DR
4.) 30% loss is a common aging factor for quality for many things. Yet 70% is used for reactive loss 1/sqrt(2) = 0.707... because of the exponential asymptote is the half power point.
The 70% of new factor (after burnin) is also used for LED luminaries which are rated at LM70 for 30% lifetime loss for lumen maintenance. and for MTBF of 50kh. The ...
4
The lowest safe voltage for a lithium cell is around 3.0V irrespective of the capacity. Below this the cell will be damaged, but for longer life don’t discharge below 3.2V
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The TP4056 cards are normally preset for 1A charge and 10% cutoff or 100 mA. The reason it is bad to charge while using, is the current is only sensed on the charger output not the battery alone.
If the load took most of the 100 mA cutoff, the charger would never cut off and the battery's cycle rate of 500 or less would be cut according the time spent with ...
2
If you are using a battery with a built-in BMS, unless you are willing to tear the battery apart, you don't have access to the individual cells, hence the issue of paralleling BMSs. If you are building the battery yourself, or are willing to tear up an existing battery and re-wire the cells, you can then put them all in parallel and use an appropriate sized ...
3
First, Li-Ion batteries are dangerous when improperly charged (or discharged, for that matter).
If you suspect that the device and the charger are not up to some acceptable standard and/or unsafe when left plugged in for any amount of time, don't use them - either dispose off them properly or find reliable information about the safety of this particular ...
0
You must use a suitable BMS for series packs as they are unlikely to be balanced <1% by coincidence and overcharge risks are high on the weakest pack. Also, undercharge risks accelerate aging on the same weakest pack.
Your charger is OK in parallel. But to use in series you must use a BMS to inform the user it is low voltage on the weakest pack and not ...
1
While you obviously can and have done so, lithium batteries should not be simply switched between series and parallel like that, especially as the batteries are not identical to begin with.
The problem is that when draining different capacity batteries in series, the weaker cell will get drained first and there is a danger of draining it to much and lithium ...
3
Li-Ion (and their subset Li-Poymer) batteries are much more complex than "above and below 50%".
What is pretty much known to degrade them:
Keeping them charged near 100%. But this is relative, because these 100% are left at the vendor discretion - some vendors just derate the battery and say it is 100% charged at 4.10V when others would consider ...
1
The schematic is wrong, but the pin numbers are correct.
Some versions of TL431 from some manufacturers have different pinouts. I guess whoever made this schematic used such a symbol from a different version and just wired it according to the pin numbers. It's quite misleading...
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Short story
Clean the optical reflector and/or remove cat hairs from the tunnel around the optical sense head.
Long-story
My cat flap has an IR diode and reflector back to a sensor. This is pulsed at a low duty cycle and thus maintains very low battery consumption. When a relatively slow moving object like a cat enters the "tunnel", the low power ...
0
The schottkies drop (even <0.4v) is too much waist in low voltage battery design. Use BJTs or Pmos rather. To switch between batteries use SR flop initially sets to reset state so Q_neg will connect Rechargeable battery first. After Rechargeable battery voltage falls below 3V (set by Ref_3V made with TL431 ref.) the comparator switches the SR flop to Set ...
1
simulate this circuit – Schematic created using CircuitLab
Figure 1. Your configuration.
Unfortunately you will not get a clean switchover from one battery to the other. As the battery with the higher voltage discharges and gets within the Schottky voltage drop of the other battery the other battery will start to contribute current in a very "soft&...
1
Initially there is a small current (that has very little to do with the battery, but more from natural potential differences any two objects have a potential difference between them), which you could think of as static being equalized.
After that, nothing happens, except for a very very small current traveling through the air and back to ground through the ...
2
Conncting two objects together, like earth and your circuit, in a way that does not close a loop will pretty much do nothing after connecting them.
When you connect two objects together, they will be at the same potential. If they originally were not at equal potential, it means that there was charge between them, and connecting the wire will discharge the ...
2
Yes, it's possible. You will need to switch both terminals of each cell individually for charging, while keeping the other terminals isolated. It must be done in a way that guarantees no shorts during switching. Doing this electronically will be difficult.
If you charge each cell to 4.2V and terminate at the same current (i.e let the charging cycle complete) ...
1
There's not a safety problem with this. However, too high or low a charge puts additional stress on the battery, and topping it off frequently burns it pretty quickly. Keeping the battery level between 20% and 80% means you only get 60% of the power on a charge, but up to 5-10 times as many charge cycles. (Of course, if I'm getting on a plane, I'll still ...
1
I am not sure exactly how would the internal resistance change with
the size of the batteries? What factors will dominate?
You should check out this EEVblog's video
He analyzes the internals of the battery (mainly the hardware part and not the chemicals) And shows how the size of the battery can be the reason of higher resistance.
After that, he shows how ...
3
12V is not a shock hazard - nothing on a motorcycle, other than the ignition coil, generates enough voltage to cause you harm from electrocution.
Shorting the battery could potentially cause a fire, so it’s wise to disconnect it while you’re working on your wiring harness, if only to prevent damage to your wiring.
The biggest danger in motorcycle wiring is ...
0
Big capacity and low power = long lifetime. That's all.
(BUT read the fine print : USB powerbanks are outrageous cheats; that 50Ah capacity (if it's even real, it must weigh about 1 kg) will be at the CELL voltage, 3.7V, giving 185Wh not at 5V giving 250Wh)
0
Capacity and power are different things. Both are connected with "voltage" and "time".
(Electrical) capacity (or charge) is current multiplied by time.
(Electrical) power is voltage multiplied by current.
Let's see:
The (fixed) voltage is \$U = 5V\$.
The maximum output power is \$P_{max} = 10W\$.
The advertized capacity is \$Q = 50,...
3
For many battery technologies, battery capacity and battery power are mutually exclusive optimisations within that one technology.
The capacity of the battery depends on the volume of changeable material that stores charge, so more area and depth of the 'storage stuff' is good.
The power of the battery depends on the area and length of the current path, so ...
1
I cannot miss this one.
First of all, your question will be removed in no time, because it is not of a StackExchange question, but of the bike gangs. I am one of them, though. And, I did that all LED bike, too. :-).
Is this all I need to do to remove my risk of electrical shock
(removal of leads)?
Yes, the reason is that (-) is connected to everywhere (...
1
Is this all I need to do to remove my risk of electrical shock (removal of leads)?
Removing the battery leads in the way you propose, and setting the battery aside where it cannot be accidentally short-circuited, is a suitable way of disconnecting the circuit to de-energize it. Be sure not to accidentally run the engine, as that can generate electricity (...
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You can't charge a battery with just a step-up converter and BMS.
The step-up converter will try to keep a constant 8.4V, and if your battery has only say 7.0V and connect that to the converter, the converter would not be able to output 8.4V no matter how much current it will output as the battery voltage can't immediately rise to 8.4V. And the converter ...
1
400kWh per month equates to 555W average. A 1200Wh battery would support that load for a little over 2 hours. A reasonably good inverter will provide about 90% efficiency. If you’re contemplating using a number of batteries then it’s typical to put a number in series to provide 12, 24 or 48V which can give somewhat higher efficiency, but still below 100% ...
4
I have an application where alkaline or lithium batteries could be
used, and I do NOT want to have the user answer which type they are,
and new/used. That seems risky to me, and the consequences of a wrong
choice could include death. (serious)
Seriously, if the consequences of battery failure may include death then you should not be using dry cells, which ...
4
The answer to this question is "No." As far as I am aware, there is no foolproof way to distinguish which type of cells are inserted in general.
You didn't ask, but I will point out anyway, that what you are trying to do sounds unreasonable. You want to exclude the use of all battery types except alkaline (automatically) and then, based on the ...
2
It seems that battery itself has a thermistor, which is used to monitor temperature during charging and provide feedback for the charging device for safety reasons.
Here is a schematic that might help explain what happens inside your battery pack (PDF from Mouser, page 3):
As you can see, you can operate the battery without connecting thermistor wire.
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