Battery management system - how complicate is it ?

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Hi folks, alike the title says,

I have just some questions to be cleared if anyone experienced member/s is ready to explain for me:

- is it true that SLA batteries can either charged or used but never both actions same time like with the Li-Ion batteries (for example notebook use) ?

- What about battery management systems for SLA batteries ? Is it complicated to build a "voltage monitoring" for 2 batteries and a switch for example ? LED tells you to switch to other battery while you begin to charge the empty one ... of course the most comfortable solution is a full automatic system.

Same questions about the more expensive LIFePo4 batteries ... are these better to handle regarding charging issues ?
 
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It is fine to float charge lead acid batteries and Lithium-based batteries. Nickel-based batteries may need special circuits since varying loads can interfere with voltage slope sensing.

If you have two identical batteries, just connect them in series or parallel and use them as one. The only time a switching system makes sense is if one is the main and the other is the extended. The extended battery should be used first so the user can remove it once it's used in order to reduce weight.
 
A battery can be charged or discharged. No battery can be charged and used at the same time.

Power can be drawn from the charging circuit and battery. If this is less than the power available from the charging circuit the battery will charge. If the power available from the charging circuit is less than the power being used, then the battery will discharge.

w
 
It is fine to float charge lead acid batteries and Lithium-based batteries. Nickel-based batteries may need special circuits since varying loads can interfere with voltage slope sensing.

Yes but I think that I had read in the past that SLA´s aren´t recommended to charge and discharge same time ... though it´s possible. Í am really not sure how problematic this could be. So here are technical issues and on the other hand audio results to be regarded.

The only time a switching system makes sense is if one is the main and the other is the extended. The extended battery should be used first so the user can remove it once it's used in order to reduce weight.
What you say here is also senseless if it should be in fact strictly not recommended to charge and discharge SLAs same time.

Are you sure you are getting same audio results then ... ? As I said above I am in the believe that I read something different in the past. Maybe another member could also give a statement.
 
A battery can be charged or discharged. No battery can be charged and used at the same time.

Power can be drawn from the charging circuit and battery. If this is less than the power available from the charging circuit the battery will charge. If the power available from the charging circuit is less than the power being used, then the battery will discharge.

w

you are speaking for the SLAs, or not ? Exact this is the alternative solution for switching between two batteries. If music plays the BMS discharges the battery but I need a BMS who says for example under 12,5 V voltage + no music plays = charge. I don´t want that every time when I stop music at full battery load that the charging begins ... this is also not good for battery life I think. Not sure what voltage a total full SLA shows ... 13,8 V ?
This means 2,3 V/cell
 
The lead acid battery in a car is essentially charged and discharged at the same time, acting as a filter capacitor and peak power reserve.
Yes,
but you cannot compare voltage demands in a car with voltage demands in a home audio system. The car battery is charged by moving the car and moving means that energy persistently is needed for the car electric system.

If a battery in an unused amplifer for example can be persistently connected to supply voltage/current - that would be O.K. but I am not sure in this case if these minimum discharge and charge values at same time

a) are good for SLAs life (car batteries are also a bit different you know)
b) have influence on listen qualities
 
Some lead acid batteries are designed for very high engine starting current. (hundreds of Amps)
Some deep-cycle lead acid batteries are designed for continuous low current.
If a battery is being used and is re-charged at the same time, then it acts as a large filter capacitor.
I would get two SLA batteries and swap them after a reasonable number of hours.
 
The lead acid battery in a car is essentially charged and discharged at the same time, acting as a filter capacitor and peak power reserve.

Drivel. Electrons flow in a wire in one direction or another, NOT both simultaneously.

w

The superposition theorem for electrical circuits states that the response (Voltage or Current) in any branch of a bilateral linear circuit having more than one independent source equals the algebraic sum of the responses caused by each independent source acting alone.
 
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Drivel. Electrons flow in a wire in one direction or another, NOT both simultaneously.

w

The superposition theorem for electrical circuits states that the response (Voltage or Current) in any branch of a bilateral linear circuit having more than one independent source equals the algebraic sum of the responses caused by each independent source acting alone.
In float charge, ripple current would cause rapid switching between charging and discharging.
I would get two SLA batteries and swap them after a reasonable number of hours.
It's better to leave them in float charge than to cycle them.
 
SLA Batteries

The reason to use SLA batteries is, they make a preamp or computer sound better than running off the main ac wall power. I am considering use one (3ea 6 volt SLA) on my Mac Mini, I have been told the sound is the best, second to running on a 5 amp 18.5 volt dc regulated linear bench power supply which I currently use.

HTML:
http://www.computeraudiophile.com/files/Mac%20Mini%20PS%20Cable_0.pdf

HTML:
http://www.computeraudiophile.com/content/Mac-Mini-power-supply
 
optical isolation?? and add jitter at the same time.

I dont know why SLA is still so popular, there are better solutions around these days. if you need large capacity there are some crazy good things from A123, or of course a heap of their M1 cells in series. SLA has its own noise and not the most amazingly low output Z, where LiFePo4 has very little noise and an output Z better than all but the very best low Z caps. linear regs still have their place for sure, charging stuff all the time can be a pain and if its hooked up on trickle and charge is greater than current draw, you may as well just use the reg thats charging them IMO, which in many cases is a crappy switching supply, but somehow people still think this sounds good???
 
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