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Bench PSU 30V/10A as a car battery charger

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mzzj:

--- Quote from: SparkyFX on June 12, 2019, 02:30:11 pm ---
Might be wrong on the NiMH and NiCD, haven´t messed around with those...
I thought that the LiPo/LiIon types have no easily detectable deltaV charging end and require thermal monitoring throughout, therefore need charge counting to really utilitze the capacity. I am sure one can get away with keeping it in between 20-80% level, i heard this is done to increase the lifetime/amount of cycles as well.

This is why one really needs a seperate charge logic for every type of battery, it could end catastrophically.

--- End quote ---

Li-ion is really easy to charge compared to Ni-Cd/Nimh but when things go wrong they go wrong in a big bang.
Ni-chemistry is real pain in the *** to charge properly and you can't for example parallel them. But lot more forgiving, even if you charge and abuse them badly they are pretty hard to make explode.

 

ejeffrey:

--- Quote from: SparkyFX on June 12, 2019, 02:30:11 pm ---Might be wrong on the NiMH and NiCD, haven´t messed around with those...
I thought that the LiPo/LiIon types have no easily detectable deltaV charging end and require thermal monitoring throughout, therefore need charge counting to really utilitze the capacity. I am sure one can get away with keeping it in between 20-80% level, i heard this is done to increase the lifetime/amount of cycles as well.

--- End quote ---

Nope.  Li-Ion cased cells work fine with a simple current cutoff.  You charge in constant voltage mode until the current drops to some threshold and then stop.  The only really tricky part about LiIon is that the charge voltage tolerance is pretty tight.  Set it too high, battery goes boom (or has greatly diminished lifetime).  Set it too low and you will be losing a large chunk of your capacity.  The main point of charge counting is to display a battery gauge and to keep track of the cell capacity degredation.

NiMH/NiCd cells are trickier which is why there have been a number of ways to charge them.  Simple trickle chargers are really slow.  Older cheap medium speed chargers used a timer designed to get "mostly charged" and then dropped to a trickle charge to finish off.  Other fast chargers do look at the delta-V or the temperature rise to detect end-of-charge.  But at least they are less likely to catch fire when overcharged although they don't like it at all.

SparkyFX:

--- Quote from: ejeffrey on June 12, 2019, 07:59:16 pm ---Nope.  Li-Ion cased cells work fine with a simple current cutoff.
--- End quote ---
Which requires the charger to know the nominal battery capacity, right?

mzzj:

--- Quote from: SparkyFX on June 13, 2019, 03:35:47 pm ---
--- Quote from: ejeffrey on June 12, 2019, 07:59:16 pm ---Nope.  Li-Ion cased cells work fine with a simple current cutoff.
--- End quote ---
Which requires the charger to know the nominal battery capacity, right?


--- End quote ---
Sort of.
But it's not overly picky about cut-off current, you can cut off early and you would only lose couple of % capacity or you can cut-off at lower than specified current with longer charging time and very slightly increased risk of something going wrong.
3000mAh battery terminated at 500mA charge current might be at 95% charge and if you terminate at <50mA it might take couple of hours extra.
You could leave li-ion battery to 4.1 or 4.2v power supply infinitely but ifwhen something goes wrong at some point after 10 years or 1000 cycles the battery can overheat, explode or start WW3.  :-DD

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