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The making of a perfect SecondLifeStorage/BLF Charger: the start of a new venture
#11
Another feature to add could be "Discharge for disposal" where you can safely discharge old/poor quality cells before disposing of them.
brettwatty likes this post
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#12
(09-03-2019, 09:29 AM)watts-on Wrote: Another feature to add could be "Discharge for disposal" where you can safely discharge old/poor quality cells before disposing of them.

Not really a feature I require in a charger. I use a 4 slot holder with resistors attached.
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#13
(09-03-2019, 09:29 AM)watts-on Wrote: Another feature to add could be "Discharge for disposal" where you can safely discharge old/poor quality cells before disposing of them.

That is a good idea. I might implement this on my battery tester.
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#14
(09-04-2019, 04:44 AM)brettwatty Wrote:
(09-03-2019, 09:29 AM)watts-on Wrote: Another feature to add could be "Discharge for disposal" where you can safely discharge old/poor quality cells before disposing of them.

That is a good idea. I might implement this on my battery tester.

You can even do regenerative discharge that stores energy in another buffer accumulator instead of wasting it in resistors.
I builded a gizmo like this with chinese modules, ZB2L3 + 2 stages of boost converters instead of resistors, it can discharge my bad 18650 down to 0.5V and store the energy in a 12V VRLA battery. Not super-efficient, but it works Wink

(09-02-2019, 02:49 AM)BlueSwordM Wrote: Hello again guys and gals. BlueSwordM here.
.../...
So, why not make a SecondLifeStorage/BLF charger, the ultimate charger from companies that we know, trust, and have confidence in their skills and experience?

Hello all

Just a few words about internal resistance measurements.
I've not tested all charger-testers in the world of course, but I think that no one of the common cheap models can do this properly and give trusty, accurate and consistent IR measurements. Even an expensive model like SkyRC MC3000 is perfectible on this aspect. Nothing can replace a true IR-meter with 4 wires sensing, like YR1030 for AC IR testing.
So, is it worth bothering with this feature, just because (almost) everyone does it (wrongly)?

Anyway, maybe there is a simple way to improve things without using more expensive parts or alloys: the "wire mod" like it is described for The Opus. The goal is to connect the mobile slider and the related rail with a piece of soldered silicon wire, around 18-24 gauge. No more bad contacts, we can even have the luxury of slightly lubricating the mechanical part of the slides for smooth movements without resistance points Tongue
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#15
With the temperatur monitoring, why not just automatically reduce the charge current if the cell starts to get warm above a certain limit. This would allow the removal of a fan from the build.

If you know the cell IR and are monitoring the charge current then you can calculate the effective thermal input to the cell and for a givent ambient temperature you should be able to work out a rough indication as to the expected heat loss.

Having a fan switch on and off while charging overnight may be an issue for some.

"Charging/discharging data to USB drive." + Opensource firmware = massive market
If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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#16
(09-05-2019, 07:42 PM)completelycharged Wrote: With the temperatur monitoring, why not just automatically reduce the charge current if the cell starts to get warm above a certain limit. This would allow the removal of a fan from the build.

My suggestion for the fan is for cooling the discharge resistors, not the cells.
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#17
I was thinking back to the late 80's (RC cars) with NiCad cells fast charging with a hurricane blowing on them.
If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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#18
Since the charger will be made of aluminium, the constant current linear FETs that will be used will need to be cooled, since they can output around 17W firing on all cylinders.

Edit: The MOSFETs will be used in full saturation mode, to use them in a linear fashion to replace discharge resistors.
The power of lithium ion is in our hands!
We'll show them what we're made of!
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#19
"constant current FETs that will be used" ?

Do you mean voltage regulators ?

FET's typically have a very low resistance and for a charger they should dissipate very very little heat ?
If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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#20
The MOSFETs will be used in full saturation mode, to use them in a linear fashion to replace discharge resistors.
The power of lithium ion is in our hands!
We'll show them what we're made of!
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