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Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061
Hi all.
Probably a stupid question, but why isn't there a device on the market for testing bare Li-Ion cells?
One possible idea is to cross connect two chargers so that battery + charger A discharges into battery + charger B, and a microcontroller logs the results to internal memory. When cell A is flat B begins charging it until it is nearly full.
Any extra energy needed is drawn from a common DC supply in order to achieve 95% charge.
Seems to make sense, why waste energy into a power resistor etc.
Obviously you would need something like a double changeover relay but it shouldn't be that hard.
Registered Member #191
Joined: Fri Feb 17 2006, 02:01AM
Location: Esbjerg Denmark
Posts: 720
what you typed sounded very confusing to me, but you seem to be thinking about cell balancing. If the answer is yes, then theres this interesting topology called cuk converter. I said its interesting because when it is set up with two series connected cells, the circuit is symmetrical...
Registered Member #509
Joined: Sat Feb 10 2007, 07:02AM
Location:
Posts: 329
The Revolectrix power-lab 8 does regenerative discharging if youre powering it from a 12V (maybe even 24v?) SLA. Charging upto 1.3kW and regenerative discharge is pretty hefty too IIRC. It handles upto 8S balanced Li-Ion packs, and you can hook it up to a PC for data logging. I dont know if their software supports multiple cycles for cell longevity testing etc, but their interface cable is just an optioisolated USB-Serial cable (power, ground and signal from the charger to power the optoisolated side, most likely TTL, but I havent metered/scoped it) So if you want something to do cycle testing then a bit of serial port sniffing might be useful.
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Reflex battery charger
