- Any child can plug in the Go-Kart, to be safely charged.
- Charger has numerous fail-safes, so that it cannot "burn" like the iCharger 1010B+ did (see here)
Part #1 - the Balancer
......Unsatisfactory situation
- 'Standard' solution (eg iCharger) seems to run cycles of charging through the main leads, and then discharging high cells, until the pack comes into balance.
- This takes !! FOREVER !! Because the discharge is slow (1A max).
- Also, this will not work very effectively when a large pack is paralleled. The slow discharge rate, means things will take practically forever, to come good.
......A proven alternative
- After searching, I found an excellent solution by "Dan Baldwin" for a very simple High Current balancer. Here is the thread for the circuit.
- At Post #332 is a picture of 12 of these circuits, protecting a 12 cell pack.
- At Post #276 is (unbelievably!) a Target 3001 file (hooray !!)
- Searched and Futurlec (Australia) has all the parts. Cheap too !
- The most important things, it seems, are to heat sink the adjustable zener, and to carefully check the circuit before adding it to batteries.
- !! NOTE !! If the Zener breaks (and this is the kind of risk that might apply to all circuitry) then the voltage to the battery can exceed the safe limit.
- !! THEREFORE !! There needs to be a back-up system, such as the Chargery sensors (on the taps) to sound the alarm (or kill the system) if something goes awry.
- Another possibility (slightly different circuit, maybe not as good) is here and explanatory (user) thread here and here ... but it is really just the same as Dan Baldwin's design ... connected to a large FET that cuts power ! Still inherently unsafe if one of the zeners croaks it !
......Proven Alternative #2
- From Endless-Spehere, Fetcher's "Even Newer 4 to 24-cell Battery Management System (BMS)" found here.
- See adaptions by "methods" for Lipo, here.
- Basically ... just replace the resistors before the LM431 (changing set point) ... and replace the "TC54" with a 3.0volt version.
- Advantage - is that the boards are pre-made (already with holes etc).
- Disadvantage - is that they will take longer to arrive, and they don't "Shunt" as hard as Dan Baldwin's, and they don't have the capacitors to stop "ringing", and there's no "over-charge" cut-off switch.
Part #2 - the 'Fail Safe' Charge Guard
This must protect against over-charging, if balancers break
- Possibility #1: Chargery BM6 (alarm at 4.22volts) ... "last resort"
- Possibility #2: A second adjustable zener, connected in parallel to discharge circuit ... and connected directly to "alarm" circuit for disconnection.
- Possibility #3: A digital circuit reading voltage (eg a PIC AXE).
Part #3 - the Power Supply
- Must be a CC/CV supply ... meaning Constant Current (reduced voltage) ... at Max C rating for batteries, until certain voltage is reached, then switching to the final voltage ... which means that current will reduce
......Possibility #1 - really good switchmode power supply
- See "methods" power supply here. Just a plain "Switched Mode" power supply, that has max amperage matched to the battery pack.
- Best supply is RSP-1000 ... see here (Australian supplier) is $362.00. Specifications state that "Overload" is 105-125% (ie 22A to 26.5A) ... and protection type is: "Constant Current Limiting" and "recovers automatically after fault condition is removed". !! PERFECT !!
- Specifications sheet also describes how can use a potentiometer on output pins, to adjust maximum output voltage ! !! BRILLIANT !!
- Have emailed them for response.
- !! NOTE !! cheaper supplies use "Hiccup" protection on overload. Not good.
......Possibility #2 -
- A fully programmable and controllable power supply, with circuit controlling the current, and voltage.
- Involves "better" quality power supply, and very reliable circuit / programming ... and failsafe.
- This permits charging of smaller packs, and charging of larger packs. Also (of course) permits errors (if used wrongly).
Part #4 - the Controller
- Input from Balancers (turns off, when all are shunting)
- Input from Balancers (reduce current, when shunting)
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