here is some info on 20v yardworks lithium ion

[Anonymous]

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[mikereidis]

I really need to rig up some kind of faster charging for these yardworks batteries. What I have right now, repackaged original chargers, works very well and reliably, but takes 3 hours to charge. I'm finding that I'm too often waiting for batteries to charge, wandering into the next room to check "are any of the lights green yet?". I suppose a deeper problem is my addiction to biking, but that's another matter.

Mike, you macgyver'ed some kind of quick charger using very few parts, and described it briefly, but I didn't quite understand how you managed that. Any chance you could draw a schematic? How about some pics? Are you charging all of your batteries at the same time from one power source? What does the wiring harness and connectors look like? Did you say you used a heater as a power supply?

Anyone else have any ideas for fast charging multiple yardworks?

Yeah, this was getting to me too, even, or especially after I had to make multiple connections/disconnections and probe around manually with voltmeter to ensure none go over 21v.

I HAVE to upgrade my current manual charging to safer, auto charging. I've left and come back and seen ungodly (for 21v lithiums) voltages on a batt when others tripped for whatever reason. Problem is life, you get distracted. Even a short period 15-30 minute timer could help.

Two of my battery BMSs are I think victims of overcharging. One trips with sustained 14-18 amps, and the other with sustained 5-6 amps. I suspect power resistors/shunts changed value after they overheated. I will open these when I have the time and hopefully I can replace the resistors. I won't return unless this doesn't work or batts are "melting" or whatever. Would be good to know how to modify BMS. I'm also thinking BMS could be used for charging, effectively extending the BMS to 1-4 batts in series.

Anyway, pics of my latest bike, and charging station etc. are here now: http://endless-sphere.com/forums/viewtopic.php?f=6&t=6224

I'll upload a schematic tomorrow, but it's pretty simple. Hot goes to one side of load, other side of load goes to AC input 1 on bridge rectifier, AC input 2 goes to neutral. Thats AC side, with addition of a switch.

DC side is 1s-4s batteries and ampmeter and voltmeter.

Vary load as desired to get "somewhat constant current mode" at desired C rate from 2c to 0, depending on your nerve and various ratings and how hot you can stand it around the charging station.

When batteries get to 21v, manually shed load to reduce current as needed to maintain 21v or less. This is manual constant voltage phase. I find lights on dimmer works well for this.

But yeah, I've got to automate this. It's much nicer than it was previously, but I must maintain constant attention for the hour or so it takes to charge 4 batts, or my batts/BMSs will end up toasted. Also, I'm still manually balancing voltages for various reasons, like my BMS issue means those batts will usually be different voltage/state of charge.

I saw 5 pocket DMMs clearance at $8.74 at Cdn Tire Aylmer, but when I went back, only 3, 2 still with the weird 12v battery. I was planning to have 1 DMM per pair of batteries to better monitor each batt. Currently, I can charge 4s, then flip a whole bunch of switches and see each individual batt voltage, but it's a lot of switch flipping to do. Ideally I 'd have 4 - 8 A to D converters going to a micro and an LCD screen to monitor all the details; maybe next year.


I'm REALLY liking this battery switch setup again. My BMS issue on two batts can be bypassed as needed, without rewiring or anything on the road. I'm going to replace these poor, spark abused light switches with some decent toggle switches in a future iteration. Relays are probably a bad idea, but solid state switches, computer controlled, might have some merit.

 

[mikereidis]

Schematic:

Because they share a connection, the ammeter and voltmeter can be the same DMM, but you have to switch back and forth sometimes and that's a pain. Didn't blow up my cheap DMM doing that, with all the resistance etc. ranges. My previous amp DMM was used on highest 10a (unfused, thankfully) range, but worked fine to at least 19-20a or so. My 20a controller showed 18 something max.

Also, shared connection on negative line results in polarity I prefer: negative for current drain (to controller or load in discharge test mode) and positive for charging. Seems right from batteries perspective.

Note that controller positive only sees batteries that have been disconnected from AC. Slightly different story for negative side of controller. Note that I don't think this design could ever be approved by CSA or UL, unless perhaps it used an isolation transformer. Anyone who doesn't understand why shouldn't even think of building such a circuit, IMO.

My discharge switched welded in the off position. I think I need a thermistor or 3, also for limiting light bulb load startup current spikes, and one for limiting controller cap inrush/outrush current.

Sometimes (like when I switch charger off at peak of AC cycle ?) I get big sparks when switching off charger to check voltages. Seems to happen most with 1 or 2 heaters as well as lights on. Maybe an inductive effect ? Sometimes my home circuit breaker trips on a big spark.

My batts that have defective BMSs are too easy to overcharge now. I'd guess their overcharge BMS protection is shot now; perhaps cells are a bit puffy too. May peak inside them next weekend; everything's wrapped up now and I'd rather ride.


Another happy plus with my current setup is no tangle of wires coming off of bike. I have 2 connections to charge: 1 PC power cable for power input, and 1 standard power plug connected to load or power bar with loads. Hmm, I think I'll take a heater with me tonight and test out my outdoor charging scenario.

I try to be very conscious of charging now if I leave the charger. Too easy to get distracted, come back and see unholy voltages on 1 or more batts. Lower current helps, and a 0-60 minute timer, like for hot-tubs etc. would be prudent if you are prone to forgetfulness or distractions.

 

[wasp]

is it possible to just dbl up on the chargers?
i mean take them out of orig packages and
wire them together?dbl'ing the amps and
cutting charge time in half?
what do you think?
or am i way off?

 

[mikereidis]

is it possible to just dbl up on the chargers?
i mean take them out of orig packages and
wire them together?dbl'ing the amps and
cutting charge time in half?
what do you think?
or am i way off?

Could be it'd work. I posted about this possibility earlier. Would be best if both chargers agreed on stop voltage; my 2 were 20.81 and 20.84. Probably no big deal.

Each charger is independent and leads are not in any way connected to 120vac hot or neutral or ground. I've series-ed them "sort of" to charge two batts with a common lead from - to +. IE the chargers were sharing one connection.

In constant current mode, each should provide 1.8 - 2 amps for total of 3.6 - 4. In CV mode, the higher charger may dominate, but thats' OK I think; it's in low current mode at that time anyway. And YW charger only has a "pseudo CV mode", IMO; it never shuts off, it just reduces current forever as batt SLOWLY climbs towards, but never reaching, 21.00 volts after several days on charger with green glowing.

Possibility of some oscillation ?

But my theory is it would work fine. If you try, make sure to check current and voltage regularly and let us know how it goes Oscilloscope could be useful if any issues (like oscillation/fighting chargers).

Note also, that you could definitely series charge (with TAPS at each battery !). I did it with 2 batts fine.

If I was going that route, I might get 8 chargers for all 8 batts. (240+tax) Should charge all 8 in 3.5 hours as standard for single batt/charger. Using 16 chargers with 2 parallel for each batt might take just over half the time; say 1.8-2 hours. That should replicate my current capacity of 8 batts charged in 2 hours, but with less danger and manual fiddling. (I could improve this with auto current control and parallel charging.) But you get into diminishing returns at higher C rates since you hit the CV mode much earlier.

So, if you have batts in series, you may want to concentrate on series charging all your batts in series first; 1 charger per batt. THEN consider doubling up, with 2 or more chargers on each batt.

 

[Anonymous]

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[Anonymous]

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[wasp]

Would be best if both chargers agreed on stop voltage; my 2 were 20.81 and 20.84. Probably no big deal.

The nominal voltage, as labeled on the actual cells, is 18.5V. Thats why I say I run 56V, it is not 60V. At full charge under no load yes its over 60V but drops as soon as you throttle up. So they're using that same "fake" voltage as other tool batteries, calling it 20V when it's really 18.5V nominal. I don't think 0.03V difference on full charge has any impact on the nominal voltage, in the larger scheme of things.

well i run only 2 yw bats on my izip and have to dissagree with saying they drop fast to 18.5...
not mine and i always keep track of starting and ending voltage...sometimes i only put 4 or 5km's
on it and my ending voltage is above 19v on each bat measured seperatly...so i disagree i get lots
of use before hitting 18.5v...btw @18.5v these bats fall quicker than the top half charge...

peace wasp

 

[Anonymous]

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[Anonymous]

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[wasp]

2 or more chargers on each batt

Okay two chargers in parallel, each measured exactly 21V not connected, two chargers charging one battery now, no smoke (whew!), both LEDs turned red, so far so good, I would expect the battery to be charged in approx 90 minutes. "2 or more" ... hehe not sure how far I'm willing to go with this ... 90 minutes would be fine for me I think ... although 45 would be spectacular.

nice keep us posted...
also just went for 6.8km ride..flats..no wind
volts left 19.48 in each bat...
if anything there underated
i need a ca

peace wasp

 

[Anonymous]

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[wasp]

90 minutes on two chargers, voltage check 20.6V, not quite but almost charged, will be interesting to see if both charger lights turn green.

EDIT: Okay 104 minutes, one charger light turned green, voltage check 20.8V, yes parallel chargers nearly halves the charge time. For this trial, pulled the battery after one green light, not sure yet if the second charger will switch off. But now I am very happy, moving on to three parallel charger test

sweet...i'm buying 2 more yw chargers tomorrow

peace wasp

 

[Anonymous]

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[mikereidis]

especially if you disconnect and reconnect the charger when near full charge.

Yes, I expected and have seen that if you pull the batt just as the charger goes green, then put it back, it's red again for a while. Just a "feature" of the way these chargers switch to low current mode and go green at 20.8v instead of charging with CV until 21.00v. I THINK this may be related to your observation.

YW chargers much safer option than my charger. BTW, the schematic had a line missing for discharge mode. Any competent schematic understander should be able to figure it out.

My range is much shorter recently, like 15-25 KM on 4 batts, instead of previous 40 KM. Not sure if batt decay/damage is playing a part. Of course those hills in Gatineau REALLY suck up the AH. Must have been two longer ones I got to 40+ KMH on downhill, and one I got to 45.5 KMH. Probably would have been a bit faster if I didn't tug on the brakes a bit to moderate the exhileration. Had this bike to max of 48 KMH on flattish road with 4s. Aero and tires probably pull me down from the 55+ KMH I got on the recumbent; and recumbent still had more room to go faster, not sure how much but it felt like 60+ KMH was possible.

Mackenzie King Tea Room seems good for 12 amps of "tea kettle". $20 AirWorks (CdnTire) heater tripped the breaker when I switched charger off at 15 minutes of "low heat" 2.5a charge to check voltages. Must be inductance/kickback ?? Will try Ceramic $25 heater next; weighs 4 lbs instead of 3, but seems friendlier for outdoor charging.

Pic of my bike in "outdoor charge equipment mode":

I added bar ends, with thumb throttle on right, and raised seat to almost max and my knees, wrists and back are thanking me this morning.

 

[Anonymous]

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[mikereidis]

My range is much shorter recently, like 15-25 KM on 4 batts, instead of previous 40 KM.

I have never been able to do 40km on 4 batteries, I needed 6 batteries running 2S to go 40km, that got me from chelsea to ottawa and back round trip 40km. Now my bike is hard wired for 3S2P and normal range is 30km running mostly full throttle 38kph a lot of the time, avg speed 32kph, top speed 43kph in ottawa area, much less hilly than gatineau. I can of course extend the range by throttling down but I don't do that very often I would actually like to double capacity to 12 batteries for range of 60km under same conditions.

My recumbent had/has it's issues, but I think the skinnier LRR tires and aero were getting me at least 50% more range. I think I'll rebuild the e-cumbent with better tires and batt placement this winter. Loved the range, but I hated the handling issues.

12 batts ? !! That's like 45 pounds or so !

I mostly ride for fun, and need a smoke etc. break at least every hour or so, so my range extension solution is to re-charge my batts while I recharge myself.

I've been thinking more about these cheap $30 YW chargers. I'd bet I can up the current to at least 3 amps, maybe 4 by modifying the current sense shunt. Perhaps a decent 120vac muffin fan to cool would help also. I'd also want to raise the green voltage to 20.95v or so.

So if I bought two more to add to my existing two, I could charge 4 batts in 3.5 hours (as usual) and with a 4a mod, perhaps 2 hours. Probably quick enough for me, especially since I don't have to watch religiously. Maybe I could even integrate these chargers into my existing charger for best of all worlds. Would save some of the weight and funny looks of a heater on back of my seat.

Charging strategy for most miles range added per minute of charge is to charge lowest batteries first for highest current. Also note that 1 hour into a full 2 hour charge, batts are OVER 50% charged. Diminishing returns once max C rate has to be reduced for CV mode.

Eventually I WILL add regen. Probably can charge a good bit coming down those scary fast Gatineau Hill roads, and lower speed = a bit less scary. Have to say those are nice, smooth, pothole free NCC roads in the park. Probably a MUST since so many lycra bikers break personal speed records downhill there every day. Roads much safer than bike paths, if you are going fast there. Thankfully, in this case, the quasi-government, sort of independent, NCC seems to have plenty of money to spend on good roads.

Had a Gatineau cop give me a REALLY good looking over, from behind and ahead on Chemin de la Montagne going towards Notch Rd last night about 1:00 AM. I was doing only 15 KMH up a 4-5% or so incline to save batteries. He left me once I guess he determined there weren't any laws I was visibly breaking. Thankfully I had just "installed" my "Legal in Canada" label, cut from a $1400 Chinese e-bike sellers pamphlet. AFAIK, I'm the manufacturer so this is completely legitimate, other than my "off road only" switches which raise the power "slightly" over the legal 500w maximum. Hmmm, haven't actually checked SAAQ website yet to see what they say about ebikes.

 

[Anonymous]

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[Anonymous]

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[mikereidis]

I've been thinking more about these cheap $30 YW chargers. I'd bet I can up the current to at least 3 amps, maybe 4 by modifying the current sense shunt. I'd also want to raise the green voltage to 20.95v or so.

I would love to figure out how to double the amperage on these chargers. You mention modifying the current sense shunt. Why would a simple charger like this even have this? I don't think they have shunts. Have you looked at the circuit boards? Can you tell from the pic below where mods could be done?

Perhaps a decent 120vac muffin fan to cool would help also.

They do generate a lot of heat, especially if you put multiples of them in close proximity.

Maybe I should just say "current sensing resistor" and not shunt.View attachment bikedcacrave 004.jpg

To the right of the right heat sink seems to be the 120vac power section, where it's rectified and cap filtered.

In the middle, more or less, is the switching power supply that probably normally supplies about 24v at up to 2 amps I guess; as I say, I assume it could handle 3-4 amps, with a bit more high frequency ripple and pushing the components a bit.

On the left, it's pretty much the battery output section. In the middle of that section is a power resistor. I imagine this is the current sensing resistor, and paralleling it with the same value resistor will possibly double the current output.

Maybe I'll try this mod today, if I have a few minutes between riding, kids and Sunday life in general.



I bought four DMMs at Cdn Tire yesterday. Normally $60, on sale for $20. Previously bought 1 for $40. Good value, IMO, they do cap testing, frequency, duty cycle, have backlight for night riding/charging. hold function, etc. etc. They were all within 10 millivolts of each other with a batt showing 21.00volts. I chose the one showing median voltage as my reference DMM, and marked all the others with "-4" to "+6" to allow me to compensate mentally. I wonder if there's a trim pot inside I can use to calibrate them ?

These DMMs are NOT good for ebike current testing. They blow their fuses when charging at 12 amps for a few minutes, as the manual warns. 10a fuse is "technician replacable", so I'll have to crack them open to replace fuse. My older, cheapie DMM 10a range is unfused and works wonderfully for several minutes of full 18a discharge rate to my controller.

I removed the $9 pocket DMMs from bike. They were OK when charging or at rest, but went crazy when I ran the motor. Perhaps a cap on their input leads would help, or perhaps they are just EMI prone. Anyway, they take funky 12v batts that cost $5 minimum to replace, while these new DMMs take standard 9v and are much better, except for size and weight.

I bought the 4 DMMs so I could monitor individual battery voltages while charging. I'm using my "old style" charging leads for this, and this will help me experiment with a safer automatic CV solution for charging, after which I won't need these DMMs for normal charging.

I'm thinking all I need is (for each battery/bank) a voltage threshold circuit, tuned to 21.00v, and connected to two FETs, one would disconnect battery from charging, the other would "shunt" the current around the battery that has reached full voltage. When all batts are fully charged, my loads should be getting their full 120vac, minus a few volts for rectifiers etc.

BTW, some of my batts appear to have broken LVC now. They are happy to keep discharging into the low 14v range ! Yes, if they go too low, they may be unrecoverable; fortunately, they recover after load removal to 15+v. Maybe I broke LVCs with no protection diodes ? Or just overcharging.

My batt that can't go over 10a or so, seems to have higher internal resistance now. I'm thinking the current sense resistor got too hot and increased in value so the BMS thinks I'm pulling 31a, when I'm only pulling 10a or so.

 

[wasp]

well i ripped my bats out of my bat box and charged them on the chargers
now it seems like i have my old range back 10+ km at 24kmh
as for the chargers...what is the size of the board in there...L..W..H
i want to remove the 2 i have and put both in a 24v sla charger case that is vented
also combining my 2 cords(for power)into 1 cord...is that alright and last i want to
keep my charger on my bike and hardwired to charge from the + and c- and wire up
the bike for + and - ...can both be wired up together as long as i unplug power to controller
before charging then when done charging unplug power cord from wall and plug power back to controller?
am i missing something?

peace wasp

 

[Anonymous]

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[mikereidis]

well i ripped my bats out of my bat box and charged them on the chargers
now it seems like i have my old range back 10+ km at 24kmh
as for the chargers...what is the size of the board in there...L..W..H
i want to remove the 2 i have and put both in a 24v sla charger case that is vented
also combining my 2 cords(for power)into 1 cord...is that alright and last i want to
keep my charger on my bike and hardwired to charge from the + and c- and wire up
the bike for + and - ...can both be wired up together as long as i unplug power to controller
before charging then when done charging unplug power cord from wall and plug power back to controller?
am i missing something?

peace wasp

So you think heat was reducing your range ? On running or charging or both ?

A 15cm long, 6cm wide, and 3cm high (including solder bumps) box would fit this board rather snugly I think. Snugly enough it might need lube and pressure.

2 cords to 1 cord just fine. I modified one YW charger to put out 3 amps and it's pulling 0.68amps from AC line. Any cord can handle a few amps.

You should be able to leave chargers connected; no current flow when unplugged. Some IMO small possibility of damaging charger if you have big spikes on your lines from motor/controller. But I wouldn't worry for a $30 replacement device.

Dinners ready. More on my 3a YW charger (apparently the limit) later...

 

[mikereidis]

On the left, it's pretty much the battery output section. In the middle of that section is a power resistor. I imagine this is the current sensing resistor, and paralleling it with the same value resistor will possibly double the current output.

Yes, this worked, to a maximum of 3 amps at normal open circuit discharge voltage of about 17v or so. Even as I approached 0 ohms resistance, 3amps was the maximum. Perhaps another resistor change (?), but more likely the limit of the switching transformer I'd guess.

With batt charging voltage at about 19.3v, current was down to about 2.4a. Somewhere around there, a low parallel resistance lowered current. I'm finding a 0.67 ohm resistor in parallel, with bat voltage 20-20.5v gives me about 2amps, and with the normal resistance, the normal 1.8amps.

I can't be positive inductance isn't some effect, especially if there is some high freq ripple, and since my 0.67 ohm resistor is wire wound. The YW current sense resistor is 0.1 ohms I beleive, so the circuitry must try to keep it's voltage drop to 0.18v for 1.8amps.

Currently, batt voltage at 20.48v, current=1.83a w/ 0.67 ohm parallel (which should give about 15% more current), but when I remove it now, current jumps up to 1.93a ! ?? And now batt voltage rises to 20.50 after it seemed stubbornly stuck at 20.48v for a while.

So I think I've confirmed charging current can be increased by 50% to 3a, but it appears a simple parallel or replacement current sensing resistor might not be the best answer. Perhaps a mod to whatever resistors set the sense current voltage to 0.18v.

 

[Anonymous]

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