≤2000w 96V charger ~$5

DrkAngel

DrkAngel

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Dec 15, 2010
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Upstate-Western-Southern Tier NY. USA
WARNING! - DANGER!

There seems to be a cadre of ES member who feel most eBikers are totally ignorant of electricity and its dangers.
Unless you understand electricity, its theory and dangers ... do not read this thread!

Warning.jpg

Ultimate lightweight charger! ... ?
Experimental!! ... hypothetical!

120V AC power outlet, power cord and a bridge rectifier will output "slightly rough*", up to 20A of 108V DC.
(108V DC output based on 120V APC brand UPS protected-regulated 120V)
This is optimal for charging 26s (96.2V) LiCo (4.15V per cell) or 30s (96V) LiFe (3.60V per cell).

120V AC >>> 108V DC observed through multiple sizes and types of bridge rectifiers , (1A - 30A.)
But some alternate samples might vary, test to confirm!

15A AC outlet provides ≤1500w charger at ~≥90% efficiency.
20A AC outlet provides ≤2000w charger at ~≥90% efficiency.

Requires AC power cord and ≥20A bridge rectifier (Available for ≥$2)
Current regulation regulated by breaker, batteries charge C capacity, BMS or other?
Gauge and length of AC wire could "trim" current?

All charge voltages are based on 120V.
115 or 110V might necessitate alternate cell count. eg. s26-29 AC rectified charger + 1s-4s charger

30A bridge rectifier


* Do not add capacitor to smooth DC current!
Might produce an initial, damaging, surge of ~170V !!!
I've been building DC led lighting using rectified AC >>> DC through LEDs in series.

WARNING! in case you didn't know Electricity is dangerous! ... to placate the fear mongers ...

See also - 500w bulk charger
MeanWell S-150-(12-24) + any generic S-350-48 MeanWell clone
 

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Hi there

It's been a wild i thinking about this simple solution but , never have the guts to try it out .

Sure , If you put a diode bridge rectifier ( as picture ) on a 120VAC circuit you gona have a " rough " DC voltage at +/- 70% off the source so Around 90VDC

But my main questioning is the power surge of the AC circuit . Without anything in-front it will go crazy and blow the breaker or else every time .

Maybe , like you said , with a ( reactance ) coil , but i don't think it will work .

I guess the best it could do its to " dephase " the efficient-currant so maybe ???

I'm really curious about it so i probably gona blow my self up with this .

Why we can't find a electronician when we need one . Dam !
 
If only it were this simple.

It will blow a fuse immediately - the battery will present basically as a dead short, and the diodes will most likely explode (or at least the bridge rectifier will crack the epoxy).

This is why people use a series capacitor - its reactance @ frequency is basically a resistor that limits the current.
 
WARNING! in case you didn't know Electricity is dangerous! ... to placate the fear mongers ...

108V into empty battery at 96.2v = an 11.8V pressure differential.

My typical (low C LiPo) 25.9V 26Ah pack displays a .8V rise at 5A charging current.
.8V ÷ 7s x 26s = 2.97V @ 96.2v from 5A current

11.8V ÷ 2.97V = 3.97

3.97 x 5A = 19.86A

I appears that a 96.2V 26Ah (2.5kWh) pack built from my low C rate cells would self regulate at slightly below 20A charge current.

A smaller, better C charge rate, LiPo pack would regulate similarly.
LiFe, with its high voltage tolerance, might allow a much larger latitude?

Also, a partially discharged smaller battery could use same method.
Also, also, a 50' 16ga extension cord would regulate current greatly, allowing use with much smaller battery. (or from 15A circuit?)

So, without active current regulation any 96V battery could use this method if:
Its size accepts less than 20A from an 11.8V charge pressure differential
and 20A does not exceed its maximum charge rate.

Larger Packs?
Say a LiFe 4kWh pack might accept 40A
Splitting into 2 banks and
charging 1 bank until drain is less than 10A then
charging 2nd bank similarly then
recombining and continuing charge

Using this method larger packs could be charged.

Also to consider!
Some BMS might provide active charge current regulation ...

WARNING! in case you didn't know Electricity is dangerous! ... to placate the fear mongers ...
 
Advice from another electronician, it seems that it can be done.

"you will need a 10A bridge recitifier, that means that you can safely use it in a 20A circuit (10A per side - it works! doubt me, look at Astron 12/35 power supply schematics)

I would use a lm317 as a regulator, at least 6 2N3055 pass transitors on a heat sink."
 
That would be a bloody big heatsink - What you are describing is a constant current regulator.

11.8V @ 10A = 110W to dissipate.

There are high voltage regulators that are better suited to this than an LM317 too - especially if you want to set it up CV as well.
 
Man I hope this is tongue in cheek :) ... kinda like the "wow, I found a great way to charge my iPhone in the microwave in only 1 min!" and then you see the people who tried it ...

Speaking first hand as someone who put a handheld electronic device in a a microwave for fun (knowing exactly what would happen) .... I recommend doing that outdoors if you really want to :). That smell ... OMG does it not go away quickly.
 
WARNING! in case you didn't know Electricity is dangerous! ... to placate the fear mongers ...

Testing methodology - cheapest-safest
Will continually update with better methods - safeties - progress - results etc

Build "device"
Attach AC power cord to bridge rectifier ... 5-10-20-30A whatever.
Attach jumper wires to bridge rectifier.
Jumper with in line Volt - amp meter and ≤5A fuse.

DANGER - 108V DC is as, or more, hazardous as 120V AC!

Measure DC voltage, should be near 108V DC, but varies with local power grid.
(108V should charge 26s LiCo to 4.15V each.)
Unplug

Build 26s LiCo battery pack.
26, tested good, used laptop cells as cheapest.
Charge 26s battery to 1V below rectified eg. ~107V if Bridge rectifier measures 108V.
(98V DC from 110V AC requires 97V charged pack 3.73V per cell or 25s@3.88V or 24s@4.04V etc.)

Attach jumpers to 26s pack.

Step back and plug into 120V AC.
If 5A fuse does not blow.
Observe Volt and amp input.
If less than ~2A charge, observe and note voltage rise and amp reduction.
Then disconnect, drain pack to an additional -1 volt and repeat test.
(100w 120V incandescent light bulb will supply ~1amp discharge)
Do not exceed more than a 1-2V differential with small test pack unless charge C rate of battery pack will accept.
If successful this should prove the concept to be possible with larger pack, lower discharged voltage and up to 20A.

Keep Amp input below 1C for laptop cells.
I will be testing with less than great, but functionally "OK" 26s2p Sanyo 2600mAh cells.
5A fuse will emergency limit to <1C charge rate on 2p = 5200mAh.

Should have prototype ready in the next day or so ...

Anyone really anxious, can't wait?
Go ahead ... give it a try.
But make sure to post up your results!

Just gotta find my 120V capable volt amp meter ...

WARNING! in case you didn't know Electricity is dangerous! ... to placate the fear mongers ...
 
This has been done and throughly documented and even named 'bad-boy' charger or something.

If you use a continuous duty motor start capacitor in series with the AC input, you get to choose the current by the size of the cap. I also used a 250w 24V incandescent bulb in series with the output. If you buy those parts surplus online, it's only a few bucks.

Why is this circuit not a good idea? Because it leaves any pack connected to it at something like ~156vdc if you forget to unplug. Most batteries transform into fire and plasma prior to reaching ~156vdc.

However, you can make a 1-2lbs > 1500w charge setup for opportunity charging by an attentive user. An inattentive user creates a charred spot where they once had a battery.
 
WARNING! in case you didn't know Electricity is dangerous! ... to placate the fear mongers ...

Please read before commenting!
Proposed method uses no capacitor!

WARNING! in case you didn't know Electricity is dangerous! ... to placate the fear mongers ...
 
WARNING! in case you didn't know Electricity is dangerous! ... to placate the fear mongers ...

Based on 1 single component!
Can't get any simpler ...
120V AC into a bridge rectifier = ~108V "rough" DC.

Do not add capacitor!
Adding capacitor will balloon "finish" DC voltage towards ~170V DC.

If you require "drawing up a circuit diagram" to understand a single component device, well ... dum'un
then I'm pretty sure you would also not understand the circuit diagram!

Please try reading! ... before commenting!!

WARNING! in case you didn't know Electricity is dangerous! ... to placate the fear mongers ...
 
The cap is so you control input current. Your suggested single component method will only trip a breaker. Try it on video for us if you don't believe me. :)

The output has no need for a cap, the battery has a massive self capacitance.
 
Gregory said:
Hi, curious to know if there was any follow through on this? Results good or bad?
Click to expand...
I am curious too, a cheap lightweight charger to carry on the bike might be useful sometimes. Luke said it can be done, that is enough for me to want to give it a try.

liveforphysics said:
This has been done and throughly documented and even named 'bad-boy' charger or something.

If you use a continuous duty motor start capacitor in series with the AC input, you get to choose the current by the size of the cap. I also used a 250w 24V incandescent bulb in series with the output. If you buy those parts surplus online, it's only a few bucks.

Why is this circuit not a good idea? Because it leaves any pack connected to it at something like ~156vdc if you forget to unplug. Most batteries transform into fire and plasma prior to reaching ~156vdc.

However, you can make a 1-2lbs > 1500w charge setup for opportunity charging by an attentive user. An inattentive user creates a charred spot where they once had a battery.
Click to expand...

I am not the distracted type, monitor temp and V continuously while charging, and have charged RC lipo very high many times without a single issue. Most of all I use old lipos sometimes, those that you don't bother burning since they have done twice their expected life already. That kind of small charger that can be carried on the bike would be an interesting addition to my inventory. Yet I am not an electronician and would prefer detailed instructions to build one.
 
WARNING! in case you didn't know Electricity is dangerous! ... to placate the fear mongers ...

84V 10A regulated charger < $5.
120V AC
≥10A bridge rectifier
12V 10A cup mug water heater

Running bridge rectified AC though 12V water heater in series with 84V battery will charge at 10A, hopefully not blowing fuse to the pop machine ...
Might work fairly well with dual 44.4V packs charged in series.
Charged voltage should regulate near 96V ... ? but ...
Continuous monitoring recommended, especially during initial testing!

You will need a cup of water and continuous refills or some mud puddle to keep water heater from melting down.

Dual heaters in series with 72-74V battery?
2 - 36-37V packs switched to in series for charging ... ?

Sorry - haven't, yet, rigged up a 26s testbed for 96V $5 charger test.
Been too busy with "real work", furnace repair etc.
1965 furnace and 30's and 40's at night.

WARNING! in case you didn't know Electricity is dangerous! ... to placate the fear mongers ...
 
DrkAngel said:
You will need a cup of water and continuous refills or some mud puddle to keep water heater from melting down.
Click to expand...

Well, I *have* been looking for a way to add a steam whistle instead of a horn. Too bad it would only work while charging.

That said, I'm not sure the place to cut corners is the one place on such a bicycle that might explode. It's a bit of a Pinto solution -- seems a good idea right up until you haven't got a vehicle anymore ...
 
WARNING! in case you didn't know Electricity is dangerous! ... to placate the fear mongers ...

DrkAngel said:
84V 10A regulated charger < $5.
120V AC
≥10A bridge rectifier
12V 10A cup mug water heater

Running bridge rectified AC though 12V water heater in series with 84V battery will charge at 10A, hopefully not blowing fuse to the pop machine ...
Might work fairly well with dual 44.4V packs charged in series.
Charged voltage should regulate near 96V ... ? but ...
Continuous monitoring recommended, especially during initial testing!

You will need a cup of water and continuous refills or some mud puddle to keep water heater from melting down.

Dual heaters in series with 72-74V battery?
2 - 36-37V packs switched to in series for charging ... ?

Sorry - haven't, yet, rigged up a 26s testbed for 96V $5 charger test.
Been too busy with "real work", furnace repair etc.
1965 furnace and 30's and 40's at night.
Click to expand...
12V 150w ceramic heater for 12.5A regulation - <$15

WARNING! in case you didn't know Electricity is dangerous! ... to placate the fear mongers ...
 
good idea! i just ordered the $3 heater. can't have too many power resistors.
could hook 2 in parallel for a 20a charge :shock:
 
WARNING! in case you didn't know Electricity is dangerous! ... to placate the fear mongers ...

Matt Gruber said:
good idea! i just ordered the $3 heater. can't have too many power resistors.
could hook 2 in parallel for a 20a charge :shock:
Click to expand...
Be aware ...
12V 10A heater will run at higher volts-amps if run in series with <84V battery pack, (lower V-A with higher voltage) .
But will supply regulation till failure, then circuit will open.

WARNING! in case you didn't know Electricity is dangerous! ... to placate the fear mongers ...
 
i'm thinking 8, 18v packs in series might not need a resistor, but will use $3 heater as a precaution at first. can't be too safe! want to limit amps to about 2-4. might switch it IN/OUT. might not need water under 2 amps. it is an experiment. i expect 1.2-1.7 amps no resistor. this would be for an emergency charge someday while waiting for a new $18 turnegy charger. 2a 36v charges to 42.0v. Now im using the charger that came with my bike. 100-240v input, so it is regulated somewhat and has short protection, and ZERO cost as it came with my bike. can't beat zero cost! i have a 60 minute timer for safety, and i use it 100% of the time with a LED DVM on the handlebar and a DVM to check individual cells.
 
WARNING! in case you didn't know Electricity is dangerous! ... to placate the fear mongers ...

Just ran some readings with my Fluke multi-meter.
AC = 119.8V
DC = 110V through 30A bridge rectifier
DC = 164V through bridge rectifier w/75µ 150V Capacitor on DC

So - AC "wave" peaks at 164V DC through the circuit. (from my 120V AC and the 30A bridge rectifier I used)

WARNING! in case you didn't know Electricity is dangerous! ... to placate the fear mongers ...
 
DrkAngel said:
J

So - AC "wave" peaks at 164V DC through the circuit. (from 120V)
Click to expand...
actually, it varies between 150-175V, depending on... stuff.
 
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