Basics of a Lithium-ion Battery Charger

[lenny]

 

[Biker44]

A video almost impossible to follow.
Whereas this video -

- makes the same thing look ridiculously easy.
At least in theory - in practise, the once highly regarded GOPHERT CPS-3205II (Portable Adjustable AC to DC Variable Switching Power Supply AC DC Converter 110V/220V switchable Great for Provide Constant Voltage or Current Supply) has vanished from reputable suppliers (Amazon and so forth) - "Currently unavailable. We don't know when or if this item will be back in stock."
All is not lost - there are many other suppliers of the same thing. However, there's a hitch. This power-supply ("charger") does 0volts to 30 volts and a 36volt lithium battery probably needs up to 50volts.
So, suppose I wanted to manually charge such a ("Silver Fish style" in an ali Extruded tube) battery, how would I do it?

 

[saneagle]

So, suppose I wanted to manually charge such a ("Silver Fish style" in an ali Extruded tube) battery, how would I do it?

Use the 60v version!

 

[Biker44]

Use the 60v version!

Ha! Thankyou! I've found it! Just £55 from a box-shifter-brings it to my door! Why are no other Bikers beating a path to this mans door?
There's even a 120 volt version for only five squid more.

 

[saneagle]

Ha! Thankyou! I've found it! Just £55 from a box-shifter-brings it to my door! Why are no other Bikers beating a path to this mans door?
There's even a 120 volt version for only five squid more.View attachment 60683

I recently bought this one (60v 5A), which was £61 all said and done. They added pre-paid tax at the time of order. Note that the max power is the same for the different versions, so if you get more maximum volts, you get less maximum current:

KUAIQU DC Laboratory Power Supply 30V 60V 120V Adjustable Voltage Regulator Bench Switching Power Supply Preset Current ON/OFF - AliExpress 13

Smarter Shopping, Better Living! Aliexpress.com

vi.aliexpress.com

 

[Biker44]

I recently bought this one (60v 5A), which was £61 all said and done. They added pre-paid tax at the time of order. Note that the max power is the same for the different versions, so if you get more maximum volts, you get less maximum current:

KUAIQU DC Laboratory Power Supply 30V 60V 120V Adjustable Voltage Regulator Bench Switching Power Supply Preset Current ON/OFF - AliExpress 13

Smarter Shopping, Better Living! Aliexpress.com

vi.aliexpress.com

Thanks for the tip - are we to understand that the picture above (from our friendly deliver-to-your-door box-shifter) is pushing the bounds of crediblity? That would be sad, they're usually quite good.
However, the safe charging rate of our e-cycle batteries is probably only around 2 amps (that's the limit of what our chargers currently deliver).
Someone tried to sell me a three amp charger (at £100!) claiming "it would be faster" - without any kind of explanation, I'm afraid I politely declined.
The new power supply is still easily capable of blowing up my batteries (in the concrete lined passage-way where I plan to use it) - I will have to be super careful.
But I will (briefly) double check what you've said about maximum current at maximum voltage before sanity returns and report back.

 

[saneagle]

Thanks for the tip - are we to understand that the picture above (from our friendly deliver-to-your-door box-shifter) is pushing the bounds of crediblity? That would be sad, they're usually quite good.
However, the safe charging rate of our e-cycle batteries is probably only around 2 amps (that's the limit of what our chargers currently deliver).
Someone tried to sell me a three amp charger (at £100!) claiming "it would be faster" - without any kind of explanation, I'm afraid I politely declined.
The new power supply is still easily capable of blowing up my batteries (in the concrete lined passage-way where I plan to use it) - I will have to be super careful.
But I will (briefly) double check what you've said about maximum current at maximum voltage before sanity returns and report back.

You don't have to check anything. The power supply itself will only allow the maximum current shown in the listing, which is 10A for the 30v one, 5A for the 60v one and 3A for the 120v one.

 

[thelarkbox]

Sure you know but with a Bench PSU Always start with power turned down and tune up the voltage/current Never Down..

 

[saneagle]

Sure you know but with a Bench PSU Always start with power turned down and tune up the voltage/current Never Down..

It's better to set it correctly before switching the power on.

 

[Biker44]

Sure you know but with a Bench PSU Always start with power turned down and tune up the voltage/current Never Down..

I'm a neophyte. I'm depending on you guys to bring me up to speed and leading me to the sun-lit highlands.

 

[saneagle]

I'm a neophyte. I'm depending on you guys to bring me up to speed and leading me to the sun-lit highlands.

You set the current to what you want with the coarse then fine adjustment, then you set the voltage the same way. When you're happy with that, you connect the device you want powered or charged, then you press the green button to activate the power.

 

[Biker44]

Sure you know but with a Bench PSU Always start with power turned down and tune up the voltage/current Never Down..

Whoopee - XLR connector arrived - did I see that two of the three pins can/should be connected together?
If that's right, I can use my nice long length of 2-core rather than cutting up a decent 3-core extension lead.

 

[saneagle]

Whoopee - XLR connector arrived - did I see that two of the three pins can/should be connected together?
If that's right, I can use my nice long length of 2-core rather than cutting up a decent 3-core extension lead.

No pins should be connected together. Only the outer pins are used.

 

[thelarkbox]

imho Even if 2x pins are ajoined on the receiving socket, dont mirror that on the input, it will limit the safe use of the charger to just the one single battery..

**Double and triple check polarity

XLR connectors are fairly easy to solder but the larger sized male pins can be a bit of a heatsink and soak up enough heat to melt the supporting plastic they are mounted in. If no spare female socket is available to use as a 'holder/steady' (the battery is not a good idea imho) a good dollop of blu-tak can be shoved in place around the pins to add further support for the hot melty pins. And give the socket a good few minutes to cool before you do a big tug test on the wires.

 

[saneagle]

XLR connectors are fairly easy to solder but the larger sized male pins can be a bit of a heatsink and soak up enough heat to melt the supporting plastic they are mounted in. .

The large pin is the one that's not used.

 

[Biker44]

No pins should be connected together. Only the outer pins are used.

Ah - thankyou. I can go ahead wiring it up with the tidy length of two-core cable I have. I wasn't sure what sellers-information I'd seen provided on a flea-bay (?) link.

 

[Biker44]

imho Even if 2x pins are ajoined on the receiving socket, dont mirror that on the input, it will limit the safe use of the charger to just the one single battery..

**Double and triple check polarity

XLR connectors are fairly easy to solder but the larger sized male pins can be a bit of a heatsink and soak up enough heat to melt the supporting plastic they are mounted in. If no spare female socket is available to use as a 'holder/steady' (the battery is not a good idea imho) a good dollop of blu-tak can be shoved in place around the pins to add further support for the hot melty pins. And give the socket a good few minutes to cool before you do a big tug test on the wires.

Several useful tips from you there, thankyou.
The decent length of two core cable I have (from a mains vacuum cleaner?) could be good for up to 2000 watts, roughly 8 amps at mains voltage.
It should handle 2 amps at 45 volts (nominal 36volt battery) with no trouble.
I note what you say about checking polarity! The 50 volt power supply comes with its own "multi-meter" style male connectors ending in pretty tiny insulated crocodile clips. Instead of which, I will use ring terminals on the supply that came with a lead with an inline fuse. I think its about 10 amp protection.