48V Charger

[wiwild]

Hi !

I'm converting my scooter to lithium (1 of my 4 Acid Battery died) and I need a new charger. I already have a 48V lead acid charger, it says on the back : "output 59VDC 1.7A"

Can I mod it to output 58,8V to charge my 14S5P Samsung ICR18650-26f battery ? I have a BMS with 16A charge max and balance function.

Here are some photos :
https://goo.gl/photos/yuiNvDUm9jhGpGxx9
( Behind the condensator it's a PWM Controller : GM3842A, the MOSFET is a SPP20N60C3 and on the back of the PCB its a simple Quad Op Amp lm 324 ) If you need I can draw a schematics.

If its impossible can you tell me which charger to buy for cheap if possible ?

Thanks!

 

[dogman dan]

Yes, you may be able to turn down your charger, but it's still going to trickle charge, which is not ideal for lithium. Some have the adjustment pot near the output wire, others do not.

You could use a lead charger set to undercharge, and not let it charge overnight. This could work as an emergency spare, when something happens to your primary charger that is a proper lithium charger.

So what I mean is, say your lithium charges to 54.6v. You could safely charge your lithium to 53.8v with the lead charger. But it would not be good to have it trickle charge, at 54.6v.

I'd say don't buy a cheap charger for a big investment in lithium. Get a good charger. http://em3ev.com/store/index.php?route=product/product&path=35_37&product_id=120

The three position switch allows you to store the pack nearly full overnight, and then fill up quickly in the am. Better for lifespan, to not fill completely till just about to ride. Lithium is not like lead, that you needed to keep full at all times.

 

[DrkAngel]

Hi !

I'm converting my scooter to lithium (1 of my 4 Acid Battery died) and I need a new charger. I already have a 48V lead acid charger, it says on the back : "output 59VDC 1.7A"

Quoted output on chargers, power supplies etc are rarely if ever accurate. - Exception being quality Lithium chargers.
Also be aware that output voltage usually varies under load.
Multi stage chargers usually have higher voltage under higher output but reduces at lower output ... might even "idle" much higher without battery attached.
Monitor any modified-adjusted "charger" very closely during entire charge period to confirm expected operation!

 

[wiwild]

Hey and thanks for the reply

I have mesured the output voltage without charge its 57,6V, I don't think there is a pot somewhere I think it's based on voltage divider and opamp with fixed value resistor.

My BMS Should cut power when 4,2V per cell and it needs trickle charge to balance the cell properly.

so if I find a way to set the voltage up to 58,8V it's ok?

There isn't some sort of CC CV method is it just CV charging ?

I think I will invest in the charger you just linked I don't want to waste my $300 pack with a bad charger but shipping cost is high to Canada $25 is there other site to buy ?

Thank you.

 

[dogman dan]

I know of no others that have the three voltage switch. That switch can help extend the life of your pack, by not always charging it full and then letting the pack sit fully charge till the next ride.

Lots of cheaper chargers out there, with one voltage, and an adjustable pot though.

 

[DrkAngel]

MeanWell Mega-Mod has fully adjustable Volts and Amps with LED volt and Amp confirmation.
A simple multi-function switch through multiple adjustable pots, instead of a single dial pot, could make 3, or more, programmed voltages a simple flip of the switch.
3 voltages through an on/off/on switch seems simple.
There would be no loss of regulation as might happen between dial connects.
Off position would be for highest resistance-lowest voltage, on positions would have various lesser resistance pots.

Should work nicely with any MeanWell clone = much cheaper!
However ...
Current regulation is likely a differing factor with many clones!

 

[amberwolf]

I know of no others that have the three voltage switch.

Not a switch, but better: Cycle Satiator, where you can setup the profiles anyway you want, and keep several active in it at once to switch between with simple arrow buttons whenever you plug it in.

Leave a default active on for what you use most often.

 

[wiwild]

Yeah cycle satiator would be the best but a bit overpriced for me.

Is there an open source diy design of charger based on mosfet and microcontroller ?

Anyway I think I'll order from em3ev it seems to be the best price/functionnality charger.

Thanks everyone.

 

[999zip999]

Luna cycle in San Francisco has a three setting charger. USA