New charger but..

Eastwood

100 kW
Joined
Jan 13, 2021
Messages
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So I got a new adjustable charger 2 - 12 amps. It charged the battery just fine but its stoping short of a full charge. Tested with my multimeter to confirm.

I’ve charged two separate times now, the first time being at 3.5 A and then the second time I tried at 6 A to see if that would help but it still stopping short :?
The green light comes on at 82.5.
How can I correct this :?:

The battery is still fairly new and each cell still charges to 4.2 V so I know it’s not the battery. My other charger stops at 84V
 

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Does the charger have a switch on the back to allow you to change from variable current to variable voltage it looks similar to the one I just purchased and mine has a red switch on the back left above the fan to change this. If your charger has this switch you may have to set the voltage higher
 
Have you left it on the charger to see if the voltage floats higher?

If it doesn't, there's probably a trim pot inside the charger that you can use to adjust the open circuit voltage. I've done this to turn down cheap 48V chargers so they don't go all the way to 54.6V.
 
Haggis_Basher said:
Does the charger have a switch on the back to allow you to change from variable current to variable voltage it looks similar to the one I just purchased and mine has a red switch on the back left above the fan to change this. If your charger has this switch you may have to set the voltage higher

This one has a turn dial for the current and on the back it has two switches, one switch turns on the controller, the second switch just changes the display from battery voltage Display to output current. So basically this charger has a set voltage but the amps can be adjusted.
 
Chalo said:
Have you left it on the charger to see if the voltage floats higher?

If it doesn't, there's probably a trim pot inside the charger that you can use to adjust the open circuit voltage. I've done this to turn down cheap 48V chargers so they don't go all the way to 54.6V.

Yeah I left it on the charger twice for a long time and it just stayed at 82.5V

Yes I think you’re right about adjusting the pot as Ive been reading about this. Here’s the pictures of the inside if you can see if it’s adjustable? When ordering you tell the seller what voltage to be set so I know it’s adjustable somehow.
https://a.aliexpress.com/_mryR6ER
 

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In the second picture the little blue box with adjustable screw I belive thays what your looking for to adjust the voltage
 
In the chargers I've adjusted, the trim pot looked like this:

4mhz-crystal-500x500.jpg
 
81 - 83V termination is good for longevity, lower end better, really not sacrificing any significant capacity
 
john61ct said:
81 - 83V termination is good for longevity, lower end better, really not sacrificing any significant capacity

Agreed. But if you go that way, you might never get the balancing function of a cheap BMS to engage. No big deal, but it means having to inspect the pack every so often.

4.05V/cell is what I go for. I can always charge to 4.2V if I anticipate a big day.
 
Yes routine charging usage profile may need to be different from various routine / scheduled maintenance / monitoring / testing procedures like cap testing and balancing.

But best to not use non-adjustable balancing gear that requires a departure from your desired charge routines
 
john61ct said:
81 - 83V termination is good for longevity, lower end better, really not sacrificing any significant capacity

But… when I’m at 84V I hit 6,700KW :lol:
I’m always trying to squeeze the most power out of my bike. I probably would like 150 amp controller a lot more but not on this frame. I’m maxed out on my Schwinn lol
Also in my situation I’m looking for maximum range. At the end of my rides I’m normally near 20% so I actually need the full charge. Well it would be better if I had more capacity. My current battery is 20S 6P.

I probably will build my next pack but finding a decent cheap spot welder has been holding me back. I’ve had this pack since early spring and I’m hoping to squeeze at least two years, well I hope so considering with all these 100% charges lol 😅
Some days I charge to 80% if my ride is short but normally I’m going over 30+ miles with a lot of stop and go, urban riding mainly.
 
Chalo said:
In the chargers I've adjusted, the trim pot looked like this:

4mhz-crystal-500x500.jpg

Yep mines the same model number too
 

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I seem to to have the same issue with a new ST Charger I just got with a new battery. It has a selectable charge level 90% or 100% and whichever one I use the charge comes up a bit short... maybe 0.75v... of the selected level. I also have a Grin Satiator that works perfectly to 58.8v or 57.6V (85%). Looks like I need to open the ST and tweak the pot. Good thread, guys.
 
Or not... this charger case is held together with weird little tamper resistant screws with a triangle head socket. And even if I were to go find that tool or drill them out the charger has no output unless connected to a battery which would make adjustment difficult. I'll probably just leave it as is. It's just a backup/travel charger and charges plenty high enough except for the longest rides.

raylo32 said:
I seem to to have the same issue with a new ST Charger I just got with a new battery. It has a selectable charge level 90% or 100% and whichever one I use the charge comes up a bit short... maybe 0.75v... of the selected level. I also have a Grin Satiator that works perfectly to 58.8v or 57.6V (85%). Looks like I need to open the ST and tweak the pot. Good thread, guys.
 
raylo32 said:
Or not... this charger case is held together with weird little tamper resistant screws with a triangle head socket. And even if I were to go find that tool or drill them out the charger has no output unless connected to a battery which would make adjustment difficult. I'll probably just leave it as is. It's just a backup/travel charger and charges plenty high enough except for the longest rides.


I seem to to have the same issue with a new ST Charger I just got with a new battery. It has a selectable charge level 90% or 100% and whichever one I use the charge comes up a bit short... maybe 0.75v... of the selected level. I also have a Grin Satiator that works perfectly to 58.8v or 57.6V (85%). Looks like I need to open the ST and tweak the pot. Good thread, guys.

Well when opening these chargers we should be extremely careful that the capacitors are empty before touching anything. So when I did my adjusting it was unplugged and I checked with a multimeter on the discharge plug to make sure all the voltage was drained. That’s why they put those tamper screws on there.

The capacitors in this charger drain pretty much instantly when I unplug it but my other charger keeps voltage for a couple of minutes so definitely check before you open it.
To increase the voltage turn clockwise but there’s a point where you reach the limit and it actually lowers it if you turn it too far
 
I know all about being careful with capacitors... but good reminder for those reading along. And I am not planning to open it since it doesn't provide output unless connected to a battery and charging it... so no way to easily check the voltage as it is adjusted. Maybe from some internal solder connections but having the battery connected just creates more ways for this to go wrong.

Eastwood said:
Well when opening these chargers we should be extremely careful that the capacitors are empty before touching anything. So when I did my adjusting it was unplugged and I checked with a multimeter on the discharge plug to make sure all the voltage was drained. That’s why they put those tamper screws on there.

The capacitors in this charger drain pretty much instantly when I unplug it but my other charger keeps voltage for a couple of minutes so definitely check before you open it.
To increase the voltage turn clockwise but there’s a point where you reach the limit and it actually lowers it if you turn it too far
 
raylo32 said:
I know all about being careful with capacitors... but good reminder for those reading along. And I am not planning to open it since it doesn't provide output unless connected to a battery and charging it... so no way to easily check the voltage as it is adjusted. Maybe from some internal solder connections but having the battery connected just creates more ways for this to go wrong.

If the charger just needs to see a load to turn on, then maybe hooking up something like a light bulb or other load will do it.
 
Well, if you are afraid to open a charger, maybe you should charge with a variable unit, like a lab PSU. Then you will have a view of power and voltage, with the control knobs to set them.

Adding a volt/Amp meter to a charger is a great improvement, cheap and easy to do. I love to see my battery voltage raising like a fuel gage. :twisted
 
MadRhino said:
Adding a volt/Amp meter to a charger is a great improvement, cheap and easy to do. I love to see my battery voltage raising like a fuel gage. :twisted

Yeah definitely good to add a volt/amp meter. That was another selling point why I bought this particular charger is because it has a meter built-in. But I still had to verify it with my voltmeter because it doesn’t go past the decimal with the voltage it just runs up or down.
 
raylo32 said:
I know all about being careful with capacitors... but good reminder for those reading along. And I am not planning to open it since it doesn't provide output unless connected to a battery and charging it... so no way to easily check the voltage as it is adjusted. Maybe from some internal solder connections but having the battery connected just creates more ways for this to go wrong.

Well when I adjusted the pot the charger is off and then before powering on I would put the cover back on and power ON, then manually test through the discharge port to get the exact voltage. I had to do this about 15 times to get it right :lol:
 
999zip999 said:
I make my screwdriver out of wood like a piece of chopsticks .
By the way would you guys purchase need chargers

I used a razor blade wrapped in electrical tape :lol: :lol:
But obviously there was no power as it was turned off and the capacitors were drained. I couldn’t find my little flat head screwdriver so I improvised
 
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