voltage of a 36V battery charger

gaetanb

New Member
hello,

i have a 36v bike.

The charger says 42 V.... how many volts must the charger give (when not connected to the battery) ?

it used to be 40.9 volt but i changed it to 42V... or must it be a little higher?

thx 4 reply

Gaetan
 
A 36 volt battery is a 10 cell battery. That means at full charge, you should be at 42 volts.
 
lunacycle is suggesting full charge of 42 v and cutoff point of 32 v. So 90% charge point would be 41 v. You only charge to full voltage when you first receive the new battery, and later once a quarter. Running daily 90% to 10% or even less, 85% to 15%, extends the life of the battery people say.
 
$20 chargers often stop higher or lower than nominal. It should hold at maximum voltage for some minutes while full charge stacks are disconnected by the BMS and lagging stacks receive more charge, but I don't see that happening here with mine. My new luna battery also sags about 1/3 volt from the cutoff in the next few minutes, so you have to be there watching a meter while it happens to see what is going on. My "54.6" v charger quits at 54.4, then the battery sags further to about 54.0.
 
It's normal for lipos to drop voltage after the charging load is taking off. 4.20 can drop to 4.19 sometimes. Were talkin 1/100th of a volt here. If you guys have any question about lipos, I would be happy to answer them without getting to technical. I own a lipo battery business.
 
Hi, i have a dumb follow on question. My dad has an ebike with a KT36ZW 500 Watt controller on it that he is having trouble with. Basically he's plugged everything together (he doesn't use PAS), so he has battery, front wheel motor, display, and throttle connected. Turns it on, display comes on but there's no motor response. I'm not sure what to make of it. The display is a KT-LCD1 that seems to have a really limited programming menu and the paperwork that comes with it is well, kinda basic. Any thoughts? or is it more likely the display not being set up right? The display seems to be defaulting to PAS as it shows up as "assist level". We had the bike working with a Brainpower 1500W controller. We were able to get motor movement by connecting the learn wires on that controller (but that's not an option on this controller) also i have checked the hall sensors and they are pulsing as they should.
 
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Possibilities.
1. Throttle is not connected. Is the signal wire going from about .5 volt to 4.2 V when you turn it? Will the motor spin in "walk mode". This is done by holding the "down" button on the LCD1 until it starts spinning. It will stop when button is released.

2. Motor phases and Halls are incorrect. Did you match colors? The KT people use a standard green/blue/yellow. and I've not owned a motor that didn't work when if the colors matched, but there are some oddball shops that use their own schemes. That's the nice thing about Brainpower. You can use any connection, and "learn mode" figures it out.

If you're getting the throttle signal to vary, then the controller is powered up. Then it's a motor connection error, and that must be a PITA to figure out.

Check thise endless sphere post. There's a flow chart to methodically figure it out. You connect the wires and flip them around methodically, using the throttle. I think they tell you to use very little throttle, because some of the wrong wire combos can burn up the controller if you give it a lot of power.

 
Hi,

Thank you very much for the reply. I figured it out, the comm wires to the display were not correct. I reterminated and everything worked. I will take a look at that thread and get the flow chart for sure.
 
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