Noobie doobie do

[wildblueyonder]

Just getting my feet wet here, building my first e-bike! Very exciting, but heck all of questions! So really any advice welcome.

So I've got myself all, or at least the major, parts that I need. 48w rear hub motor w/ controller, throttle, regen. system, 48v30ah LifePO4 battery w/ BMS, charger, and of course the bicycle.

1) I think my charger sucks, that or my multimeter because when I plug it in and tested it it briefly showed 55.2v. The mm is a cheapo thing I got on e-bay - any way to test?
2) Is there any kind of prep I should do with the battery itself? I hear this talk of 'balancing' et. al., what advice on how to break in / care for a new battery? Its a vpower battery I got from China (took 3 1/2 months to arrive, that can't help), it does appear to have fully charged for me.
3) Any preference on adapters to hook the battery to the controller? I was thinking some Andersons but admittedly I've never used them before.
4) Do I want a front and rear derailer? Or should I just stick with a rear to be simpler?

I'm sure I'll have tons more but again, any help at all would be tremendous!

peace
Marcus

 

[John in CR]

Welcome ES and to a whole new experience aboard the most efficient form of transportation available.

Your charger is fine. 48V is the nominal voltage. Go ahead and connect it to the battery to let it fully charge and balance. It may turn on and off for a while, which is a sign of the pack balancing.

 

[wildblueyonder]

So the charger does the balancing, there isn't some other step for me to take? What confuses me is that, as I said, I got a 55.2v reading for a second when I first tested it, but the the multimeter went to '1' and I haven't been able to get any other reading since. Shouldn't it just hold at a steady reading?

Also, when plugging the battery to the charger, do I need to watch it? I've read some posts that imply that overcharging is a concern, but with my charger it has two lights that seem to stay on green and red, even though I left it charging for like 6 hours.

Sorry I do know these questions seem facile but as I said, I'm a noob!

 

[dogman dan]

Leave it on the charger for a few hours, and it sounds like you have done that. Once you have the bike put together and it runs, then go for a few short rides, followed by full recharges of several hours after each ride. Just a couple low depth of discharge cycles helps the new battery get balanced better. By the 4th ride, you should be able to go for as long a ride as you like.

The charger should show red while charging, green when done, but leave it on the charger longer. If it needs any balancing, the bms will handle that, but it will take hours, and the charger light will go red briefly from time to time.

I have never had a problem from leaving the bike on the charger overnight regularly. The bms is supposed to prevent overcharge, and undercharge can lead to problems like getting out of balance.

Re the voltmeter. so many ways to use one wrong, including just not geting good contact at the probes. If you are seeing about 56v when you connect the voltmeter to the battery discharge terminals, you are about where it should be. Some lifepo4 will come off the charger higher, but about 55-56v is the fully charged voltage for 48v lifepo4. 48v is about completely discharged.

Regarding the charger lights. Green only is either charged, or the plug is broken or disconnected from the battery. So what the lights look like when you plug in the charger not connected to the battery, is what "charged" should look like. Sometimes the green light partialy leaks over to the red spot making both look lit. Both may be lit fully when it is charging a battery, then the red light goes out, or just gets dimmer when it's done.

Some of the cheaper chargers can be confusing what the lights mean, but you should see some change when your battery is charging vs when it's done.

 

[wildblueyonder]

Tremendous brotha, I do appreciate it!

 

[bluegoatwoods]

Welcome aboard. I just know you'll like it here and on your bike.

FWIW, I don't mind the newbie questions one single bit. The guys who answered your questions and gave advice have this stuff down cold. (And a tip of the hat to them, by the way)

But some of us others have only a murky understanding of this stuff and it doesn't hurt to review at all.

 

[dnmun]

you have a 48V30Ah Vpower pack? that thing must weigh 100 lbs.

not sure what you have for a voltmeter, but does the battery actually measure 1V or did you just not have it stuck into the battery leads?

there was just another guy on here with a Vpower pack and a blown charger asking for help but refused to help us diagnose his charger problem. they are famous for being broken from the get go. it is an easy fix so when your charger blows, let us know, i have the part.

 

[dogman dan]

Or, if you are like me and should be shot for trying to solder, replacement chargers in 2 amp variety are quite cheap.

30 ah will be pretty heavy, at least 30 pounds. But you shoud have about 40-70 mile range.