Connections for battery broke, please help with replacements

[tmb41]

Hello,

I purchased a LifePO4 battery on eBay which came with a charger and connectors. See pictures:

The female end where the charger connects to used to have a red wire going to it but it has broken off. Can anyone help me with where I can buy a replacement? The seller has not contacted me back. Thank you.

 

[arkmundi]

Go down to your local Radio Shack or automotive supplier and get some connectors rated for the amperage draw of your controller/motor (something like 20 amps or 40 amps or some such). Get both a male and female. I use Anderson Powerpoles, which can be had many places, including Amazon. Cut the existing connectors off and replace - only a POS+ and -NEG set off leads. Crimp or solder. Done.

 

[skeetab5780]

That looks like it is just the charging port, so it shouldn't need to be rated for more than 5-10amps really. Those RCA jacks can hardly handle 2-3amps, they are just not meant for this application really. 30a andersons are fairly common and are small enough to use, but it is all personal preference.

 

[tmb41]

The charger's wires are Blue and Brown and appears to be manufactured in China. Any idea which is power and which is ground?

Thanks

 

[docnjoj]

The charger's wires are Blue and Brown and appears to be manufactured in China. Any idea which is power and which is ground?

Thanks

Time to check with a meter(VOM). If you don't have one, Harbor Freight sells them for 3 bucks. Don't guess!
otherDoc

 

[tmb41]

Is there a quick non technical way for me to check this.. without blowing myself up? I'd like to use it tomorrow

 

[skeetab5780]

blue is black and brown is red. That is standard color coding.

 

[d8veh]

blue is black and brown is red. That is standard color coding.

Absolutely not. Never go by the colours on Chinese stuff, especially chargers. It's very common to find that brown is ground and blue is positive. The only way to know is with a meter. If you get it wrong, disaster will follow. Get yourself a meter. You shouldn't mess with this stuff without one.

 

[mark5]

Have seen two incidents at E-S so far when red and black wires were not + and - as expected on Chinese stuff. And other incidents where wires were reversed by mistake resulting in damage. Best check the wires with a multimeter first.

 

[dnmun]

just solder the leads back onto the plug and use it again. those plugs are larger than the standard RCA jack and it is hard to find them. the center is always +. never assume polarity of any part based on color. always check with the voltmeter.

 

[tmb41]

So I had been attaching the wires to charge the battery after the wire broke off and successfully charged it twice. I either broke the charger or battery because now the charger thinks the battery is charged when it isn't (Properly connect wires, charger shows Green Light [fully charged] and doesn't charge the battery].

Arg.

 

[dnmun]

not much useful info in that. can you put an ammeter in the charging leads to measure current? how did you damage it? did you short the output leads on the charger or somehow short the battery to the BMS? did you inspect the fuse?

 

[tmb41]

All I know is what I described to you; I dont have any of these electrical meters/devices

 

[dnmun]

can you solder the lead back onto the plug? can you buy a voltmeter and a watt meter so you can measure current? can you post a picture of the inside of the charger so we can look for the fuse if there is no fuse on the output?

 

[tahustvedt]

My charger is brown negative, blue positive. I changed the connector today. Bought from EM3EV.

A multimeter isn't optional when working on electric systems, it's absolutely necessary.

 

[lbz5mc12]

You could always pop the charger open. Then look on the board and find where the blue/brown wires are on the board. One should be marked positive and the other negative, + and - signs. Those crappy RCA charge connections always seem to fail. In other words I had the same problem.

 

[tmb41]

After opening up the charger I dont see any kind of fuse where I could check to see if it's blown or not. Nothing that looks easily replaceable like in a car's fuse box

 

[tmb41]

I'd like to check the battery directly... can anyone help me with which device I need (ohm meter, volt meter..?) and what I need to do exactly to test it.

 

[mark5]

Below is one of a few Youtube videos on how to use a multimeter. Checking DC voltage is at 1:05-2:20 with a mention of checking polarity at 1:50. I think a minus sign at 9 o'clock shows on his meter LCD to indicate reverse polarity if red and black are improperly crossed. You can practice with an AAA, AA, or other small battery at first to see what yours will show. A cheap multimeter from Harbor Freight (example) should be good enough.
[youtube]bF3OyQ3HwfU[/youtube]

 

[tmb41]

But what exactly will I be looking for? Will I see an error if the battery is broken?

 

[mark5]

Why don't you start by going to the store and getting a multimeter, measuring your battery voltage, and then post here what the voltage is.

 

[cal3thousand]

John in CR is up the right tree.

This is a standard RCA plug. Go cut one off of unused RCAs in the box of old pre-HDMI crap you have. (everyone has a box like this at home right? :wink: )

Get a multimeter too. Fixing ebike related parts without a meter is like doing construction without a ruler. You might get something right without one, but it makes things difficult and the results can be interesting.

 

[lbz5mc12]

What I meant is that on the board there should be a negative sign next to one wire and a positive next to the other one where the wires connect to the board. If you do it my way you don't need to measure anything. It just helps you to determine which wire is positive and which is negative.

 

[USAEBIKECO]

Anderson connectors will work just fine. You just need to wire and solder the positive and negative ends.

 

[mark5]

So I had been attaching the wires to charge the battery after the wire broke off and successfully charged it twice. I either broke the charger or battery because now the charger thinks the battery is charged when it isn't (Properly connect wires, charger shows Green Light [fully charged] and doesn't charge the battery].

Arg.

So in your first picture above you show the battery side's female jack with the wire broken clean off. And you wrote there was a red battery wire that connected to the jack. But there was also a black wire that connected to the jack's shell too that you didn't mention, right?

And you're saying you had reattached the red wire (and black wire too, right?) to the jack and successfully charged twice after the jack broke off. How did you reattach the wires to the jack? Just wrap the wire's bare ends around what metal was there? You weren't just attaching only a red wire to the jack, right?

If you were reattaching the wire to the jack by wrapping the bare end around what metal was there you can get an inexpensive butane soldering iron from Harbor Freight or Home Depot to make a more solid connection.