Why is my charger not charging?

[HighNear90]

I bought this : http://cgi.ebay.com/ebaymotors/48V-Volt-battery-Charger-Electric-Scooter-ATV-BC05-/250451914369?pt=Other_Vehicle_Parts&hash=item3a5018ee81 after my original charger stopped working (no lights, no voltage output). This new one charged fine for a few weeks of daily use and now the green light will come on, but the red "charging" light will not. At first I thought it was my battery (which is a 48v LiFePo4) that is currently reading 44v. But I got a 48v SLA and it STILL won't charge. I hooked up the wattmeter inline and here's the strange thing..........The charger is outputting 56v, but only 0.05 amps! Is it broke? what am i missing?

PLEASE HELP!

 

[dogman dan]

The most common reason for that is a bad connection on the dc output side. Full battery, and not connected cause the same green light. Usually it's a loose wire in the plug, either on the battery or the charger itself.

 

[Lessss]

Or you have really crappy electrical grid and it has popped the fuse inside both chargers. Are you using a surge suppressor or just plugging into any ol outlet?

Open the case locate the fuse and see if it is popped.

 

[HighNear90]

The most common reason for that is a bad connection on the dc output side. Full battery, and not connected cause the same green light. Usually it's a loose wire in the plug, either on the battery or the charger itself.

Yes, but it's putting out 56v DC and no amps

 

[HighNear90]

Or you have really crappy electrical grid and it has popped the fuse inside both chargers. Are you using a surge suppressor or just plugging into any ol outlet?

Open the case locate the fuse and see if it is popped.

I looked in the "Old dead" charger and there's only one fuse and got 124v on the output side of it, so i'm assuming there's another component that's dead. I think I'll toss that one in the trash. But the newer eBay one is putting out 56v but no amps. I'll open that one in a few minutes and see if there are any fuses in there.

Thanks for all the advise,

Leo

 

[Lessss]

If your charger is giving you voltage then look at the battery itself. Make sure the battery fuse is not blown, make sure the wires are firmly attached to the battery terminals. Most chargers don't pump amps until they detect the battery voltage.

 

[mwkeefer]

I assume your attempting to charge through the provided charging leads? There may be a FET on that charger port or even a fuse (inside the battery not the charger) which could be preventing the current from flowing into the pack. Since I assume you tested both the charger port (on the battery) and also the discharge terminals for presence of pack voltage and it was there on both...

Normally I would say try connecting the charger clips to the discharge leads and seeing if current flows but many lifepo4 BMS won't accept back current.

-Mike

 

[dogman dan]

The bad connection is then likely to be on the battery side of the plug, or a broken connection in the wire itself, or something.

It sounds to me like the charger is normal, it's just not getting connected to the battery. But it could be the charger itself. I just had the bad connection problem enough times myself to know it's the likely culprit.

 

[HighNear90]

Thank you all again for the advice. Here's what I did this morning:

I checked the continuity on the 2 fuses in the charger and they were fine. So I decided to try to charge through the discharge port (just like mwkeefer suggested) and the chrager started charging!!!!!! I let it run for about 20 sec and then tried the charging port and it started charging again!!!! Woo Hoo. This is an old 48v LiFePo4 pack with an old v1 SignaLab BMS. Could the BMS stop the charging if the pack voltage is too low? Anyway, I think maybe the charger has some smarts in it too since I tried to hook it up the the SLA pack and it wouldn't charge. FYI, the resting voltage of the SLA pack was around 38v.

Thanks Again!!!!!

 

[mwkeefer]

The pack had collectively dropped down below the "safe" voltage - I would have pulled the end cap or made sure to hit b-as in direct to pack.

That few seconds of charging got the whole back above basically a secondary cutout where even charge is prevented - the quick charge enabled the bms power up and that enabled the charge switching or regulation fet

Glad to be of service!

Mike