What is safe & cheap way to charge my new LiFePO4 battery

[Sacman]

Hello guys,

I'm such a noob with lithium batteries and chargers... can anyone help me with this?
My LiFePO4 battery that I bought on eBay finally arrived from China 2 days ago. Actually it's 3 separate batteries with 3 separate BMSs (so I have options of mounting them on separate locations on the bike to more evenly distribute the weight (see pic).

I really had a terrible time dealing with that vendor (I've made other posts on this forum warning everyone about him). After paying money for the battery, it took over 1 month of sending angry emails and openning a dispute on PayPal to get the vendor to finally send it. Well I got the battery but now the problem is he didn't send me the charger. So I got no way to use or test this battery 'cause I can't charge it.

I've seen the thread that Doctorbass wrote on charging and balancing Li Ion batteries with an AC-DC power supply and DC-DC converters (here's the link to that http://endless-sphere.com/forums/viewtopic.php?f=14&t=4215). Ultimately I would like to build a setup like that but for now I just need to charge this battery safely and properly. So what's the best and quickest way for me to get a proper charger? I got a few ideas, please help me pick the right one:

1) After doing much reading on this forum I come to understand that the BMS on my battery will control the charge that gets to the cells and all that I really need to do is hook up a 48-volt power supply to charge it. Is this right? Can somebody with better knowledge please correct me if I did not understand this right. Well I've looked around quite a bit for 48-volt power supplies and variable power supplies and they're actually not that easy to find somethng to give 48-volts. The ones I do find are pretty expensive. If this charge method is okay does anyone have any good sources they can point me to?

2) The same thing would apply if I were to get a charger that wasn't made for lithium based batteries right? Does that mean I could also safely use a charger meant for SLA's? The BMS doesn't care whether the charge is coming from a power supply or SLA charger right? If this is correct then I could just go buy an SLA charger from ebikes.ca or ElectricRider.com right?

3) Lastly I could get a lithium battery charger. I was recommended to get a Soneil charger. I looked up the Soneil website and found they do NOT have a 48-volt lithium charger. They do list a 50-volt and a 54-volt model. The ones listed on the Soneil website and ARE specifically for lithium batteries are:
50.4V, 2A - Model No. Li5004SR
54.6V, 2A - Model No. Li5504SR
Their descriptions actually states "Suitable for Li Ion and Li Polymer Batteries". And are these voltages too high or are they okay? I've been thru their authorized vendor list and visited each vendors websites but none of them seem to carry these models. I've written a few emails to these vendors but I'm still waiting for replies. Does anyone know where I can buy these specific models? Or does anyone know of a good and safe lithium charger (not Soneil) that they can recommend to me?

Now I got another question but this is regarding HOW TO HOOK UP the charger to my battery. Here's a picture of one of my batteries.

I hooked them up to my ebike. That was strait forward enough. I just connected all 3 in parallel (3 thick red wires to the red wire on my controller and 3 black wires to the black on the controller). I was able to ride around for about 4 miles before the LVC on my BMS cut out.

But now how do I hook up the charger? Again, after doing reading on this forum I'm thinking I connect the red (+) on the charger to the thick red battery wires and also to the thin red BMS wire right? The I also connect the black (-) wire on the charger to the THIN black wire going to the BMS right? Please tell me if I'm doing this wrong...I'd hate to fry a perfecly new BMS.

Lastly, can someone tell me why there is a removeable connector on the thick black wire between the battery and BMS? What's the purpose for having this connector here? ... to remove the BMS? Why would I want to do that? Whether charging or discharging I think that BMS is a good thing to keep in there. Am I missing something important? :?

Sorry again for these nooby questions but I've been read and searched up and down this forum already and still not sure what to do. I really appreciate any kind of help you guys can give me.

 

[mcstar]

You could just write Li Ping and ask him to sell you a 48V charger. I'm pretty sure he'd be glad to. I'm guessing it will be around 50 bucks, then you'd have it next week. He sent me some extra cells and an BMS with no problems at all a couple months ago. Write him at pingping227@hotmail.com

 

[Johnbear]

Hello guys,


But now how do I hook up the charger? Again, after doing reading on this forum I'm thinking I connect the red (+) on the charger to the thick red battery wires and also to the thin red BMS wire right? The I also connect the black (-) wire on the charger to the THIN black wire going to the BMS right? Please tell me if I'm doing this wrong...I'd hate to fry a perfecly new BMS.

Lastly, can someone tell me why there is a removeable connector on the thick black wire between the battery and BMS? What's the purpose for having this connector here? ... to remove the BMS? Why would I want to do that? Whether charging or discharging I think that BMS is a good thing to keep in there. Am I missing something important? :?

Sorry again for these nooby questions but I've been read and searched up and down this forum already and still not sure what to do. I really appreciate any kind of help you guys can give me.

Your correct on the hook up for the charger but be very careful to double check the polarity of the charger. Those 3 prong chargers are not always the same polarity. If the charger is opposite you could smoke the charger or BMS. I would also hook up a fuse inline with the red discharge wire. Better to be safe.

I suspect the removable connector is just for a quick connect for the bms.

I agree that ping is probably your best bet for getting a charger.

Thanks for posting the pictures!

 

[Johnbear]

ebikes.ca sells 2a lifepo4 chargers

http://www.ebikes.ca/store/


CG482LiF-EC 48V (15 cell) 2A Plastic LiFePO4 charger
0.46 kg (1.01 lbs) $50.00

 

[Sacman]

Thanks for your help guys. I did see that $50 charger on ebikes.ca earlier this morning and sent them an email but Allison sent me a reply email informing me that the ebikes.ca online store is shut down for the rest of the summer and won't open back up until September. I am considering just contacting Ping but I really don't want to wait over a week for that long shipping from China. There is also another form member who contacted me and said he might have a used 48-volt lithium charger he might sell.

Thanks johnbear for confirming my charger-to-BMS wiring hookup.

 

[dogman dan]

If you have a 48v sla charger laying around, just use that for now till you get one from Ping. I've been using sla chargers for most of the summer since I did stupid with my ping charger. No problems. When I still had the ping charger, I found if I charged with the sla, and then put it on the ping charger, the ping would run 10 minuites more max. My 36v chargers are putting out about 43 v wich is nearly the same as the ping which put out 44. Im still balanced and my range is exactly the same as it was when the battery was new. Since your pack is new, it may not fullly balance itself untill you get the real lifepo4 charger, but it will be fine to run it on a regular sla charger for a month or so till you get a lifepo4 one.

 

[olaf-lampe]

What bothers me, is the short riding distance you achieved on the first testdrive. Usually all Li-xx batteries come 50% charged from factory. Would be interesting to know how much power you where drawing and if these packs can handle it. Maybe only the BMS tripped due to overcurrent?

-Olaf