Headway charging question.

[StudEbiker]

So I have two chargers here. One charger (from e-bikekit.com) charges my current HIghtekbikes 36v 10ah battery to 42.3v, the other charger (hightek) charges the same pack to 44.88. I believe with both chargers the voltage drops some immediately after removing the charger. I recently purchased one of the 36v10ah packs from EV Components and want to use these same chargers with the new pack. I have read in other threads that the maximum recommended charge on Headway cells is 3.65-3.7. The E-bikekit charger would equal 3.525v per cell and the Hightek would be 3.74v. I am a little concerned of overcharging with the higtek charger, but the voltage drops some right after the charger is taken off so I think it should be okay. Can anyone see a problem with using either of these chargers with the Headway pack?

 

[RPA]

I would use the ebikekit charger myself. The max charging spec on Headways is 3.65 +or- .05. The chargers probably are adjustable so you can tweak them right where you want them.

 

[dogman dan]

Either one ought to work for a 12 s pack of lifepo4. My old v1 pingbattery came with a charger set to 46v. So I doubt that 44 is too high for 12s lifepo4. I do hear people say you don't want to go to 4v per cell though! So 48v would be too high.

 

[Ypedal]

Assuming the pack has a BMS, any of the chargers will be fine.

The BMS will shut down the charger once the 1st cell hits 3.7v, bleed power and allow the charger to pump more energy into the pack as required.

If the pack has NO bms.. then the lover voltage charger would be the safest to use :wink:

 

[patrickza]

What BMS are you using if any?

My headway BMS needs about 3.67v per cell to balance perfectly.

 

[mwkeefer]

The chargers from e-bikekit.com for the 36v LiFePo4 pack can be adjusted internally via a pot resistor approx 1v maximum range.

-Mike

 

[StudEbiker]

Good info. Thanks. The pack has the Headway BMS in it. I am going to keep the amps low and try running it like it is. That is good info about the Ebikekit.com charger though mwkeefer. Now that you mention that I think I did see something in a thread about that awhile back. I may have to try that. It would be great if it charged as high as my other charger.

 

[Steff]

I'm considering building a 12s Headway pack and was also wondering about chargers and their output voltage. I'm thinking about going for the Ping V1.0 BMS and getting a charger from him while I'm at it. However, his chargers are rated at 45V which is 3.75V per cell and thus higher than the Headways recommended 3.65V per cell. Would that charger be ok for the Headway cells if I use the Ping v1.0 BMS?

Do I need that higher charger output voltage due to any voltage drops in the BMS? Or should I get a charger rated at 43.8V, which I've found on kennedyalternativeenergy.com for example. I'd rather not need to adjust the charger's voltage myself, since I got no clue if it should be measured with or without the load etc. and I don't even know if Ping's 2.5A charger actually is adjustable. Thanks.

 

[Ypedal]

As a general rule, all LiFePo4 cells will be pretty much fully charged at 3.6v, to get them from 3.6v to 3.8v takes only a few mah so it's not very critical as long as all cells get to 3.60v and none are allowed to go above 3.9v

The Voltphreak single cell chargers i've been using for a few years now will charge at 2 amps up to the 3.7v mark and slowly creep up to 3.9x volts, this has been perfectly fine on headway, PSI, 12ah prismatics, 18650 cells, etc etc etc i have used them all at these voltage levels without any aparent harm.

 

[BMI]

I agree with Ypedal's observations.
Our factory cell testing has shown that cells are fully charged at 3.65V and the voltage can be increased up to 4.0V with no apparent cell damage occuring. Over discharging is more likely to result in shortening of cell life compared to slight over charging.

 

[dnmun]

go with the ping charger and the v1 signalab from ping. it doesn't charge all the cells to 3.75V but when several cells are ahead of the others, it does not shut off the charging FET until 3.9V which is standard for all of the BMS.

the trick is that if it cuts off when the high cell gets to 3.9 and there is no voltage left in the charger, then the low cells may not make it all the way up to fully charged. this is why ping has pushed the charging voltage up to 45V and 60V for the 12S and 16S lifepo4.

it makes the pack balance sooner essentially and keeps you from having a low cell that would not be fully charged. that's the logic.

plus the charger and BMS are both reliable and well worth the money. in fact i consider that to be one of the better deals around in chargers since it so well built. the 5A charger is built like a tank, huge inrush current limiter so it will never blow up.

 

[Steff]

I decided to go with the Ping BMS (v1) and charger (2.5 A) and now that I've finally gotten my pack together and taken my first ride today, I got some more questions about charging that I hope someone perhaps could answer:

First off, is a high pitch noise from chargers common or did I just have bad luck with mine? We're talking a really annoying noise. I can just imagine all the dogs in the neighborhood going all out mad when I plug it in.

Secondly, why does the charger keep trying to start charging again every 5 seconds or so after it stopped the first time? Is this behaviour normal ? :?

And finally, should I disconnect my controller while charging or is that not necessary? There's just an on/off button on the controller, so I assume it's constantly in some sort of standby-mode?

Thanks in advance!

 

[StudEbiker]

I decided to go with the Ping BMS (v1) and charger (2.5 A) and now that I've finally gotten my pack together and taken my first ride today, I got some more questions about charging that I hope someone perhaps could answer:

First off, is a high pitch noise from chargers common or did I just have bad luck with mine? We're talking a really annoying noise. I can just imagine all the dogs in the neighborhood going all out mad when I plug it in.

Secondly, why does the charger keep trying to start charging again every 5 seconds or so after it stopped the first time? Is this behaviour normal ? :?

And finally, should I disconnect my controller while charging or is that not necessary? There's just an on/off button on the controller, so I assume it's constantly in some sort of standby-mode?

Thanks in advance!

A high pitched noise is not normal, at least on any of the chargers I've used. Sometimes the chargers have loose bits floating around inside them. Might be a good idea to open it up and see if you can find the source of the sound, the fan may be rubbing on something. The charger cycling every 5 seconds or so is probably the balancing taking place in the pack. As I understand it, the BMS is working at that time and and as it balances the pack it will cycle the charger some. It's not necessary to disconnect the controller during charging.

 

[dnmun]

nope, something is wrong. it should not cut in and out unless the pack is fully charged and then it will pump the shunt current. the switch mode power supplies use high frequency oscillation for the transformer, but it should be in the 100kHz range minimum i think.

 

[The Journey Guy]

First off, is a high pitch noise from chargers common or did I just have bad luck with mine? We're talking a really annoying noise. I can just imagine all the dogs in the neighborhood going all out mad when I plug it in.

When I bought my pack and charger from Mr. Ping, the charger I got did the same exact thing. The first time I plugged it in, it sounded like it was going to overcharge and pack and blow up something. A very high pitched squealing coming from the charger.

I wrote Ping about it, and his reply included the instructions to take the charger apart. Once apart, remove the small cooling fan from the assembly. Once the fan is out on the bench, carefully peel back the small round sticker on one side of the fan. Apply a very small
drop of high quality lubing oil to the fan bearing behind the sticker. Assembly is the reverse.

I did what he suggested, and while it did help the noise some, I have to admit that it never entirely went away. To be totally honest, after that I just did not use the Ping charger, but instead used another charger that I had from before. The noise bugged me too much.

Talk with Mr. Ping and see if he suggests the same approach.

TJG

 

[999zip999]

My ping charger makes the same type of noise. I did the fronzie slap it stopped for a second, then I took it apart put some light oil through needle. It stopped for 2 weeks,then came back. I will live with it. Would like that 5amp.ping charger sounds strong. After the battery is fully charged unplug it and let the bms eat down the battery till the lights all blink. Then a short ride then fully charge unplug let bms drain down the cells to balance. Plug the charger to the battery 1st. the plug into the wall.

 

[999zip999]

That's then plug into the wall 2 second.

 

[Steff]

I'm gonna try to see if I can get rid of my temporary zip-tie battery pack mounting solution this weekend so I finally dare to run some more cycles on the pack.
Hopefully after that I'll have some idea of whether the charger/BMS is behaving properly or not, despite that the charger keept toggling on and off at the end of the charging. Perhaps it's still charging so that the pack balances even when the LED on the charger is green? I haven't actually measured the current or volts during charging, I only assumed that the charger's LED would tell me whats going on. And since I only got the v1 Signalab I can't watch the LED light show from the BMS, but thanks for the tip 999zip999.

I'll probably gonna cough up some more $ the next time I need to buy a charger and just get some earplugs for now...