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HEADS up on PTC in battery packs.

I am a newbie to unicycles but have 30 years experience in LiPo batteries for rc model airplanes/drones/etc at Sony and Amazon.

When you have a 16S configuration (which my Mohoo does) then the 67.2 volts DC (max voltage) is distributed against the sum of all units.

The PTC has a significant tolerance that it will allow when it charging first starts.  If 4.2 volts DC is peak, the PTC will typically allow 5.2 volts to go across the terminals for 1-2 minutes before it will shutdown.  This is in-rush current startup.  Since there are 16 cells in series, that slop in the PTC startup voltage could really compromise a "weak sister" cell in the pack.   We have seen this in our big glider packs which have only 6S.  One of the cells got "pushed over the limit" and swelled up and vented.

 

So it could happen with the 16S packs in unicycles that your startup voltage over one cell could cause series damage to that cell.   Over time that bad cell gets worse and worse.   It could possibly go to "vent and flames" which happens altogether too often in aircraft flight packs.  Now the unicycle cells are typically 18650 in "silver sausage" cells, so they have a much less chance of catching fire and exploding.  But there are documented examples (in a commercial aircraft) where a laptop battery using 18650 units did burst and catch fire causing the plane to have to do an emergency landing.

So bottom line: 18650 units are about the safest thing out there (except for AA123 cells) for mobile devices.  But because there are many of them in series, the individual PTC may not "save the day".  Only a thermal probe and a current monitor for the whole pack could insure nothing bad could happen.

    tjcooper

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First version of CD was a wonder. Your CD V2 is a real jewel. NICE JOB HOBBY.

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I just ordered a Charge Doctor V2!!!

they Are in Stock and i am excited to get One!

i will Report here :-)

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16 minutes ago, KingSong69 said:

I just ordered a Charge Doctor V2!!!

Me too! :D

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I have C D V 2, love it, works great!:)

So nice to know that you charge to 90% and AUTO shut off simply kicks ass!

Side note,

I let it continue after charger LED (kingsong) went green, it took at least 2 hours to fully balance all cells best I can see.

For best care I think a balance charge about every 15 charges or so is good.

There is also a dongle to plot graph, but have not got around to understand it yet.

UKJ

Thanks H 16!

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@hobby16 - i just sent you 19 Euro, hope this is still the right price, sent a private message too with my address etc.

 

Thanks

 

Stuart

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I Received my Charge doctor Version 2b(Double Charger attached) on saturday! It's a Great Device and for The First Time i Know what is going on while charging!

 

look here:

http://hobby16.neowp.fr/2016/02/29/what-is-the-recommanded-charge-current/

 

thanx to @hobby16

 

Edited by KingSong69

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On Wednesday, July 01, 2015 at 4:30 PM, Gimlet said:

It's a great piece of kit with very useful information but it could do with a 4 pin converter so that it can be used on IPS wheels as well. :)

jaycar electronics have the adaptor $4.99aus pretty sure they ship world wide

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14 hours ago, Dr Bob said:

jaycar electronics have the adaptor $4.99aus pretty sure they ship world wide

Would have been great but I've recently sold on the second of my IPS wheels to one of my son's friends.

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21 hours ago, Dr Bob said:

jaycar electronics have the adaptor $4.99aus pretty sure they ship world wide

Couldn't find it, can you give a link?

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I just ordered the charge doctor, Fred was incredibly helpful and is going to fit the correct IPS connector prior to shipping. 

Looking forward to getting it, excellent customer service!!

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Sorry I am totally new in the game here, but I have had issues with killing a few e-bike batteries before, and I just ordered a Xiaomi Ninebot mini (not the pro version). Would the hobby charge doctor version 2 fit the Ninebot mini? Do you think it would be beneficial to use in my case (e.g. battery packs lasting longer). Just looking for opinions, since I am not really that clued up regarding charging of these types of battery packs.

http://www.aliexpress.com/snapshot/7528087220.html?orderId=74275304472968

Thanks!

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I would contact hobby16 through his web page and see. In general the benefit of a Charge Doctor is that you can see the charging voltage and rate, plus there is a function to shut off the charge before it is completely full. That reduces stress on the battery if you do not always need a full charge for your trip.

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On 5/4/2016 at 3:23 PM, Lintott said:

Sorry I am totally new in the game here, but I have had issues with killing a few e-bike batteries before, and I just ordered a Xiaomi Ninebot mini (not the pro version). Would the hobby charge doctor version 2 fit the Ninebot mini? Do you think it would be beneficial to use in my case (e.g. battery packs lasting longer). Just looking for opinions, since I am not really that clued up regarding charging of these types of battery packs.

http://www.aliexpress.com/snapshot/7528087220.html?orderId=74275304472968

Thanks!

Hi, it's possible to use CD V2 (and the "older" V1) on Ninebot MINI (Pro or Xiaomi) but you have to add connector to make an adaptor . That's what I've done here :

 

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When I ordered mine I told Fred which wheel I was using and he supplied it with the correct connector for IPS. I have only just started using it but have to say it is an excellent bit of kit, really useful to see that total amount of w/h you are putting back into the wheel. Can't recommend it enough!!

Fred is very helpful and quick to respond to any questions or issues.

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I simply can not say enough good about Fred and his kick ass CD!

So EASY to use and the auto shut off at 90% and never going below 20% has to help your expensive batteries health!

And as I posted elsewhere so interesting to know that at least my beloved Ks14c needs about 3 hours to fully balance which I do about every 10 charges, I would have had no way of knowing this without Freds well thought out and priced correct CD!!!

At least for me 10/10

ukj

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OK I just tried to buy another Charge Doctor and no success.  Both email addresses listed for charge doctor (hobby16@free.fr & chris.tresmoins@laposte.net) are dead and your email will bounce back.  I believe he set up the PayPal payment as a "friends and family" payment, so there is no buyer or seller protection.  If you paid via credit card, open a dispute and have the charge reversed.  The seller does not have seller protection and will lose in the event of a reversal.  If you paid with bank transfer or your PayPal balance, you are out of luck.  Caution to anyone thinking of buying a Charge Doctor from the charge doctor website.  Don't do it until further notice. 

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11 minutes ago, GQS said:

OK I just tried to buy another Charge Doctor and no success.

Yes - @hobby16 seems to stopped CD

Maybe this new project can help you?

 

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Hello everyone 
It's about Hobby16

@smallexis and and I, knew Hobby16, Smallexis for having worked and tested with him on the CD, me I was in contact with him about Ninebot Mini.

We had his phone number, the French community knew him well, but no one had heard from him for a very long time.

We are worried about him, we imagined many things like an accident, a dramatic personal event.

I wanted to inform you, because recently, last month, we tried again to contact him, without success. He disappeared.

If Hobby16 reads this message, we sincerely hope you are in good health

Sincerely to all

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