Geekzone: technology news, blogs, forums
Guest
Welcome Guest.
You haven't logged in yet. If you don't have an account you can register now.


21382 posts

Uber Geek
+1 received by user: 4333

Trusted
Subscriber

Topic # 95530 6-Jan-2012 23:42
Send private message

I have something I want to run portable in a bag, its 12v and I was looking on aliexpress at something like this massive link - price is right for sure but....

I am a little concerned about the safety of something like that as it has a 12.6v input, so I would assume that it is just 4.2 x 3 - as in there are 3 lipo cells in there in series, without knowing what it has to ballance them, and if there is a low cell cutoff provided I expect that it would just run down once and then on the next charge over volt one of the cells leading to something going fireball in my manbag.

The requirement for 12.6 also means that charging off the car isnt going to happen unless I use an inverter and their wallwart, or else use my hobby charger on it, which I dont even know if it will charge if I dont have a balance lead connected. Also it will probably me more like 10v out once the cells start to discharge.

So what else is there that can provide a reletivly long runtime for a small 12v load? I have found many many packs that deal in 5v for USB devices, and have a decentish looking lipo charger and then a boost converter, not seen anything for 12v however.

Otherwise I may as well just use one of my 3S lipo hobby packs since at least I can charge them without concern.




Richard rich.ms

Create new topic

gzt

10117 posts

Uber Geek
+1 received by user: 1539


  Reply # 565683 7-Jan-2012 10:02
Send private message

I think you have ruled it out for safety reasons anyway but the 12.6 requirement might not be a problem for a fully charged car battery, or while driving. Check the output from your socket.


474 posts

Ultimate Geek
+1 received by user: 9


  Reply # 565686 7-Jan-2012 10:18
Send private message

Isent Li-ion safer then Li-po. I know the safety risks with lipo as I use them in my rc.

12.6v should charge from a car when running as the output will be closer to 14v



21382 posts

Uber Geek
+1 received by user: 4333

Trusted
Subscriber

  Reply # 565759 7-Jan-2012 13:38
Send private message

There's up to 15v on the lighter socket at times when running, so that will either trigger the over volt protection if it really exists (I have doubts myself) or else overvolt one or more of the cells.

AFAIK the only benefit of Li-ion over LiPo is the physical aspect of the hard metal cell. Both are totally safe so long as you never under or over volt the cells or exceed their discharge rate to overheat them. Most hobby fires you see/hear about are damaged packs or that are being charged at well over 0.5C with no thermal monitoring.

The lack of any balance connector on the "12v" packs is concerning too as chances are the cells will just go out of balance. Unless the protection circuits they claim to have also take care of balancing them while charging.




Richard rich.ms

Create new topic

Twitter »

Follow us to receive Twitter updates when new discussions are posted in our forums:



Follow us to receive Twitter updates when news items and blogs are posted in our frontpage:



Follow us to receive Twitter updates when tech item prices are listed in our price comparison site:



Geekzone Live »

Try automatic live updates from Geekzone directly in your browser, without refreshing the page, with Geekzone Live now.



Are you subscribed to our RSS feed? You can download the latest headlines and summaries from our stories directly to your computer or smartphone by using a feed reader.

Alternatively, you can receive a daily email with Geekzone updates.