Speakerplans.com Homepage
Forum Home Forum Home > General > 12v Powered Systems
  New Posts New Posts RSS Feed - Lithium jump-start thingy's for 12v power ?
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Lithium jump-start thingy's for 12v power ?

 Post Reply Post Reply
Author
Message
slaz View Drop Down
Old Croc
Old Croc
Avatar

Joined: 27 November 2009
Location: London E2
Status: Offline
Points: 2629
Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Topic: Lithium jump-start thingy's for 12v power ?
    Posted: 07 July 2020 at 2:14pm
H all - first post from me for quite a while .... (been lurking though).

Wondering if anyone has tried using something like one of these :-

https://www.ebay.co.uk/itm/12000mAh-600A-Car-Jump-Starter-Booster-Emergency-Battery-Charger-USB-Power-Bank/183535100354?_trkparms=ispr%3D1&hash=item2abb8b61c2:g:hT8AAOSwQNNenV~m&enc=AQAFAAACYBaobrjLl8XobRIiIML1V4Imu%2Fn%2BzU5L90Z278x5ickk8Fd9si%2FIbtWQr%2BhnlRwjDWlEb4p1MloS0%2BiP8g7OxqG6dQb66QGzIvBjkBNKPkRYXcsDMETC97CylW3fhM6QlF5xKoUSAtPPvBDS3%2FbKZ%2By8NfGAi6nphlDDUtGhjli09oklm8WcdVeoh8uVP8u4mJVfRmo8i%2BHHZ%2Fgtw5iDsEqfvp6PXHB11AvxVqySNLPamCUkXq9bi9BwGJK2KQMS7%2F1xd9t4Vy%2BRhZZnzMpGx9YGJ2D%2FxgpxR11llM%2BtbuacRHOYQgO4ZPNbtsTUi2c7EvOKPW22z2lb1jVv4Q9gLeBIFh8yMjzm%2BgmilaDpqq%2BSBhYAvObORTM4lKaKBqGPOb3Fx0RebBfMo2H%2BlcVJYX3uyhOh67eqE9z9%2FUnvblu4e8kV%2FJj%2BzYUfKs16Rt8g8FmuJ6Vxj0grv8bQFQiy9hpFfdL%2BdXm4EGUBE0CuJviq1fg%2BQPaGKt8JT5kfTnJNXmuCQSB5TpIwzbQXJJqnAVsBWAyyDvPbWm76hYE2JFxPbB5075SQZrkI%2FulG9o2sqebQdzU2TTr7zHqbPBPZZcO94aynVgInrnU0Nib1PV6CcgAeZcYUeytwmNyho2ye4l3J%2FwU3U67O7XhtpzMzrpn1PsZeEj8zoDLfBa4b8Hwu5P1%2F30hT3v1wiyEOdpkmVmVCP0KArVaIUQ%2BLXF4Mtfyz7F%2FzFsvv9P2I4kNIRILEZXkKu7fOAA60rR%2F80vsH%2Fy2yXfx3s1jxKWpFoNKnnffAW83OEU0e2dt6mUmWVZlc&checksum=18353510035495acc1586cba41be99bc0ee2d0674999

... to power sound system.

On the surface they seem like a possible solution, but I'm wary of the quality of the cells in these kind of gadgets. Does the panel think the ability to start a car (very heavy current draw for very short time) implies the ability to supply much less current for much longer times ? If 12Ah is real ... well it could be a decent option to play certain amps.

The ebay supplier is offering "60day refund" - so I'm tempted to buy with the option to return if not up to scratch - but "it won't run my sound system" might not be as strong as "it won't start my car" as a reason for returning (especially as I have don't have a car :-) ).
REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
Back to Top
MattStolton View Drop Down
Old Croc
Old Croc
Avatar

Joined: 04 September 2010
Location: Walthamstow
Status: Offline
Points: 4227
Post Options Post Options   Thanks (0) Thanks(0)   Quote MattStolton Quote  Post ReplyReply Direct Link To This Post Posted: 07 July 2020 at 10:08pm
Originally posted by slaz slaz wrote:

If 12Ah is real


If...

IIRC "Ah" are measured over 10 hours, and then converted back to "per hour", as we may measure SPL at 16W/10M, but then back convert to 1W/1M. So should give 1.2A for 10 hours. 0.6A for a smidge more than 20 hours, 2.4A for a bit less than 5 hrs

Doesn't look big enough to give out 1.2A for ten hours? Perhaps designed just to give a one hit splurge to crank engine once.

Worth a punt for the price. You never know. How quick is it to charge? How easy is it to charge from alternative power sources, such as solar, if that is a goal?
Matt Stolton - Technical Director (!!!) - Wilding Sound Ltd
"Sparkius metiretur vestra" - "Meter Your Mains"
Back to Top
Andylaser View Drop Down
Registered User
Registered User


Joined: 16 April 2010
Location: Southampton
Status: Offline
Points: 225
Post Options Post Options   Thanks (0) Thanks(0)   Quote Andylaser Quote  Post ReplyReply Direct Link To This Post Posted: 08 July 2020 at 10:19am
"music so loud, that if we move in next door to you; your lawn will die" - Lemmy
Back to Top
studio45 View Drop Down
Old Croc
Old Croc
Avatar

Joined: 16 October 2007
Location: United Kingdom
Status: Offline
Points: 3845
Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 09 July 2020 at 2:51pm
The specs are very confusing. 
On one hand it claims to be able to supply 600 amps for cranking via the "start socket" but elsewhere it states the output current is limited to "16-20A". I can't see another 12v output on it, so I would guess that refers to the USB outputs - but it can't because there's no way any 5v USB device will ask for 16A, the connectors would just melt.
The voltage window of 12.75v to 8.1v suggests they are LiFePO4 cells, arranged 4s; however 8.10v is a real MINIMUM voltage for such a pack (~2v per cell) and represents very deep discharge. 12.75v on the other hand is just about 60% SOC so not quite a full charge. This is a strange arrangement and the extreme low cutoff will probably damage the pack long term, while the high cutoff means the pack can never really be fully charged. Alternatively if it is 3s Li-Ion, then the low cutoff represents 2.7v per cell (very low!) and the high represents 4.25v per cell (very high!) - again this arrangement will not offer much protection against long term damage.
If you can watch it like a hawk and only use it within a "good" voltage window it may work well and last a long time. But if you let it run out against the low cutoff, and charge up to the high cutoff, many times it will probably lose capacity and swell up quickly.
Studio45 - Box Builder Commotion Soundsystem -Mobile PA
Back to Top
slaz View Drop Down
Old Croc
Old Croc
Avatar

Joined: 27 November 2009
Location: London E2
Status: Offline
Points: 2629
Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 09 July 2020 at 6:00pm
Well I've since decided the 12Ah spec is basically impossible - based on the physical size.

My "RC-type" 5Ah 3S Lipo pack has too much volume to fit inside that case .... and those Turnigy packs do give you real-world specs.
So I'm concluding that 12Ah must be Chinese Ah. The CBF (Chinese Bullsh*t Factor) would seem to be about 3-4-5 or so ..... not as extreme as the typical Power Bank CBF or the car amplifier watts CBF.
Not even gonna bother buying then returning.

Shame - as the package type could be nicely convenient/handy for some of my purposes. I suspect if there _were_ real top spec cells in there it would cost at least double.
REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
Back to Top
slaz View Drop Down
Old Croc
Old Croc
Avatar

Joined: 27 November 2009
Location: London E2
Status: Offline
Points: 2629
Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 09 July 2020 at 6:09pm

But with that thing, where would I get 12V at 3-4-5 amps from ?
the purpose I have in mind would likely draw average of 1.2-1.5A, but with peaks up to 4-5A.

REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
Back to Top
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.03
Copyright ©2001-2019 Web Wiz Ltd.

This page was generated in 0.093 seconds.