I just swapped my car battery out and the old one is still in pretty good shape.
In a few weeks I am off on a long weekend away with my mates.
We have enough spare space to take the battery. We also between us have quite a high demand for charging various devices.
We all can't have a set of car keys, and we wouldn't want to run the car battery down anyway (mate's A6).
So how about I bodge up my own accessory socket with some crocodile clips and an accessory outlet? Would that be dangerous? What amps would I get? (- I'm thinking about the likes of Qualcom Quick charging). What could go wrong?
It'd have a lot more capacity than the battery packs I have (albeit less portable), which would be good for all the devices we have between us. Especially as my phone is gobbling battery right now for some reason.
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USB charge points give out 5v, your battery is 12v, so you'll need a bit more than crocodile clips and a cigarette lighter.
Have a look at the following;
www.instructables.com/id/Charge-your-phone-with-a-car-battery-6V-24V/
Just your sort of project, I should think.
Last edited by: No FM2R on Wed 17 Jul 19 at 16:53
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...I'll bet one of you has a standard cigarette lighter USB charger (one with two USB outputs would be good), so one of these or similar is all you need.
www.amazon.co.uk/Accessory-Socket-Battery-Clamps-Crocodile/dp/B003SQ6U6Q
If the battery is still holding charge and you don't want to knacker it, expect to take no more than 50% of the capacity out without recharging. (Take it lower if you aren't bothered).
A full 60AH battery at a nominal 12.7 V to 50% discharge delivers 381WH.
Then allow for inefficiencies in the 12V to 5V conversion and charging. Say 80% to be probably on the conservative side.So that will deliver just over 300WH at the USB output.
My phone has a 3000mAH battery; at 5V that equates to 15Wh, so 20 empty to full charges from the above regime (you're more likely to top-up).
Easy enough, though I'd want to make sure the battery was secure/protected whilst travelling - I'd put it in a plastic box/stacking crate or similar to avoid acid spills.
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Thanks Mark, that's a bit complicated for me - I'm OK with software and plug-together stuff but the circuit diagrams might put that beyond me. Also would end up costing more than the couple of quid I had in mind :-) But not yet fully discounted.
I found one on YouTube but also found that the latest Windows update has knocked out my sound so won't get to watch it till I've fixed that (or rolled back!)
Those figures sound good T&E, it would provide us with more than we need. I just found I already have a spare accessory socket in the garage from a project years back when I put a live feed into the boot of my Omega for a cool-box but at £4.99 that Amazon one seems the way to go.
The car battery is an AGM type, from my leccy car, so is safe to be inside a car. The useful and knowledgeable forum for my car suggests these ought to be changed every three years as it seems there are lots of spurious (and sometimes real, causing bricking) errors thrown up by a 12v battery which isn't tip-top. So I swapped it a few weeks back, even though the readings showed no sign of deterioration.
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>>
>> Those figures sound good T&E, it would provide us with more than we need.
...I've used example values, YMMV.....
(but you can do the Math ;-) )
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'what could go wrong" - Shock and awe Smokie !
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The one thing that you must do is fuse the feed say 10A, as close to the battery as possible. A short cct car battery can be somewhat destructive!
Also make sure that the terminals are protected against some one dropping a spanner or BBQ grill on the top of the battery.
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I fitted a charging port for my re-chargeable razor in a caravan. Forget the numbers, but I used a 6V, low wattage bulb in series to limit the current. The razor battery pack provided the rest of the resistance.
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And I had a wet shave. No fire.
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You can buy accessory socket USB chargers with Qualcom Quick Charge for £5 to £10. The cheap ones can generate RF interference as Alanovic discovered in the other forum.
With croc clips, accessory socket, inline fuse and a bit of cable you should be fixed up for less than £15 in total.
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"You can buy accessory socket USB chargers with Qualcom Quick Charge for £5 to £10. "
Yes, got some and they do cause interference, but not a problem when camping.
Also have a single socket then I can pug into it a multiway one but do they meed to be different for Quick charge?
And what steps down the voltage in that lot Kevin? Or does the device (phone etc) regulate that? That's more or less what i was thinking when I started the thread (I was missing the fuse)
Last edited by: smokie on Wed 17 Jul 19 at 23:23
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>Yes, got some and they do cause interference, but not a problem when camping.
Not a problem for camping. I only mentioned it in case you were buying a new one and might want to use it later in a car socket.
>Also have a single socket then I can pug into it a multiway one but do they meed to be different for Quick charge?
If I understand you correctly (plugging a multi USB fan-out into a single Quick Charge USB socket) then I don't think Quick Charge will work unless the fan-out spec specifically states that it supports QC. I've never come across one that does because they're usually intended for peripheral connections. Should work fine for standard charging though.
>And what steps down the voltage in that lot Kevin?
The USB gizmo that plugs into your accessory/lighter socket does the voltage conversion and will be a variation of the second (Efficient) circuit shown in Mark's link above. It should work with any DC supply voltage between about 6V and 24V depending on what chip they used. Typically better than 80% efficient for your calculations.
Check if the battery terminals have a threaded hole in the centre (some do) and you may even be able to do without the croc clips if you have suitable bolts lying around.
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Do all the devices have USB plugs?
If so, then how about something like this?
www.ebay.co.uk/itm/DC-Converter-Module-Connector-12-V-To-5-V-3A-15W-Double-USB-Output-Power-Adapter/163671478703
Last edited by: VxFan on Thu 18 Jul 19 at 19:09
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No, but I found what he meant tinyurl.com/y2zhxlyu
For the weekend away that doesn't cut it really as I would like to charge more than one device at a time
BUT
for running my (intermittent) wildlife Raspberry Pi camera when it's set up looking out of the shed window that is ideal! Thanks!
Last edited by: smokie on Thu 18 Jul 19 at 08:36
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But at that price you could afford to buy 2 or 3 and connect them all up to the battery. They even offer a discount if you buy 2 or more!
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>> Linky no worky.
Should work now. When I copied/pasted, I missed off a digit from the end of the link.
Smokie, the one in my link does have two USB outputs.
Last edited by: VxFan on Thu 18 Jul 19 at 19:11
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Ah so it does. That would deffo be more useful than just one.
I imagine the 3A is across both outlets?A single Quick Charge 4 device (,y phone might be) requires 2.5A and 4.6A,
I suppose there'd be nothing stopping me having two of those devices on the battery at the same time. I'd save a whole 4p on one if I bought two!! :-)
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Quick Charge requires the charger to be able to ramp up the output voltage. I don't think those adapters in the link above can do that.
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>> I imagine the 3A is across both outlets?
Yep. Spec says "Output Current: 3A Max"
What is odd though, is that it also says "It can't be used for iPhone, iPod, Tablet GPS navigation, Tachograph, USB speakers"
I have seen other similar ones that have no mention of this.
>> Quick Charge requires the charger to be able to ramp up the output voltage.
Don't you mean current, rather than voltage?
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>Don't you mean current, rather than voltage?
No. QC devices and chargers talk to each other to change the charge voltage.
www.androidauthority.com/fast-charging-explained-889780/
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>> >Don't you mean current, rather than voltage?
As the voltage increases, so does the current (unless it's restricted). I=V/R and all that.
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Why did you swap your car battery if old one still fine?
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Preventative maintenance Bobby - as I said above, "the useful and knowledgeable forum for my car suggests these ought to be changed every three years as it seems there are lots of spurious (and sometimes real, causing bricking) errors thrown up by a 12v battery which isn't tip-top. So I swapped it a few weeks back, even though the readings showed no sign of deterioration."
It's not something I'd normally do but reading the threads there are a more than significant number of error codes and conditions, some of which are spurious, which seem to get fixed by replacing the battery regularly. The car is a bit quirky in that respect!!
Just in case you're interest has been piqued, here is the forum in question. www.speakev.com/forums/ampera-volt/
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I know you like fiddling with stuff but it seems like taking a sledgehammer to a monkey nut. The battery probably weighs 20Kg.
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Well if you're going to be all sensible about it.....
It takes my P20 45 minutes to charge from 0% to 80%. And since I rarely let it get under 20% it usually gets around 30 minutes charge a day sometimes skipping a day. I'd assume that most modern phones would be about the same.
And wherever I was in the UK, I'd be fairly sure I was going to be spending more than 30 minutes a day in a McDonald's, a Cafe, a Pub or a reference library, all of which have plug sockets.
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I know what you mean Manatee but I'll be camping for four days on a village playing field with no power. The event takes place around a pub but there;s probably 500 people thee and I don't know the publican well enough to get priority on the power sockets!
I can actually live without a phone but I like to take some fillum of the bands playing at the blues festival. The phone does have "issues" with power so I also take my old one but that's not great either. This morning my phone wasn't doing much and went from 100% down to 60% in a few hours.
I do have a couple of decent size power banks for my own use but I was just in project mode, using stuff I already have here (almost) to assist me and my buddies. As it seems do-able, why not? :-)
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What about using an inverter, a powerstrip and your existing AC chargers?
You can get 200W inverters for less than £20 from Amazon.
tinyurl.com/y5eqkhat
Not as efficient as the accessory socket solution but gives you the option of charging a laptop or non-usb stuff as well. Most also have a couple of built-in USB ports.
Just be careful of battery drain.
Last edited by: Kevin on Thu 18 Jul 19 at 23:03
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The AC output socket looks a bit weird in that link.
Here's a 300W unit for £4 more that even supplies you with croc clips.
tinyurl.com/y5x6tw89
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Thanks but they are getting a bit pricey for a lash-up bodge for one weekend only :-) AFAIK it's only "USB devices" which would need charging, no laptops or anything.
Quick charge may not be so important but I do already have QC compat USB plugs for the accessory socket, and all the right cables.
Remember this is a spare battery so not concerned about running it down (even though they aren't designed for that). As well as my decent condition battery I also recently swapped the battery in daughter's Fiesta, but that was losing condition on it's own.
I am thinking that your orig suggestion may be the best way to go though, rather than the USB ones from Dave.
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I ordered a cheap (£1.26) 12v to 5v step down BUCK board from China with dual USB. it arrived today and I just hooked it up. It blew when first put on power... refund requested!! :-)
I have something else on order though - the accessory socket with croc clips. I think someone linked above
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Making a mega battery pack... - No FM2R
