What capacity power bank do I need?

What capacity power bank do I need?

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Discussion

Dr Mike Oxgreen

Original Poster:

4,209 posts

172 months

Sunday 8th September
quotequote all
I am an HGV driver, and frequently do multi-drop delivery runs to places I’ve never been before. I therefore rely heavily on my TomTom Go Expert 7” satnav.

As an agency driver, I have to drive a variety of vehicles for a variety of companies. A few weeks ago I was in a vehicle where I couldn’t find a power outlet to run the satnav, and this was a worrying moment because its battery will only last an hour or two. I did eventually find the cigarette lighter socket, well hidden at the bottom of the dash trim - but it made me realise that it’s only a matter of time before I’m in a vehicle that doesn’t have a working power source.

So I’m considering getting a power bank to keep in my bag. But I have no idea whether one of these would be capable of running my satnav for a 10-12 hour shift. Typical capacity seems to be around 27,000 to 30,000 mAh. Would that keep it going all day?

It would also be good if it could simultaneously keep my iPhone 11 going, as that provides the data for traffic info. Its battery is elderly and doesn’t reliably last all day.

Would a power bank do the job, or am I expecting too much?


Edited to add: I guess the key question is how many Amps does a large TomTom satnav draw when you’re using it, assuming it starts off with a fully charged battery so it’s not pulling Amps to charge itself up?

Edited by Dr Mike Oxgreen on Sunday 8th September 12:35

Merry

1,415 posts

195 months

Sunday 8th September
quotequote all
From a quick Google it probably has a 1300mAh internal battery.

If you're saying that will last an hour, the device probably pulls 1.3A. Therefore 30,000 mAh battery will last 23 hours.

So it would probably be enough, by my (very) crude reckoning for a 12 hour shift. Maybe 2.

Dr Mike Oxgreen

Original Poster:

4,209 posts

172 months

Sunday 8th September
quotequote all
Thanks!

I’ve realised the obvious and looked at the tiny writing on the back of the satnav, which says 5V 2.4A.

So that would mean a 27,000 mAh power bank could keep it going for about 11 hours. And probably a lot longer than that, because I imagine it hardly ever actually draws 2.4A - perhaps when it’s trying to charge the battery as quickly as possible, but I imagine the draw is a lot less when just using it and the battery is already full.

And hopefully it could support my phone as well, which is sitting there with its screen off, doing a bit of 4G data and delivering that traffic data to the satnav (via Bluetooth or wifi hotspot, not sure which).

Does my logic sound right?

And power banks are not hugely expensive, so I could always buy two.

Merry

1,415 posts

195 months

Sunday 8th September
quotequote all
Dr Mike Oxgreen said:
Thanks!

I’ve realised the obvious and looked at the tiny writing on the back of the satnav, which says 5V 2.4A.

So that would mean a 27,000 mAh power bank could keep it going for about 11 hours. And probably a lot longer than that, because I imagine it hardly ever actually draws 2.4A - perhaps when it’s trying to charge the battery as quickly as possible, but I imagine the draw is a lot less when just using it and the battery is already full.

And hopefully it could support my phone as well, which is sitting there with its screen off, doing a bit of 4G data and delivering that traffic data to the satnav (via Bluetooth or wifi hotspot, not sure which).

Does my logic sound right?

And power banks are not hugely expensive, so I could always buy two.
Sounds pretty logical to me!

miniman

26,306 posts

269 months

Sunday 8th September
quotequote all
Couple of these should do the trick - I have a few Ankers and they are great.

https://www.anker.com/uk/products/a1277?variant=37...

Hoofy

77,492 posts

289 months

Sunday 8th September
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I'd think about getting a couple of 15-20maH packs, if only because you can swap them in and out of bags, they're less chunky even if you're carrying two, and you can have one charging via the 12V socket even if it's at the back of the van.

coach

1,092 posts

259 months

Sunday 8th September
quotequote all
Hang on, if it’s 5v 2.4A then it will run off USB. Surely trucks have USB? Then a case of getting the right tomtom adaptor cable or clone off Amazon?

Dr Mike Oxgreen

Original Poster:

4,209 posts

172 months

Sunday 8th September
quotequote all
coach said:
Hang on, if it’s 5v 2.4A then it will run off USB. Surely trucks have USB? Then a case of getting the right tomtom adaptor cable or clone off Amazon?
Yes, it runs off USB.

Most of the trucks I drive have 12V cigarette sockets. I use a dual cigarette-to-USB adapter that provides a pair of 5V USB-A outlets. I plug my iPhone into one of them, and the TomTom into the other.

But the scenario I want to guard against is jumping into a vehicle and finding that the power socket isn't working, perhaps a fuse has blown and I have to manage without power. Or maybe I can't find a power source at all - I'm often in totally unfamiliar vehicles. In these cases, a power bank would be a nice thing to have.

coach

1,092 posts

259 months

Sunday 8th September
quotequote all
Ahhhh. Wise move indeed!

Merry

1,415 posts

195 months

Sunday 8th September
quotequote all
miniman said:
Couple of these should do the trick - I have a few Ankers and they are great.

https://www.anker.com/uk/products/a1277?variant=37...
I wouldn't be buying anything with a micro USB charging port, like those have anymore. It's just another cable to carry when everything else is USB C.

I'd be very suprised if Anker dont do a USB C version.

OutInTheShed

9,355 posts

33 months

Sunday 8th September
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A typical phone has a battery of maybe 1.5Ah.

There are a lot of 'power banks' with comically overstated capacity.

9 million mAh, that's 9000Ah at 3 point something volts, 30-odd kilowatt hours?
Yeah, right!

I have a cheap one, I think it was a tenner at Toolstation.
5200mAh at 3.7V it says, I think that's realistic, it will fully recharge my iphone and not be flat.
I sometimes taking it hiking, when a long day of GPS use can spank the phone battery.

The 3.7V is the cell inside it, it converts that to 5V out, so obviously less Ah come out!

OutInTheShed

9,355 posts

33 months

Sunday 8th September
quotequote all
I don't know what the satnav would actually use on average over a shift, but you can get USB adapters with an ammeter built in.

I'd guess lighting the display to be daylight visible will be a bit sweaty.

miniman

26,306 posts

269 months

Sunday 8th September
quotequote all
Merry said:
miniman said:
Couple of these should do the trick - I have a few Ankers and they are great.

https://www.anker.com/uk/products/a1277?variant=37...
I wouldn't be buying anything with a micro USB charging port, like those have anymore. It's just another cable to carry when everything else is USB C.

I'd be very suprised if Anker dont do a USB C version.
That’s a fair shout, maybe that’s why it’s the cheapest one hehe

Dr Mike Oxgreen

Original Poster:

4,209 posts

172 months

Sunday 8th September
quotequote all
Well, I’ve ordered the one that mini man linked to (although cheaper on Amazon). Just one for now, as I suspect it’ll be plenty.

I’ve also got some Anker multi-way USB chargers and like them. Also the TomTom’s charging port is micro USB so I have two of the cables anyway.

Thanks for the advice, everyone - I’ll report back when I’ve had a chance to put it to the test.

JamesCarter8632

4 posts

3 months

Sunday 8th September
quotequote all
Ridgemonkey power bank best thing I’ve bought!

biggiles

1,835 posts

232 months

Sunday 8th September
quotequote all
I have done all the maths, and bought too many power-banks over the years.

I now just reach for the power-banks which have the wires already built-in, and the 20,000mAh capacity. 20k capacity is masses, so you never worry about power, and having the wires built-in is a godsend. Hopefully you only need usb-c which makes life even easier. If possible, get a branded Anker one.

miniman

26,306 posts

269 months

Sunday 8th September
quotequote all
The MagSafe ones are fab, just grab onto the phone case and away you go.

thetapeworm

11,893 posts

246 months

Sunday 8th September
quotequote all
I have some high capacity Anker 270000 ones but picked up 4 of these just to take on holiday and have as spares, they seem OK for the low price.

AsperX 2-Pack Power Bank Portable Charger Fast Charging 10000mAh

https://amzn.eu/d/6HXiWSl

Dr Mike Oxgreen

Original Poster:

4,209 posts

172 months

Wednesday 11th September
quotequote all
Well, I’m quite pleased with what I bought.

It took quite a while to charge fully, even using two micro USB inputs and it arrived 50% charged. And the charger got quite warm. But no matter, I left it charging overnight.

I used it the following day, powering the satnav and my phone without using the vehicle’s cigarette socket. Both devices started with full batteries, so it was only powering them, not charging. This would be a fairly normal use case.

Yesterday was a comparatively short shift of 6 hours, and today about 7 hours. So about 13 hours total.

The power bank has four LEDs to indicate its charge state, and at the end of 13 hours powering both devices it still had three of its four lights lit. Not bad at all!

Tony1963

5,328 posts

169 months

Wednesday 11th September
quotequote all
miniman said:
Couple of these should do the trick - I have a few Ankers and they are great.

https://www.anker.com/uk/products/a1277?variant=37...
I’ve an older version of that, similar spec.

I haven’t charged it since… I really can’t remember when, and it still shows fully charged. For the money, these powerbanks are worth their weight in gold.