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Power Bank Charging Quandary

Blog Date - 20 May 2019

Errrrm Yeah. 

Under the seat of my CB500X is a 12v power point, what we used to call in the good old days a cigarette lighter socket. It is used to power the airbed pump and to charge my power bank. I fitted it myself, it's not a standard feature

Just to avoid any confusion in this instance a power bank refers to those battery packs with USB sockets to charge up phones, tablets and in my case my e-cig sucky-stick. 

A power bank, essentially a small box with USB connectors to charge phones and the like
My power bank. You know the things surely.

Sharon has one fitted under the seat of her Z250SL too. She also charges her power bank and can directly power her Sat-Nav because the battery life on those things is awful. Again this is something we fitted, it is not a standard feature.

The 12v power or cigarette socket fitted to Sharon's Z250SL Kawasaki
Sharon's 12v socket on the Kwakker.

Both were wired directly to the battery. However due to Pocketpete's terrible misfortune I acquired the necessary pins, plugs and bits of plastic to wire my 12v power/cigarette lighter socket to the "option plug" under the seat. The option plug is in fact a standard feature and provides 12v power that is switched with the ignition. 

The options plug on the CB500X
The options plug on my 500

So now my 12v power/cigarette socket only becomes "live" when the ignition is on. To blow up an airbed the ignition would be on for say 1 minute, that's fine. To charge the power bank I would NOT leave the ignition on for several hours! What I will do is just leave the power bank under the seat during the day. It will get a good charge over the several hours of riding we are sure to do.

The 12v socket, the adaptor, the cable and the power bank under the seat
Option plug to 12v socket to 12v-USB adaptor to USB cable to power bank. Sorted.

Except. Eerrrrrm. Power banks take a long long time to charge. At home with a 3 amp wall plug adaptor it takes 7 or 8 hours to get a good charge if it is quite flat. The 12v power/cigarette socket to 5v USB socket adaptor under my seat is 1 amp. Meh, it'll be fine. On a long ride we'll be out all day, it'll have plenty of time to charge.

Except. Eerrrrrm. We might be on the road for say 8 hours but we stop for tea and cakes and the ignition is off. We stop for a look around and the ignition is off. We might be out for 8 hours but the bike may only be running for 4 or 5. With a 1 amp feed the power bank is not getting enough juice. 

Sharon's directly wired to the battery charging system is charging for the whole 8 hours though. This may drain the motorcycle battery a little during our stops but it gets more than enough boost during the intervening ride time to overcome this. This set-up works well on her bike and worked just fine on my bike when it was hard-wired to the battery.

This is causing me something of a quandary. 

The correct thing to do is leave the 12v power/cigarette socket connected to the options plug that is switched with the ignition. This prevents the possibility of flattening the battery with things sapping power without the bike running. But the bike may not be running long enough to fully charge the power bank. 

I think I have 2 options. 

1 - get a 2 amp or even 3 amp 12v power/cigarette socket to 5v USB socket adaptor. This will give the power bank more charge while riding, hopefully enough to keep up with my usage.

2 - re-wire the 12v power/cigarette socket to the battery directly. 

I think I will try option 1. If that doesn't work then I'll likely return to option 2 in spite of the risks.

Further Research.

The under seat option plug on *MY* CB500X has a 10 amp fuse. This implies I can run a 3 amp charger from it. But why did I emphasise *MY* CB500X? I am aware that Honda has various versions with various option plugs. My model comes with a 2 pin option plug under the seat that leads to a 10 amp fuse. If anyone is reading this please ensure you understand that your version of the CB500X may be different. Don't screw with the wiring if you are not sure.

Dagnammit! My Energizer power bank has a power input of 1 amp. So I could fit a 300 amp USB charger and it would still not charge any faster. This leads me in a great big circle right back to the start. 

The input on Ren's power bank show 1 amp at 5 volts.
Gosh Darn IT!! Back to square 1.

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Reader's Comments

Ian Soady said :-
Connect direct to the battery (with a 15 amp fuse) but controlled by a relay triggered by your "option plug". I'd ignore the markings on the power bank. It will take exactly as much as it needs and no more. For instance, I have a motorola charger for a tablet which is quite high capacity. But it happily charges a mobile phone at a high rate.

If the answer isn't a relay then you're asking the wrong question......
20/5/2019 10:08:33 AM UTC
Ren - The Ed said :-
OK let me establish I'm no electrical expert - but.

Why the relay? The option plug is fused in the fusebox at 10 amps. I would hope Honda, who probably know a little more than myself, would be happy for an attached item to run at 10 amps with that wiring etc if they fitted a 10 amp fuse.

Excusing my ignorance but I figure these power packs have electrickery within them. It "knows" when an attached item is charged and stops charging to reduce the risk of things blowing up according to the manual. If they're smart enough to know these things then I figure they're smart enough to control it's own draw from a power source too. This will be presumably to stop the internal batteries from sucking in too many electrons in one go and blowing themselves up too.
20/5/2019 12:54:26 PM UTC
Ian Soady said :-
10 amps (or a tiny bit more) is what it will blow at. Without knowing the exact wiring, it's common for the wire from plugs like this to take a tortuous route and to be the minimum the manufacturer can get away with to save a couple of yen. The result of this is of course that there will be possibly a significant voltage drop, meaning your charging will take even longer. Getting the power direct from the battery means you'll be getting 13.5 - 14 volts reliably.

I just use relays as a matter of course as they're cheap and it means I can decide what's going on rather than somebody who hasn't a clue what I want to do. I have no idea what "option plug" means anyway other than that it seems from your description to be something switched by the ignition. There is probably a permitted list of things you can attach.
20/5/2019 4:32:15 PM UTC
Bill said :-
Having it wired directly to the battery via a correctley rated fuse mounted as close to the battery as you can, close as short wire to fuse not close as proximity, should not cause any issue. You could put a switch in circuit if you want the option to switch it off such as overnight.
Just remember it all works on smoke, if it stays in the wire everything is fine if you ever see smoke leaking out you have a problem????
20/5/2019 7:32:47 PM UTC
Ren - The Ed said :-
The issue still remains that it takes around 8 hours to charge the power bank from mostly discharged.

I either wire (with fuses and switches and thick wire and whatnot) directly to the battery. While only a minor risk there's still a risk of flattening the battery. Or be it relayed, fused, OE or whatever I charge from something that only comes on with the ignition (and therefore the bike running and supplying charge)

I'm looking at different power banks that can be charged "faster". IE that can receive say 2 or 3 amps of charge rather than one. This may allow me to charge the power bank sufficiently quickly in the comparatively short time the engine is running.
21/5/2019 11:36:10 AM UTC
Bill said :-
Ren, I use a Ravpower RP- PB044 capacity 10050mAh/37.1Wh the input 5v/2A. It has two outputs depending on what you need one at 1A and one at 2.4A and is in a rugged casing from Amazon I think. You would need a two amp USB on the bike
Www.ravpower.com hope it's of some help
21/5/2019 2:20:16 PM UTC
Ian Soady said :-
I can't quite work out why you need the power bank anyway - why not charge the devices direct? My motorola tablet charges fully in about 3 hours; less for my mobile phone. If you rig up a set of USB charging points like what I've described somewhere here before that means that you can have everything charging at once. With the power bank you then have to charge the devices once you stop. My way they're ready to roll. I do have one of those power bank things lying around but have never actually found a use for it......

Of course this may take more than Mr Honda's 10 amps so my recommendation for a relay stands.
21/5/2019 2:26:41 PM UTC
Ren - The Ed said :-
Aaah of course, I've not explained the why of the power bank. Good point Ian.

As you may have noticed I'm usually on a motorcycle. I have in the past charged my mobile phone while on the road. However if I need my mobile, say for navigational or communication purposes, it is a fair task to remove the luggage from the rear seat to gain access to the phone under the seat.

Why under the seat? This is in my experience the driest place on the vehicle where a power point and phone may safely survive the inclement weather that occasionally finds me on my travels.

Also the space under the seat is insufficient for the tablet.

Well then, I hear you cry, set up a charging point in the top box for example. It is hopefully dry and offers at least a basic level of security. I have considered this and it is a fair option. This almost came to fruition before I notioned upon using a power bank. This could be charged under the seat then used at night to recharge the various electricals.

But as stated above this too is proving to be not without its issues.

My options are various and this is very much a classic first world problem. I am indeed fortunate to be in the position where such frivolities are my concerns.

Bill - I'll have a look at the ravpower site. Good call sir.
21/5/2019 7:50:23 PM UTC
Borsuk said :-
I don't normally carry a tablet with me on the bike but I do have an Iphone and so I always carry a battery pack ( the battery life was never great when new and now is laughable). I have a dedicated battery pack in the UK and Spain for the bikes as well as my daily use one so I have 2 available at all times when on the motorbikes. I can switch between using and charging with no worries about flat phone and or battery pack . Both the 125 and the Himalayan are wired for charging and the interceptor currently has only a hard wired Sat Nav point. The Himalayan has a handlebar mounted switched weather proof charge point with integral volt meter so can monitor my bike battery charging status as well, 1x 12v car charge socket, 1 x 2.1 amp and 1 x 1 amp USB sockets. This is enough to keep the Phone and the battery on constant charge in the tank during dry weather and the phone can be topped up in the tank bag when hissing down. The Sat Nav on the Himalayan is a Garmin Montana from my hill walking days so it has an onboard battery with about 12 hours life and I have an extra battery or 2 for it, It can also take AA batteries as a second back up so I have no real worries about it when out and about. The 125 has as below in the top box direct wired to the battery . Each socket is switched so these are always off when the bike is parked for the night. She has a kick start as well which has been proven to work when the battery is in pancake mode so no starting worries if they are left on during breaks when out and about. The two top box reflectors are also wired in so I have high level LED tail and brake lights.
I have not done any overnight camping trips but have done around 400 km in a trip several times ( around 12 hours total time) and find what I have is sufficient to keep my phone alive at all times even with the bluetooth on all the time to talk to the intercom unit. The main problem is my intercom battery only lasts about 6 hours so when I stop for a break that tends to get plugged in to extend the life a bit.

22/5/2019 7:02:32 AM UTC
Ren - The Ed said :-
That setup in your back box seems like a logical solution. I'd have to ensure there's a quick release connection for the wires coming into the top box as when I'm camping the top box is also my seat in the tent.
22/5/2019 9:20:27 AM UTC
Ian Soady said :-
What Borsuk has described is more or less what I meant. But I would still wire direct from the battery with a relay switched by the ignition (or if you want to be really fancy, a parallel manual switch (with the obligatory LED) as well.

Waterproof QD connectors are readily available. I used some to fit a high level brake light to the top box on my V-Strom.

22/5/2019 2:07:32 PM UTC
Pocketpete said :-
Glad you worked out how to connect the forklift truck connectors to the options plug. It took me a couple of goes to get the pins in properly but then it's easy. I would definately use the relay and fuse box now I understand how it all works and pop it in the top box. Use one of those little quick release connectors they have on trickle chargers cant remember what they are called 'sig' or something then you can use your mobile topbox seat.

Then you can still run an extra USB or cig lighter to the front cowling with using the relay.
26/5/2019 9:35:35 AM UTC
Borsuk said :-
I'm planning on retrofitting SAE connectors to it when I am back over in June to make it removable. I will probably do the same to the Himalayan at some point. Fit lights to the panniers which I can take of prior to her ITV.
26/5/2019 12:03:30 PM UTC
Pocketpete said :-
That's them 'SAE' I new it was 3 digits. The alzheimers home awaits me.
26/5/2019 12:10:10 PM UTC
Ren - The Ed said :-
ITV? That's the Spanish equivalent of the MOT I believe?

I have plans and a few simple experiments to carry out. I'll report back soon.
26/5/2019 12:48:29 PM UTC
Mark c said :-
I have a battery unit with a solar panel on it, they work well and we keep them topped up from a standard USB plug that goes direct to the battery.
They will only draw a certain amount of current and towards the latter stages the current level drops due to internal resistance of the unit hence the ev situation when charging where you can get an 80% charge in a short time period.
30/5/2019 6:14:29 PM UTC
Ren - The Ed said :-
I have wondered Mark c that my lack of complete charge is not really an issue. From my initial research it appears the battery charges quite quickly then then final part of the charge to full is that which takes an age. This all rather reminds me of my "Why So Complicated" post - nothing is ever as simple as it seems and as I'd like it to be.
30/5/2019 8:09:28 PM UTC
├ůsa said :-
I have chosen to connect my USB outlet directly to the battery. I don't like to charge while I'm riding as the vibrations from the bike seems to damage the USB plug and the socket - this happened on my old phone and old bike (kawasaki versys). I suspect your Honda vibrates less, but I think this is something to coniderate.
1/6/2019 7:08:19 PM UTC
Bill said :-
Hi Ren, came across this and thought it maybe of interest as its higher output.
15/6/2019 12:13:29 PM UTC
Ren - The Ed said :-
Cheers Bill. At 3.1 amps that'd be 3 times faster than my current (ha!) USB charger. The downside with this one is the connectors is the SAE type but it wouldn't be hard to chop that off and fit the one that would plug into the Honda's option plug.

Of course my power bank will only swallow one amp at a time but there's plenty out there that swallow more and they're cheap enough too these days. Good call, thanks.
16/6/2019 8:28:42 AM UTC

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