How long would it take an accessory to kill a motorcycle battery?

[TheRiddler]

I'm considering hooking up an accessory plug-in to my bike to charge my phone. I know that with the bike running it won't be an issue. I'm concerned with the bike off.

If my phone battery is rated for 1800mAh, is there any risk of going from 0-100% taking a toll on the bike's battery?

 

[V4]

a sportbike that is designed for light weight which comes with a lighter battery such as a ytz7s or smaller and you're just riding around town, it may drain it quickly...theyre just enough to start the bike..

the average battery, ytz9 and up, it may be a little bit more durable but gotta ride it frequently to keep the charge...

 

[TheRiddler]

Mine is running a YTZ10S. I know that battery is relatively strong, but on the flip side it's not strong enough to start an SV650.

 

[HappyHighwayman]

I have the same question. My BMW has a euro socket and I have a USB adapter to charge my iPhone. It charges pretty slowly with the bike not running, and I'm worried about killing the F800GS's battery if I do that.

 

[ahnh666]

charging a phone while the bike is off?...usb outlet with nothing plugged in draws about 10mA....typical cellphone draws about 500mA, but some take as much at 900mA....typical motorcycle battery is rated at about 10,000 mA...a cellphone will drain a battery dead in about 10 to 20 hours....you need about 100mA minimum to have one chance at starting a motorcycle (probably 500mA or more for few attempts)...i'm sure clock and other items will also take some power while the bike is sitting...

 

[HappyHighwayman]

charging a phone while the bike is off?...usb outlet with nothing plugged in draws about 10mA....typical cellphone draws about 500mA, but some take as much at 900mA....typical motorcycle battery is rated at about 10,000 mAh...a cellphone will drain a battery dead in about 10 to 20 hours....you need about 100mA minimum to have one chance at starting a motorcycle...

usb adapter takes about 10mA...i'm sure clock and other items will also take some power while the bike is sitting...

Lights, LCD screen, etc.

 

[}Dragon{]

What about a small solar charger and put it in a tank bag?

http://www.wirelessground.com/solar-battery-charger.html

 

[Gary856]

usb outlet with nothing plugged in draws about 10mA....typical cellphone draws about 500mA, but some take as much at 900mA....typical motorcycle battery is rated at about 10,000 mA...a cellphone will drain a battery dead in about 10 to 20 hours....

But USB/cell phone charges at 5V, while a bike battery is at 12V, so you can't divide the amp-hr directly. You should calculate power (voltage x current) instead. Unless the moto battery is already borderline low it should have no problem charging one cell phone battery while the bike's not running.

you need about 100mA minimum to have one chance at starting a motorcycle (probably 500mA or more for few attempts)...

How did you get that info? Isn't starting more about cold cranking amps (50-60A for a few second for a moto)? If the battery is that low cannot it put out enough CCA?

 

[guineapig]

I was researching a similar setup for my motorcycle (in regards to putting a 12V cigarette adapter to charge my iphone). I found this on ebay:
http://www.ebay.com/itm/Motorcycle-...ries&hash=item4165f8809e&vxp=mtr#ht_578wt_899

Would this drain the battery if left plugged in? I was thinking of adding a switch (that I bought from Radio shack) to manually shut off the power, as I don't want to return to a dead battery.

 

[Roadstergal]

What about a small solar charger and put it in a tank bag?

I've started looking into that - I'd like to find something that can charge a phone in a tank bag while on a moto trip, or on a backpack when we're bicycle touring.


12V outlets on bikes are mighty handy, but I've never worried about what happens when the bike's off - when I leave the bike parked, the phone comes with me.

 

[ScottRNelson]

I'll sometimes leave my GPS connected to both my KTM and my Honda. I suppose that charging one of those would be similar to charging a cell phone. I haven't had battery issues with either one, leaving it on there for a few days.

I don't know off hand the exact battery in either bike, but they're stock batteries in both, so if you're really curious, you can look it up.

 

[ahnh666]

have a power outlet...and, a usb adapter...so, i was collecting information last year...that was some of the information i collected...never thought about the 5v vs 12v...never really tried to drain a battery either to test it out....but, i've charged a garmin and cellphone while the bike was off for couple hours...never had any problems...

But USB/cell phone charges at 5V, while a bike battery is at 12V, so you can't divide the amp-hr directly. You should calculate power (voltage x current) instead. Unless the moto battery is already borderline low it should have no problem charging one cell phone battery while the bike's not running.

How did you get that info? Isn't starting more about cold cranking amps (50-60A for a few second for a moto)? If the battery is that low cannot it put out enough CCA?

 

[HappyHighwayman]

I burned out my Yamaha battery in about 8 hours leaving my hand warmers on all day.

But I think they use a ton of electricity. I re-wired them to a relay/fuse box and it doesn't happen now.

 

[Kewl Breeze]

I don't know what the answer is but what I do know is ..
- I had a fairly new battery (always on battery tender when off)
- Bought one of those multi usb outlet things to keep in tank bag (has a tiny little red power light). Battery was about 1 year old and same exact model I had previously used for 5 years on same bike.
- Never used it one time but kept it plugged up to battery and within 2 weeks starter would take more effort to start (still would start though and still on tender at nights) but each start kept taking more effort
- 1 week later battery was drained to the point where it would not start or keep a charge.
- Bought a new same brand battery, disconnected usb charger and everything seems to be fine now again.

Again, don't know the answer is and how long it actually take to drain one but if I plug up another one I'll probably disconnect usb charger cable from a y splitter altogether until needed and only while bike is on.

 

[guineapig]

Do motorcycle batteries have problems with low discharge (like how Li-Ion batteries get damaged if voltage goes below a certain level (like 3.7V)?

I've been using external li-ion USB battery charger tucked underneath my fairing to charge my iPhone during long trips. (However I noticed that due the proximity of engine, they do get hot, even when not charging anything). I'm a bit worried that my li-ion external battery may explode if they go past a certain temperature on a really hot day, so moved it to my jacket pocket instead.

(Basically: http://www.energizerpowerpacks.com/us/products/xp8000/ and similar li-ion based external batteries).

I have several solar panels, but the problem that I have is that leaving any type of electronics out in the open charging in the sun = typically means that everything is missing when you get back. Hence, I went the external battery route. However, if I can get a 12V charger setup (hooked from battery), then I can avoid external battery route all together. I'm thinking of ordering that ebay item I posted, and putting a manual switch to kill its power, so as to avoid dead batteries (which does seem drain a little even if no cell phone is plugged in from responses above).

 

[cynner]

I have several solar panels, but the problem that I have is that leaving any type of electronics out in the open charging in the sun = typically means that everything is missing when you get back.

Most solar chargers have an internal battery; they don't charge your phone/iPod/whatever directly. You can strap the panel to your bike to charge its battery while you ride, then when you stop you can plug in your phone and transfer the juice.

 

[monkeythumpa]

Took a camping trip on my GS and charged my phone at night (phone was off at night) straight from the battery. Not a problem for four days. The moto batteries are 12V with 14 amp hours while the phone is 5V around 1 amp hour. There are orders of magnitude difference.

 

[ST Guy]

Any accessory will discharge a battery given the time. Depends upon the draw. If you're actually charging the phone, then it will draw more current from the battery than if it's just sitting. And if it's a decent charger, it won't draw anything. The only way to tell is to measure the draw on our bike's battery with the charger plugged in but not charging anything.

'Simple solution is to use a relay to turn off the power to the accessory when the ignition is turned off. It's super easy to do.

 

[CAmudgeon]

I'd leave a 12v cigarette adapter charging 2 phones/accessories overnight on my trips. F650 always started fine. Mind you the battery will be fully charged to begin with after riding all day. That is probably crucial with a small Moto battery.

 

[DannoXYZ]

But USB/cell phone charges at 5V, while a bike battery is at 12V, so you can't divide the amp-hr directly. You should calculate power (voltage x current) instead. Unless the moto battery is already borderline low it should have no problem charging one cell phone battery while the bike's not running.

Yep, there's a regulator in the USB cigarette-lighter plug that converts the 12v down to 5v. These vary greatly in efficiency and the best-case scenario may be up to 80%. Worse case with a linear-regulator such as a LM317T would be around 38%. So let's say the USB adapter has one of those. It would take input of 13v@800ma (10.4w) and dump 8v of it to ground. So 8v@800ma = 6.4 watts lost to charge the phone at 5v@800ma = 4.0w.

Do motorcycle batteries have problems with low discharge (like how Li-Ion batteries get damaged if voltage goes below a certain level (like 3.7V)?

Yes, lead-acid batteries shouldn't be discharged below 25-30% of their capacity. The plates would get severely damaged by sulfation. So if you've got a 10ah battery, you've got 7.5ah worth of charge to play with. Round down to 7ah to give some reserve for actually starting the bike.

In the above USB-adapter example, 13v@800ma draw = 0.8ah per hour. If we have 7ah capacity to work with, then 7ah/0.8ah/hr= 8.75 hours of charging before we reach the battery's limit.