Help with battery packs

[minibeer]

New here, lots of great stuff on this site. Been looking around for a while, thought I'd finally post as I need some help with a project.

http://shop.tristatepse.com/Feniex-Apollo-F6-F6.htm
I'm going to be purchasing 2 of these lights to use on my bike. Each light is 6 LED @ 4 watts each, total of 48 watts. At 12 volts this requires 2 amps. 2 lights will require 4 amps. They are rated from 9-13 volts DC.
I'm trying to find a rechargeable battery pack to put into a pack on my bike. I don't want it to be huge but it has to be large enough to provide 3-4 hours of run time for both lights. I'm not new to the electronics scene but I'm having some confusion figuring mAh and the other variables to this project. Also I'm trying to figure out what type of battery would be best suited for this application. Does it matter if I use 9 volts or 12? Does this affect the size of the battery? Lots of things to consider, all input is valued.

 

[BobK]

A battery will be rated in mAH (milliamp hours) or AH (Amp Hours).

Since you have two lights that draw 4A, your battery will have to have about 12AH (or 12000mAH) in order to run the lights for 3 hours.

I would look at 3S Lithium batteries that are nominally 11.1V.

Bob

 

[lilmatt119]

I agree with Bob. Lithium would seem to be the way to go.

Are you using these lights as "headlights" or just lights for riding at night so you have less chance of getting run over?

 

[minibeer]

I was going to put 1 red flashing one on the rear and 1 flashing white one on the front, both for extreme visibility because drivers here are extremely distracted and inconsiderate. I'll also have a steady white headlight on the front but I'll probably just use a cheap battery light for that.

Here's a battery pack I found on Amazon:

http://www.amazon.com/RAVPower-15000mAh-Portable-External-Battery/dp/B00DVB7F0S/ref=pd_ybh_2

 

[lilmatt119]

Awesome. The flashing will extend the life of the battery pack to some extent, and as you already mentioned help to increase visibility.

 

[Gryd3]

I was going to put 1 red flashing one on the rear and 1 flashing white one on the front, both for extreme visibility because drivers here are extremely distracted and inconsiderate. I'll also have a steady white headlight on the front but I'll probably just use a cheap battery light for that.

Here's a battery pack I found on Amazon:

http://www.amazon.com/RAVPower-15000mAh-Portable-External-Battery/dp/B00DVB7F0S/ref=pd_ybh_2

As a biker, motorcycle rider, and car driver I urge you to watch the brightness of the lights you are putting on your bike.
Many motor vehicle acts prohibit the use of flashing lights for anything other than emergency vehicles or traffic advisors. You are a bicycle, so this is acceptable for you, just be aware of a couple other points.
Putting extremely bright flashing lights on your bike will certainly grab attention but will also distract motorists. Additionally, many people suffer from 'Target Fixation' so they may be looking right at you when they nail you with their mirror for being too close.

And on a personal note. Bright lights without the proper lens introduce glare and can inhibit night vision. There is a reason HID headlights should only be placed in the appropriate housing... This same reason should have you build a safe device not just for you, but EVERYONE else too. Please take this into consideration.
(If your bike light hurts to look at, it's too bright!)

 

[lilmatt119]

These notes are extremely true, and something I didn't think to mention. Normally around my area bicyclists are somewhat encouraged to have a slow flashing light. Not like a strobe light, but more like a 4-way hazard light on a car. Check local laws, and as Gryd3 said, don't make them too bright.

 

[minibeer]

I have thought about these things as well. I will have the light angled down to some extent so as to keep the light out of people's eyes and also to create a flashing pattern on the ground around me (for night riding). There are similar products (i.e., laserlane) but they are cheap junk and aren't really that effective. I do alot more day riding and not so much night riding. While they lights will be very bright for night riding, I needed something that would really stand out when it's sunny and bright. People in Florida drive so terribly that I need something extreme to stay out of trouble - I've already been hit by a motorist once (she was on the phone). These lights have several flash patterns, I can choose something moderate so as not to create fixation.

 

[lilmatt119]

Sounds like a good plan. the ground effect is actually very effective, and from some studies I have seen on emergency warning lights (Being a volunteer firefighter in NC), ground/ambient changes in lighting actually catch attention more than the light itself.

 

[minibeer]

I found this battery pack on Amazon. I know it's Chinese junk and I wouldn't rely on it it to heavily to start my car but it's only going to power 2 - 2 amp LED lights. It's rechargeable and the perfect size. Input?

 

[lilmatt119]

Have you got a link for it?

 

[minibeer]

Sorry! Don't know how I forgot to do that lol..

http://www.amazon.com/Hot-sale-1500...5743758&sr=8-1&keywords=15000mah+jump+starter

 

[lilmatt119]

Reviews on amazon are none too nice as to the longevity of the pack. Common complaint seems to be the charging circuitry fails after a while...If it wasn't $55 I'd say go for it...If it were my money, I believe I would continue to look for a better option.

My only other concern is what cells it uses...If you are familiar with lithium batteries at all then you know the deal with Ultrafire cells, so I won't blab on like some folks have on other sites about how dangerous they are (they say are, I say can be, but only if one is really stupid with them lol. I've got probably around 30 ultrafire cells, and yes, they suck, but they work until you can get some good cells).

 

[Gryd3]

Sorry! Don't know how I forgot to do that lol..

http://www.amazon.com/Hot-sale-1500...5743758&sr=8-1&keywords=15000mah+jump+starter

Something does not seem right about that thing...
Full charge time in 4 Hours would require 3.75Amps, but the input states only 2Amps... so charge time would certainly be much longer. That also looks like a tiny little battery to be able to put out that much energy.
Id look for an alternative myself.

 

[lilmatt119]

One thing that i noticed in the reviews was someone stated it was actually only 12000 mah instead of 15000, so that could change things a little. I'm no math expert anymore, been too many years since highschool lol

 

[minibeer]

Reviews on amazon are none too nice as to the longevity of the pack. Common complaint seems to be the charging circuitry fails after a while...If it wasn't $55 I'd say go for it...If it were my money, I believe I would continue to look for a better option.

My only other concern is what cells it uses...If you are familiar with lithium batteries at all then you know the deal with Ultrafire cells, so I won't blab on like some folks have on other sites about how dangerous they are (they say are, I say can be, but only if one is really stupid with them lol. I've got probably around 30 ultrafire cells, and yes, they suck, but they work until you can get some good cells).

I know very little to nothing about batteries. I looked into lithium batteries but found that you have to use the right charger or you could ruin them charging. I know even less about how to find the right charger. I was hoping to find a pre-made battery pack that I could just throw on the charger overnight after a ride. That's why the amazon one piqued my interest. But I don't want to get stuck with a piece of junk either. I've searched all over for lithium packs that have the 15000mah I need but they are super expensive. Maybe I'm not looking for the right thing?

 

[lilmatt119]

No, you're probably looking at the correct things lol. Good lithium cells are still ridiculously expensive. For the most common size, an 18650 (panasonic, sony, AW, etc), you could pay anywhere from $10-$20 for a single cell. However, they are worth their weight, as the brands I mentioned and at the prices I mentioned, normally have a protection circuit built in to keep the cell from discharging too far, ensuring the cell can be used for a long time indeed.

As for my mention of Ultrafire, If you see that brand name in a battery cell, stay away for the most part. I ordered mine only to have a solid base of cells to keep my flashlights running until I could get a solid base of good cells. I was even running unprotected Ultrafires, which according to some folks should have exploded as soon as I looked at them lol. However, they have not.

With that pack you found, it is possible the charging problem could be an easy fix, but that's a pretty good gamble.

Check this one out, it has a 2A 12v output available, and the company RAVpower has numerous 4 and 5 star reviews on all the products they offer. The one I am linking to has over 70 total reviews with an average rating of 4.5 stars.

http://smile.amazon.com/RAVPower-15...19&sr=1-1&keywords=15000+mah+12v+battery+pack

You could also use it to charge your phone or other USB device while out on the bike ride, which I'm sure would come in handy. I am aware that it may be underpowered at 2A, so I'm still looking to see what I can find.

 

[lilmatt119]

http://smile.amazon.com/20000mAh-Mu...-fkmr3&keywords=15000+mah+12v+4a+battery+pack

There is another option that has a 12v 4a output, and 20000mah capacity, and over 300 5 star reviews. With that many reviews, it's a good bet it's a quality product that does what it says it does, however it is expensive (for my blood anyway lol).

 

[minibeer]

I like both of these battery packs. My only reservation is I need at least 4 amps @ 12 volts. This uses up all of the available power from the round DC port. I can't use the USB ports for the lights as they are only 5 volts, the lights are a minimum of 8.4 volts. These packs have great power but a limit on how it is used. I'd like to be able to use 1 battery for tail and head light but with my current configuration it's too much. I liked the first pack I linked because I could make a distribution center and run everything off the "jump start" port. If there was a pack that wasn't so focused on USB power it would be perfect. It's a lot to consider, there's gotta be one out there that works.

 

[minibeer]

I think I've settled on this one:

http://www.amazon.com/RAVPower®-230...d=1426124774&sr=8-1&keywords=RAVPower+RP-PB14

It's a bit pricey but it's plenty of power and supports 2 x 2amp lights on the DC out port. I also have the option of using the USB ports should I need them. I hate spending this much but it's the best thing I could find for the money that isn't Chinese junk.