LiPo battery pack for motorcycle use

[djsb]

Hi,
I am following a thread on a motorcycle forum I frequent regularly on the topic of using a LiPo (Lithium Polymer) battery pack instead of the standard lead acid battery. I am sceptical about using these packs as they require special chargers. I feel that they can not just be substituted without modifying the motorcycles charging system. Does anyone have any experience with these battery packs and their chargers?
Thanks.

David.

[Zero999]

I don't see the point, maybe you'll save some weight but there are other places from where you can trim excess baggage.

[Kiriakos-GR]

The most important issue , are the charging time .
LiPo  needs very long time to charge , as it uses lower charging amperage.
The motorcycle its not possible to stay that long in action .

So this is the first issue .

[saturation]

LiPo do require special charging to avoid explosions.  Since you can get standard chargers than plug into a car's lighter, adapting a revised charger is theoretically possible.  

However, how LiPo will do in extreme environments SLA are exposed too, not just as a battery but as a safety issue: high heat, freezing cold, etc., plus protective casing in case of a crash are problem that needs addressing.  Further the charger has to function perfectly to never overcharge LiPo and its consequences.  In use, it should take the shock, vibration the humidity and ambient temp exposures of a moving vehicle.

This is the large collection of explosions, fires, misuse etc., using LiPo technology.  Live and learn, many videos:

http://www.rcgroups.com/forums/showthread.php?t=209187

[KTP]

There are other chemistries that are a bit safer.  I am currently building a ebike out of LiMn Sony 26650VT cells (4.1V 2500mAH).  I have considered LiPo but would like to be able to sleep at night while it is charging.

[Zero999]

Are you talking about a conventional motorcycle which just uses a battery to start the engine or an electric motorcycle which uses electricity for propulsion?

If it's for propulsion, 4.1V 2.5Ah cells won't get you very far unless you connect lots of them in series to get a much higer voltage, say 30 to get 123V.

[KTP]

Are you talking about a conventional motorcycle which just uses a battery to start the engine or an electric motorcycle which uses electricity for propulsion?

If it's for propulsion, 4.1V 2.5Ah cells won't get you very far unless you connect lots of them in series to get a much higer voltage, say 30 to get 123V.

Not to hijack this thread but I must come to my defense.

ebike = electric bicycle, and yes the 4.1V 2.5AH cells are  paralleled and series connected.  I currently have a small 9 pound battery made up which 45 volts off the charger at 10 AH and can output over 100 amps if needed (I don't).  I can probably only go about 20 miles with this battery without pedaling, but I like to pedal...the motor is mostly for hills.  Here is a pic of my bike with the stealthy hub motor mounted and the batteries which I have placed temporarily in a plastic first aid box 

[David]

I do not believe that it would be possible to put them in as a "drop-in" replacement. The alternator would surely ruin them for a start! The lead acid batteries also have a high "cranking" amps value for the high current required by the starter motor. I really see no advantage at all?

[Zero999]

Connecting batteries in parallel is not a good idea, if there's a significant difference in charge between cells because a high current can flow between the near-fully charged cells and the nearly empty cells.

I do not believe that it would be possible to put them in as a "drop-in" replacement. The alternator would surely ruin them for a start! The lead acid batteries also have a high "cranking" amps value for the high current required by the starter motor. I really see no advantage at all?

Did you read his previous post? He isn't talking about a conventional motorcycle.

[David]

Connecting batteries in parallel is not a good idea, if there's a significant difference in charge between cells because a high current can flow between the near-fully charged cells and the nearly empty cells.

I do not believe that it would be possible to put them in as a "drop-in" replacement. The alternator would surely ruin them for a start! The lead acid batteries also have a high "cranking" amps value for the high current required by the starter motor. I really see no advantage at all?

Did you read his previous post? He isn't talking about a conventional motorcycle.

Ah no problem. I can't see where he mentioned it was conventional? I may be being blind though!

[Zero999]

That's my point, it isn't a conventional motorcycle, the alternator can't ruin the batteries because it doesn't have one!

[David]

That's my point, it isn't a conventional motorcycle, the alternator can't ruin the batteries because it doesn't have one!

Now I'm confused...I can't see anywhere in the thread where he said that it wasn't a conventional motorbike. He has only posted once and it doesn't mention anything in the first post? 

[Zero999]

That's my point, it isn't a conventional motorcycle, the alternator can't ruin the batteries because it doesn't have one!

Now I'm confused...I can't see anywhere in the thread where he said that it wasn't a conventional motorbike. He has only posted once and it doesn't mention anything in the first post? 

My unreserved apologies, I'm the one who's not read the thread correctly, the original posted has disappeared and I confused KYP's posts about his bike with the original poster's

[David]

That's my point, it isn't a conventional motorcycle, the alternator can't ruin the batteries because it doesn't have one!

Now I'm confused...I can't see anywhere in the thread where he said that it wasn't a conventional motorbike. He has only posted once and it doesn't mention anything in the first post? 

My unreserved apologies, I'm the one who's not read the thread correctly, the original posted has disappeared and I confused KYP's posts about his bike with the original poster's

It's good to know I'm not just going crazy 

[djsb]

Too solve the confusion I'm talking about a conventional motorcycle that uses a lead acid battery. The people proposing the use of a LiFePO4 battery pack are hoping to save some weight

http://www.mzriders.com/viewtopic.php?f=3&t=4358

However I posted on the forum that the charging of the batteries would be a problem. I just wanted some other views.
Thanks.

David.

[Zero999]

You should use a bike with aluminium frame, engine block and wheels and add an aerodynamic faring before even thinking about saving weight on the battery.

[David]

I think I can safely say that changing the battery is going to make no difference whatsoever!

[Pyr0Beast]

If you add a protective circuit to the battery (temperature, voltage, current) it should be fine, also with load balancing to extend its life.

And don't run more than 3 or 4 cells in parallel.