LiPo battery pack for motorcycle use - Page 1
Forum section: electronics / projects

author: djsb
author_rank: Super Contributor
timestamp: July 07, 2010, 10:27:28 pm
content: 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.

author: Zero999
author_rank: Super Contributor
timestamp: July 07, 2010, 11:07:21 pm
content: I don't see the point, maybe you'll save some weight but there are other places from where you can trim excess baggage.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 07, 2010, 11:36:39 pm
content: 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 .

author: saturation
author_rank: Super Contributor
timestamp: July 07, 2010, 11:38:35 pm
content: 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

author: KTP
author_rank: Frequent Contributor
timestamp: July 08, 2010, 02:49:46 am
content: 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.

author: Zero999
author_rank: Super Contributor
timestamp: July 08, 2010, 08:02:19 am
content: 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.

author: KTP
author_rank: Frequent Contributor
timestamp: July 09, 2010, 12:36:32 am
content: Quote from: Hero999 on July 08, 2010, 08:02:19 amNot 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

author: David
author_rank: Frequent Contributor
timestamp: July 09, 2010, 08:00:01 am
content: 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?

author: Zero999
author_rank: Super Contributor
timestamp: July 09, 2010, 08:21:21 am
content: 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.Quote from: David on July 09, 2010, 08:00:01 amDid you read his previous post? He isn't talking about a conventional motorcycle.

author: David
author_rank: Frequent Contributor
timestamp: July 09, 2010, 10:01:18 am
content: Quote from: Hero999 on July 09, 2010, 08:21:21 amAh no problem. I can't see where he mentioned it was conventional? I may be being blind though!

author: Zero999
author_rank: Super Contributor
timestamp: July 09, 2010, 10:09:13 am
content: That's my point, it isn't a conventional motorcycle, the alternator can't ruin the batteries because it doesn't have one!

author: David
author_rank: Frequent Contributor
timestamp: July 09, 2010, 10:25:24 am
content: Quote from: Hero999 on July 09, 2010, 10:09:13 amNow 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?

author: Zero999
author_rank: Super Contributor
timestamp: July 09, 2010, 11:47:54 am
content: Quote from: David on July 09, 2010, 10:25:24 amMy 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

author: David
author_rank: Frequent Contributor
timestamp: July 09, 2010, 12:15:53 pm
content: Quote from: Hero999 on July 09, 2010, 11:47:54 amIt's good to know I'm not just going crazy

author: djsb
author_rank: Super Contributor
timestamp: July 09, 2010, 04:18:36 pm
content: 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 weighthttp://www.mzriders.com/viewtopic.php?f=3&t=4358However I posted on the forum that the charging of the batteries would be a problem. I just wanted some other views.Thanks.David.

author: Zero999
author_rank: Super Contributor
timestamp: July 09, 2010, 08:06:27 pm
content: 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.

author: David
author_rank: Frequent Contributor
timestamp: July 09, 2010, 08:10:36 pm
content: I think I can safely say that changing the battery is going to make no difference whatsoever!

author: Pyr0Beast
author_rank: Contributor
timestamp: July 10, 2010, 10:07:12 pm
content: 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.