3.2 lb. LiFePO4 Track Battery
06-10-2011 | 07:34 PM
#27
Great thread. I am very interested in the art of weight reduction. I have been thinking about gutting my stock seats and taking out the power and the heat. I just need to make a slider bracket for the drivers side. But yeah, keep us posted!
06-29-2011 | 09:01 AM
#28
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I enjoy seeing threads like this. It's only a matter of time before lithium batteries are the norm for all cars; kudos on being an early adopter and reaping the benefits. Interesting that you chose 38120 cells. I may have missed it, but where did you get the cells from? How are you charging, with a balanced r/c charger?
By the way, as an aside to the guy who was wanting to use LiPos...please consider the safety issue:
http://www.youtube.com/watch?v=IsgnZCEeqsE
As a shameless plug, there is a forum-sponsor option for the less DIY-oriented amongst you.
By the way, as an aside to the guy who was wanting to use LiPos...please consider the safety issue:
http://www.youtube.com/watch?v=IsgnZCEeqsE
As a shameless plug, there is a forum-sponsor option for the less DIY-oriented amongst you.
06-29-2011 | 10:50 AM
#29
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Excellent point and vid. Caveat Emptor to those that use other than LiFePO4 cells. LIPO batteries and most other Lithium batteries catch fire when misused or if they fail, whereas this is impossible for a LiFePO4 chemisty battery.
It's all about the chemistry and the construction... and after that your own common sense to use what's best rather than the more dangerous Lithium chemistries. Cylindrical (wrapped) cells (vs sheets in a pouch type prismatic cells) are superior for high discharge as they improve performance as they are discharged (wrapped sheets get closer together as they warm and expand) vs the opposite for prismatic.
The ones I used are seen here at www.headway-headquarters.com but are available other locations. Charging is (when required outside the car) with a LiFePO4 charger, else the alternator does charging just fine.
It's all about the chemistry and the construction... and after that your own common sense to use what's best rather than the more dangerous Lithium chemistries. Cylindrical (wrapped) cells (vs sheets in a pouch type prismatic cells) are superior for high discharge as they improve performance as they are discharged (wrapped sheets get closer together as they warm and expand) vs the opposite for prismatic.
The ones I used are seen here at www.headway-headquarters.com but are available other locations. Charging is (when required outside the car) with a LiFePO4 charger, else the alternator does charging just fine.
11-27-2011 | 09:01 AM
#32
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http://www.batteryspace.com/smart-ch...de-use-ce.aspx
Others are out there, but should have similar specs.
•The Smart Charger is designed for rapidly charge 10Ah - 60Ah 12.8V (4 cells ) LiFePO4 Battery pack. It features a three stages charging method without overcharge the battery. 10A max charge rate.
Others are out there, but should have similar specs.
•The Smart Charger is designed for rapidly charge 10Ah - 60Ah 12.8V (4 cells ) LiFePO4 Battery pack. It features a three stages charging method without overcharge the battery. 10A max charge rate.
11-27-2011 | 09:47 AM
#35
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http://stores.headway-headquarters.c...EV,/Detail.bok
The specs for the batteries I used show no problems - however charge temp =>0 C. Not sure how the spec was arrived at, so ??. I've only used it for warm weather, the full size is in now
The specs for the batteries I used show no problems - however charge temp =>0 C. Not sure how the spec was arrived at, so ??. I've only used it for warm weather, the full size is in now
11-27-2011 | 09:48 AM
#36
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11-27-2011 | 01:37 PM
#39
This is awesome. Looking forward to your track testing. My car is sitting at about 2900lbs with a full tank of gas right now but I haven't gotten very serious about weight reduction yet.
Next on the list is new seats, taking out interior carpeting, and sound dampening material in the engine bay, but all this will probably be offset when I put the roll cage in.
As far as weight reduction goes I have a catless midpipe, catback, back seats removed, trunk liner removed, lightweight wheels, and that's about it.
Next on the list is new seats, taking out interior carpeting, and sound dampening material in the engine bay, but all this will probably be offset when I put the roll cage in.
As far as weight reduction goes I have a catless midpipe, catback, back seats removed, trunk liner removed, lightweight wheels, and that's about it.
Last edited by Arca_ex; 11-27-2011 at 01:48 PM.
11-27-2011 | 04:09 PM
#40
11-27-2011 | 05:34 PM
#42
Found this on the Shorai site, good to know:
*
Q. I hear that lithium crank poorly when it gets cold, is that right?
A.Lithium do increase in resistance more as temperature drops, compared to lead-acid. However, they also react to cranking under cold conditions in a much better way. Lead-acid will increase resistance on each subsequent cranking attempt, until it won’t turn over. If your LFX fails to start the engine on first crank, that first crank has warmed the battery, and the second attempt will be much stronger, and so on until you get a good start.
Shorai LFX are much better in cold-weather conditions than other-brand lithium starter batteries, due to our eXtreme-rate formulation with low resistance. Down to about 20 degrees*fahrenheit (-7C) most users find that they can start normally on first crank. If your headlight comes on at key-ON, it is good for the batteries to flow some current before cranking in cold weather. The suggested headlight-on time before cranking depends on the temperature. If starting at 40f (5C), 30 seconds will help wake the battery and increase cranking performance. If at 0f (-17C), leave the lights on for 4~5 minutes before cranking. The result will be a better first crank, and longer battery life. Any other accessories that can be turned on before cranking can also be used for this purpose, such as heated gear, radio, etc...
Q. I hear that lithium crank poorly when it gets cold, is that right?
A.Lithium do increase in resistance more as temperature drops, compared to lead-acid. However, they also react to cranking under cold conditions in a much better way. Lead-acid will increase resistance on each subsequent cranking attempt, until it won’t turn over. If your LFX fails to start the engine on first crank, that first crank has warmed the battery, and the second attempt will be much stronger, and so on until you get a good start.
Shorai LFX are much better in cold-weather conditions than other-brand lithium starter batteries, due to our eXtreme-rate formulation with low resistance. Down to about 20 degrees*fahrenheit (-7C) most users find that they can start normally on first crank. If your headlight comes on at key-ON, it is good for the batteries to flow some current before cranking in cold weather. The suggested headlight-on time before cranking depends on the temperature. If starting at 40f (5C), 30 seconds will help wake the battery and increase cranking performance. If at 0f (-17C), leave the lights on for 4~5 minutes before cranking. The result will be a better first crank, and longer battery life. Any other accessories that can be turned on before cranking can also be used for this purpose, such as heated gear, radio, etc...
11-27-2011 | 05:44 PM
#43
Neither do I, but like myself recently you may find yourself at a late season event where it just may encounter such conditions. Mine just cranked slow and I didn't have the info from the previous post, but then I also have triple or quadruple the output you have. Don't be so hostile about this. I am only adding to the knowledge base and clearly you weren't aware of this since you haven't experienced it yet.
11-27-2011 | 06:57 PM
#44
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Not being hostile 
see I'm smiling and yes I am aware of LiFrPO4 chemistry and it's physical attributes under discharge conditions such as getting warmer. I always enjoy an in-depth discussion, just most peps want to cut to the chase, not understand how things really work and why I've found.
For example, concerning warming - I choose these large cylindrical (round, wrapped) LiFePO4 cells over the more typical prismatic (multiple pouch) cells for my project on purpose. Many of the small car sized batteries out there I noticed use the prismatic cells (bunch of pouches in a case). They are not that expensive and I could have easily bought one and be done with it. It also makes packaging easy and it looks like a typical battery but there is a small problem.
As they discharge and heat up the cathode and anode expand away from each other and separate, intimate contact is reduced, reducing current output, esp. w/high discharge periods, i.e., car starting loads. So this counteracts the benefits of warming ... not ideal.
Round wrapped cell on the other hand, do the same thing, they expand as they heat up. The difference is that being wrapped and in a metal case, this expansion actually forces the anode and cathode closer together as they expand. Maximum output current capacity increases due to the more intimate contact! And bigger cells are far simpler to construct and manage than multiple tiny LiFePO4 cells.
So large cylindrical cells offer a physical characteristic that improves performance in two ways when used in an automotive application!! That's just one of the consideration out of many that went into parts selection before constructing this project.
see I'm smiling and yes I am aware of LiFrPO4 chemistry and it's physical attributes under discharge conditions such as getting warmer. I always enjoy an in-depth discussion, just most peps want to cut to the chase, not understand how things really work and why I've found.For example, concerning warming - I choose these large cylindrical (round, wrapped) LiFePO4 cells over the more typical prismatic (multiple pouch) cells for my project on purpose. Many of the small car sized batteries out there I noticed use the prismatic cells (bunch of pouches in a case). They are not that expensive and I could have easily bought one and be done with it. It also makes packaging easy and it looks like a typical battery but there is a small problem.
As they discharge and heat up the cathode and anode expand away from each other and separate, intimate contact is reduced, reducing current output, esp. w/high discharge periods, i.e., car starting loads. So this counteracts the benefits of warming ... not ideal.
Round wrapped cell on the other hand, do the same thing, they expand as they heat up. The difference is that being wrapped and in a metal case, this expansion actually forces the anode and cathode closer together as they expand. Maximum output current capacity increases due to the more intimate contact! And bigger cells are far simpler to construct and manage than multiple tiny LiFePO4 cells.
So large cylindrical cells offer a physical characteristic that improves performance in two ways when used in an automotive application!!
That's just one of the consideration out of many that went into parts selection before constructing this project.
12-13-2011 | 04:44 PM
#45
Looking into this at the moment, it seems the best cell for this now is the 38120HP.
weight is 330g, the same at the 38120p, but performs a little better. Max discharge pulse is rated at 25C, still 8Ah capacity.
weight is 330g, the same at the 38120p, but performs a little better. Max discharge pulse is rated at 25C, still 8Ah capacity.
12-13-2011 | 05:05 PM
#46
Voltphreaks uses the large cylindrical cells
I've seen the results of these large cylinder cells going off because they did not have an electronics control board monitoring and protecting them. You have more ***** than me to build and use your own that way.
They have it rated for -22 degF - 140 degF normal operating range with a 170 degF max rating. Most people don't realize that the Braille, Odyssey, etc. batteries also have a 170 degF max temp rating. I wouldn't put one in the engine bay myself.
.
I've seen the results of these large cylinder cells going off because they did not have an electronics control board monitoring and protecting them. You have more ***** than me to build and use your own that way.
They have it rated for -22 degF - 140 degF normal operating range with a 170 degF max rating. Most people don't realize that the Braille, Odyssey, etc. batteries also have a 170 degF max temp rating. I wouldn't put one in the engine bay myself.
.
Last edited by TeamRX8; 12-13-2011 at 05:23 PM.
12-13-2011 | 06:33 PM
#47
I have huge *****
Seriously though, I have not done anything yet. I am using a 17lb deka. It starts the car, but my minimum was lowered to 2300 for 2012. I need to find another 100lbs.
The controllers don't seem too expensive, would that not solve the issues?
Seriously though, I have not done anything yet. I am using a 17lb deka. It starts the car, but my minimum was lowered to 2300 for 2012. I need to find another 100lbs.
The controllers don't seem too expensive, would that not solve the issues?
12-13-2011 | 09:56 PM
#48
anyone know about this guy:
http://www.lithiummoto.com/battery-sizing.html
not much info on the site, but I can see from the pics that he is using a123 systems
ANR26650M1A in multiples to get to the rated Ah. I have no idea where he comes up with the CCA numbers he's stating.
http://www.lithiummoto.com/battery-sizing.html
not much info on the site, but I can see from the pics that he is using a123 systems
ANR26650M1A in multiples to get to the rated Ah. I have no idea where he comes up with the CCA numbers he's stating.
12-31-2011 | 12:55 PM
#50
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(later)... in fact these new ones have awesome specs esp. for car use! The max charge rate is huge @80A vs 16A for the 38120Ps, I'd say that's approaching supercapacitor charge levels! I'm going to a set of these and retrofit them!
Last edited by Spin9k; 01-02-2012 at 08:48 AM. Reason: after another look at these... :)