1.5kg 10Ah LiFePo4 Battery including Seven Cover

[Daniel French]

Not been blogging for a while due to other commitments, but I've finally managed to get this beauty installed:-
http://www.caterhamr500.co.uk/2016/11/15kg-10ah-lifepo4-battery-inc-carbon.html

at 7.5kg less than the banner battery, and easy to fit this is definitely an 'essential' upgrade.

[Jonathan Kay]

I always enjoy your blogs, but you might like to think again about the wording of the second paragraph, which includes:

"It's important to make clear that a LiFePo4 battery is NOT a lithium ion battery, and as such is not dangerous."

As the Wikipedia article to which you link puts it:

"The lithium iron phosphate (LiFePO4) battery, also called LFP battery (with "LFP" standing for "lithium ferrophosphate"), is a type of rechargeable battery, specifically a lithium-ion battery, which uses LiFePO4 as a cathode material."

Jonathan

[Daniel French]

LiFePo4 is Lithium Iron Phosphate, and not Lithium-Ion.  For further information about the differences have a look at this article:-
https://www.batterystuff.com/kb/articles/battery-articles/lithium-battery-overview.html 

Either way to be totally clear, I've changed my post to say 'Lithium-Ion' and also linked to the above as well as the Wiki article which is a touch misleading.

[Jonathan Kay]

It's one type of "lithium ion battery", and, as you say, it's safer than some other types.

Jonathan

[Alan Archer]

Your blogs can cost a man a lot of money Daniel, thanks for sharing yet another great article. 

Alan

[Daniel French]

In terms of the Lithium-Ion thing - what I'm getting at is LiFePo4 batteries aren't the type that are blowing up, but are safe, and have slow discharge rates... 

Alan (and anyone else reading this) - these are a MUST BUY.  It's not far off removing a tillet seat in terms of weight saving, and for £320 it's practically a no brainer.  Sorry to hit you in the pocket with such a necessity , but when you hold one for real and feel how little it weighs you know it'll be money WELL SPENT 

***disclaimer***
There is nothing in this for me if you buy one - apart from the satisfaction of helping a fellow Seven owner to add lightness to their car 

[Alan Archer]

Hi Daniel, never doubted that and appreciate you taking the time to help others who want the help :) I wonder if enough of us want them if we could get a group buy together? 

I can see from the pictures that you have kept your heater in, good man, I hear so many saying that the heaters are not worth having but I have to disagree, I don't think my other half would even get in the car without. 

Alan

[DJ.]

It does look good, and is quite a large weight saving, but I think I will spend my £320 on 15 tanks of fuel.

Having said that if you were more local, I'd be offering to give your old battery a new home

[Alan Archer]

You must have a source of really cheap petrol, please share. :)

Alan

[DJ.]

No I'm just a chicken and fill up early. It's usually £18 to £22. I did manage to squeeze in £28 once when the gauge was below the red and fuel was more expensive.

[nickh7]

Junk that heater , it will save so much weight and it will save you money as you could sell it to those who need a bit of heat when blatting

I have to say it looks fab and that really is a good weight saving

[Julian H]

Top bloke Daniel, good to have you back. 

An earlier adopter to LiPo weightsaving, I have been running mine for 16 months now without issue. Its got to be the best bang for buck in Seven weightsaving there is.  Love the CF plate on top.

Julian

[Martin J]

That does look very neat.

[John Vine]

Very interesting topic!

To help other readers, and for the sake of clarity, it's worth pointing out that JK's statement (in post #2):

...you might like to think again about the wording of the second paragraph, (...."It's important to make clear that a LiFePo4 battery is NOT a lithium ion battery, and as such is not dangerous....")

is correct, and that the statement (in post #3):

LiFePo4 is Lithium Iron Phosphate, and not Lithium-Ion.

is incorrect.

 

LiFePO4 (why don't subscripts work here?) is one of several cathode materials used in lithium-ion batteries.  Another is LiCoO2.  Both come under the heading of Lithium-Ion because both involve the transfer of lithium ions from the cathode to the anode during charging and vice versa during discharging.

It's also worth adding that the quoted article by "batterystuff.com" is itself misleading as it suggests that "Lithium-Ion" and "Lithium Iron Phosphate" are separate "chemistries", whereas in fact the latter is simply an example of the former (as JK correctly states).

If you want to delve deeper, this website contains a detailed explanation of battery chemistry in general, and lithium-based chemistry in particular.

 

Hope this helps!

JV

[Daniel French]

Awesome info - thanks John... I went on some info someone else gave me, which clearly was incorrect.  I've updated my blog post to be more accurate.

I hope everyone has got their batteries on order, or at least on their Xmas lists 

[John Vine]

I've just come across this page of the Battery University website, sponsored by Cadex Electronics Inc of Vancouver. 

It contains a detailed description of the various Li-ion "chemistries", and summarizes very well how LiFePO4 compares with others.

JV

 

[Alan Archer]

So reading the article, does paragraph coped below not mean that LiFePo4 is not ideal for car batteries? 

"Li-phosphate is often used to replace the lead acid starter battery. Four cells in series produce 12.80V, a similar voltage to six 2V lead acid cells in series. Vehicles charge lead acid to 14.40V (2.40V/cell) and maintain a topping charge. With four Li-phosphate cells in series, each cell tops at 3.60V, which is the correct full-charge voltage. At this point, the charge should be disconnected but the topping charge continues while driving. Li-phosphate is tolerant to some overcharge; however, keeping the voltage at 14.40V for a prolonged time, as most vehicles do on a long drive, could stress Li-phosphate. Cold temperature operation starting could also be an issue with Li-phosphate as a starter battery"

How are you supposed to stop it charging once the battery is charged?

Alan

[Jonathan Kay]

Cold temperature operation starting could also be an issue with Li-phosphate as a starter battery

That's probably only answerable by experience in use, and there should be enough by the end of this winter. (Here's a discussion of Teslas at low temperature.)

How are you supposed to stop it charging once the battery is charged?

Are you thinking of charging from the car while it's running, or from a mains charger, or both? There are dedicated conditioning chargers for lithium ion batteries, but I haven't seen anything specific for this type.

Jonathan

[Alan Archer]

Hi Jonathan,

I know there are specific chargers for litho batteries, however it is talking about not having the 14.4v input from the car going in for too long once fully charged. Short of installing complicated electrics I don't see how you would stop this.

Alan

[Roger Ford]

ith four Li-phosphate cells in series, each cell tops at 3.60V, which is the correct full-charge voltage. At this point, the charge should be disconnected but the topping charge continues while driving.

Does that make sense to anyone else? If the batteries are at 14.4v, and the alternator is providing 14.4v, then no current is going to flow in either direction. What's this "topping charge" they're talking about? The only thing I can think is that the battery voltage is supposed to be able to drop lower after charging, but can't. I'm not sure why that should be - in my experience with "conventional" LiIon batteries which have a full-charge voltage of 4.2V, they'll hold that voltage for some considerable time when disconnected from the charger.

[Daniel French]

Not sure if I'm answering the questions correctly or not, but the battery has the complicated charging electronics built into it - speak to Carsten directly about this though, but in essence (and as far as I understand) you can use this LiFePo4 battery just like a normal lead acid battery, which is why I took the punt.

[Jonathan Kay]

... but the battery has the complicated charging electronics built into it...

Yes. That seems to be the key. From what I can tell this type of cell is pretty tolerant, but you won't get maximum charge in without that extra control.

If the batteries are at 14.4v, and the alternator is providing 14.4v, then no current is going to flow in either direction. What's this "topping charge" they're talking about?

Charging curves in this article.

Jonathan

[Daniel French]

But you'll get more than enough, and if you want the maximum then get the CTEK charger I've listed on the blog post 

[Roger Ford]

I find it hard to see how it can have "complicated charging electronics" in it and still maintain a 400 amp path from the cells to the outside world. About the only way I can imagine that happening is if there was a way to disconnect the "starting" circuit from the "charging" circuit. But that would need a solenoid as large as the one on the starter motor.

[Simon.Rogers]

As many will know I was one of the first to use and sell LiFePo4 batteries back at the end of 2010.

I did quite a bit of testing and development trying to find comparable cranking power.

Its not a simple comparrison and I found that I had to more than double the CCA (Cold Cranking Amps) figure when converting to PCA (Pulse Cranking Amps).  The main issue is that the Lithium has a flat line of power delivery where the regular battery has an initial spike which I feel is important.

That spike gets the crank turning - like towing a lorry as a strong man.  Its the start that takes the most effort, once rolling it is far easier.

In the end although they worked for customers using the car for regular longer journeys they did not work for me.  In competition we had to many engine starts for time running at anything more than tickover.

Last year i fitted the Varley  

http://www.meteormotorsport.com/shop/caterham/batteries-electronics/varley-lithium-li5-battery/

It has been far more successful than any other type or model.  However for my use it still struggles over a double weekend or double drive.  I am 100% certain that would not be the case for others doing other type of work.  At a hillclimb or sprint you may start the engine 5 or 6 times between leaving the pits and taking a run. x 4 or 5 runs a day and perhaps x 2 drivers.  It can not cope and needs a jump.

Lets face it I would have done less than 5 minutes running at full revs for all those starts.   It is however a match for my PC680 Odyssey in terms of power.  Others have not come close.  

Carstens unit is double the Ah so that looks very interesting and it looks great.  

My battery is just fixed using 3M Dyloc HD velcro.

What is the PCA of Carsten's?