Saturday, 12 November 2016

1.5kg 10Ah LiFePo4 Battery inc Carbon Seven Cover

Although I've not (properly) been out in the R500 since the Llandow track day, my desire to keep chipping away at the weight of the car is still there... The next 'lightness added' is a 1.5kg, yes 1.5kg!!! 10Ah LiFePo4 Battery with a CNC cut custom carbon fibre seven cover, and it is absolutely one of the best weight saving goodies I think you can get in terms of bang for your buck.
Beautiful 1.5kg 10Ah LiFePo4 Battery inc Carbon Seven Cover
Beautiful 1.5kg 10Ah LiFePo4 Battery inc Carbon Seven Cover
Let's get the 'technical stuff' out of the way first...
Lithium battery technology can be a touch confusing at times, so for a clear overview this article is good at explaining everything. The battery is built with A123 Cells with a balancing module inside which means it is used just like a normal acid battery. The battery can be charged with the standard alternator but for a complete recharge this CTEK charger should be used (which I have purchased).

It is recommended in Caterham installations to have a battery master cut off switch because the Caterham electronics have a tendency to drain the battery (just a bit) when the car is not running, and as the the battery capacity is lower, the battery will discharge somewhat faster.

During the winter, it is recommended to put the battery inside the house but that is the same as with normal acid batteries (I'm not going to bother though).  A big plus of LiFePo4 technology, is that the battery self discharging (while not plugged into anything) is much lower than the discharge rate of an acid battery and also the lifetime is a longer too.

So onto my 'battery journey':-
The car was originally supplied with the rather 'tardy' Banner battery and tray, which weighed in at just over a whopping 9kg with tray...
Original Banner Battery and tray weighed in at over 9kg!
Original Banner Battery and tray weighed in at over 9kg!
Naturally the Banner battery had to be swapped out to what was (at the time) the lightest and 'safest' battery option, with a few lashings of carbon too!
Odyssey Extreme Battery with Bespoke Cage and Housing in Caterham R500
Odyssey Extreme Battery with Bespoke Cage and Housing in Caterham R500
The Odyssey Extreme PC680 battery with carbon cage (some of which I made) weighed in at 5.5kg which was over 3.5kg saved off the Banner Battery.  I wrote a full post about the battery swap out, and a link to that is here.
My partially home-made carbon housing for the PC680 battery upgrade.
My partially home-made carbon housing for the PC680 battery upgrade.
And now, I have this beauty!  A 10Ah LiFePo4 Battery that weighs less than 1.5kg, has it's own cage and a beautiful CNC cut Seven in the top, in Carbon!  Can't wait to get it in the car!!
A 10Ah LiFePo4 Battery that weighs less than 1.5kg, has it's own cage and a beautiful CNC cut Seven Carbon cover
A 10Ah LiFePo4 Battery that weighs less than 1.5kg, has it's own cage and a beautiful CNC cut Seven Carbon cover
So the PC680 Odyssey Battery was removed sharpish, and I began to put the new battery in a number of different locations to see where it would fit best, also taking into account what would look like the 'cleanest' installation.  I settled on putting the battery in front of the heater unit, pretty much just where the old two batteries were.

I stumbled on a slight problem though, as there just wasn't quite enough space (due to the red bolt on the right of the picture below).
With the initial 'portrait' carbon cover the battery wouldn't quite fit where I wanted it to
With the initial 'portrait' carbon cover the battery wouldn't quite fit where I wanted it to
I took some pictures of where I wanted to install the battery, sent them over to Carsten and we agreed on making a new 'landscape' style top with the battery terminals on the front of the carbon housing top.

This took a couple of weeks to come through, and now it was time for the full fitting!

Firstly I test fitted everything, measured and lined everything up - this seemed to take an eternity as I was desperate to get the battery in, but I took my time as I wanted to do a good job.  Upon having everything test fitted and happy with where the final battery position was going to be, I thought I'd just double check to see if the engine turned over ok on such a small battery (it doesn't seem possible that it could) but it did; with flying colours too - as good as, if not better than with the PC680 battery!
Test fitting of landscape topped battery cage and wiring in progress
Test fitting of landscape topped battery cage and wiring in progress
The battery is mounted on a laser cut custom (matte black powder coated) aluminium cage, and has some foam strips too, so everything is held in place perfectly with no chance of rattles / movement.  The battery is sandwiched between the base and the carbon top with some long ProBolt aluminium bolts which are encased in some carbon tubes (it all looks lovely) and then the allen bolts secure everything to the car with rivnuts.

The rivnuts naturally required riveting into the car, and as I wasn't entirely sure what was below the panel I had decided to rivnut into, I thought it wise to remove the panel.  But to get access to all the rivets in the panel the heater element and fan had to be removed.
Heater element and fan needed removing to get access to all the rivets holding the metal panel below secure
Heater element and fan needed removing to get access to all the rivets holding the metal panel below secure
Using a 3mm metal drill bit, all of the rivets (about 10) were drilled out (with any remaining pins tapped through) and then the panel just lifted out - this is well worth doing as it made lining everything up, marking, drilling etc so much easier than it would've been had it stayed in situ.

A little over a year ago, one of my rear wings was knocked off by an X5, which meant I needed to fit some rivnuts, and bought this rivnut tool.  The rivnut tool is required to fit the four rivnuts that the battery cage and ProBolts fit into, and the picture below is of two rivnuts in, with the other two holes for the final two rivnuts (which will be fitted when the panel is back in the car).  Incidentally, for the supplied rivnuts you'll need a 9mm metal drill.
Two rivnuts in, and the other two holes for the final two rivnuts
Two rivnuts in, and the other two holes for the final two rivnuts
Time for another test fit / build.  This time with the CTEK charge leads, which I trimmed and spliced so that the CTEK connector plug fits neatly around the rear carbon post.  The CTEK charger works just like the old CTEK charger I had for the PC680 battery - nothing complicated, just plug and charge!
CTEK charge leads, spliced and fitted to battery housing with plug around the rear carbon post
CTEK charge leads, spliced and fitted to battery housing with plug around the rear carbon post
And then for the FINAL test fit - the entire battery, all bolted together and fitted to the metal plate prior to drilling the tube for the leading edge rivnuts to be fitted.  
Final test fit of battery, cage, CTEK wiring, all mounted to metal plate prior to leading edge rivnut fitting.
Final test fit of battery, cage, CTEK wiring, all mounted to metal plate prior to leading edge rivnut fitting.
I then placed the battery and cage whilst still mounted to the plate, back into the car, made sure 100% everything would fit and then marked out where to drill the holes for the rivnuts.
Leading edge rivnut holes being drilled - no going back now!
Leading edge rivnut holes being drilled - no going back now!
The battery was then removed from the metal plate, and then I got to work riveting the plate back to the car... If you haven't got a compressor this 14.4v cordless riveter makes light (and very tidy) work of rivets.
Sealey CP312 14.4 V 1.8 Ah Cordless Riveter takes the pain out of endless riveting
Sealey CP312 14.4 V 1.8 Ah Cordless Riveter takes the pain out of endless riveting
After a touch of 'fettling' where the metal plate and the holes in the tube didn't quite line up, the leading edge rivnuts were in.
Final leading edge rivnut going in
Final leading edge rivnut going in
Then the heater was put back, secured and then the battery went in...  Oh my god, it looks sooooooooo cool!  The four large(ish) holes on the plate will be filled with either rubber grommets, a large rivet, or (and most probably!) I'll make a carbon plate, which I'll get matte lacquered and will use that instead.
10Ah LiFePo4 Battery fitted to my Caterham R500 and it looks amazing and only weighs 1.5kg!
10Ah LiFePo4 Battery fitted to my Caterham R500 and it looks amazing and only weighs 1.5kg!
How on earth can you get your hands on one of these 1.5kg gems?
Speak to Carsten Filmer from FiTECH Motorsport Parts:-
Website: www.fi-tech.net
Email: info@fi-tech.net and phone number : +49 176 322 435 73.

Carsten is also the chap that fabricates the Carbon Handbrake lever, amongst a number of other cool items.

The battery manufacturers recommend to use the 10Ah battery for 2 litre engines with high compression ratios like the R500 etc but Carsten is aware of a few people who use the 7.5Ah battery on a 2 litre car too.  So some of the decision is up to you... The weight difference between both batteries is roughly 300g (the 10Ah being heavier).  To be on the safe side the recommendation would go with the 10Ah battery for R500 and 485, 2 litre (Duratec) engines and also the 2.3 from the CSR.  All others should easily be able to use the 7.5Ah battery.

What's the cost:- 
7.5Ah Battery: 199 Euro
10Ah Battery: 239 Euro
Battery Tray: 129 Euro (for both versions with the CNC cut Seven in either portrait or landscape)

Custom covers are also available for 20 Euro. I'm well informed these batteries can be fitted to any kind of cars and are running really well in Lotus Elise's, other sevens, Porsches etc.

Bang for your Buck:-
At 368 Euro's (plus shipping) this upgrade on the face of it seems like quite a lot of money... But... and to put it into context, the cost is around £320 (based on today's exchange rate) and the weight saving is over 7.5kg which works out to approximately 4p per gramme saved!  Which no doubt makes this the most 'cost effective' lightness improvement to date and MUCH cheaper than my carbon fibre bonnet :-)

I hope it won't be too long before lightweight battery tech like this is standard Caterham componentry, as given the massive weight saving on offer, I think it should be.

2 comments:

  1. That's proper smart, nice work Dan.

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    Replies
    1. cheers Steve - hope you've got yours on order :-)

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