Lithium Iron Phosphate Lightweight Battery

[just-right]

My old Bosch AGM battery had unfortunately lost charge to the point of no return. A faulty charger was deemed the culprit.

The longer term aim is to shed quite a few kg's from the Z4M. The misfortune of the Lead Acid battery seemed like a good time to investigate lighter weight alternatives. I came across the Touge 500 battery from Deadweight Industries. The batteries had all around good reviews and are slightly more affordable than some of the more well known alternatives.

LiFePO4 Technology, utilising A123 cells
Custom integrated battery management system
60Ah Lead Acid equivalent

Old Bosch AGM : 20.2 kg
New LFP DW Touge 500 : 5.2 kg

A solid 15 kg weight saving. The build quality was very good with a very sturdy plastic casing and poles. Cold start has been excellent even after sitting still for a little while. The only slight problem was the foot of the battery seemed wider than the original. I needed to pry open the tray slightly to be able to slide it in place. Additionally you will need a new bracket to clamp the foot down as the DIN size will have reduced by one from H6 to H5. Bimmerworld, liteblox and a few others have these available. I am happy with the purchase and so far I would recommend this to others!

 

[MrPT]

It’s a great upgrade. People are put off by the price but in terms of bang-per-buck it makes more sense than a lot of other things we do to these cars.

Interesting about the slight size change. The Touge MAX is a straight swop, but I also think, having lived with one for a few years, that the 500 would probably be fine for an occasional use car (especially since you can’t kill it through lack of use).

 

[Sajk]

I have been investigating this. Seems it is critical that the battery management system on the battery is what's known as alternator safe. Some are and some are not. If not and the bms disconnects the battery completely from the alternator then the DC voltage can spike quick and high in a few milliseconds subjecting all the electronics in the car to a huge voltage spike. The alternator usually falls,on its sword with at least the voltage regulator being fried.

Check it out on YouTube and Google. The marine guys were early adopters and have learned the lessons.

I really want to do this. Please share your experience

 

[a340driver]

Interesting, I just had a Bosch AGM fail on my Z4M after 2 years recently, the previous, "original" battery lasted from 06 when I bought a replacement in 2023.

I bought the car in 2011 and it was on its original battery allegedly. So 7 years in my ownership, possibly 17 years on the car.

All sorts of weird symptoms as is usual with a failing battery. The garage said the new one was showing 37% of the original capacity.

I use a CTEK whenever it's in the garage and it was replaced under warranty, So I'me not hugely pissed off.

I'll keep an eye on it, not least because it's a lovely 19 year old car.

I does seem that older battery's are better quality from this example of one.

 

[TomK]

I've been using a cheapo £180 MSA approved LifePO4 battery for 8 years or so, no issues. Weighs 1.4 kg.
I do have a kill switch mind, so for a more normal use car you'd probably want something a little bigger.
I bought a charger for it for another £20 or something but have never had to use it. Left it for 11 months last year, started immediately.

 

[Mr Tidy]

I like the idea of one of these to get a bit more boot space (I have a full size spare wheel)!

I'm not so bothered about the weight, but are they physically small enough to allow for removal of all or most of the standard battery carrier?

 

[TomK]

I can't find a photo, but I had mine on the bulkhead next to the amp for a short while before I cut it out. Had the 3.0 boot trim, there was a bit of a bulge iirc but worked well. I think the batteries being mentioned above are probably bigger than mine though.

 

[MrPT]

Touge MAX doesn’t save any space but it’s 120Ah-equivalent.

Looking at Tom’s setup, maybe a couple of identical, smaller rectangular ones in parallel, up against the rear bulkhead, might be a neat solution.

 

[Mr Tidy]

I can't find a photo, but I had mine on the bulkhead next to the amp for a short while before I cut it out. Had the 3.0 boot trim, there was a bit of a bulge iirc but worked well. I think the batteries being mentioned above are probably bigger than mine though.

Many thanks for that Tom.

I fitted a new AGM battery in 2021 so hopefully it has a few years life left, but Li-ion might be worth investigating if/when the time comes!

 

[Vanne]

ive had a lipo4 batt in my car since the braille one packed up after hardly any use. gotta say its been awesome. I do charge this one up a bit between sessions, so expecting a good run out of it.

 

[abar121]

ive had a lipo4 batt in my car since the braille one packed up after hardly any use. gotta say its been awesome. I do charge this one up a bit between sessions, so expecting a good run out of it.View attachment 289341

Great. Which one is that?

I've been running Bosch AGM / non AGM batteries, not really noticed any difference in life with the zed. On motorcycles, it's a different story with the AGMs lasting longer / being more tolerant to discharging over time.

 

[Vanne]

Kepworth 46b24l *(though that size prob wont suit you) LiFePO4 680-720CCA 46AH I bought mine from Amazon, but they also have the identical thing on Ali. again, youll need to have a look at the size requirement, as mine is different. so i bought that originally on the 15th dec 22, and still kicking no worries. and it weighs absolutely FA. spec sheets says 3.3kgs