Which lithium battery is the best and why there is so much price difference between the different models?
When I started Muller Energy, my aim was to offer great batteries at a good price to the Australian market.
Like most people, I love a good bargain! For me this means not only a good price, but also good quality. So it pained me a bit when I saw that some other LiFePO4 batteries were selling below our cost price and our sale price would have to be a fair bit higher than what the bottom of the market was going for.
If you search online marketplaces like eBay, you’ll find 12V “200Ah” LiFePO4 batteries that start at just over half of what our battery retails for.
How can this be? Do we just have sky high margins and rip our customers off? As mentioned previously, no, that’s not the reason.
The answer is in the components that are put into our batteries, compared to what the cheapest batteries use.
“Which lithium battery is the best?”
The BMS (Battery Management System)
A member of our Facebook group recently posted pictures that shed some light on why some batteries can be sold for such a cheap price.
He recently had a BMS failure in a fairly popular cheap battery that’s sold online (I’ll refrain from mentioning any vendor or brand name for legal reasons), so he opened it up to see what had happened.
Picture 1: Destroyed cheap BMS with blown MOSFETs
As you can see, nearly half the MOSFETs on the BMS are visibly destroyed. Cheaper BMSs don’t include a heatsink on the MOSFETs and may contain lower quality MOSFETs and/or fewer MOSFETs than a quality BMS.
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Picture 2: Our 250A Daly Smart BMS on top of the cell pack
For comparison, here is the BMS that we use in our 12V 200Ah lithium battery, a 250A Daly Smart BMS with Bluetooth. Note the big heatsink and the chunky power cables at the far end.
But of course, it doesn’t stop there. There are quite a few more differences that are crucial as well.
“Which lithium battery is the best?” The Battery Box
Picture 3: Creative approach to building a battery with expanding foam
You can see that an ill-fitting battery box that was originally designed for a lead-acid battery was used. While there isn’t really anything wrong with repurposing the case, I’m not entirely convinced of the use of builder’s foam, nor the thickness of the wires.
Picture 4: Showing 4s12p soldered 33140 cylindrical cells
“Which lithium battery is the best?” The LiFePO4 Lithium Cell
Moving onto the cells, they appear to be 33140 cylindrical cells. Those aren’t great cells and pretty much the cheapest LiFePO4 you can get, but at the same time, they’re not absolutely terrible either. I myself have used these for prototyping and proof of concept (due to their low price point), I’d just never use them in a production battery!
But what the cells are, isn’t the worst about it. You can see that they haven’t been spot welded or laser welded, but soldered. This is a big no-no when building batteries, as there’s a considerable risk of heat damage to the anode or cathode on the cell.
Now, depending on which specification of the cell you look at, they are either 15Ah or 15.5Ah each, meaning that the 4s12p array that’s used will give you a capacity of between 180Ah and 186Ah, best case scenario.
Picture 5: Quality Lishen prismatic cells being laser welded
Again, as a comparison, here is a picture of the cells we use inside our batteries.
We use quality Lishen cells and have them laser welded, to ensure good contacts.
Conclusion
This is just a very brief overview and obviously, it’s not where the differences end, for example, we use a stainless steel case that’s custom-made, offers a 5-year warranty, includes a cell balancer and a whole host of connectors as well as Bluetooth.
If you take all the differences between a cheap and a quality lithium battery into account, the cheap battery just seems… well… not just cheap, but also very cheaply made! And in the end the high-quality battery doesn’t seem overpriced anymore.
Whether you buy our battery or another manufacturer’s, make sure you buy a quality one that won’t give you headaches down the road! So ask what’s inside the box and if they can’t tell what’s in there, they probably don’t want you to know.
