Using low self-discharge NiMH for a portable power station?

Question

Portable power stations - the large type with AC outlets - typically utilize lithium-ion or lithium iron phosphate (LiFePO4) chemistries. I haven't found any which use NiMH.

LiFePO4 batteries are often advertised as having a "low" self-discharge of 2-5 % per month.

I am interested in a portable power station with a minimal self-discharge rate but ideally still rechargeable. This could be useful for e.g. an off-grid location. I noticed LiSOCl2 but it's not rechargeable.

I noticed that Sanyo Eneloop 5th generation NiMH batteries advertise 70% charge after 10 years (see https://en.wikipedia.org/wiki/Eneloop#Variant_comparison_tables) but I can't find any larger power packs that use something like this.

Is there a technical reason there's no larger power pack of NiMH available on the market? I'm not an expert on batteries and such - how hard is it for an amateur to create a DIY power station from a bunch of AA Sanyo Eneloop batteries? Ideally it could provide an AC power outlet similar to the LiFePO4 portable power stations.

Answer 1

Is there a technical reason there's no larger power pack of NiMH available on the market?

What's available on the market is commercial decision. Once a power pack gets 'large', I would imagine the producers thinking that customer would want 'as light as possible', and so want lithium, and so not bother making a heavier version. Build yours with nickel by all means. How far do you need to carry it off grid?

If constructing a large battery assembly, then there are technical things you should bear in mind. The cells might need cooling if you are going to be drawing high power for any period of time. Any large parallel blocks should be fuse protected, so that all the other cells can't 'gang up' on a short-circuited cell and cause a fire.