LiPo or NiMH: is NiMH still worth it?

LiPo or NiMH: is NiMH still worth it?

if you're buying a new battery for your AEG today, the answer to lipo vs nimh airsoft is LiPo nine times out of ten. but NiMH isn't dead, and there are situations where it's still the better choice. here's why.

the difference in one paragraph

NiMH (nickel-metal hydride) is the old standard: robust, forgiving, heavy. LiPo (lithium-polymer) is the new standard: light, higher output, better trigger response, but you have to stick to the rules on charging and storing.

weight and size

here the difference isn't subtle. at the same weight a LiPo delivers roughly two to three times as much energy as NiMH. a 1300 mAh LiPo weighs around 80 grams, a NiMH pack with comparable usability easily double that or more.

more important is the shape. NiMH is made of round cells soldered together. you get those in a stick or a block, and that's about all the flavours there are. LiPo is a flat pouch made in any size you want.

that's why modern AEGs with tight handguards and small buffer tubes really only work well with LiPo. there simply isn't room for NiMH.

trigger response

LiPo holds its voltage much better under load. a NiMH pack sags when the motor pulls current, and you feel it: there's a fraction of delay between your trigger and your shot.

with LiPo that's noticeably tighter. for semi-auto play, and especially for DMR, that's a real advantage.

also: NiMH has a falling voltage curve. your AEG shoots harder at the start of a pack than at the end. LiPo keeps its voltage much flatter and then drops off quickly at the end. more consistent, but you do have to pay attention to when you swap.

self-discharge

NiMH goes flat on its own in the cupboard. classic NiMH can lose up to 20 percent per month. low self-discharge NiMH (LSD, like Eneloop-type cells) is much better at this and still holds a large part after a year.

LiPo holds its charge well, provided you set it to storage voltage.

lifespan and abuse

here NiMH scores points. you can leave a NiMH pack fully charged in the cupboard without anything happening. you can run it flat. it isn't happy, but it doesn't catch fire.

a LiPo stored full degrades quickly. a LiPo pulled below 3.0 V per cell is irreparably damaged and dangerous to charge again. and a damaged or overcharged LiPo can go into thermal runaway and catch fire.

that's not meant to scare you. LiPos are perfectly safe with normal use. but it takes discipline NiMH doesn't ask for: balance charger, 1C, LiPo bag, storage voltage. i've got a separate piece about that and i'd really read it.

cost

comparable these days, with LiPo often even cheaper per pack. where LiPo costs you money is the charger: a decent balance charger plus a LiPo bag is a one-off outlay of around 40 to 70 euro.

for NiMH a simple charger does the job, but one with delta-peak detection. a dumb charger that just charges for a fixed number of hours slowly cooks your pack to death.

why NiMH sticks around

there are three real reasons NiMH is still in circulation.

1. old replicas and old gearboxes. a lot of AEGs ten to fifteen years old have stock pistons with plastic teeth, unreinforced cylinder heads and simple trigger contacts. those were designed around 8.4 V NiMH. putting 11.1 V LiPo on them is asking for damage. an 8.4 V NiMH is just right for a replica like that.

2. club replicas and rentals. if you're lending out twenty replicas to people who don't know any better, you don't want twenty LiPos that can be stored wrong. NiMH is duller, and that's exactly the point.

3. forgetfulness. if you play twice a year and your battery sits in a drawer in between, NiMH is more forgiving. a forgotten LiPo is often a dead LiPo.

what you should know about voltage

side by side, because the numbers are different:

note the third column versus the fourth. an "8.4 V" NiMH sits at nearly 10 V fully charged. a "7.4 V" LiPo sits at 8.4 V full. so a 2S LiPo loads your gearbox less than an 8.4 V NiMH, even though the number looks higher.

that's why switching from 8.4 V NiMH to 7.4 V LiPo is always safe. switching to 11.1 V is a completely different story, i've got a separate piece about that.

my advice

new or modern AEG, you play regularly: LiPo, 7.4 V, 1300 to 1600 mAh, 25C. buy a decent balance charger and a LiPo bag right away.

old replica with stock internals: 8.4 V NiMH is fine, or 7.4 V LiPo if you have a modern charger.

you play twice a year and don't want to think about it: LSD NiMH.

tight battery space: LiPo, no choice.

you have a strong spring and a heavy setup: LiPo, because NiMH sags too much under that load.

i've run only LiPo for years myself. but i also have a balance charger on my workbench and a bag they live in. if you're not going to bring that discipline, NiMH is honestly the wiser choice.

---

Also on Airsoft-FOB

• also available in dutch: LiPo of NiMH: is NiMH nog zinvol?