This article has been a long time coming, but first a little history. My wife and I have 2 houses, hers is 1.2 miles from the road up a 900 ft hill and has an off-grid solar system. She is also Chemically Sensitive so we don’t really have anything that runs with gasoline except our cars. Even the generator that we use in the dead of winter is converted for use with propane so we don’t have to deal with the hassle of gasoline. The lawn has a mind of its own (it’s not really a lawn, more like 600 acres of goldenrod) and we decided for our wedding reception we wanted to actually have a lawn for our guests. On her own volition without consulting the battery expert she went out and bought a 40v Electric cordless lawnmower (it was probably only 36v and they were just liars). 40v on a lawnmower was a joke your boss tells you that isn’t really that funny but you still have to laugh, so after a few attempts to knock down the overgrown weeds we just took it back. The next purchase was a much more expensive $500 EGO 56v cordless lawnmower which turned out to be all kinds of awesome. We quickly fell in love.
The mower was powerful enough to knock down most everything (including 3ft high goldenrod) and for the most part, the design was very solid. The 4Ah battery pack ran for about 30 minutes of hardcore mowing, but it also recharged in about 20 minutes and worked very well with our PV system as long as it was pretty sunny. This article is not a review for an overpriced cordless lawnmower that you will never buy. Instead, this article talks about a very smart way to buy good lithium batteries with a built-in BMS and a decent warranty from your local hardware store, and then mount and use them on your high-power ebikes. Fasten your seatbelts because it’s going to be a hell of a ride.
I recently destroyed $800 worth of 6v Lead Acid Golf Cart Batteries from my wife’s solar system my setting them to equalize for 2 hours right before we left for 3 days to hike in the Catskills with visiting in-laws from Denmark. When we returned to the house it was full of smoke and the battery box was over 200 degrees and there was battery acid everywhere and the batteries were squealing and bubbling like crazy. So I donned an old Spinach container as a face shield and threw on some chemical gloves and carefully disconnected the batteries and carried them outside while trying not to get battery acid all over me. I did what any loving, supportive partner would do and agreed to pay for half of the replacement cost of the new cells (which will be closer to $1500) then I secretly sneaked away with her $500 lawn mower battery and went to my house for the weekend to extensively test them with my ebike.
Moral of the story : Don’t marry me if you want your batteries to live a long full life.
In the past if you wanted a small lithium pack that would have <5Ah of power and still produce 25Amps or more of continuous power then you either had to build your own 2P pack with a BMS out of 25R 18650 cells or another high current cell or risk using Hobby King Lipos. I pretty much rip on HK Lipos with every article I write and I assure you this one will be no different. HK Lipo’s suck and they are not worth wasting your time and energy with. Building your own 25R 14S2P pack from scratch is a time-consuming, expensive and potentially dangerous proposition. With the new bunch of high power tools on the market like cordless lawn mowers and chainsaws there are reputable companies that are producing these high power packs for cheap and selling them right down the street at your local Building Supply store. Some of these batteries are way better than others, and right now the Ego packs seem to be the best.
When is 56 volts not 56 volts? When it’s 52 volts
Another marketing misnomer is calling these packs 56v packs when really the rest of the battery industry would call them 50v, 51v or 52v packs, which is closer to the nominal rating of these cells. They are referring to peak volts fresh off the charger which is a hair over 57v, so you probably couldn’t actually sue them, but it sure is confusing. In any case, almost all the companies that make power tools are advertising their 14S packs as 56v so there you go. If you don’t like it then you should write a letter to some politician somewhere that they will almost certainly ignore (it’s their job to ignore you).
There were two ways I tested this battery, one with a modified charger (which was heavy) then I took the charger apart and just used the connector piece. I bought a used slow charger for $20 on eBay shipped. I think there are a bunch of them out there that were floor demos or something because the seller I bought from had 10 of them. I took the charger apart using a security keyed Torx (the ones with the dimples on them). Then I cut the leads to the positive and negative and soldered some wire and some Anderson 45 Amp Powerpole connectors to them. I covered the junctions with heat shrink tubing then carved out a tiny notch on the case. I wrapped the two wires with duct tape, put a small zip tie on there as tight as I could then tucked the zip tie inside the case to work as a kind of strain relief so the cable would not get ripped out.
I tried this configuration and it worked pretty well, although it seems silly to ride around with an extra 3 lb charger that you don’t really need. I took the charger apart again and then with two screws on the top I removed just the conductors to the battery. You can slide these conductors into the battery and they stay pretty well situated even when bouncing around in a backpack. The weight for just the connector was pretty nominal.
This battery pack did much better in the woods than I expected it to. I tested it pretty extensively with the BBS02 and the BBSHD without issues. The BMS can do 30 amp bursts but seems happiest running at 15-20 Amps. At these power levels, the pack does not even get warm. When the battery gets run down it will intermittently stop and start so it seems the low voltage cutoff on these packs is set very, very low. According to the marking for these batteries, they also are surrounded by a blanket of phase-changing material that will convert from a solid to a liquid if the batteries get too hot. I’m sure you remember from your physics class that going through a phase change like this absorbs a tremendous amount of energy from the surroundings, so this is the way they are able run these cells very hard, and still not worry about them overheating.
The BMS on the Ego packs is potted so it is completely waterproof, but the batteries themselves are well ventilated and the Ego packs are not really designed to be waterproof. The marketing video linked to below mentions someone leaving this pack outside for the whole winter under 7 feet of snow.
“See honey, there are people who abuse batteries worse than I do in this world. At least you’re not married to him.”
Personally, I would keep them in a waterproof bag or a backpack if you’re going to be riding in the rain or snow. Keep in mind I was testing with a 4Ah pack so you might find that the 2Ah pack does not produce as much power. I cannot find any specs on the packs rated output or the cells that they are using, but if I had to guess I would say the 2Ah pack is 14S1P 20R cells, the 4Ah pack is 14S2P 20R cells, the 5Ah pack is 14S2P 25R cells, and the 7.5Ah pack is 14S3P 25R cells. The 20R and 25R are incredibly reliable and widely used in the power tool industry for several years. They don’t pack the capacity of the newer 2016 cells like the 3500Mah GA cells that I’m crazy about, but they can put out 20Amps all day long without breaking a sweat. These older cells are also dirt cheap in quantity, and Ego is probably getting them for around $3 a cell wholesale.
It is pretty cool to think that you can just buy a battery at Home Depot then throw your 3 lb battery into a backpack and get about 40 minutes of pedal-assist riding out of it. For a lot of people who just want to bang around town with a small ebike, the Ego packs might make a lot of sense. There are other people like Echo who are also creating 14S 56v packs that are quite frankly not engineered even close to what these Ego packs are. For an annoying Ego marketing video click here and for an independent 20 minute 56v Echo vs Ego pack teardown here. The Ego pack has a 3-year manufacturer warranty which is pretty much unheard of in the industry. That being said, if you buy an Ego pack and hook it up to your ebike, then it will certainly void the warranty.
Should you spring for an Ego battery pack? In all honesty, if you had asked me yesterday I would have said ‘yeah go for it’ but just today I just ordered a newly released 6Ah 14S2P 30Q pack that only weighs 3.3lbs from Lunacycle for a scant $319 right here. At that weight, you will not find any 18650 pack that even comes close that will be able to do 30Amps continuous and has 6Ah of range. My large 21Ah 7P 30Q pack (reviewed here) does not even get warm pulling 50 Amps continuous so I’m certain that the 2P 3lb pack from Luna will be fine at 30Amps and less (and it has a thermal cutoff just in case). The pack is so small that it will literally fit in your pocket with room to spare. The same could not be said of any of the Ego packs, even the 2Ah one which is pretty huge. I will be doing a review of this new Luna Mighty Mini 3lb pack as soon as it arrives so stay tuned, suckers.
The industry marches on as our old packs are quickly made obsolete.
Thanks to Ron\Spinningmagnets for the terrible idea to write this article. Ron both looks and acts like my Jedi ebike Master, but instead of saying wise things like Obi-Wan does, he is more like “Hey Karl, don’t be such a dick and maybe people will like you more”.
Thank you, master Yoda.
It’s not easy being green.