4 ms·

It's most likely an 56 volt Ego 7.5 Ah battery. I bought mine a few years ago on eBay for $200.

by skt5 6y ago

csours 6y ago
Yes, this is the one I was talking about. I looked at retail cells because I was curious and $5 looked about right for retail, but I can't imagine the OEM Manufacturer would be paying that much. My initial uneducated guess before I did any math or looked anything up was that the BOM cost for the battery pack would have been like $50, but $200 seems more reasonable. I guess a $150 markup isn't that unreasonable, but it is a bit of a sticker shock when you compare the cost of a mower bundle [0] to a bare battery pack [1]. Still, the margin seems fat here. I really am of two minds on this, because I realize what the race to the bottom could do here. I don't want a battery pack that would burn my house down. I want a battery pack that lasts a long time (durable over usage cycles). I'd love to hear about your experience with the system if you don't mind sharing. 0. $370 Mower + 5 Ah battery + Charger https://www.homedepot.com/p/EGO-21-in-56V-Lithium-Ion-Cordless-Electric-Walk-Behind-Push-Mower-5-0-Ah-Battery-and-Charger-Included-LM2101/206515766 https://www.homedepot.com/p/EGO-21-in-56V-Lithium-Ion-Cordle... 1. $350 7.5 Ah battery https://www.homedepot.com/p/EGO-56-Volt-7-5-Ah-Battery-with-Fuel-Gauge-BA4200T/308667794 https://www.homedepot.com/p/EGO-56-Volt-7-5-Ah-Battery-with-...
- xxs 6y ago
  It's US where LiIon is presumed 4V nominal, so effectively 42 elements. Pretty nice margins. Indeed battery pack is where the tool companies make their profit with all of them being incompatible with each other, including Dewalt/Black and Decker (same company different brands) having just a small plastic notch to prevent interchange usage. -- Edit: durability depends on max charge and min/cut off discharge voltage (something like 4.13v/3.3 would be decent) - you can test those with voltmeter easily, temperature the batteries are run at, and discharge current. At around 400 cycles they should be at ~85% capacity.
  - xyzzy123 6y ago
    You can find x to y battery adapters on ebay, in case you found it as annoying as I did.
- snovv_crash 6y ago
  $5 is low volume consumer prices. Those cells are more like $3.50 if you go for MOQ 20. Eg. https://www.bulkbattery.com/batteries/18650/samsung-30q-18650-3000mah-15a-battery/ https://www.bulkbattery.com/batteries/18650/samsung-30q-1865...
xxs 6y ago
the 56V assumes 3.75v nominal for LiIon - so I'd guess 3x15 of 2.5A elements. The good ones LG/Sony/Samsung/Panasonic are quite expensive when they come with high discharge current - most of the ebay stuff uses Chinese knockoffs that suffer greatly when discharged over 7-8A but since there are 3 elements in parallel, it should be easy for over 20A/50V, say 1kW. ...now I am really curious what's inside. What are you using the pack for?
- csours 6y ago
  https://www.youtube.com/channel/UC0yqhjYwmhqQPxhu_TORMsg/videos https://www.youtube.com/channel/UC0yqhjYwmhqQPxhu_TORMsg/vid... This guy has some teardowns and repairs.

It's most likely an 56 volt Ego 7.5 Ah battery. I bought mine a few years ago on eBay for $200.

by skt5 6y ago

It's most likely an 56 volt Ego 7.5 Ah battery. I bought mine a few years ago on eBay for $200.

Yes, this is the one I was talking about. I looked at retail cells because I was curious and $5 looked about right for retail, but I can't imagine the OEM Manufacturer would be paying that much. My initial uneducated guess before I did any math or looked anything up was that the BOM cost for the battery pack would have been like $50, but $200 seems more reasonable. I guess a $150 markup isn't that unreasonable, but it is a bit of a sticker shock when you compare the cost of a mower bundle [0] to a bare battery pack [1]. Still, the margin seems fat here. I really am of two minds on this, because I realize what the race to the bottom could do here. I don't want a battery pack that would burn my house down. I want a battery pack that lasts a long time (durable over usage cycles). I'd love to hear about your experience with the system if you don't mind sharing. 0. $370 Mower + 5 Ah battery + Charger https://www.homedepot.com/p/EGO-21-in-56V-Lithium-Ion-Cordless-Electric-Walk-Behind-Push-Mower-5-0-Ah-Battery-and-Charger-Included-LM2101/206515766 https://www.homedepot.com/p/EGO-21-in-56V-Lithium-Ion-Cordle... 1. $350 7.5 Ah battery https://www.homedepot.com/p/EGO-56-Volt-7-5-Ah-Battery-with-Fuel-Gauge-BA4200T/308667794 https://www.homedepot.com/p/EGO-56-Volt-7-5-Ah-Battery-with-...

xxs 6y ago
It's US where LiIon is presumed 4V nominal, so effectively 42 elements. Pretty nice margins. Indeed battery pack is where the tool companies make their profit with all of them being incompatible with each other, including Dewalt/Black and Decker (same company different brands) having just a small plastic notch to prevent interchange usage. -- Edit: durability depends on max charge and min/cut off discharge voltage (something like 4.13v/3.3 would be decent) - you can test those with voltmeter easily, temperature the batteries are run at, and discharge current. At around 400 cycles they should be at ~85% capacity.
- xyzzy123 6y ago
  You can find x to y battery adapters on ebay, in case you found it as annoying as I did.
snovv_crash 6y ago
$5 is low volume consumer prices. Those cells are more like $3.50 if you go for MOQ 20. Eg. https://www.bulkbattery.com/batteries/18650/samsung-30q-18650-3000mah-15a-battery/ https://www.bulkbattery.com/batteries/18650/samsung-30q-1865...

xxs 6y ago

the 56V assumes 3.75v nominal for LiIon - so I'd guess 3x15 of 2.5A elements. The good ones LG/Sony/Samsung/Panasonic are quite expensive when they come with high discharge current - most of the ebay stuff uses Chinese knockoffs that suffer greatly when discharged over 7-8A but since there are 3 elements in parallel, it should be easy for over 20A/50V, say 1kW. ...now I am really curious what's inside. What are you using the pack for?

csours 6y ago
https://www.youtube.com/channel/UC0yqhjYwmhqQPxhu_TORMsg/videos https://www.youtube.com/channel/UC0yqhjYwmhqQPxhu_TORMsg/vid... This guy has some teardowns and repairs.