Greenworks 60v rebuild

[ngant17]

Opened up a Greenworks 60v battery that I use on my e-bike. After getting past the T8 torx security screws (hint: pound down the tiny internal pin with hard whacks from a punch, then use a normal T8 bit): Internals seem to show the following: Panasonic UIG95GD cells(sp.?), 6x5 array w/ 60v nominal battery rating. Don't know if I id'd the cell number as it was hard to read. I assume a combination of parallel and series connections to get 60v panasonic, as other Greenworks batteries are same external dimensions to fit their lawnmowers and accessory equipment, but batteries go up to 80v.

https://knightsucfedu39751-my.sharepoint.com/:i:/g/personal/ngant17_knights_ucf_edu/EQXkEvkyKJhLpahYLBWRcboBYNeDLmHGxYl8XXowni9k9Q?e=7r2hNk

This battery normally charges to ~61.5v. I have some bad cells in the pack because BMS circuit board inside the battery causes charger to light up red instead of green when plugged into a charge. So I am looking for an experienced battery builder who can suggest correct cell replacements, and any tips for rebuilding this. Especially wrt disassembly and removing bad cells. I've peeled off the gasket and plastic sheathing but some other tricks are involved to access the individual cells.

 

[e-beach]

If your battery pack has 30 cells then it is probably 15s 2p (2 parallel blocks of 15 cells in series.) 4.2v x 15 = 63v
The cells are probably 2a each. 2p x 2a = 4a

With that being said, mixing new batteries with used batteries put stresses on the new cells because during usage the used cells give up their charge more quickly due to age and usage. It is generally not recommended to mix old and new cells.

If you use all new cells, by the time you pay for everything, it would probably be almost the same price to purchase a new battery.

(yea I know....... they are $170 on amazon.)

Another thing to keep in mind the unknown amp rating for the cells you have. Unless you can identify the type of cells you may not get the proper cells needed. A high discharge cell is needed, just how high is unknown. (Samsung INR18650-20S 2000mAh - 30A ....?)

You will need battery tab welder and pure nickle strip if you are going to do tab welding. Maybe somebody in your area has one otherwise it is at least $100 to buy one. If you are going to solder, a very hot soldering iron, 100w, and a quick touch so not to degrade the new cells as you solder them.

The first thing is to meter all the cells one at a time to check their existing voltages to try and figure out which ones are bad. That is, if it is the cells and not the electronics (bms?)

 

[ngant17]

Yes, you're correct on charged voltages. I checked my notes from 2018 thread, and noted that a fully charged 60v 4Ah Greenworks batteries will have +64v. Which will automatically shut down the 48v Bafang controller, so my DROK buck converter is a mandatory item in the system.

There is a vendor on ebay who continues to do a brisk rebuilding business for this brand of 60v 4Ah battery for under $100(+160 sold so far). IMHO it's a waste of money to buy the cheaper 2.0 Ah or 2.5 Ah for running an e-bike. Space is critical on the bike, and you waste it by using a battery with the same external dimension but half the amp-hours.

My previous purchase from the seller has proved to be a smart idea, as recently the original 60v battery that came with my lawnmower, it began hitting the red light on charging, while the rebuilt one is performing flawlessly at this point in time. So it may not be cost-effective for me to do my own rebuilding given the price and the quality of the rebuilt ones currently selling on ebay. In the future, when confidence and expertise of working with these batteries gets to the level of the pros, I will have to reconsider my options.

 

[ngant17]

Until I can get competence with battery rebuilds, as of March 2019, it looks like the 60v 4ah Greenworks rebuilt ones give me the best deal. I've been running for over a year with the rebuilt 60v one I currently have:

Greenworks 60v 4 amp-hour battery, rebuilt - $96.85 (amazon and ebay). That's $24 per amp-hour at 60v.

I can also use my battery purchases as a legal tax deduction since they are primarily used to run my lawn business equipment.

However, the new Echo 58volt batteries have just caught my eye.
ECHO CBP-58V4AH 58V 4.0 Ah Lithium-Ion High Capacity Battery, new - $79-$110 (ebay, amazon)

If you can get the newly-introduced Echo 58v 4ah batteries for under $100, that would be a better deal. $20 per amp-hour at 58 volts. That's a plus as I could use a Bafang BBS02 on a full Echo 58v charge and eliminate the DROK voltage regulator altogether.

I haven't got up to speed on the Echo 58v message threads out there, but it looks like has been pretty brisk from a casual viewing of past messages here.

IMHO Echo's main competitor in commercial mowing business, Stihl, it has totally missed the boat on 58-60v batteries in landscaping business. Their Flex-volt 20/60v series are a waste of time and money if, for example, you want to swap them off a weed-eater and onto an 48v Bafang e-bike.

Aliexpress.com has slightly competitive prices if you're confident on buying Chinese mainland 60v 4aH batteries. Generally under $85 for 60v 4ah. Free shipping. Almost equal to the Echo 58v 4aH purchase here in good ole USA.

The other brands are running over $30 dollars per amp-hour in 60v range:

Powerworks 60v 4Ah, new - $155.10 (walmart)
Greenworks G-MAX Li-Ion 60v 4Ah Battery, new - $130.25 (hayneedle.com)
Earthwise 58V 4Ah Lithium Battery BL85840, new - $172.00

I hope I don't get accused of comparing apples to oranges with the 58v and 60v battery comparisons!

Also I haven't got into fully-charged 80v batteries to see how they can compare to 60v. My excellent DROK adjustable buck converter is rated for 75v input. May be possible to push it to higher input voltages without damage, but I don't want to make a smoke test to find out.

 

[ngant17]

I should note that if you buy locally at hardware stores, paying $40 per amp-hour for the larger voltages needed on an ebike is not a bad idea as you generally will get a no-hassle return and decent warranty.

For example, the ECHO 4 Ah 58v battery new comes with 90-day money-back guarantee, a 5-year consumer warranty and a 2-year commercial warranty.

A close comparison is the EGO 56v "arc-lithium" batteries which go up to 4.0, 5.0 and 7.5 amp-hour. Also available locally in the $45 per amp-hour range. With similar warranty.

Those three brands, Greenworks, Echo and EGO, are where my smart money is going.

 

[e-beach]

IMO if you had a good experience with a re-builder then go with him if it is cheaper then new. If it is about the same price, go with the one with the best guarantee.

 

[ngant17]

Reviewing the earlier 2015 posts on the Echo 58v 4ah batteries, I didn't realize they were available 4 years ago. In any case, it is obvious that I am returning back to some original ideas: using existing off-the-shelf, plug n' play batteries for cheaper and good quality power sources to run an e-bike. Essentially using them for multi-tasking, biking and mowing, that's going to prove their worth very quickly

Although I don't consider Greenworks equipment as commercial-grade, I haven't found much faults with its batteries. As for Echo, those who would question the quality don't seem to realize that when Echo is putting its brand and reputation on the line, it would be a horrible business decision to sell cheap, low quality equipment when there is a large number of small businesses that use Echo's commercial-grade equipment to run their operations and make a profit. Which includes me. Believe me, I know the difference between cheap junk landscaping equipment that won't last 6 months on a commercial basis. Consistently the top dogs in this business offer products that are built to last: Echo and Stihl. Though, as I emphasized in previous message, Stihl hasn't quite gotten the Big Picture yet with those measly Flex-Volt low amp-hour 20v/60v batteries. Not a decent plug 'n play option for e-bikes IMHO.

The 2015-16 message threads are generally favorable to the Echo 58v, with some criticism of BMS circuit board built inside battery.

Experience is the best teacher, and in near future I'll probably be running my e-bike with a combination of Greenworks 60v and Echo 58v batteries to see which ones will work best in long run. I'm needing to hook up in series for 12 amp-hours so I can run the distances I want, given my granny-gear single-speed which is not really pedal-friendly beyond PAS 1 on the Bafang BBS02. This was my first project e-bike which got me started with everything for cheap, especially as good quality batteries are the major cost of an e-bike.

 

[ngant17]

I've took the plunge and ordered a rebuilt 60v Greenworks and a 'reconditioned' 58v Echo to get my e-bike up to an amp-hour level (i.e., 'gas tank' size) that I want to travel on current ride.

Unlikely that I'll be able to use Echo equipment to interchange with Greenworks equipment on job sites. I haven't fully converted all my 2-cycle lawn maintenance equipment over to 58-60vdc power yet. This is the long term objective as I wasted a couple of hours on lawns today with an ICE (gas) Honda lawnmower(bad plug, poor vacuum/compression/idling issues). At same time, the starter pull cord on my 2-cycle Stihl blower became frayed and I lost time with a fix. Never would have happened with DC power.

As for e-bike, the idea is to avoid putting all the eggs into one basket with a single 60v 12aH battery. Keep 2 or 3 separate battery connected in series so one failure won't shut down the whole system. Like how CIA and secret intel works, information is compartmentalized on a need-to-know basis so one captured agent isn't able to compromise the other agents and disrupt overall operations.

 

[flippy]

sorry, but that is very dangergous idea, especially for commercial usage.
having 2~3 packs in a product and one dies for whatever reason means the load gets transferd to the other packs wich means those will also conk out.
commercial use means it will keep being used as long as its works so you can be down to one pack and they will still hammer it.
a recepy for disaster and very expensive repairs.
in commercial uses it MUST shut down otherwise it will be run into the ground.

 

[ngant17]

OK got that. Can this issue be addressed by dropping in diodes or relays? Such as using a battery isolator or dual/triple isolator switch?

I'm looking at some marine battery isolator switches on Amazon that look useful. Something like a single-pole, triple-throw switch, Battery One, Battery Two, or all off. I guess I'd need two switches for 3- battery isolation.

Using only one single 60v (with 30 internal cells) makes me feel insecure. I like separate but equal systems, you know, like the Space Shuttles had, what, 4 redundant guidance-control computers. They still managed to get blown to smithereens, twice if memory serves me correct. 1986 Challenger and 2003 Columbia. Murphy's Law affects us all.

 

[fechter]

You could use diodes, but they would run pretty hot under load. Generally it's better to use one big battery as opposed to several smaller ones used one at a time. This reduces the strain on the cells and they will live longer. Combining multiple smaller ones in parallel works but you have to use diodes or have some way to prevent connecting packs of significantly differing voltage.

 

[ngant17]

Cheapest off the shelf option for me is the battery switches used on RVs and boats to manage multiple batteries. Experience will be best teacher in long run but I'm definitely listening carefully to advice from battery pros here.

So you're saying running on a single 60v 4aH battery at a time , and swapping out with fresh ones with my e-bike, that method wouldn't be in theory as cost effective as using , say, one 60v 12aH all the time?

I'm guessing there may be more than one variable in this optimization equation. Operations research may yield a bigger picture here. Anyone looking to decompose a linear matrix to suggest hypotheticals?

 

[flippy]

thinking is way too complex.

simplfy.

make the battery as stable as possibe. you do this by making the battery as big as possible so the cells have the lowest current per cell you can get. then get proper cells that can deliver such a load -with ease- so the pack is not stressed. that makes for a happy, productive pack that will last a long time.

 

[ngant17]

That sounds like the winning argument.

If Luna Cycle is a good metric, and that is as good quality as anything, the 60v Triangle 24ah Panasonics are $850, which is a little hard on my budget. So yes, you can say that being pennywise and pound foolish.

In the future, I'm hoping I won't have to depend on Aliexpress and mainland China to get a 60v 12ah battery that's comparable in price to what I trying to do with three smaller 60v 4aH Greenworks batteries at the moment. However that got my first step into an ebike, and once the foot was in the door, I'm ready to move on to bigger things.

Battery-building is not for amateurs and learning from mistakes can really burn you. At this time, I'm willing to take the hit on earlier replacements using lawnmower batteries, but I definitely want to be isolating individual packs, possibly with some kind of marine battery switch based on what you stated of potential electrical failure issues.