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I was given a Greenworks 25292 cordless mower and a pair of Li-Ion batteries + charger, but the mower does not work. I charged the batteries before trying, so the question is if the problem is with the mower or with the batteries. Each battery has 4 contacts and I tried measuring voltage between each pair using a multimeter. For most pairings I got 0, for one of them I got a number around 13. Does this mean that both batteries are bad? Did I measure correctly? Can a battery like this be tested using a multimeter? Thx!

Not sure if you have the manual and if not here you go:
http://www.greenworkstools.com/uploads/documents/25223_gw_19in_40V_LITHIUM_mower_E_manual.pdf

It says to fully charge the batteries before use and that the battery charger will tell you is the battery is bad. If you have a local battery shop near by you might take the batteries to them and let them test them.
Tom

That mower uses the Gen1 40 volt battery that is wired in a rather strange way. You cannot measure the total voltage between any two points on the battery terminals. Instead, a fully charged battery should measure approximately 24 volts between terminals C and + and between terminals Omega and +. Since you are only getting about 13 volts, the battery is probably not properly charged. When you depress the test button on the battery, how many green LEDs do you see ? All four LEDs should illuminate when the battery is fully charged. If both batteries will not charge, then the problem could be with the charger.

MowerMike said:

That mower uses the Gen1 40 volt battery that is wired in a rather strange way. You cannot measure the total voltage between any two points on the battery terminals. Instead, a fully charged battery should measure approximately 24 volts between terminals C and + and between terminals Omega and +. Since you are only getting about 13 volts, the battery is probably not properly charged. When you depress the test button on the battery, how many green LEDs do you see ? All four LEDs should illuminate when the battery is fully charged. If both batteries will not charge, then the problem could be with the charger.

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Thanks for the info.

Yes, all 4 LEDs light up on both batteries with the test button is pressed. So that suggests "fully charged"

However, I measured the voltages one more time. For both batteries, I got about 14v between C and + and about 15v between Omega and +. So "not fully charged" or "defective"?

I have a feeling that even if they are not fully charged, the mower should have shown at least some signs of life when turned on. There was none so maybe the switch or the safety key is defective. I'll tinker with it when I have a chance.

Are you aware that to start the mower you must first press and hold the button on the handlebar, and then pull back on the bail bar ? Do you feel any resistance on the bail bar when you pull it back ? Also, the actual switch is located inside the deck housing, and the cable from the handlebar might not be connected properly to actuate it.

ilyaz,
Adding to what Mike said do you have the "key" that you insert in the battery holder? Look at the owner's manual and you can see what is needed.
Tom

Looks like it's working but the pull cable seems to be a bit loose. Maybe that's why it was not starting before. Which is good news. Bad news is that the batteries don't hold much juice, the mower often stops even on short grass and needs to be restarted. It might be time to invest in a new mower...

you probably have is sorted now, but a common problem on the twinforce was the bracket at the deck-end of the cable being bent. maybe check there.

1 Lucky Texan said:

you probably have is sorted now, but a common problem on the twinforce was the bracket at the deck-end of the cable being bent. maybe check there.

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Speaking of cable problems, they've done away with the cable and remote switch on the new digipro brushless version of this mower, and relocated the switch up on the handlebar start button assembly with a conventional two lead electrical wire connected to the motor housing. The wire is protected by a large plastic flexible conduit to prevent damage when the handlebar is folded for storage. Along with the elimination of the unnecessary safety key, the new mower is a lot simpler and more reliable.

Not sure if reviving this thread is against rules, but the follow-up is on exactly the same topic. So almost exactly 2 years to the date, I now have another dead 25292. The battery is showing as fully charged. When I measure voltage between + and C, I get about 18v. When I measure between + and Omega, I see about 18v displayed for the first fraction of a second and then the voltmeter shows "1.". Does it mean the battery is bad? Just like with the one 2 years ago, when I tried to use the mower with this battery, it shows no signs of life at all, like there is no battery in it at all. Thx

It definitely looks like you have a bad battery. Just because the battery charge indicator shows a fully charged battery doesn’t mean the battery is good. I have several batteries that show all charge LEDs on, yet as soon as I put them in a tool and switch it on, it immediately shuts down or doesn’t start at all. It only takes one bad cell in a lithium-ion battery pack to make it fail.

So is it possible to repair this battery by replacing bad cells? A new battery costs $100+ and that's a lot of money. Hate to throw away a good mower for this reason. If I could repair the battery for much cheaper that would be awesome!

It is possible, but not easy. Some manufacturers will refurbish batteries, but I don’t think Greenworks does this. I just looked at one of my Greenworks 40 volt Gen1 batteries, and the case is held together with screws with rejection pins, so I looks like they are not meant to be opened for repair. I did open two other dead batteries, and the cells were connected with welded steel strips that I destroyed when I disconnected them from the bad cells, so I gave up trying to repair them. The only other possibility I can think of is to take it to a Batteries + Bulbs store store, and see if they can repair it.

Well, I took it apart. I did such a fine job that I don't think anyone can put Humpty Dumpty together again... So looks like my only options at this point is to buy a new battery or take the mower apart for spare parts.

I think there are 1 or 2 aftermarket compatible units around - dunno about their quality.

check ebay and amazon.

1 Lucky Texan said:

I think there are 1 or 2 aftermarket compatible units around - dunno about their quality.

check ebay and amazon.

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There are a few of them, but they are really expensive now, well over $100, and take over a month to ship from China.

ilyaz said:

So is it possible to repair this battery by replacing bad cells? A new battery costs $100+ and that's a lot of money. Hate to throw away a good mower for this reason. If I could repair the battery for much cheaper that would be awesome!

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Yes and no.
The battery is made up of individual 3V cells.
They are very easily damaged by excessive heat so you need a big soldering iron that will heat the region where the cells are attached very quickly and some compressed air to cool it down quickly.
Lots of videos on repacking computer batteries worth watching.
If you just have one or two bad cells then replacing them will be fine.
However these cells are prone to exploding and this gets worse with age so many have a counter in the control circuit built into the battery and these can not be reset.
After "x" number of discharges they shut down and that is that.
Attempting to bypass the control chip usually ends up with the cells exploding or the house burning down.

There are some specialists battery remanufacturers but weather they do your particular battery will depend upon demand as it is labour intensive.
The other problem is getting the exact same cells to replace the bad ones.

I have done a dozen or so for my old Wallstreet laptop with about 60% success because you used t be able to get the replacement chips.

I watched a couple of Youtube videos about people converting cordless mowers into corded. Might want to try it just as a fun experiment (hopefully not resulting in electric shock, fire or explosions )

So I am wondering if I can wire in something like this. It says 40V output but only 0.5A, so not sure if that would be enough for the mower to actually cut grass.

ilyaz said:

I watched a couple of Youtube videos about people converting cordless mowers into corded. Might want to try it just as a fun experiment (hopefully not resulting in electric shock, fire or explosions )

So I am wondering if I can wire in something like this. It says 40V output but only 0.5A, so not sure if that would be enough for the mower to actually cut grass.

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10 of those in parallel wouldn't be enough.

if you can use corded, just buy one. small-ish yards with few obstacles are good candidates. I used to like to start near the house and work 'outwards', leaving the cord on the new-mown surface. I always preferred the 'reversible' mowers with the swing-over handles - dunno if that style is made anymore but, much less cord flipping/whipping/manipulation.

1 Lucky Texan said:

10 of those in parallel wouldn't be enough.

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Ok thx that's good to know

Hate to throw out this working mower but it might be the only viable option at this point

Although just now I found this posting on eBay. Model numbers are different and the price is much lower than anything else I've seen so not sure if this is legit and would match my mower. Sent a message to the seller but no response yet.

FWIW, I just called Greenworks and they gave me the model number of batteries compatible with my mower (25292):

• 29302 (2 amp hours)
• 29662 (4 Ah)
• 29282 (4 Ah)
• 2907002 (5 Ah)

Of course, the smallest one is still $100+ if I buy from them, so I'll do another pass at findings a discounted one somewhere

Recently bought some Greenworks 40V GMAX tools then found this forum yesterday while searching for pricing / reviews of their 40V Self Propelled 21" mower. I then posted in the "Welcome to the Electric & Battery Operated Equipment Forum!" thread as my into.

Anyway, I then stumbled upon your thread here with the GEN 1 battery problems. As I stated in the other thread, I bought 3 GW tools that came with 4Ah batteries … one of them however came with the WRONG battery, it for some strange reason came with a GEN 1 4Ah battery # 29662. Tool was purchased from HomeDepot.com and it shipped to me from a HD warehouse in Arizona … there was no indication that it was a return or box had been opened and re-sealed, so this battery had to be a factory mistake.

I contacted GW and they sent me the correct battery, so I've now got this brand new GEN 1 battery sitting here that I have absolutely no use for.

This brand new 29662 4Ah / 146Wh Battery has a 12/13/16 date code. It is externally the same, but the terminals are arranged slightly different so it will not click in to a GEN 2 tool, so I can't "run" test it. It displays 4 bars (fully charged) and checked the voltage per MowerMike's post and it shows 30.45V between "+" & "C" and 31.17V between "+" & "ohmega" … quite a bit higher readings than the "approx. 24V" he stated; whether this is good or bad I don't know. I had checked it prior across the "+ & -" terminals and found it strange I got just a small mV reading, so I was happy to see this thread showing the proper way to test it.

So, do you have any interest in this battery ?? Just as you have done, I searched to see what this battery sells for and saw it is around $114.00. I had recently bought a brand new compact 2.5Ah GEN 2 battery from a guy that was parting out a kit on ebay. It regularly sells for around $100 and I got it for $67 delivered … would this be a fair price ?? Let me know, probably can't post pics being a new forum member but could e-mail you some.

Thanks,

Doug

Just chiming in here to report my first bad 40V battery. It's a 2Ah. It will charge OK and the leds will report a full charge. But, it has reduced lidespan and any device (well, mower or blower so far) it is in will shut-off with 2 leds still illuminating.

weird thing, it's one of the newer batts I own, manufactured 04/13/2018 . I have others that are close to 8 years old.

1 Lucky Texan said:

Just chiming in here to report my first bad 40V battery. It's a 2Ah. It will charge OK and the leds will report a full charge. But, it has reduced lidespan and any device (well, mower or blower so far) it is in will shut-off with 2 leds still illuminating.

weird thing, it's one of the newer batts I own, manufactured 04/13/2018 . I have others that are close to 8 years old.

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You got a bad one, it happens. Quality control on Chinese li-ion cells can be spotty. It only takes a couple of weak cells to take down the entire battery. Unfortunately, you are outside the Greenworks 2 year warranty. The new generation Greenworks 60 volt batteries now carry a 4 year warranty, which is why I’m now focusing on that lineup.

MowerMike said:

You got a bad one, it happens. Quality control on Chinese li-ion cells can be spotty. It only takes a couple of weak cells to take down the entire battery. Unfortunately, you are outside the Greenworks 2 year warranty. The new generation Greenworks 60 volt batteries now carry a 4 year warranty, which is why I’m now focusing on that lineup.

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I THINK, this is one of the 'free' batts I inadvertently got when I purchased my, 'supposedly tool only', 21" MO40L01 from the Amazon Warehouse (the one I had to replace an axle on) so, no great loss really. At first, I though about continuing to use it but have now decided it could be a fire hazard when charging or ???, so, I'm gonna recycle it.

1 Lucky Texan said:

At first, I though about continuing to use it but have now decided it could be a fire hazard when charging or ???, so, I'm gonna recycle it.

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I doubt it would be a fire hazard when charging, as long as the charger shuts off when it reaches the max voltage setpoint or if it overheats. I have experienced SLA batteries overheating and leaking acid when their chargers failed to shut off and overcharged them. I've never seen this happen with a bad Li-Ion battery.