Opening an EGO 7.5AH battery to test cells

One of my 7.5AH Ego batteries stopped running my lawnmower (red flashing light after running for 10-30 seconds, then back to green light upon recovery). It looked like the voltage was sagging due to heavy draw. BUT, then it started to do the same thing under low loads (70 watt draw with the PAD1500 inverter...).

I opened it up to measure the individual cell voltages to see if I could find one set of bad cells. With the exception of the exact middle of the pack, I could only measure the voltage for every other set of cells. However, the measurements sure looked like all of the cells were well balanced.

After I put it back together and charged it up, it suddenly stopped misbehaving and ran my lawn mower like it was supposed to with 340 watt/hours of capacity.

I still don't know why it fixed itself. Possibilities include the lower temperature in the AC inside the house, or a loose/cracked wire that got moved into a better position when I took it apart and then put it back together again.

[jimmydavis]

Hello… I had same issue you had… took apart and put back together and it now works… EGO Rep. said I need to replace the battery… saved a lot of $$$.

[BGittins]

Hi, there is a pattern that I am seeing with EGO batteries with high resistance developing across the connector plug connectors. Sometimes just bumping the battery will fix it. If you pull it apart and simply plug & unplug connectors you fix 'unexplained' faults as recorded on the BM system. Best to have a can of contact cleaner (eg CRC NF Contact Cleaner) at hand and give the connectos a spray whilst seperated. One other point, thre main personal danger of opening these batteries is arcing faults between the high energy cables. (Any any short can also kill the electronics) A heavy arcing fault could also lead to battery explosion or fire both of which could be quiet bad. However, your skin is fairly resistive to 60 Vdc and so it is virtually impossible to get an electric shock off these batteries so your gloves are not really required for electric shock protection. That said, in other circuits with large inductors, 60 Vdc could be 'enhanced' with inductive loads, but not in these batteries.

[litreland]

Ty for the video, I think I fixed mine by reseating/cleaning the connection that is between the 2 halves of the cell packs
Check out 13:30 of this video: "EGO 56V Gen1 5AH Blinking Orange Fix" by Thrifty Tool Shed


My original complaint was that the mower would randomly cut out while mowing. I think the battery would flash orange, and the mower might have flashed yellow. You would have to wait 10-30 seconds, and then it would be able to be restarted/used as normal

I did the Thrifty Tool Shed "fix" (basically pull the 2 halves apart, pull the connector or two out, reseat them). I then mowed my lawn. The mower did not die. It also seemed to automatically kick into a "turbo" mode when about to bog down. I don't recall it doing that before the fix. So maybe the turbo boost is related; like, it draws more power, which overloads some loose connection or something, and causes a safety fault. I don't know; I'm not even 100% sure it's fixed, but it's been through 3 charges since, and no cutouts yet. Previously I think it would cutout once every 1-2 mows.

[CaedenV]

Huh... Well... I'm stumped. My old battery appears to be perfectly fine. I was sure I had some bad Leakey cells because of some white stuff that showed up behind the holes of the covers, but nope, it's just the insulation they use. All the cells look great, and the voltages are right where I would expect... So... Vrm or connection issues?

[philmccracken]

The screws on the outside of the case that you need to start to remove first to get inside the battery is "Torx #15" security bit.
It's like a normal torx bit that has a hole in the middle. The actual screw that you need to remove has a little nipple dead center on the head of the screw. That is the "security" part.

Once you removed all of the screws that are on the outside of the battery case there is a possibility if you're wanting to take apart the battery packs inside with the individual cells that you will need a "Torx #10"

[TooncesLives]

Wondering if you're able to provide the order for the 12-pin connector on the 7.5 batteries? Was taking mine apart for a different reason and they pulled out with very little force (was quite surprised). Thanks!

[briansbausch]

My mower had the same failure: full charge 7.5Ah flashes Red after 10 feet, not using self-propulsion. Watched videos, was leaning towards checking the 3 safety relays and for frayed wires @ pivot point, then I remembered hitting a stone with the blade and having to Dremel an edge on the resulting ding. Put this blade on a nail and discovered it was a couple degrees off level so unbalenced. A new mower blade fixed this problem, have had no problems for over a month mowing 2 lawns that total 1.5 acres.

[Ksport]

my 7.5 kept showing a overheat condition when just starting and I got the solid red light on the quick charger. it happened 10 days prior to the end of the 3yr warranty. EGO replaced it, so kudos to them....I haven't pulled it apart yet...prior to failure, my mower would cut out due to over-temp, even on 60* days

[parkgee]

May I ask what is the part number of the Samsung li-ion battery? Is it INR18650-20R or INR18650-25R?

[grandpaworks]

according to ego tech support if the batteries do not have that extra shell around the cells then its a rebuild battery. ego tech told me that all they use in all their batteries and has not change their technique.

[toddk]

Some wires came loose from the connector while taking apart. Its the upper right connector (low side?) 12 pins, but with only 10 wires. Here is what I know I have three wires that pulled out. They are Blu, Red, and Yel. Can anyone help?

[TranTek]

when you took them apart
you un tangle those wires

i seen a few report that is how to fix most of Ego issue unless your cells go bad, those Samsung cells are pretty reliable

[Decscorpion]

Do you happen to have pics of the connectors on the “BMS”
I’m trying to repair one that was found and curiosity is stringing of proper order for the wires and which one should be in which terminal of the plug.

THANKYOU and great video! 5 7.5ah batteries

[miken]

Very helpful, thanks. My battery is 2 years old and after 10 mins of running it will flash orange. It’s so confusing and curious if you have had to repair or test that issue yet.

[Suzukii-DIY]

The tool to remove the screws is a T6 Security tamperproof torx bit. Your welcome

[markbrown]

56 volts will wake you faster than a cup of coffee.

[victoryfirst]

How much did the battery pack cost you fella ??

[paradislarry]

I've read other comments where they just take the battery apart like you did, moved some wires out of "crunch positions" re-assembled & wallah !!! just like what happened to you.

[NaughtyGoatFarm]

Test the cells by probing the balance cable plug.

[arthurhudgens]

I fixed my ego mower by cleaning the carb on my old gas lawnmower it had replaced.too many battery and control module problems.too costly to replace as often as they give problems...