WalMart EverStart Battery Test

Batteries, Chargers, and Battery Management Systems.
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Alan B   100 GW

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WalMart EverStart Battery Test

Post by Alan B » Apr 14 2016 3:29pm

Image

I picked up a couple of these car starting batteries from a Walmart online sale recently, and today I made an adapter from EC5 to Anderson PowerPole. I charged the EverStart battery a few days ago and it has been sitting since.

The test was conducted with a West Mountain Radio Computer Battery Analyzer IV which has a 100W maximum discharge capacity.

The ratings on the package suggest 12000mAH capacity, however this rating is if the cells were parallel, since it is 3S1P instead the rated capacity is 4AH at 11.1V.

EverStart Battery Test #1

8 amps
8.4 volts end of test
3.761 amp hours
42.356 watt hours
28:15 runtime
battery slightly warm, not significant

Image

At least one ES member has been using four of these for an ebike battery. Clearly they can handle high current. I didn't see any sign of BMS protection down to 8.4 volts, however, so controller LVC will have to protect the cells.

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Re: WalMart EverStart Battery Test

Post by Ykick » Apr 14 2016 4:01pm

Thanks for taking the plunge. Do you mind sharing what they cost you?
Talent must not be wasted.... Those who have talent must hug it, embrace it, nurture it and share it lest it be taken away from you as fast as it was loaned to you.

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Re: WalMart EverStart Battery Test

Post by teklektik » Apr 14 2016 4:30pm

<<< $29 now at Walmart >>>
(Apparently $19 a couple of months back according to YouTube)
Walmart wrote: About this item

This Everstart Jump Starter features a durable ABS with rubberized housing. It has a built-in 0.5W LED as a flashlight and a 12,000mAh lithium battery. Use this lithium battery jump starter product as a jump starter, flashlight or an emergency charger. It is also a portable power bank. The 5V 2A USB output charges tablets, smartphones and other portable devices like video games and cameras.

This multi-function jump starter comes with a portable bag and a battery level indicator.
The reverse connection protection and short-circuit protection make it even safer to operate.
This Everstart Jump Starter has rubberized housing that absorbs shock and impact.
...
The kit includes reverse protected clamps, a car charger and a home charger.
Would also keep electric winter-wear cooking for hours...

Thanks for the test results!
Last edited by teklektik on Apr 14 2016 5:14pm, edited 1 time in total.
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Re: WalMart EverStart Battery Test

Post by Hillhater » Apr 14 2016 5:04pm

You do know most of these are simply 3S ,4Ahr, lipo pouches inside.
Multistars are cheaper $/Whr.
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Re: WalMart EverStart Battery Test

Post by Alan B » Apr 14 2016 5:43pm

(Most of this has been covered before I posted this). These starter packs are on sale at Walmart for $29 right now. I did the two for $59 with free home delivery when the single price was $39, but now you can get singles for $29 online.

The peak starting current capacity of these packs is higher than what I would expect for a 3S 4AH Multistar. It might be more comparable to a higher C rated lipo such as a NanoTech, I don't know for certain.

For $29 you get a few more things than just a lipo:

3S1P 11.1V 4AH Lipo plus

Plastic/rubber case with:
Battery state display (10 LEDs and pushbutton)
EC5 high output current connector
LED flashlight
USB charging output (and 5V regulator)
3S BMS inside

Plus accessories:
Car starting cable clamps with protection circuit with EC5 connector

Nylon carrying case
12V charging cable
120VAC charging transformer
Much better warranty than most RC Lipo

While I would not use these for powering an ebike (as some folks have), they are useful devices if you need to start a vehicle or power a 12V device or charge a phone. They are much safer to use for vehicle starting than a loose Lipo. It would run an Elecraft KX3 for a long time, or an FRS radio in an emergency. I'm changing over from the old lead acid starting batteries as they self discharge and die, and are very heavy. The lithiums won't start quite as well, but I think they'll be adequate. I do have a Nanotech pack as well but I wouldn't want others to use that one. These can be used by anyone.

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Re: WalMart EverStart Battery Test

Post by Alan B » Apr 14 2016 8:23pm

Recharging the Walmart Everstart battery just finished.

So it took about 5 hours.

This from the supplied 120 VAC wall charger.

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Re: WalMart EverStart Battery Test

Post by Chalo » Apr 14 2016 11:46pm

Hillhater wrote:You do know most of these are simply 3S ,4Ahr, lipo pouches inside.
Multistars are cheaper $/Whr.
The Walmart starter batteries are demonstrated to discharge at close to 200A. They come with BMS and charger. That makes them cheaper than comparable Hobbyking batteries if you compare like for like.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Re: WalMart EverStart Battery Test

Post by Hillhater » Apr 15 2016 3:09am

No doubt if you intend to jump start autos, or if you really need the high output, these are a good choice.
..I was really pointing out that if anyone was thinking of buying these in the hope of "harvesting" some high power 18650's cheaply to build a ebike pack with .....then its not the answer.
(Most of the similar backup "Power Packs" are powered with 18650's...but wont jump start a Barbie car!)
Also, i dont think anyone has tested the cycle life of these cells at anything like their claimed output.
This forum owes its existence to Justin of ebikes.ca

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Re: WalMart EverStart Battery Test

Post by Boyntonstu » Apr 15 2016 8:00am

Hillhater wrote:No doubt if you intend to jump start autos, or if you really need the high output, these are a good choice.
..I was really pointing out that if anyone was thinking of buying these in the hope of "harvesting" some high power 18650's cheaply to build a ebike pack with .....then its not the answer.
(Most of the similar backup "Power Packs" are powered with 18650's...but wont jump start a Barbie car!)
Also, i dont think anyone has tested the cycle life of these cells at anything like their claimed output.
see: https://endless-sphere.com/forums/viewt ... 4&start=75

60 cycles at 15+ mph PA.

LVC at 22.8 miles.

I use my bike everyday for 6 miles exercise loops and immediately recharge. I store it in the garage unless on the daily ride.

They never feel warm, and using the LED indicators, they all appear to have the same voltage.

The smallest battery that gets the job done limits the potential fire size.

I love these Walmart Boosters and they are under a 2 year replacement or money refund warranty.

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Re: WalMart EverStart Battery Test

Post by wineboyrider » Apr 15 2016 8:38am

.
ES IS SAVED! THANK YOU JUSTIN.

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Re: WalMart EverStart Battery Test

Post by Alan B » Apr 29 2016 10:44pm

Hillhater wrote:No doubt if you intend to jump start autos, or if you really need the high output, these are a good choice.
..I was really pointing out that if anyone was thinking of buying these in the hope of "harvesting" some high power 18650's cheaply to build a ebike pack with .....then its not the answer.
(Most of the similar backup "Power Packs" are powered with 18650's...but wont jump start a Barbie car!)
Also, i dont think anyone has tested the cycle life of these cells at anything like their claimed output.
I haven't opened one of these up but I found similar batteries on the internet disassembled and none had 18650's inside. I don't think they can cheaply and easily get to the peak currents they need that way, there's too much cost for the manual interconnects and they add resistance as well. So I suspect that all these are using some form of Lipo batteries due to the high peak current capacity.

I agree that these are not cheap batteries if you want to take out the cells, whatever they are.

They have a number of valid uses, but ebikes isn't a good one. There is one user that is using them for that, but his battery needs are unusually small, for most ebike users these would be too bulky and not cost effective for a normal range, especially at the normal price. Some of the new batteries for electric yard tools might be a better direction to go, they have serious voltage and energy capacity.

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Re: WalMart EverStart Battery Test

Post by Boyntonstu » Apr 30 2016 2:59pm

Alan B wrote:
Hillhater wrote:No doubt if you intend to jump start autos, or if you really need the high output, these are a good choice.
..I was really pointing out that if anyone was thinking of buying these in the hope of "harvesting" some high power 18650's cheaply to build a ebike pack with .....then its not the answer.
(Most of the similar backup "Power Packs" are powered with 18650's...but wont jump start a Barbie car!)
Also, i dont think anyone has tested the cycle life of these cells at anything like their claimed output.
I haven't opened one of these up but I found similar batteries on the internet disassembled and none had 18650's inside. I don't think they can cheaply and easily get to the peak currents they need that way, there's too much cost for the manual interconnects and they add resistance as well. So I suspect that all these are using some form of Lipo batteries due to the high peak current capacity.

I agree that these are not cheap batteries if you want to take out the cells, whatever they are.

They have a number of valid uses, but ebikes isn't a good one. There is one user that is using them for that, but his battery needs are unusually small, for most ebike users these would be too bulky and not cost effective for a normal range, especially at the normal price. Some of the new batteries for electric yard tools might be a better direction to go, they have serious voltage and energy capacity.

After a ride of 6 miles at 17 mph pedal assist, my four Walmart Booster batteries in series are discharged to just under 3,9 V per cell.

My bike will go 22.8 miles to LVA at 3.5 V/cell if I PA at 15 mph.

Not too shabby and not an unusual small ride.

Not a lot of bulk or weight.

To date over 70 charge/recharge cycles.


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Re: WalMart EverStart Battery Test

Post by Alan B » Apr 30 2016 3:50pm

Image

OK, let's pick an example. This arrived recently in the mail. This 3.3 pound Luna mini pack has 52V at 6AH of 18650 cells, higher voltage and TWICE the total energy (52:44V, 6:3.5AH, 312:154WH), is much smaller, and it has a BMS that actually protects the cells during charge AND discharge. At the regular prices these packs are less than 2x different in cost (229:159). For ebike use the Walmart packs are bulky, inconvenient to mount, heavy and low capacity, and they don't provide BMS protection during discharge. They will fail long before a good ebike pack would, so their low price is hiding the short life they will ultimately have. In cost per mile the ebike pack will win due to the extended life and improved protection, there is a larger up front investment compared to buying Walmart on sale, but it will pay off in the life cycle. A single mistake overdischarging the Walmart packs will ruin them. Twice the range, smaller, lighter, full BMS protection, longer life. There is really no comparison. The Walmart boosters are occasionally sold at lower prices to clear out old stock, so that reduces the price but the batteries are already getting older and this will have an effect on total life. It is a cheap battery, but not a great one. Take care and enjoy.

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Re: WalMart EverStart Battery Test

Post by Boyntonstu » Apr 30 2016 9:22pm

Alan B wrote:Image

OK, let's pick an example. This arrived recently in the mail. This 3.3 pound Luna mini pack has 52V at 6AH of 18650 cells, higher voltage and TWICE the total energy (52:44V, 6:3.5AH, 312:154WH), is much smaller, and it has a BMS that actually protects the cells during charge AND discharge. At the regular prices these packs are less than 2x different in cost (229:159). For ebike use the Walmart packs are bulky, inconvenient to mount, heavy and low capacity, and they don't provide BMS protection during discharge. They will fail long before a good ebike pack would, so their low price is hiding the short life they will ultimately have. In cost per mile the ebike pack will win due to the extended life and improved protection, there is a larger up front investment compared to buying Walmart on sale, but it will pay off in the life cycle. A single mistake overdischarging the Walmart packs will ruin them. Twice the range, smaller, lighter, full BMS protection, longer life. There is really no comparison. The Walmart boosters are occasionally sold at lower prices to clear out old stock, so that reduces the price but the batteries are already getting older and this will have an effect on total life. It is a cheap battery, but not a great one. Take care and enjoy.
1: Walmart has BMS on charge. The controller kicks out the battery when the cells reach 3.5 Volts.
My cells charge to 4.25V and after my rides they are at or very near 3.89V.
I use them in a very narrow Voltage range and that will hopefully keep them alive a long time.
I have tested then at full throttle at 30 mph and they cut off after they ran cool at maximum Amps.

2. How much did your BMS and charger cost?

3. How long will your batteries last, how many cycles?

4. I will get all my money back if they degrade or fail within 2 years as per the $12 unconditional warranty,

5, Heavy and hard to mount? I am not sure of the total weight, my guess is under 10 pounds for the 4 of them.
(Anyone out there, did you weigh one?)
Heavy duty nylon zip ties or even SS zip ties make for a 10 minute mounting process.
It seems to me that my 4 rectangular thin packs, 2 per side, are easier to mount than your single brick.
I can place a pair on each side of my rectangular bike tube and the result is a thin profile, with a low CG as shown.

Please show us your mount and your BMS/charger.

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Re: WalMart EverStart Battery Test

Post by Alan B » Apr 30 2016 11:18pm

The Luna Mini pack is 2-3/4 by 3-1/4 by 6 inches and 3.3 pounds, about the size of two of the Walmart packs, of which you need four. So this pack is half the volume of the four Walmart batteries but contains twice the stored energy for 4x volumetric energy storage improvement. That is even including the BMS, which is inside that pack! It will fit in any number of little nylon bike bags, or in the triangle or trunk packs I already have, and this pack will be able to be used on three of my bikes (without cutting tiewraps). Mounting this tiny pack is not a problem, even compared to simply tiewrapping four Walmart packs.

The BMS is included in the prices mentioned, and built inside the pack. It is a 30 amp continuous and 50 amp peak BMS on discharge, where the Walmart has zero BMS on discharge in the ebike configuration.

I have a number of chargers that will work with this battery, starting at about $20 or $30, and they are 150W-360W. They work with other batteries I already have, so I didn't need to purchase yet another charger for this pack. Any voltage and current regulated power supply settable to 58.8V can do the task. My favorite is the ebikes.ca Satiator which costs more but gives complete information about the charging energy and voltages put into the pack, so I can keep track of how deeply I'm discharging it and gauge the range and capacity accurately. The Walmart chargers are 15W each, times four for a total of 60W, and they give zero information about energy needed to recharge the pack. They charge quite slowly which encourages the user to not be present when charging. Again the Walmart product falls short of the weakest lowest cost ebike charger, by factors of 2-6x.

The Walmart packs are 1.1 pounds each so the four required are 4.4 pounds for half the energy, plus a wiring harness is needed to connect them in series. So the Walmart packs are 2.6 times as heavy per watt hour. So far the Walmart packs are heavy, large and slow to charge.

Specs for these packs are for 80% capacity at 400 to 1000 charge cycles (so even then far more capacity than the Walmart packs new). The Walmart packs have no specifications (actually the spec they have is a lie, they claim 12,000 mAH and 11V), and the life cycle of the cheap cells inside are typically nowhere near the life cycle of quality 18650 cells. Walmart can choose to honor their warranty or not, depending on their whim when you return the packs. If you warranty one of them, they will be even further out of balance, if you warranty all four of them at once they may decide not to honor the warranty at all. There is lots of fine print in those warranties they can invoke.

The Walmart packs have NO BMS protection on discharge in ebike use, and relying on controller low voltage cutout (LVC) can lead to overdischarging cells within the pack WITH NO OUTWARD EVIDENCE. A few cycles like that, even one cycle in some cases, will destroy the battery. Since there is no BMS during discharge this can lead to using a damaged pack unknowingly with a resulting fireball while riding, whereas a BMS protected pack will shut down before that happens (watching each cell group's voltage), and additionally the 18650 cells have various built in protections that the lipo in the Walmart pack does not have. The controller LVC protection has NO IDEA about the individual cell voltages, it only sees a total. They can be significantly out of balance and still be above LVC. If one cell gets a mere pinhole in the mylar from ebike vibration it can suffer reduced capacity and fireball when the other 11 cells ram full operating current through it at a total pack voltage above LVC (eg 3.9 times 11 cells is 42.9 volts which is above the 42V LVC, so until the per cell voltage hits a little over 3.8V per cell there is NO protection for one cell failing).

By every measure except initial cost, the Walmart packs fall short. Even in cost per use they will likely fall short, but predicting the future is hard.

The Walmart product is somewhat cheap. But it could end up being very, very costly depending on if, when and how it fails. There are lots of ways to save money in life, this may not be the best place for economy. Over a life of say 4 years the Luna Mini costs less than 16 cents per day (a bit more including shipping). It will likely last longer than that so cost even less. I'll use my Walmart packs for starting cars and charging phones and toys, in my opinion they are unsuitable for serious ebike usage. When they die, which I expect will be somewhat after the 2 year extended warranty would be over (do you think it is an accident they offer that period?) I'll recycle them and move on. I will likely gift them out long before that. I saved the warranty investment, very rarely do those warranties pay out. They bring in a handsome profit for both the vendor and the insurance company, in fact. I heard someone just yesterday with an 84 month warranty on their car battery received 25% toward a new battery when it failed at 48 months. And that is only if the new battery is purchased from them, at regular price. Not much value in that warranty. If the pack will start a car then it meets their use case, and it could do that even if the total capacity is significantly reduced and useless for your ebike. Product works, warranty denied. Cheap lipo life expectancy is about 3 years, some of which is already expended in shelf time before the product is sold, so it comes out about right -- for them.

For starting cars these packs are fine - occasional short-term use that is monitored where an incendiary event will be easily dealt with. That is a different use-case and one for which they have been designed (and the protection is provided for in the charging clamp interface box).

Ride safe and enjoy,

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Re: WalMart EverStart Battery Test

Post by Boyntonstu » May 01 2016 7:26am

Alan B wrote:The Luna Mini pack is 2-3/4 by 3-1/4 by 6 inches and 3.3 pounds, about the size of two of the Walmart packs, of which you need four. So this pack is half the volume of the four Walmart batteries but contains twice the stored energy for 4x volumetric energy storage improvement. That is even including the BMS, which is inside that pack! It will fit in any number of little nylon bike bags, or in the triangle or trunk packs I already have, and this pack will be able to be used on three of my bikes (without cutting tiewraps). Mounting this tiny pack is not a problem, even compared to simply tiewrapping four Walmart packs.

The BMS is included in the prices mentioned, and built inside the pack. It is a 30 amp continuous and 50 amp peak BMS on discharge, where the Walmart has zero BMS on discharge in the ebike configuration.

I have a number of chargers that will work with this battery, starting at about $20 or $30, and they are 150W-360W. They work with other batteries I already have, so I didn't need to purchase yet another charger for this pack. Any voltage and current regulated power supply settable to 58.8V can do the task. My favorite is the ebikes.ca Satiator which costs more but gives complete information about the charging energy and voltages put into the pack, so I can keep track of how deeply I'm discharging it and gauge the range and capacity accurately. The Walmart chargers are 15W each, times four for a total of 60W, and they give zero information about energy needed to recharge the pack. They charge quite slowly which encourages the user to not be present when charging. Again the Walmart product falls short of the weakest lowest cost ebike charger, by factors of 2-6x.

The Walmart packs are 1.1 pounds each so the four required are 4.4 pounds for half the energy, plus a wiring harness is needed to connect them in series. So the Walmart packs are 2.6 times as heavy per watt hour. So far the Walmart packs are heavy, large and slow to charge.

Specs for these packs are for 80% capacity at 400 to 1000 charge cycles (so even then far more capacity than the Walmart packs new). The Walmart packs have no specifications (actually the spec they have is a lie, they claim 12,000 mAH and 11V), and the life cycle of the cheap cells inside are typically nowhere near the life cycle of quality 18650 cells. Walmart can choose to honor their warranty or not, depending on their whim when you return the packs. If you warranty one of them, they will be even further out of balance, if you warranty all four of them at once they may decide not to honor the warranty at all. There is lots of fine print in those warranties they can invoke.

The Walmart packs have NO BMS protection on discharge in ebike use, and relying on controller low voltage cutout (LVC) can lead to overdischarging cells within the pack WITH NO OUTWARD EVIDENCE. A few cycles like that, even one cycle in some cases, will destroy the battery. Since there is no BMS during discharge this can lead to using a damaged pack unknowingly with a resulting fireball while riding, whereas a BMS protected pack will shut down before that happens (watching each cell group's voltage), and additionally the 18650 cells have various built in protections that the lipo in the Walmart pack does not have. The controller LVC protection has NO IDEA about the individual cell voltages, it only sees a total. They can be significantly out of balance and still be above LVC. If one cell gets a mere pinhole in the mylar from ebike vibration it can suffer reduced capacity and fireball when the other 11 cells ram full operating current through it at a total pack voltage above LVC (eg 3.9 times 11 cells is 42.9 volts which is above the 42V LVC, so until the per cell voltage hits a little over 3.8V per cell there is NO protection for one cell failing).

By every measure except initial cost, the Walmart packs fall short. Even in cost per use they will likely fall short, but predicting the future is hard.

The Walmart product is somewhat cheap. But it could end up being very, very costly depending on if, when and how it fails. There are lots of ways to save money in life, this may not be the best place for economy. Over a life of say 4 years the Luna Mini costs less than 16 cents per day (a bit more including shipping). It will likely last longer than that so cost even less. I'll use my Walmart packs for starting cars and charging phones and toys, in my opinion they are unsuitable for serious ebike usage. When they die, which I expect will be somewhat after the 2 year extended warranty would be over (do you think it is an accident they offer that period?) I'll recycle them and move on. I will likely gift them out long before that. I saved the warranty investment, very rarely do those warranties pay out. They bring in a handsome profit for both the vendor and the insurance company, in fact. I heard someone just yesterday with an 84 month warranty on their car battery received 25% toward a new battery when it failed at 48 months. And that is only if the new battery is purchased from them, at regular price. Not much value in that warranty. If the pack will start a car then it meets their use case, and it could do that even if the total capacity is significantly reduced and useless for your ebike. Product works, warranty denied. Cheap lipo life expectancy is about 3 years, some of which is already expended in shelf time before the product is sold, so it comes out about right -- for them.

For starting cars these packs are fine - occasional short-term use that is monitored where an incendiary event will be easily dealt with. That is a different use-case and one for which they have been designed (and the protection is provided for in the charging clamp interface box).

Ride safe and enjoy,
The weight ratio is therefore 4.4/3.3 or 1.33 . I carry 1.1 pounds more battery. (I lost 24 pounds of body weight)
My rides never deplete my batteries, they have more capacity than I need.

I have a series fuse and I believe that it is 20 A. I could lower it as necessary.
If 1 cell shorted and the other 11 attempted m0re than 20 A, there is no discharge. Is a discharge BMS necessary if there is a fuse?

How many 18650's make up your battery?
My guess is four 2,000 mAh cells in parallel by 12 in series, for 48 total. Am I correct?

Site of discharge indicator. See http://media3.webcollage.net/5926c6e74f ... Ukcp010%3D

I never go below 75% of capacity as indicated by 2 blue LED's.

"they give zero information about energy needed to recharge the pack." Correct for the charger, but the pack LED's certainly tell the story.

"They charge quite slowly which encourages the user to not be present when charging." I set a 4 hr timer and that is enough for a full charge.

The cells start at 4.25V and discharge to 3.9V. I have to recharge .35V @ 48V nominal x 12 cells or 218.88 Watts.

I am out of town at the moment but IICRC each charger can put out 1.8 A at 12V or 21.6 Watts x 4 = 86.4 Watts

218.88 / 86.4 = 2.5 Hours or using your 60 Watt figure, 218.88 / 60 = 3.6 hours.

In 4 hours it's charged and the charger is off.



Walmart Warranty. I have a HP2000 laptop that is very slow. It has an AMD 300 at 1.3 GHz running Lubuntu 14.04LTS at the moment. Dual boot with Win 8.1.
Impossibly sow in Win 8.1, very fast using Lubuntu!
At 23 months, I dropped it in my garage and the screen shattered and badly dented the case.
The insurance company sent me a free mailer box and they sent it back to me completely refurbished. I could not detect any dents or damage,
They assured me that if they could not repair it, they would refund my full purchase price. I believe them and I no reason to doubt that they will repair my batteries or refund my money.

This has been a good thread. Thanks.

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Re: WalMart EverStart Battery Test

Post by nutnspecial » May 01 2016 7:46am

Alan, where you included facts, they were very helpful to me. It's obvious the boosters are a niche compared to actual packs, and more user-involved to safely and properly operate. I don't necessarilly find that or them a bad thing for multiple aspects, and some of the other stuff you said about the packs was just a perspective.

Great vids boyntstu, and great job on the bike!!! :D

I think you're making great use of the batteries, and think they'll last you a long time. Also, the warranty is a great deal too. Their 3yr replacement on lead acid is very good too.
As I mentioned elseware, it's also good to know what individual cells are doing rather than assuming they're all at an average. This particular chemistry especially. Anyway, great job.


Obviously I wouldn't recommend these packs or my naked lipo to the general masses that often have no desire to even be smarter than the battery and bms in their phone. . . . but I don't think the general negativity towards boynt or the 'boosters' are warranted here at all, in this way.
. . . statements like “the controller protects @3.5V/cell” is downright dangerous info . . . controller doesn’t measure cell voltages.
"The controller cuts @ 3.5v/cell Average " Would be an accurate and important distinction/correction.

If the bms' protection on charge won't allow charge of a low cell, I'd say the packs are about as safe as any other bms pack (for the standards of the masses)- though one overdischarge will then cripple the pack for standard use of standard user.

I would definately test cell drift at various discharge rates and levels, and test full bms fuction if I owned one or more.

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Re: WalMart EverStart Battery Test

Post by Boyntonstu » May 01 2016 8:40am

"The controller cuts @ 3.5v/cell Average " Would be an accurate and important distinction/correction. I agree.

Thanks for your comments.

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Re: WalMart EverStart Battery Test

Post by Alan B » May 01 2016 11:10am

The weight ratio is therefore 4.4/3.3 or 1.33 . I carry 1.1 pounds more battery. (I lost 24 pounds of body weight)
My rides never deplete my batteries, they have more capacity than I need.

I have a series fuse and I believe that it is 20 A. I could lower it as necessary.
If 1 cell shorted and the other 11 attempted m0re than 20 A, there is no discharge. Is a discharge BMS necessary if there is a fuse?

How many 18650's make up your battery?
My guess is four 2,000 mAh cells in parallel by 12 in series, for 48 total. Am I correct?

Site of discharge indicator. See ...

I never go below 75% of capacity as indicated by 2 blue LED's.

"they give zero information about energy needed to recharge the pack." Correct for the charger, but the pack LED's certainly tell the story.

"They charge quite slowly which encourages the user to not be present when charging." I set a 4 hr timer and that is enough for a full charge.

The cells start at 4.25V and discharge to 3.9V. I have to recharge .35V @ 48V nominal x 12 cells or 218.88 Watts.

I am out of town at the moment but IICRC each charger can put out 1.8 A at 12V or 21.6 Watts x 4 = 86.4 Watts

218.88 / 86.4 = 2.5 Hours or using your 60 Watt figure, 218.88 / 60 = 3.6 hours.

In 4 hours it's charged and the charger is off.


The weight ratio is 1.33, for only half the energy, or 2.66:1 per unit energy.

Great job on the weight loss.

Limiting time for the charger may have the unintended effect of preventing the BMS from fully balancing the cells. It needs continued power after the end of charge for some time to do the balancing.

The amount of current needed to cause a cell to burst into flame is less than the value required to open a 20A fuse. In fact in this case the loss of one cell would slightly lower the voltage to the controller (without crossing LVC) and it would continue to power the bike, so the current would NOT tend to open the fuse. The dying cell would be reverse charged by the load current from the other 11 cells and this tends to cause the receiving cell to fail spectacularly on a short timescale.

Fuses don't prevent packs from flames (they really only protect against shorts in the wiring or load), though they are a useful component of a protection system that includes a number of elements. Fuses do not interrupt current instantaneously, they do so only after having conducted enough current to raise the temperature of the low resistance value of the fuse (remember i squared r) to a very high temperature then continue to conduct via the arc that develops as they melt, and then still continue to conduct up to the time the arc is finally extinguished (which can be a very long time if the fuse is incorrectly selected, especially in a DC system). This can deliver a considerable amount of energy to the fault causing the overcurrent, enough to cause a significant plasma explosion.

A BMS shuts down the load and charge if ANY INDIVIDUAL CELL voltage gets too low or too high, or if the temperature is too low or too high.

The Luna Mini pack is 14S2P, 28 cells. The Samsung 30Q cells are rated to deliver up to 15 amps continuous and 3 amp hours capacity hence the pack rating of 30 amps continuous and 6 amp hours. The Luna BMS also has thermal detection so if the pack gets too warm it will shut down. This feature is also missing from the Walmart packs when using them on an ebike.

The pack LEDs tell a voltage story, which is useful but not accurate, and it tells almost nothing about the energy required to recharge the pack, or how much the pack capacity is dropping from when it was new. Lower capacity cells follow the same voltage curve, the energy also needs to be inspected to understand the condition of the cell and pack.

The Walmart chargers that came with the two packs I have are rated at 15V 1 amp output. Charging is a nonlinear process and near the end of the cycle the current and charge rate is much lower, so charging takes longer, and then balancing occurs during and after that. Inspecting the current consumption is the best way to tell when charging and balancing are complete. This information is not available on the Walmart units. Stopping the charge when the LEDs are all illuminated may be adequate for the pack voltage to be near full, but it may not be sufficient for balancing to have completed. If the individual cell voltage taps were brought out we could use a Battery Medic or other per-cell meter to measure the cell voltages such as all the RC packs allow, but this Walmart pack does not provide that ability, which makes curating the pack difficult.

We are rather at a disadvantage with the Walmart packs, even if we want to manage them well. We don't have specs on the batteries or on the BMS. We don't have the connections to measure the individual cell voltages, charge current or energy. We don't have any BMS functionality during discharge, either for cell voltages or pack temperature. Normally with an RC pack we would have the connections to measure the cell voltages. We would be able to inspect the cells for signs of swelling and measure the cell voltages and temperatures easily. We don't have any of that here. So it seems we have a pack that is perhaps even more dangerous than an RC pack when used for an ebike.

This could be improved by hacking the Walmart batteries, at the cost and risk of losing the warranty.

Keep an eye on those batteries, and ride safe. Regardless of any small risks from the battery, traffic is the most serious threat we all face.

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rborger73   10 kW

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Re: WalMart EverStart Battery Test

Post by rborger73 » May 01 2016 12:12pm

Boyntonstu wrote:
Alan B wrote:
Hillhater wrote:No doubt if you intend to jump start autos, or if you really need the high output, these are a good choice.
..I was really pointing out that if anyone was thinking of buying these in the hope of "harvesting" some high power 18650's cheaply to build a ebike pack with .....then its not the answer.
(Most of the similar backup "Power Packs" are powered with 18650's...but wont jump start a Barbie car!)
Also, i dont think anyone has tested the cycle life of these cells at anything like their claimed output.
I haven't opened one of these up but I found similar batteries on the internet disassembled and none had 18650's inside. I don't think they can cheaply and easily get to the peak currents they need that way, there's too much cost for the manual interconnects and they add resistance as well. So I suspect that all these are using some form of Lipo batteries due to the high peak current capacity.

I agree that these are not cheap batteries if you want to take out the cells, whatever they are.

They have a number of valid uses, but ebikes isn't a good one. There is one user that is using them for that, but his battery needs are unusually small, for most ebike users these would be too bulky and not cost effective for a normal range, especially at the normal price. Some of the new batteries for electric yard tools might be a better direction to go, they have serious voltage and energy capacity.

After a ride of 6 miles at 17 mph pedal assist, my four Walmart Booster batteries in series are discharged to just under 3,9 V per cell.

My bike will go 22.8 miles to LVA at 3.5 V/cell if I PA at 15 mph.

Not too shabby and not an unusual small ride.

Not a lot of bulk or weight.

To date over 70 charge/recharge cycles.


Please... do not use wirenuts or poor connectors on an ebike. This is asking for problems..

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Re: WalMart EverStart Battery Test

Post by Boyntonstu » Jun 02 2016 11:36am

[quote=

OK, let's pick an example. This arrived recently in the mail. This 3.3 pound Luna mini pack has 52V at 6AH of 18650 cells, higher voltage and TWICE the total energy (52:44V, 6:3.5AH, 312:154WH), is much smaller, and it has a BMS that actually protects the cells during charge AND discharge. At the regular prices these packs are less than 2x different in cost (229:159). .[/quote]

Let's compare:

http://lunacycle.com/batteries/packs/52 ... ffordable/

with 5 Ah $219

http://www.amazon.com/EGO-Power-56-Volt ... B00NP1MZFO

or 7.5 Ah $299

http://www.amazon.com/EGO-Power-56-Volt ... B00NP1MZFO

My opinion is that the EGO package is far superior to the Luna brick in cooling and in fire prevention.

My only doubt is whether 56V be acceptable for a 48V controller?

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Alan B   100 GW

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Re: WalMart EverStart Battery Test

Post by Alan B » Jun 02 2016 1:30pm

Boyntonstu wrote:

OK, let's pick an example. This arrived recently in the mail. This 3.3 pound Luna mini pack has 52V at 6AH of 18650 cells, higher voltage and TWICE the total energy (52:44V, 6:3.5AH, 312:154WH), is much smaller, and it has a BMS that actually protects the cells during charge AND discharge. At the regular prices these packs are less than 2x different in cost (229:159). .
Let's compare:

http://lunacycle.com/batteries/packs/52 ... ffordable/

with 5 Ah $219

http://www.amazon.com/EGO-Power-56-Volt ... B00NP1MZFO

or 7.5 Ah $299

http://www.amazon.com/EGO-Power-56-Volt ... B00NP1MZFO

My opinion is that the EGO package is far superior to the Luna brick in cooling and in fire prevention.

My only doubt is whether 56V be acceptable for a 48V controller?
This thread is about the Walmart pack, not the Luna or EGO packs. There are threads for the EGO packs since 2014:
https://endless-sphere.com/forums/viewt ... 14&t=60064
https://endless-sphere.com/forums/viewt ... 14&t=61642

The Luna pack is 6 AH not 5.

The Luna pack is $36.50 per amp hour, while EGO is $39.87 per amp hour. The EGO pack is more expensive (per amp hour), larger, heavier, and there is no protection circuitry in the pack (protection is in the powertool). Luna cells are better quality (less voltage sag) (with full data available), have protection in the pack and are easier to connect to and deploy on a bicycle. There is no contest here at all.

There is no basis for stating either pack is "far superior" for fire prevention. The phase change materials add weight and bulk to the pack, and are not "fire extinguishing material". Allcell has been claiming superiority for years but proof is lacking. It is NOT COOLING technology, it is heat storage. A battery with this technology will weigh more and take longer to actually cool down. Instead of trying to capture heat, most vendors are working to reduce heat generation which has even greater benefits.

EGO packs have a very small volume of phase change material. I really wonder if it is enough to do much, or just an advertising gimmick. I suspect gimmick.

Here's one EGO customer comment:
After 2 years (5mo per year) mowing, the battery went from 45 minutes to 25 minutes. The price of a replacement battery doubled ... ($100 2015, $200 2016). ... not happy at all.
Further discussion of the EGO packs should take place in the EGO threads. In the two years since they were started there have been no ebike uses of those packs noted, and comments in those threads indicate other superior choices in the tool battery category.

I would consider the EGO power tools for yard work, and if the batteries were already on hand it might make sense to use them in low powered ebikes, but there are better batteries available for ebike use. I do see that buying it from other than Home Depot may lead to warranty problems, apparently the warranty is in some way tied to HD.

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jumper box/boost box used as is as pack module?

Post by classicalgas » Mar 03 2019 7:39pm

Can't seem to find any previous mention, anyone tried this?

These are lithium packs with built in bms,10-18 (claimed) Ah at 12-15 v, typically 10a sustained output, much higher peak,rugged enclosures, and cheap. Some extras (lights, device charging ports, charge state readouts...)

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Re: jumper box/boost box used as is as pack module?

Post by mark5 » Mar 03 2019 7:51pm

Boyntonstu's Walmart Booster Batteries
https://endless-sphere.com/forums/viewtopic.php?t=74610

Alan B's WalMart EverStart Battery Test
https://endless-sphere.com/forums/viewtopic.php?t=79627

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Re: WalMart EverStart Battery Test

Post by classicalgas » Mar 03 2019 9:24pm

Good stuff, thanks. Evidently my search used the wrong terms.

I don't understand why the massive volume production of boosters and tool packs doesn't result in better tech for the money than home built packs, at least for legal level wattage.

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