Boyntonstu
10 kW
Hillhater said:
Correct! Not even warm to the touch,
They re available as shown above.
Walmart Booster Batteries
- Thread starter Boyntonstu
- Start date
Correct! Not even warm to the touch,
They re available as shown above.
nutnspecial
10 MW
Very cool, thankyou! That's a large bonus to charge while series'd with stock ac charger. Those connectors are a good find also- I use similar bullets, but those w/ housings would be very useful and likely they're way cheaper than similar 'housed' connectors of similar rated current.
If you're newer to lithium as I am, the best life from packs will be found by:
-keeping as close to 1/2- 3/4 charge as much as possible and at all possible times,
-keeping in temperate location (as close to 50deg F) as much as possible for use and disuse. . .
-and that's all I can think of when draws are very friendly for the battery, such as in this use.
This is at least my most general take, I'm not sure if and what major exceptions should be considered, outside the near necessity of full charge and deep discharge likely in their use.
So we established that these are lipo batteries... $120 for ~200wh is not bad when you consider that it comes with charger and BMS. It will be interesting to see how many charge cycles you get out of these before they start pooping out.
For comparison, a 48v 10ah ping battery is going to be about $400 with charger and BMS. It has 2.5x the capacity and will probably get 4-5x as many cycles in the long rate at the same discharge rate you are using. In the long run it is still a much better deal if you don't want to abuse Walmart warranty claims and have something that is proven to work. I doubt they are going to let you bring 4 of those booster packs back 2 or 3 times under the same warranty.
For comparison, a 48v 10ah ping battery is going to be about $400 with charger and BMS. It has 2.5x the capacity and will probably get 4-5x as many cycles in the long rate at the same discharge rate you are using. In the long run it is still a much better deal if you don't want to abuse Walmart warranty claims and have something that is proven to work. I doubt they are going to let you bring 4 of those booster packs back 2 or 3 times under the same warranty.
Boyntonstu
10 kW
ecycler said:
Use them for 2 years and you get your money back if they fail.
Buy another 4.....
They are fine after many cycles since December 19.
The controller does not allow them to drop below 3.5V.
I usually recharge at 3.9V.
They love me for that.
Chalo
100 TW
Boyntonstu said:
That's your motor controller?
I'm curious whether the BMS in the pack enforces a hard cutoff, or only gives a warning light as it discharges the cells too deeply. For safety and liability reasons, it seems like it would have to have a minimum cell voltage cutoff.
Boyntonstu
10 kW
Chalo said:
I'm curious whether the BMS in the pack enforces a hard cutoff,
Yes, the motor will cut off at VLC.
Boyntonstu
10 kW
Update: 50 charge/discharge cycles with no battery deterioration noticed.
Go for a 6 mile ride at 15+ mph, charge for 2 hours, done!
Go for a 6 mile ride at 15+ mph, charge for 2 hours, done!
Boyntonstu
10 kW
ecycler said:
My "What Meter" is What's happening.
(I have no need to buy, wire, and mount a Watt Meter.)
Boyntonstu
10 kW
Update: Test to VLC at 15 mph PA 22.8 miles.
On a single charge:
First day: two 6 mile rides for 12 total.
Second day: 6 miles
Third day: 6 miles.
Fourth day: 4.8 Miles until the controller cut off. I pedaled 1.2 miles at 9 mph -10 mph without batteries.
I now know that the Walmart Boosters can take me into some strong headwinds on a one way trip of 22+ miles.
Not too shabby!
On a single charge:
First day: two 6 mile rides for 12 total.
Second day: 6 miles
Third day: 6 miles.
Fourth day: 4.8 Miles until the controller cut off. I pedaled 1.2 miles at 9 mph -10 mph without batteries.
I now know that the Walmart Boosters can take me into some strong headwinds on a one way trip of 22+ miles.
Not too shabby!
DAND214
10 MW
All I can say is, WOW! I got 28.8 out of what I read. 12+6+6+4.8=28.8?Boyntonstu said:
Dan
Boyntonstu
10 kW
DAND214 said:
Dan,
I was right and also wrong:
Update: Test to VLC at 15 mph PA 22.8 miles.
On a single charge:
First day: two 6 mile rides for 12 total.
Second day: 6 miles
xxxxxxxxxxxxxxxxxx.
Third day: 4.8 Miles until the controller cut off. I pedaled 1.2 miles at 9 mph -10 mph without batteries.
I now know that the Walmart Boosters can take me into some strong headwinds on a one way trip of 22+ miles.
Still not too shabby!
dogman dan
1 PW
Assuming you are getting no worse than 20 wh/mi, you have a 300 watt hour pack. about 6 ah.
Alan B
100 GW
I think we already established this is a 3S 11V 4AH pack (times four so 44v 4ah or 176wh). It is a small pack by most ebike standards, but one can always just pedal when it runs out.
In this market (car starting batteries) manufacturers normally claim the amp hours as though the three cells were in parallel, even though they are in series. This WalMart pack claims 12AH, but in reality it is only 4AH. The giveaway is the Watt Hour rating, if they give it. Some do, some don't.
In this market (car starting batteries) manufacturers normally claim the amp hours as though the three cells were in parallel, even though they are in series. This WalMart pack claims 12AH, but in reality it is only 4AH. The giveaway is the Watt Hour rating, if they give it. Some do, some don't.
Boyntonstu
10 kW
Alan B said:
Whatever the rating, 22+ miles on a single charge is 100% OK with me.
Boyntonstu
10 kW
ecycler said:
I suggest that you ride every day and slowly build up your endurance.
I lost 23 pounds and my blood pressure went from 135/89 to 110/60. My physician told me great!
Get the lowest blood pressure without any dizziness as you get up fast, is the goal.
When you carry 23 less pounds on your bike, it gets easier.
Alan B
100 GW
Capacity test of these batteries here:
https://endless-sphere.com/forums/viewtopic.php?f=14&t=79627
https://endless-sphere.com/forums/viewtopic.php?f=14&t=79627
Alan B
100 GW
I didn't see any BMS action on the pack output during the capacity test here:
https://endless-sphere.com/forums/viewtopic.php?f=14&t=79627
I suspect the voltage cutoff is in the protection circuit mounted in the box on the charging cable clamps, so if you take power directly from the EC5 connection you may not have the benefit of the BMS.
https://endless-sphere.com/forums/viewtopic.php?f=14&t=79627
I suspect the voltage cutoff is in the protection circuit mounted in the box on the charging cable clamps, so if you take power directly from the EC5 connection you may not have the benefit of the BMS.
heavymetalthunder
100 W
- Joined
- Oct 7, 2013
- Messages
- 185
I don't see any problems with the mount except you might want to use a few extra zip ties. On my ride to lower the center of gravity I was able to mount 6 5000 mak lipos om the frame where you see the large Mongoose decal. Four lipos were mounted between the space between the frame and front wheel and two on one side with the speed controller mounted on the other side.
Boyntonstu
10 kW
Alan B said:
https://endless-sphere.com/forums/viewtopic.php?f=14&t=79627
Alan B writes:
"3S BMS inside"
I believe that the BMS quoted is for charging, As for discharging, the ESC cuts off a 48s 4 pack (4 in series) at 3.5V per cell.
Good setup for my bike.
Alan B
100 GW
That would be the Motor Controller LVC doing the protection shutdown.
Not a per cell system, the motor controller has no idea what individual cell voltages are. Some could be lower while others are higher. It only sees the sum of the voltages.
You are depending on cell capacity being matched across four separate boxes. A risky proposition. Have you measured each pack after shutdown to see how well matched they might be on one occasion?
3.5V per cell is a good cutoff point for this battery.
Not a per cell system, the motor controller has no idea what individual cell voltages are. Some could be lower while others are higher. It only sees the sum of the voltages.
You are depending on cell capacity being matched across four separate boxes. A risky proposition. Have you measured each pack after shutdown to see how well matched they might be on one occasion?
3.5V per cell is a good cutoff point for this battery.
Boyntonstu
10 kW
Alan B said:
Thanks for your input.
Let's talk risk.
Each pack is balance charged separately to about 12 V.
The motor controller (I call it ESC electronic speed controller) receives a Voltage high enough for it to operate.
Should I be concerned what the voltage of each booster is as the series string is discharged to cutoff?
I do not understand the risk of a series string imbalance.
The batteries have been through 60 cycles without any problems.
I get 22+ miles at 15 mph.
What is the risk?
Alan B
100 GW
Motor controllers are called ESCs in the RC business. ESCs don't have the variety of features and inputs that motor controllers have such as battery and motor (phase) current limiting, ebrake inputs, three speed switches and cruise controls. Your ebike has a motor controller rather than an ESC.
I was under the impression that there was (or might be) a discharge BMS in these packs that was causing a pack to drop out and cause the controller to see LVC, based on what you said earlier. Thus protection on a per cell basis. My testing shows this is not the case. This EC5 connector apparently leads directly to the cells which makes sense given the current demands of starting a car engine.
So let's examine what you have there.
You have 12 cells in series spread across four separate modules. If the capacity of any of these cells does not match the rest it will drop low in voltage first and be damaged or destroyed before the pack voltage drops enough to cut off the motor controller. You are depending on all cells having matched capacity for the total voltage to represent the charge state of the lowest cell. Your fully charged voltage is 48V. Your cutoff is 42V. 6V is enough to lose a cell completely without losing enough total voltage to shut down the controller.
If you aren't checking this now, it may already be happening to some degree, not enough to prevent the success you have seen, but enough to be placing more wear on certain cells than on others (cycling some cells more deeply than others). It is normal for this process to occur in a battery pack over time and use.
Normally a BMS watches each cell and cuts off the system when any one of them drops low. This prevents further damage and fireball.
This problem does not crop up if the pack is only partially discharged. Operated in shallow cycles. Then the cells are not on the steeper slope at the end of discharge where the differential voltages can cause a cell to go low ahead of the others and suffer more wear and damage than the rest.
If the pack is fully discharged each time the risk of imbalance occurring increases with each cycle as the cells age unequally.
Most folks who don't have BMS's don't fully discharge their packs. They intentionally and purposefully use packs that have paralleled cells and are larger in capacity than they need to avoid getting down into that region near pack LVC where the risk of damage increases. You really NEVER want to hit LVC. It is not good for the pack, it ages prematurely.
With such a small pack you are cycling deeply a lot more often.
So you have increased risk with a very small unmanaged pack. Your setup is less safe than someone using cheap RC batteries and charging with an RC balance charger -- an RC balance charger is likely much higher quality than the walwart/BMS of the Everstart pack. The RC charger also gives a lot more information about the status of the cells, with individual voltage and per brick amp hours to recharge information. Information that helps the user recognize battery problems early before they become fireballs.
Your experience shows that the cells you have are fairly well matched now. So far. How long will this continue? How will you know when they start diverging in capacity? Will you catch it before the fireball? Cells do not age the same.
Your pack is not protected. Small things change the capacity of the cells. Things like cell temperature. If a pack sits in the sun awhile it will perform differently than others at ambient temperature.
Self discharge is different between different cells. Sitting for awhile (weeks) can drain different amounts of energy from the cells. BMS circuits often draw unevenly from the cells, so the BMS causes imbalance when sitting unused. So if you charge and don't use the packs for awhile, and then use them there is increased chance that they will be unbalanced from a number of factors.
My advice would be one of the following, in decreasing order of safety:
A) Buy a BMS managed 18650 pack and matching charger. The best situation. There are some really good deals on batteries these days.
B) Build a pack that has twice the capacity you need (or at least 25% more), charge it with a balancing charger, and never run it more than halfway down. If you use a bulk charger then monitor the cell voltages manually frequently to insure balance is good, and periodically balance charge it.
C) Acknowledge, accept and understand the increased risk you have and manage your undersized battery pack more carefully and realize it may still fireball on you at some point. Always charge it right before you use it. Keep it at 50-70% charge in between uses. Try to never deeply discharge the pack. Try to never hit LVC. Each time your motor controller hits LVC (and at the end of every deep discharge even if it didn't quite hit LVC) you should measure the voltage (with an accurate meter) across each pack and keep a record. Number the packs to keep the data sorted and compare them to each other, and watch the trend. If you do this you should be able to see which pack is weakest and possibly catch it before it fails, which could be in a fireball.
Perhaps you are prepared for a fireball on your bike, and you have a way of dealing with that at 20+ mph. Or it might happen after you get home and park your bike. Or while you are at the store, or the park, or visiting at a friend's house. Or during charging. Hopefully these charging circuits are well done and won't charge a damaged cell. But at this price point we have concern that the BMS may not perform well and may fail to prevent the fireball.
Have you seen the flaming fireball hoverboards? Their BMS's didn't prevent the fireballs.
We've had ES members burn their houses down from ebike battery management failures. I can think of one who didn't think it could happen to him and he ran a bunch of batteries in series that were not carefully curated, and ultimately lost his house to flame and smoke damage. Your risk is probably less than his, but it only takes one experience to really change your experience and attitude about safety.
I hope you never have to deal with the aftermath of a fire from your batteries that caused harm to others.
Just so you know.
Have fun, be safe and enjoy your ebike.
I was under the impression that there was (or might be) a discharge BMS in these packs that was causing a pack to drop out and cause the controller to see LVC, based on what you said earlier. Thus protection on a per cell basis. My testing shows this is not the case. This EC5 connector apparently leads directly to the cells which makes sense given the current demands of starting a car engine.
So let's examine what you have there.
You have 12 cells in series spread across four separate modules. If the capacity of any of these cells does not match the rest it will drop low in voltage first and be damaged or destroyed before the pack voltage drops enough to cut off the motor controller. You are depending on all cells having matched capacity for the total voltage to represent the charge state of the lowest cell. Your fully charged voltage is 48V. Your cutoff is 42V. 6V is enough to lose a cell completely without losing enough total voltage to shut down the controller.
If you aren't checking this now, it may already be happening to some degree, not enough to prevent the success you have seen, but enough to be placing more wear on certain cells than on others (cycling some cells more deeply than others). It is normal for this process to occur in a battery pack over time and use.
Normally a BMS watches each cell and cuts off the system when any one of them drops low. This prevents further damage and fireball.
This problem does not crop up if the pack is only partially discharged. Operated in shallow cycles. Then the cells are not on the steeper slope at the end of discharge where the differential voltages can cause a cell to go low ahead of the others and suffer more wear and damage than the rest.
If the pack is fully discharged each time the risk of imbalance occurring increases with each cycle as the cells age unequally.
Most folks who don't have BMS's don't fully discharge their packs. They intentionally and purposefully use packs that have paralleled cells and are larger in capacity than they need to avoid getting down into that region near pack LVC where the risk of damage increases. You really NEVER want to hit LVC. It is not good for the pack, it ages prematurely.
With such a small pack you are cycling deeply a lot more often.
So you have increased risk with a very small unmanaged pack. Your setup is less safe than someone using cheap RC batteries and charging with an RC balance charger -- an RC balance charger is likely much higher quality than the walwart/BMS of the Everstart pack. The RC charger also gives a lot more information about the status of the cells, with individual voltage and per brick amp hours to recharge information. Information that helps the user recognize battery problems early before they become fireballs.
Your experience shows that the cells you have are fairly well matched now. So far. How long will this continue? How will you know when they start diverging in capacity? Will you catch it before the fireball? Cells do not age the same.
Your pack is not protected. Small things change the capacity of the cells. Things like cell temperature. If a pack sits in the sun awhile it will perform differently than others at ambient temperature.
Self discharge is different between different cells. Sitting for awhile (weeks) can drain different amounts of energy from the cells. BMS circuits often draw unevenly from the cells, so the BMS causes imbalance when sitting unused. So if you charge and don't use the packs for awhile, and then use them there is increased chance that they will be unbalanced from a number of factors.
My advice would be one of the following, in decreasing order of safety:
A) Buy a BMS managed 18650 pack and matching charger. The best situation. There are some really good deals on batteries these days.
B) Build a pack that has twice the capacity you need (or at least 25% more), charge it with a balancing charger, and never run it more than halfway down. If you use a bulk charger then monitor the cell voltages manually frequently to insure balance is good, and periodically balance charge it.
C) Acknowledge, accept and understand the increased risk you have and manage your undersized battery pack more carefully and realize it may still fireball on you at some point. Always charge it right before you use it. Keep it at 50-70% charge in between uses. Try to never deeply discharge the pack. Try to never hit LVC. Each time your motor controller hits LVC (and at the end of every deep discharge even if it didn't quite hit LVC) you should measure the voltage (with an accurate meter) across each pack and keep a record. Number the packs to keep the data sorted and compare them to each other, and watch the trend. If you do this you should be able to see which pack is weakest and possibly catch it before it fails, which could be in a fireball.
Perhaps you are prepared for a fireball on your bike, and you have a way of dealing with that at 20+ mph. Or it might happen after you get home and park your bike. Or while you are at the store, or the park, or visiting at a friend's house. Or during charging. Hopefully these charging circuits are well done and won't charge a damaged cell. But at this price point we have concern that the BMS may not perform well and may fail to prevent the fireball.
Have you seen the flaming fireball hoverboards? Their BMS's didn't prevent the fireballs.
We've had ES members burn their houses down from ebike battery management failures. I can think of one who didn't think it could happen to him and he ran a bunch of batteries in series that were not carefully curated, and ultimately lost his house to flame and smoke damage. Your risk is probably less than his, but it only takes one experience to really change your experience and attitude about safety.
I hope you never have to deal with the aftermath of a fire from your batteries that caused harm to others.
Just so you know.
Have fun, be safe and enjoy your ebike.
Boyntonstu
10 kW
Excellent and informative reply! Thanks.
For my daily exercise use, I go 6 miles and immediately recharge.
I plan on making a video to show how I set up the timed charge and make the connections.
Once in a while I might go a mile to a local shopping center on an errand.
I am retired and I never commute.
There are 4 green LED's when fully charged.
When I connect the charger I can see how many LEDs are moving towards their charge position.
My guesstimate 1-1/2 out of 4.
Thus the number of solidly on LED's are fairly good Voltage indicators.
I purposely allowed LVC 2 times for test purposes only.
Based on your advice, I will not do it again.
Therefore, If I never go beyond 6 miles and during charging I do not see unequal lit LEDs, the packs should be fairly even.
My bike is either in my garage or on a ride. It is never left out in the sun.
This summarizes my situation quite well: "This problem does not crop up if the pack is only partially discharged. Operated in shallow cycles. Then the cells are not on the steeper slope at the end of discharge where the differential voltages can cause a cell to go low ahead of the others and suffer more wear and damage than the rest."
After some rides I have touched each booster to feel the temperature and they all have been cool.
Should I consider a metal shield (Aluminum OK?) wrap when the bike is in the garage to limit potential fireball damage?
BTW A smaller battery that suits my needs seems safer with respect to fires.
Many thanks.
For my daily exercise use, I go 6 miles and immediately recharge.
I plan on making a video to show how I set up the timed charge and make the connections.
Once in a while I might go a mile to a local shopping center on an errand.
I am retired and I never commute.
There are 4 green LED's when fully charged.
When I connect the charger I can see how many LEDs are moving towards their charge position.
My guesstimate 1-1/2 out of 4.
Thus the number of solidly on LED's are fairly good Voltage indicators.
I purposely allowed LVC 2 times for test purposes only.
Based on your advice, I will not do it again.
Therefore, If I never go beyond 6 miles and during charging I do not see unequal lit LEDs, the packs should be fairly even.
My bike is either in my garage or on a ride. It is never left out in the sun.
This summarizes my situation quite well: "This problem does not crop up if the pack is only partially discharged. Operated in shallow cycles. Then the cells are not on the steeper slope at the end of discharge where the differential voltages can cause a cell to go low ahead of the others and suffer more wear and damage than the rest."
After some rides I have touched each booster to feel the temperature and they all have been cool.
Should I consider a metal shield (Aluminum OK?) wrap when the bike is in the garage to limit potential fireball damage?
BTW A smaller battery that suits my needs seems safer with respect to fires.
Many thanks.
