Can a battery have different cut off voltages?

[PCeBiker]

What does your owners manual say about charging?

Are you supposed to unplug the charger as soon as the light turns green or is it just sort of an option?

My Das-Kit battery charges in 7 hours, but I can leave it on charge for 14 hours.

 

[m@Robertson]

Looks like I missed the party. Thanks to the weather here, I have been running my house on batteries (big ones) since Thursday nite.

Trying to catch up on everything at once, its possible one stone is left to turn: Creating an absolutely steady load on the battery pack to eliminate that variable in the discharge test. Noted some questions on throttle draw vs. PAS draw up above.

I use these, albeit for practical reasons (Usually to take a 100% charged pack lower if I charged up to ride, don't do it and don't want the pack to sit like that), not for test purposes. This may be a little heavy handed as they create a steady 7a on a 48v pack. But for $28 they are an inexpensive tool. Also dangerous as they get up to around 500 degrees so set it on a brick on top of a cement surface like a garage floor. Set it straight down on a painted garage floor leaves scorch marks.

Load Resistor 6.8

6.8 Ohm 400 Watt Load for Battery Discharge Testing.

ebikes.ca

I have seen DIY banks made that use a row of cheap light bulb sockets. Maybe not so good anymore now that LEDs only pull like 3-5w.

 

[Art Deco]

Looks like I missed the party. Thanks to the weather here, I have been running my house on batteries (big ones) since Thursday nite.

Trying to catch up on everything at once, its possible one stone is left to turn: Creating an absolutely steady load on the battery pack to eliminate that variable in the discharge test. Noted some questions on throttle draw vs. PAS draw up above.

I use these, albeit for practical reasons (Usually to take a 100% charged pack lower if I charged up to ride, don't do it and don't want the pack to sit like that), not for test purposes. This may be a little heavy handed as they create a steady 7a on a 48v pack. But for $28 they are an inexpensive tool. Also dangerous as they get up to around 500 degrees so set it on a brick on top of a cement surface like a garage floor. Set it straight down on a painted garage floor leaves scorch marks.

Load Resistor 6.8

6.8 Ohm 400 Watt Load for Battery Discharge Testing.

ebikes.ca

I have seen DIY banks made that use a row of cheap light bulb sockets. Maybe not so good anymore now that LEDs only pull like 3-5w.

Looking for some big batteries for the house, too. I will PM you.

 

[PCeBiker]

I have seen DIY banks made that use a row of cheap light bulb sockets. Maybe not so good anymore now that LEDs only pull like 3-5w.

I've got everything I need make my own discharge device.



I use incandescent bulbs to heat my hot box.
I can use 1 or 2 bulbs 40, 60, or 100 Watts each bulb to get 40-200 Watts of heat.



I can still get incandescent bulbs at the dollar store.
They're good for heating my crawlspace in the winter to keep the pipes from freezing.

 

[Nvreloader]

I wrote out the numbers and stuck em to my power supply for quick reference,..

View attachment 149134

It looks like your percent gage is off.
80% is 51.5v and 100% is 54.6v

So use your volts display instead. It's accurate.

Did you use batteries #1/2 or is that what they are reading after the light turned green and you unplugged the battery from the charger?

PC
The 1/2 batteries had a short ride on them, then the wind started blowing sideways,
this was the charge left in them. I don't normally charge these batts until the v reading is around 43.5v.
I normally pull the battery's OFF the charger, when the fan stops, but still shows a Grn lite. The manual just states Red charging, Grn full charge etc.

The 3/4 batts were charged and read 54.0v when full, they have dropped down to 53.9v just sitting. I have charged the 3/4 batts and the best/highest charge always stops at 54.0v, no matter how long on the charger. The v meter always reads 54.0v,
regardless how long these batts have been charged.
My charger will only charge to 54.0v, it seems.
Tia,
Don

 

[Nvreloader]

Hey Guys
Updated Batt info, all throttle use only,
The wind decided to die down for a while, so I hit the road.

Using both Bat #3/4 checked was 53.8V per VM and Display read 100%,
Checked at 45% (Display) Volt checked @47.6V, (both batt).
Checked at 34% = 46.9V (2 Batt).

Changed to only #4 Batt = 49.0% = 47.7V
and finished test @ 19% Display = 45.9V. (Could not feel any power from bat).
Too cold to finish test Bat 3.

The display % is not accurate as compared to the Voltage Reading.

Letting batts get back to room temp before charging, was 39* cold N breeze.
40 miles total travel, for this test, all throttle.

Your thoughts and suggestions...............
Tia,
Don

 

[tomjasz]

Looks like I missed the party. Thanks to the weather here, I have been running my house on batteries (big ones) since Thursday nite.

Trying to catch up on everything at once, its possible one stone is left to turn: Creating an absolutely steady load on the battery pack to eliminate that variable in the discharge test. Noted some questions on throttle draw vs. PAS draw up above.

I use these, albeit for practical reasons (Usually to take a 100% charged pack lower if I charged up to ride, don't do it and don't want the pack to sit like that), not for test purposes. This may be a little heavy handed as they create a steady 7a on a 48v pack. But for $28 they are an inexpensive tool. Also dangerous as they get up to around 500 degrees so set it on a brick on top of a cement surface like a garage floor. Set it straight down on a painted garage floor leaves scorch marks.

Load Resistor 6.8

6.8 Ohm 400 Watt Load for Battery Discharge Testing.

ebikes.ca

I have seen DIY banks made that use a row of cheap light bulb sockets. Maybe not so good anymore now that LEDs only pull like 3-5w.

I have a second GRINSPECTOR kit. And have decided to not continue with any battery testing, or repairs.

Sold

https://ebikes.ca/dual-resistor-battery-load-bank.html

endless-sphere.com

 

[6zfshdb]

I have a second GRINSPECTOR kit. And have decided to not continue with any battery testing, or repairs.

Sold

https://ebikes.ca/dual-resistor-battery-load-bank.html

endless-sphere.com

Tempting Tom, but I'm also getting away from working on these batteries. I'm not expert enough and there are just too many risks. I'm not using questionable aftermarket batteries anymore and deal only with quality name brand pre assembled products.

It's a good deal on the Grinspector though!

 

[PCeBiker]

The display % is not accurate as compared to the Voltage Reading.

The % and battery bar graph are estimates generated by your computer.
Just because your voltage drops to half, doesn't mean that your capacity has dropped to half.

My new display allows me to adjust the battery bar graph and % to more accurately represent the actual capacity.

If I set it to zero, the bar graph follows the actual instantaneous voltage, and the graph will be bouncing around following the voltage.


In your case, it's best to view your actual voltage because your battery will shut down and stay that way if you reach your low voltage cutoff point.

It will be up to you to monitor your voltage and your Wattage output to know what point your batteries cut out at.

If your batteries can cut out when you still have 50% capacity, then you really need to watch your instantaneous voltage to avoid hitting that cutoff voltage.

 

[PCeBiker]

@Nvreloader try charging one of your batteries that has shut down for just a few seconds or a minute.

If that battery was at 50% voltage maybe all it needs is a few seconds of charge to reset the BMS.

It's too bad that you can't reset the battery by simply removing and replacing it.

 

[Nvreloader]

@Nvreloader try charging one of your batteries that has shut down for just a few seconds or a minute.

If that battery was at 50% voltage maybe all it needs is a few seconds of charge to reset the BMS.

It's too bad that you can't reset the battery by simply removing and replacing it.

PC
I'll try the recharging for a few seconds,
I can monitor the V thru the battery as the discharge slots are at the other end.

I'll also install and remove the 19% batt to see the difference, on the bike.

I'll change the display back to Voltage, as it is accurate in the readings,
when I compare it to the VM etc.

Thanks,
Don

 

[PCeBiker]

I'll change the display back to Voltage, as it is accurate in the readings,
when I compare it to the VM etc

It's the combination of voltage and wattage that shuts down your batteries.

I looks like you can go heavy on the throttle or PAS mode on fully charged batteries.
It's when you get to around 50% charge/voltage that your batteries want to cut out.

If you can monitor wattage or current as well as voltage, then you should be able to get the most out of your batteries.

If you can keep your wattage output to about 100 Watts or less, you should be able to drain them down much closer to the 40 volt cutoff point.
But, one little twitch of the throttle when your below 50% may very well shut down a battery.

 

[Nvreloader]

PC
On yesterdays test,
I used the throttle/with lock and was running in Eco1 and the 35T gear
which averaged 15-17 mph for the whole throttle test.

Just checked the #4 batt
Was at 19% = 45.9v at the end of the ride.
This batt now reads @ 38% = 47.2v
After sitting all night, and was NOT on the bike.
Tia,
Don

 

[PCeBiker]

PC
Just checked the #4 batt
Was at 19% = 45.9v at the end of the ride.
This batt now reads @ 38% = 47.2v
After sitting all night, and was NOT on the bike.
Tia,
Don

I'm pretty sure that's normal.
Your battery did warm up, and voltage can also recover to some degree after heavy use.

I'm just guessing here, (maybe others can comment) but I think that better quality, newer, high capacity, fast charge/discharge cells have less of that voltage recovery?

I read that there are new li-ion battery cells that charge or discharge at something like 5 or 10 amps continuously !!
They have such a low internal resistance that they don't get hot when charged or drained quickly.

 

[Nvreloader]

PC
These cells are LG 21700 brand/name.

 

[PCeBiker]

PC
These cells are LG 21700 brand/name.

As far as I know, those are high quality cells.

But I wonder why your batteries are cutting out at ~50%
You have 30ah total feeding your motor so there shouldn't be that much voltage sag?


You might want to consider new chargers that don't put out so much current.
5 amps into a 15ah battery is A LOT and is hard on the battery.
Perhaps that's why your used batteries are cutting out so soon? They are kinda wearing out?

You may be able to charge two batteries at once with a single charger and a Y Splitter on the output?

It's that third pin on your charger and your Canbus that I'm not familiar with.
It's possible that the third pin on your charger connector isn't used? Perhaps it's only used when the battery is installed on your ebike to allow the controller to "talk" to the battery?
Maybe the charger doesn't need to "talk" to the battery?

Maybe @6zfshdb , @Gionnirocket , @tomjasz or @m@Robertson can shed some light on that idea?

It may well be that one battery could drain into the other if two batteries are connected in parallel to a single charger?
Maybe the BMS's prevent that? I dunno?

It's just that charging a 15ah battery at 5 amps is pretty hard on the battery.

It's like running your car at red line.
It's possible, but your engine isn't going to last that long.

 

[Nvreloader]

Up date:
I don't know nothing about these battery's............LOL

I bought back my used OEM battery Alum shell, that couldn't be repaired,
so I could block/filled the bottom bat hole in the bike, to keep crap out of the main battery hole, front tire throws all kinds of crap every where.

This battery shell, (no battery's or nothing inside), has the all the OEM plugs still attached to each end.
I pulled the main connection end out of this shell and found this information,
the Power plug into the battery has only 2 wires attached to the + and - terminals,
1 Black and 1 Red colored.
The third pin has NOTHING attached to it.

The Hailong Power plug, 4 flat pronged slots are wired this way,
the main + plug #1 (Red) has a second smaller wired soldered to it,
and the same for the #2 - plug side. These plugs are numbered 1+ & 2-.

So the Positive has 2 wires attached together and the same for the negative wires,
unknown where these wires go to or used for.

On the other end of the battery, there is a small switch that when pushed
lites up in Blue, Green and Red colors, show state of charge?
HTH's
Don

ps, It appears that the wind is dying, so I am headin out for a ride.
Do I take 3/4 out and use them down to around 41.0v just to see the results?

I will note all spec's during the test, and would it be better if I kept the throttle speed
in the 10/15 mph range I normally ride in?

 

[Gionnirocket]

You would need to check the spec sheet for the specific cells.... but that said, 5a divided amongst 13 cell groups is far from ridiculous.
For example... Here's the spec for a single Samsung 18650 cell. One cell can handle a 4a charge and the recommended charge is 1.25a
That, that said... the lower and slower the charge, the better. Especially if it's not a necessity.

 

[Gionnirocket]

Don

A lot of what you are doing is just spinning your wheels. If you want to know the cut off voltage for your batteries you need to run them to that point and it can't be battery specific when you run them in parallel.

Run both batteries as you normally ride until one or both shut down. Then test V on each.
Now you know the set (parallel pair) capacity and characteristics.

From this point use only one and see what you can ride that down to... Test
Now the same with the other
Now you know what each individual LV cutoff is.

If you have a well matched pair as how they should be sold... The individual should be very close to what the pair is. Actually in theory the parallel should run a bit lower as the output capacity is increased and V sag should be lower.

Now roll!

 

[PCeBiker]

.... but that said, 5a divided amongst 13 cell groups is far from ridiculous.

Ohh, OK
I was just comparing Don's battery to my battery.
My battery is 48v 21ah with a 3 amp charger.
Maybe Das-Kit was keeping costs down with a 3 amp brick charger with no fan?