Can a battery have different cut off voltages?

Nvreloader said:
The OEM battery's #1-2 have been charged 8 times,
from 43.5v up to 53.8v average voltage range,
and this is the first charge of the new bought #3-#4 battery's,
from 39.5/40.4v up to 53.8v (both the same).
Click to expand...
Gionnirocket said:
2. Full charge should be 54.6v, not 53.8v
Click to expand...

It looks like you have been charging your batteries to 80%

I was going to do that too but have changed my mind.
As long as I don't fully charge my battery then store it, I should be fine.

electricbikereview.com

Reention newly upgrade 48V 25Ah&36V 30Ah (505L) interchangeable for eBikes Surface 604,NCM,Rize,Magnum,Aventon

Thank you for your trust! @PCeBiker I'm just wondering. Does the battery's BMS balance the cells?
electricbikereview.com electricbikereview.com

Your 2 batteries combined are 30ah and at 80% you get ~24ah.
That isn't really all that much, and you really need to get the most range out of your batteries.
 
PCeBiker said:
I think that would be a great idea for @Nvreloader
It's really important for him to know where his batteries are at.
He's out in the middle of nowhere where pushing or pedaling his bike really isn't an option.
Click to expand...
Making your own Coulometer isn't difficult if you're a DIY'er. I use one of these on my bikes:

51Ftg-3jgOL._AC_SL1000_.jpg


Here's a link on how to do it:

electricbikereview.com

Accurate Battery Gauge Project

I've searched in vain for some time now for an accurate, programmable, handlebar mounted battery gauge. Some high end bikes come equipped with this type of gauge and the displays on many others are up-gradable. Unfortunately, the controller on my bike isn't one of them. The battery gauges on...
electricbikereview.com electricbikereview.com
 
PCeBiker said:
It looks like you have been charging your batteries to 80%

I was going to do that too but have changed my mind.
As long as I don't fully charge my battery then store it, I should be fine.

electricbikereview.com

Reention newly upgrade 48V 25Ah&36V 30Ah (505L) interchangeable for eBikes Surface 604,NCM,Rize,Magnum,Aventon

Thank you for your trust! @PCeBiker I'm just wondering. Does the battery's BMS balance the cells?
electricbikereview.com electricbikereview.com

Your 2 batteries combined are 30ah and at 80% you get ~24ah.
That isn't really all that much, and you really need to get the most range out of your batteries.
Click to expand...
53.8v is 96.5% of actual battery capacity if you calculate using the batteries spec'd full range of 34.6 - 54.6v.
Most people and charts calculate the usable range only going down to 40v which has built in safety margins.
Splitting hairs but for testing it's proper/accurate to use the actual.
 
Gionnirocket said:
53.8v is 96.5% of actual battery capacity if you calculate using the batteries spec'd full range of 34.6 - 54.6v.
Most people and charts calculate the usable range only going down to 40v which has built in safety margins.
Splitting hairs but for testing it's proper/accurate to use the actual.
Click to expand...

OK, so with that in mind, and if @Nvreloader were to charge his battery to 54.6V instead of 53.8V, he should get ~20% more range, not ~3.5% more range, correct?
 
Last edited:
Gionnirocket said:
Don
I'm sorry but I think you've got some bad batteries... But to know what's going on you can't run two in parallel to test.
1.Run each battery individually to test capacity and voltage range.
2. Full charge should be 54.6v, not 53.8v
3. As others have mentioned LV cut off should be around 40v
4. I know you have an Ultra.. What's you controller LV set to on page 1 of the settings.
5. Check the voltage output of your charger... Should be 54.6v

From the information we have so far I'd guess you have a battery(s) with bad cells. The internal resistance of one group is lower than the rest of the pack causing it to charge and discharge faster than the others in that battery. This is why you're only reaching 53.8v on a full charge.. because the one bad group is reaching HV cut off before the others and the BMS only allows charging until the first group reaches 4.2v. You don't have a balance BMS otherwise this wouldn't be a problem on the charge side of reaching 54.6v.

I'm of the opinion that and no amount of cycle charging to 100% is going to correct this as you can't correct the internal resistance problem of the bad cell group. You may get it to incrementally take a higher charge but be careful as you'll repeatedly be pushing a defective group to its HV limit. In other words don't try to force it by charging repeatedly in the same use cycle... This is how fires start.
Click to expand...
GR
Thanks for the information,
Let me clarify how I charge all my battery's, as I may not be doing it right.
When I charge these battery's, I use the V meter and get a reading of the low voltage on the battery's, log this info into my bike log book.

Then I plug the battery charger into the battery and then plug the charger into the wall socket. The charger comes on and the fan starts and the idiot light comes on RED colored. I have this bat/charger set at eye level and NEVER leave it while charging etc.
When the charger switches color (Green), and the fan stops running, (about 3-1/2hrs average time, per bat), I unplug the charger from the wall socket and then unplug the charger from the batt.
Then I take a V meter reading and log the information, per each battery's number.
The V meter reading are almost at 53.8v, right off the charger, for all 4 battery's, numbered 1 thru 4.

When using these battery's (2 at a time), I use them down to 43.5v per display reading, and then check them when I get home. Then recharge them as above information.
I use this battery voltage calculations for the reading's etc.
docs.google.com

48v Li-Ion Charge Chart

docs.google.com docs.google.com
I have checked with the designer and he advised me that this calc sheet should also work for the 21700 battery's I am using.

On Bat # 3-4, (just newly bought) used in the first road test, I used/set the cruise controller only, as close to 15mph and when I FELT a decrease of power from the bat's, the readings on the display read 46.6v and the same readings on the V meter when checked.

I'll rerun these road/bat tests, as soon as I get some decent weather,
I don't do 30+mph cross winds............with a single bat for each test,
using all 4 bat's and note the spec's.

I don't know what the LV settings are, as I have not changed to the Uart motor,
I am still running the Cbus motor.

I can't find/know which of the plug pins are + or - as there is no information on the plug, the plug is a 3 pin and looks like a FAT HEART design.

Tia,
Your thoughts and suggestions..........
Don
 
You may already know this but you didn't mention it in your charging routine. Long term storage voltage should be between 40 and 60%. Unless you plan on riding in the next few days, I wouldn't fully charge immediately after a ride.
 
Reloader, Let's assume your batteries have balance BMS and that your voltmeter is accurate. By the way, can you get a reading off the charger with no load? It should be 54.6V too,
.
When the charger turns green, it doesn't mean that the battery is balanced, especially for the initial few charge cycles,.
.
This winter, I've built a pair of ebike batteries with balance BMS, and know from watching them charge the first time that the green indicator only means that the charger has flipped into low current mode, It is during this mode that a battery really balances, and it can take a few hours on a brand new pack, maybe a day or more on a older poorly balanced pack,
.
I believe that many ebike manuals now instruct users to do a long charge for the first few charges just to make sure the above happens. Give those new packs an extra five hours, supervised of course. See what happens.
 
6zfshdb said:
You may already know this but you didn't mention it in your charging routine. Long term storage voltage should be between 40 and 60%. Unless you plan on riding in the next few days, I wouldn't fully charge immediately after a ride.
Click to expand...
Not well enough known or followed, BTW.
 
PCeBiker said:
@Nvreloader
Just to verify, you have a battery blender and not a toggle switch correct?
Click to expand...
PC, I don't know what you are talking about, ref above.

"It looks like you have been charging your batteries to 80%",
according to this calc sheet,
docs.google.com

48v Li-Ion Charge Chart

docs.google.com docs.google.com
I am doing 93% down to 29% = 53.5v > 43.5v.

6Z
I'll look into that meter, I need something decent to go by,
as I will not push this tank out, I'll either pedal it out (no power/bat) or hide it,
and come back and pick it up, with my PU.

I'll check the voltage off the charger as soon as I find the + & - sockets,
I don't need to blow things up, Just yet,
I have 2 OEM chargers, that came with the bike,
they are F-300 Battery charger, with these spec's,
input: 110/220vac, 50/60hz,6a
Output: 54.6V - 5a
Red = charging
Green = Fully charged

Your thoughts and suggestions......

Thanks Guys,
and remember that I am new at this stuff,
and I greatly appreciate all the info passed along so far,
and don't leave me dangling..........Lol
 
Nvreloader said:
I can't find/know which of the plug pins are + or - as there is no information on the plug, the plug is a 3 pin and looks like a FAT HEART design.
Click to expand...

My old charger (with the different instructions) has that sort of plug.

It's the two outer pins that have the voltage. The third pin is ground.
If you connect a digital voltmeter to the outer pins, you will get a reading.
If you connect the + & – backwards, you just get a – on the voltmeter.

If you connect either outer pin to ground, your reading is 0

20230310_145145.jpg
20230310_145151.jpg20230310_145204.jpg20230310_145223.jpg20230310_145410.jpg
 
Nvreloader said:
PC, I don't know what you are talking about, ref above.

"It looks like you have been charging your batteries to 80%",
according to this calc sheet,
Click to expand...

Yeah, sorry I was all mixed up.
I thought that 53.8 was only 80% charge.

And, some ebikes with two batteries have a big switch that you flip to go from one battery to the other.

If the batteries are used simultaneously, then they have to go through a "blender" so that a battery with more charge doesn't dump into the lesser charged battery which is like a dead short.
 
Meanwhile, I need to get those voltage numbers memorized.
I'll memorize the quick reference list.
There's less to memorize.
 
Thanks PC
But, my charger is different, my changer ends are a round chrome colored
and has 3 small pins that go into the battery socket hole.
Hey PC, no problems at this end.
Tia,
Don
 
Don
As your charger states it should be putting out 54.6v...and that's what it should be charging to for the green light to come on.
As Harry said it is possible that the green light comes on as it reaches the CC to CV threshold and it is still putting out a low current, but that's not been my experience. That said there's a million ways to skin a cat and the hardware variations are endless. From my testing the CC to CV handover starts above 54V... and typically around 54.2v.
Additionally it could be that your chargers are not properly matched to your battery. 5a is considered fast charging and it may be too sensitive and still be at high current as it reaches full charge and it's shutting down prematurely. You can try buying a 2a charger and try to topping it off with that to 54.6 if Harry's suggestion doesn't work.
The only way to know exactly what's going on is to use a current meter as you charge or bench top power supply.
Now on the other end the only way to know what's going on with the LV shut down is to test each battery individually. You can ride out on both in parallel but when you feel the drop in power its probably because one has shut down on LV cutoff. At this point try one, then the other and ride them each to LV shutdown and note the voltage... again the standard being near/at 40v

edit: Photo of your charge connector
 
Nvreloader said:
Thanks PC
But, my charger is different, my changer ends are a round chrome colored
and has 3 small pins that go into the battery socket hole.
Click to expand...

I'm almost positive that one of the pins is ground.
You can most likely just test two pins at a time until you get a reading.

Even if the third pin is some sort of communication pin between the battery and charger, probing it with a voltmeter shouldn't be an issue.

Perhaps @Gionnirocket can verify that for me.
 
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