How do I know my battery is empty?

S

Swe

100 W
Joined
Aug 11, 2014
Messages
170
Location
Stockholm, Sweden
Hi,

I have a 48V11,6Ah bottle-09 battery from BMSB:
https://bmsbattery.com/ebike-battery/684-48v116ah-bottle-09-panasonic-battery-charger-battery.html

The display is this one, and the controller is a 36V:
http://www.xofomotor.com/display.asp?id=807

How will I know how long trip I can use it? Is there some protection in the battery or can I destroy it if I use it too long?

I have not tested the bike that much but I guess my display shows 36V because I never see the battery indicator on the display show anything but full battery. Even though on the link I see now it says 24/36/48V...

Should I get a mini volt meter and sometines check the status? (Will hide it in the controller bag) And if so, on what voltage level should I stop driving?
http://www.ebay.com/itm/Mini-DC-5-120V-Voltmeter-Blue-LED-Panel-3-Digital-Display-Voltage-Meter-2-wire-/151440905015?pt=LH_DefaultDomain_0&hash=item234294d337
 
I went looking for the controller you linked but cant find inside pics- max voltage on capacitors 67v is safe iirc? on 48v.
 
It depends on how far the batteries are from your controller which dictates voltage ripple. You can add some 1000uF 100V capacitors in parallel close to the controller to reduce this ripple somewhat, combined with some smaller value exotic capacitors to fight the ESR problem. Next value from 63V capacitor is often 100V. 200V capacitors are to big for the same capacity, they do not fit inside. My controller blew 100V mosfets at 54.6V, but it took several months and high current abuse/tests (20A+ on 6-fet controller). The funny thing is that 50V capacitor survived 54.6V abuse, but 100V mosfet didn't.

My 48V controller from aliexpress have 63V capacitors. 36V 6-fet from bmsbattery have one main 63V and one smaller 50V that serves the LM317 voltage regulator. I have inside pictures of S06S and 48V versions, I'm not sure which one (linked?) you mean? The one I've linked in the other thread?
 
How do I know my battery is empty?

Pick it up and shake it, you can hear if it's still got anything left in it.
 
The bike will have less power. You could check with or fix a watt meter on the positive and negative side of the battery. So when you getting to the lower end of the battery you know you not got much juice left.
 
Swe said:
Hi,

I have a 48V11,6Ah bottle-09 battery from BMSB:
https://bmsbattery.com/ebike-battery/684-48v116ah-bottle-09-panasonic-battery-charger-battery.html

The display is this one, and the controller is a 36V:
http://www.xofomotor.com/display.asp?id=807

How will I know how long trip I can use it? Is there some protection in the battery or can I destroy it if I use it too long?

I have not tested the bike that much but I guess my display shows 36V because I never see the battery indicator on the display show anything but full battery. Even though on the link I see now it says 24/36/48V...

Should I get a mini volt meter and sometines check the status? (Will hide it in the controller bag) And if so, on what voltage level should I stop driving?
http://www.ebay.com/itm/Mini-DC-5-120V-Voltmeter-Blue-LED-Panel-3-Digital-Display-Voltage-Meter-2-wire-/151440905015?pt=LH_DefaultDomain_0&hash=item234294d337
Click to expand...
Everything is automatic, so your battery is protected and you have nothing to worry about.

I'm pretty sure that your display will show the actual voltage if you scroll through the screens using the middle button, so you shouldn't need a voltmeter.

I have the same battery and a similar display. On mine, the first segment goes when the battery reaches 48v, which is when I've used about 1/3 the capacity. The next segments go at 46v and 44v. It switches off at 41v. When I lose the third segment at 44v, my wattmeter shows that I've used about 350wh.
 
I was about to say something similar, 42v or thereabouts will be the very end.

In some ways, if you repeat a similar ride enough, you get to know where about half is by odometer better than by volts.

Only really accurate way is a real watt meter, that counts the watt hours. I don't know if your display does that. Once you know how many real world watt hours your battery has, (or ah) then you will know what half of that is. It's a moving target too, you have less in cold weather, and less as the battery ages. So you need to keep running a battery empty from time to time to know what half is.

Knowing that for sure is real nice, and why I have 4 cycleanalysts. I want one on every bike.
 
Thanks everyone for your replys.

Today on my ride the battery suddenly shut off by itself after 36km. When I was almost home I tested it again and this time I could start again and run on 100w, but when using more it shutted down again. When I was home I measured 44V with a ordinary volt meter. So as some of you have said, the battery seems to have a protection so I dont have to worry.

The power on light at the battery went out so I think it was the battery, not the 36V controller that in the display still showed full dots on battery. The small manual I got says nothing about selecting voltage. If I cant select, do you think the controller (36V in my case) tells the display this or should it be automatic depending on what voltage there is at the start?

There is no wh-meter only w-meter.
 
The display battery bars are based on a 36 volt battery, and very likely a SLA 36 volt battery. Sadly, that is totally useless information for your battery, even if it was the correct voltage.
What you need is something like this: Watt Meter

Run the battery down once from a full charge to almost 44 volts. If the battery cuts off, you'll lose those numbers when the meter resets, so just get close. Then you will know exactly how many watts you have available in the battery. On rides after that, you can tell how much is left by how much you have used.
 
You need the instruction manual for the LCD. If you send an email to Xofo asking for it, they should be able to provide one. There's lots of settings and adjustments you can make through the LCD.

Normally, the 48v/36v setting for the battery display is automatic, though I have seen them where it has been manual.

44v is the resting voltage. When you draw a high current, the voltage sags, which is why it hit the low voltage cut-off and were then able to continue with low power. Mine's the same. I live on a hill, so the last part of my ride is always a high power climb, when both myself and the battery are tired. It's a bit of a bummer when I have to reduce power to get up the final climb.
 
Maybe my display is the same as S-LCD3? The shorter operational manual for lcd3 looks exactly like the manual I got with my display. When I read the longer user manual for lcd3 I see that I actually have a voltmeter in the display! In "display 3".

If you look at the manual on page 22, Parameter P5 power monitoring mode". Is this parameter for the battery indicator or something else? And what should it be set to with my battery?

The wattmeter Drunkskunk linked to was not that expensive so maybe it could be interesting to install even though I now know I have a volt meter.

Link to manual on bmsb:
https://bmsbattery.com/index.php?controller=attachment&id_attachment=5
 
As the rule do not run the battery to cutoff.
Do not unplug and plug the battery to reset the bms to get more range. This shouldn't be your practice.
 
Swe said:
Maybe my display is the same as S-LCD3? The shorter operational manual for lcd3 looks exactly like the manual I got with my display. When I read the longer user manual for lcd3 I see that I actually have a voltmeter in the display! In "display 3".

If you look at the manual on page 22, Parameter P5 power monitoring mode". Is this parameter for the battery indicator or something else? And what should it be set to with my battery?

The wattmeter Drunkskunk linked to was not that expensive so maybe it could be interesting to install even though I now know I have a volt meter.

Link to manual on bmsb:
https://bmsbattery.com/index.php?controller=attachment&id_attachment=5
Click to expand...
The parameter P5 is some sort of damping coefficient that stops the battery display jumping up and down when the voltage sags under load.
 
d8veh said:
Swe said:
Hi,

I have a 48V11,6Ah bottle-09 battery from BMSB:
https://bmsbattery.com/ebike-battery/684-48v116ah-bottle-09-panasonic-battery-charger-battery.html

The display is this one, and the controller is a 36V:
http://www.xofomotor.com/display.asp?id=807

How will I know how long trip I can use it? Is there some protection in the battery or can I destroy it if I use it too long?

I have not tested the bike that much but I guess my display shows 36V because I never see the battery indicator on the display show anything but full battery. Even though on the link I see now it says 24/36/48V...

Should I get a mini volt meter and sometines check the status? (Will hide it in the controller bag) And if so, on what voltage level should I stop driving?
http://www.ebay.com/itm/Mini-DC-5-120V-Voltmeter-Blue-LED-Panel-3-Digital-Display-Voltage-Meter-2-wire-/151440905015?pt=LH_DefaultDomain_0&hash=item234294d337
Click to expand...
Everything is automatic, so your battery is protected and you have nothing to worry about.

I'm pretty sure that your display will show the actual voltage if you scroll through the screens using the middle button, so you shouldn't need a voltmeter.

I have the same battery and a similar display. On mine, the first segment goes when the battery reaches 48v, which is when I've used about 1/3 the capacity. The next segments go at 46v and 44v. It switches off at 41v. When I lose the third segment at 44v, my wattmeter shows that I've used about 350wh.
Click to expand...

I have the https://bmsbattery.com/ebike-battery/680-48v116ah-bottle-09-panasonic-battery-pack-battery.html with KT LCD3 too. I installed the configuration with a fully loaded battery. The motor stopped at appr. 41V but the battery indicator was only minus one stripe at that moment. Possibly it "thinks" I have a 36V battery? How to solve this problem?

As I understand it's better not to unload completely your battery, appr. 41V is that on the safe side?

As I understand it's better not load 100% the battery, at which voltage I better should stop loading?
 
All too typical for those 5 bars battery meters, some are great, others horribly mis calibrated.


In general, its fine to discharge your battery deeply because the bms or controller lvc stops it before its killed for good , but it is still better to avoid that last 10% of the discharge, and if you do get into that part, slow way down.

Your problem is how to know when you are low. By the last 5%, you will know, the bike will get noticeably sluggish compared to earlier in the ride.

But the best way to really know what you are doing with your battery is a real voltmeter that displays a number. There are very inexpensive lcd volt displays that work in a range of voltages, like 12-60v. Look for the one with only two wires, that runs on whatever voltage your battery is. ( others require a 12v supply to run the meter)

Next up, the cheap blue watt meter. I would recommend one of those if easy to install. It will go on the wire leading from the battery to the controller.

Best is pricy, but nothing can beat the Cycle Analyst watt meter. If on a budget, I'd at least get the blue wattmeter on ebay.

Meanwhile, use your odometer to guess, combining that with occasional stops to look at your voltage with a regular volt meter. Figure out your range in miles in general, and then return for home when about 40% of that is done.
 
What I normally do is pick the battery up and feel if it's changed weight if it feels the same then I put it to my ear and give it a shake see if I can hear how much is left if this fails I try to shine a torch through it so I can see the level.

On a serious note use a watthour meter to monitor the total pack and let the bms keep the individual strings in check, Ideally the bms needs a way of checking its operating corectly bluetooth ones are decent for that.

Always obey the 5 lithium commandments to assure good battery health other than manufacture defaults etc.

Thou shall not charge or discharge a pack that is outside it's working temps be it high or low.
Thou shall not discharge below 2.8v.
Thou shall not discharge at or above the nominal c rating.
Thou shall not charge above 4.1 / 4.2v chem depending.
Thou shall not charge above 1c chem depending.

Visually inspect your pack before use and if your charger supports it then IR test too, Touch wood I've caught all my bad cells using this method but I still choose to charge in my shed.

I don't think I'd feel so comfortable with my hobby if I lived 20 floors up in a tower block for example but it must go on for sure.
 
Hunza said:
I have the https://bmsbattery.com/ebike-battery/68 ... ttery.html too. I installed the configuration with a fully loaded battery. The motor stopped at appr. 41V but the battery indicator was only minus one stripe at that moment. Possibly it "thinks" I have a 36V battery? How to solve this problem?
Click to expand...

Your link did not work for me but if you mean that the LCD3 display shows wrong as mine, I still have not solved it. Once when I left the bike unused for a long time it then suddenly indicated correct on the meter, but like half of the other stuff showed norhing at all. Then on next run it was back to think I have 36V again (and all other stuff/numbers worked again).

Now I dont care so much, I press two times on the power button to display the voltage meter and use that to have a feeling of how much is left. I look at how much it sags under load and then voltage unloaded. I bought a cheap watt meter but never installed it...

But if you ever solve it please tell anyway!
 
For an LCD3, the P5 setting determines how fast the the battery icon reacts to the battery voltage. I leave mine set at 15, as I typically use a 36V battery although I have the controllers that run up to 52V. If I set P5 low, like at 1, I recall the icon will follows the voltage sag of the battery too quick. Maybe you can experiment to see what seems most real. Like others, I toggle the LCD3 to show voltage if I want to see voltage.

A couple of long rides ought to tell you what to expect from a battery without any instrumentation, except for an speedometer/odometer.
 
Thanks for all your reactions.

It seems I have to live with a non function battery indicator, no problem the VOL is much preciser.

As I understand the automatic stop at 41,5V is safe, the battery isn't empty by then.

The maximum voltage of my battery pack is 54,5V, 48V is 88% .... so loading up to 48V should be fine (I hope).
(correction afterwards: for about the percentage ...here I made a mistake, see below)

If I fully load the battery up 54,4V the KT LCD3 is not functioning well, after a few km. my Q100H starts to stutter. So that's another reason to stick to 48V.
 
I guess none of us read your opening post.
48V battery
LCD3 display
36V controller.

Probably explains why it stutters when the battery is fully charged.The controller probably has an overvoltage limit, or the internal components are taking a beating. Also explains why the battery ICON is off. It may be set by the controller protocol to 36V.

Is it the BMSBattery S06S controller? I understand it only has 50V filter capacitors. You'll kill the controller soon running it with a fully charged 48V battery. ANother poster here mentioned the stuttering on an S06S, and I think he did kill it.

By the way, I believe 48V on a 13S battery is 60% of full capacity. not 88%.
 
Thanks for your reaction.
You're fully right about the voltages&capacity. https://endless-sphere.com/forums/viewtopic.php?t=9268

I have the BMSB 48V11.6Ah Bottle-09 Panasonic Battery Pack,that has the sin-wave controller and S-LCD3 included. As I understood this controller automatically determines the voltage of your battery. Somehow I have the feeling my LCD3 is 36V based yet.
 
Hunza, your first post showed a link to a 48V bottle battery without the integrated controller, and you said you had a 36V controller. You later mentioned a controller bag.

Your last post says you have a 48V bottle battery with an integrated controller. You would expect that to be a 48V unit.

When you overvolt a controller, you should consider the filter capacitors. If they are only rated for 50V like most 36V controllers, they lose their ability to filter at high voltage and will eventually pop. If they are rated for 63V, all should be well. The only way to tell is to look at them as in this pic.

P1540039.jpg

You also need the low voltage protection circuit to match the battery. Dual voltage controllers should do this, but a single voltage controller may let your 48V battery go lower than you want. You still have the battery BMS to protect you though.
 
If you want your batteries to live much longer be nice to them and never find out when they are empty. I haven't run my packs down to LVC a single time in the past 8 years, and I get much much longer than rated life from them.
 
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