How do I know if my battery...

jaizon

Active Member
How do I know if my battery is discharged to 50% capacity. The graph on my display on my bike is wildly inaccurate. Thanks.
 

Taylor57

Well-Known Member
On my Lectric XP there is a voltage indicator but I'm having trouble finding it on my ESPIN Sport. What ebike do you have?
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
I think you're going to need a voltmeter. I don't like pulling my battery down much below 46 volts for instance. On mine, that means I should be on my way home when the 3rd light goes out (3rd of 5).

The way I figured this out was measuring the battery voltage soon after one of the bars goes out. Takes a while, but I'm in no hurry often anymore.

Noteworthy maybe is that my 1st light won't go out until the bike has about 18 miles on it (give or take), and indicates I have about 1/2 of my USABLE charge left (about 35 miles total). The 3rd light goes out somewhere in the high 20's (say 28 miles or so, and we'll have about 47 volts).
 

Bruce Arnold

Well-Known Member
I'm with @AHicks - a multimeter can be bought at any Lowe's, Harbor Freight or online for next to nothing. It will give you an accurate read on your state of charge. If you're not sure how to use one, give us a holler. (I'm not assuming you don't already know, just offering.)
 

Taylor57

Well-Known Member
Just curious as I now try and charge my bikes up to around 90 percent and not let them go down below 30 or so, but really, what if I just plug em in and unplug em the next day before my ride? Am I going to blow something up or shorten my battery life by a significant amount? Tryin to keep this ebike experience as simple as possible...
 

jaizon

Active Member
I think you're going to need a voltmeter. I don't like pulling my battery down much below 46 volts for instance. On mine, that means I should be on my way home when the 3rd light goes out (3rd of 5).

The way I figured this out was measuring the battery voltage soon after one of the bars goes out. Takes a while, but I'm in no hurry often anymore.

Noteworthy maybe is that my 1st light won't go out until the bike has about 18 miles on it (give or take), and indicates I have about 1/2 of my USABLE charge left (about 35 miles total). The 3rd light goes out somewhere in the high 20's (say 28 miles or so, and we'll have about 47 volts).

So I get home from my ride today (started with a fully charged 48v battery). I plugged into my Satiator to charge it and it read 49.1 volts. The thing is, It was down to 1/4 of the bars on my led. And under the load of the last hill up to my house ALL the bars had disappeared. I think I have a voltmeter around here somewhere.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Just curious as I now try and charge my bikes up to around 90 percent and not let them go down below 30 or so, but really, what if I just plug em in and unplug em the next day before my ride? Am I going to blow something up or shorten my battery life by a significant amount? Tryin to keep this ebike experience as simple as possible...

Simple = stop worrying so much. If the bike is going to be ridden soon (lets say 12- 24 hours) after topping the battery with a nice balance charge you aren't hurting a thing.

Things to avoid (IMHO) are over discharging (riding until you can't go any further), storing a fully discharged battery long term (more than a day or 2), and storing a fully charged battery for weeks. Avoiding those issues and trying to keep the battery from temp extremes (high and low, within reason) should yield a max usable lifetime.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
So I get home from my ride today (started with a fully charged 48v battery). I plugged into my Satiator to charge it and it read 49.1 volts. The thing is, It was down to 1/4 of the bars on my led. And under the load of the last hill up to my house ALL the bars had disappeared. I think I have a voltmeter around here somewhere.

Pretty good example of a good reason not to be running around much on a low charge. That big voltage dive your battery takes with a BIG load on it can sometimes send you into LVC country (low voltage cut off) where the power shuts down completely, forcing you to do a re-set to protect the battery.

Knowing in advance that the last part of your ride is going to involve that hill, and saving enough battery to do that is really going to cut into your available range.

Having just just 1 bar lighted at 49.1v is interesting (worth double checking with another device), and loosing that on your climb up to the house is too.

Have you tried making that hill at a lower power setting, or is this one of those that will stall the motor without full power?
 

jaizon

Active Member
Pretty good example of a good reason not to be running around much on a low charge. That big voltage dive your battery takes with a BIG load on it can sometimes send you into LVC country (low voltage cut off) where the power shuts down completely, forcing you to do a re-set to protect the battery.

Knowing in advance that the last part of your ride is going to involve that hill, and saving enough battery to do that is really going to cut into your available range.

Having just just 1 bar lighted at 49.1v is interesting (worth double checking with another device), and loosing that on your climb up to the house is too.

Have you tried making that hill at a lower power setting, or is this one of those that will stall the motor without full power?

I cannot make the hill without using full power and it is the only road leading into or out of my house, so I am stuck. Can you tell me how to use the voltmeter with my battery? Thank you.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
How hard is it to remove the battery, exposing the output contacts?
 

jaizon

Active Member
It's quite a pain in the butt. But I figured out how to get a reading using 2 of the three plug holes. 53.9 volts now. When I took it off the charger the charger read 54.9. That's odd, but at least I can get a reading after my ride tomorrow. Thanks for all your help, Mr. Hicks.
 

Bruce Arnold

Well-Known Member
It's quite a pain in the butt. But I figured out how to get a reading using 2 of the three plug holes. 53.9 volts now. When I took it off the charger the charger read 54.9. That's odd, but at least I can get a reading after my ride tomorrow. Thanks for all your help, Mr. Hicks.
I'm glad you figured out how to take a reading with a multimeter. Sounds like that LED panel that came with your kit is pretty useless. If it's reading that low at 49.1 volts, it's misleading. Could you feel that you were still getting sufficient power on that last hill?

On my former bike that had a 48 volt system, there was a definite drop-off in power -- not just a reading, but in actual performance -- starting around 46 volts and getting progressively worse, until at 42 volts (roughly 20 percent state of charge) it was downright anemic. I never went any lower than that. Up until then, the power was quite good. BTW, I consistently charged to 95% up until the day I sold it, with around 4500 miles, and never noticed any battery degradation besides that initial loss over the first few weeks that is characteristic of lithium ion batteries. In other words, it performed as well on my last ride as it did when it had around 500 miles on the odometer.

What I want to suggest is going to be a bit of a pain, but not for long, and it will save you range anxiety in the future.

Carry the multimeter with you for the next 3-4 rides. Get off the bike and check the voltage every 5 miles. Try to take different routes with different terrain. Take notes, on your phone or (as I prefer) good old paper and pencil. This will give you useful averages (voltage drops X amount after 5 miles, Y amount after 10 miles, etc.) and some idea of the variation (X+x on hilly terrain, X-x on level ground.) Re-check once every 100-200 miles to see if your initial calculations still hold up and adjust the averages as necessary. If you don't have an odometer, every bike shop sells them, or use a GPS program on your smartphone. Put some duct tape over the LEDs so you don't even see their lying tales.
 

jaizon

Active Member
I'm glad you figured out how to take a reading with a multimeter. Sounds like that LED panel that came with your kit is pretty useless. If it's reading that low at 49.1 volts, it's misleading. Could you feel that you were still getting sufficient power on that last hill?

On my former bike that had a 48 volt system, there was a definite drop-off in power -- not just a reading, but in actual performance -- starting around 46 volts and getting progressively worse, until at 42 volts (roughly 20 percent state of charge) it was downright anemic. I never went any lower than that. Up until then, the power was quite good. BTW, I consistently charged to 95% up until the day I sold it, with around 4500 miles, and never noticed any battery degradation besides that initial loss over the first few weeks that is characteristic of lithium ion batteries. In other words, it performed as well on my last ride as it did when it had around 500 miles on the odometer.

What I want to suggest is going to be a bit of a pain, but not for long, and it will save you range anxiety in the future.

Carry the multimeter with you for the next 3-4 rides. Get off the bike and check the voltage every 5 miles. Try to take different routes with different terrain. Take notes, on your phone or (as I prefer) good old paper and pencil. This will give you useful averages (voltage drops X amount after 5 miles, Y amount after 10 miles, etc.) and some idea of the variation (X+x on hilly terrain, X-x on level ground.) Re-check once every 100-200 miles to see if your initial calculations still hold up and adjust the averages as necessary. If you don't have an odometer, every bike shop sells them, or use a GPS program on your smartphone. Put some duct tape over the LEDs so you don't even see their lying tales.

Thank you, Bruce. I checked my battery today after my 10 mile ride (when I got home from a less hilly ride than the other day). The voltmeter read 48.9 volts. However, I do not know what percentage that is (for long term storage, e.g.). But the power on the flat was still okay. Maybe someone could tell me what percentage that is, or what voltage I should store the 48v battery at. Thanks.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Jaizon, no focus on "percentage" necessary, nor any exact number for long term storage. I think you''ll be fine storing at anything from 46v to 50v or so.

The voltage it comes off the charger at, you said 54v and change, would be 100%

The voltage where your controller or BMS calls it quits (40v or so/LVC/low voltage cut off) would be 0%

So if you wanted to be exact 47v would be about 50%
 

Bruce Arnold

Well-Known Member
Thank you, Bruce. I checked my battery today after my 10 mile ride (when I got home from a less hilly ride than the other day). The voltmeter read 48.9 volts. However, I do not know what percentage that is (for long term storage, e.g.). But the power on the flat was still okay. Maybe someone could tell me what percentage that is, or what voltage I should store the 48v battery at. Thanks.
I downloaded this chart so I could refer to it when needed. I don't know how many times I've checked it to refresh my memory. I bet you'll find it useful too.
Battery SOC.png