How to measure Battery Power left . .

[Wolf krannich]

Hello Folks
Quick question:
I have a Golden Motor kit 48 volt - 10 AH on my bike.
It comes with a simple battery indicator: Green - Yellow - Red = dead
Thats all the indication I get and then the battery is DEAD. I tried counting kilometers to determine range, but that seems to be variable (wind, temperature, hilly or not etc.)
If I attach a multi meter (voltmeter) to the battery, can I determine how much juice / range I have left??
Is itr the voltage of the amperage that determines the range?

I am sorry if this is covered elsewhere, and I know there is a huge dissertation on the grin bikes website, but I am just looking for some way to avoid getting stuck on my commute..
(PS I know I could buy a Cycle Analyst, but honestly, I find the 150$ plus taxes kind of expensive)..

Thank you for nay hands on tips!!

Ride safely.

Wolf

 

[harryS]

What happens is that your controller shuts off the bike and shows the Red LED when it senses that the battery has gone down to the low voltage cutoff. This will be around 41 volts, I think for your kit. Some batteries also have internal circuits that shut it off if the voltage goes too low.

These batteries only deliver power safely for a limited range. If allowed to discharge too low, you can damage the battery. Might cause a fire later.

I bought a digital readout good for 18-60 volts for $9 on amazon.com, with the intent of putting it on my ebike, but I am OK with the 4 led's on the controller. Otherwise, I could give my experience with looking at the voltage. Looking at the voltage will give you a more exact reading when you're running low, but it may drop really fast too.

If you do it, be careful with the meter wiring. You don't want to have any short circuits. That's full battery power.

 

[Wolf krannich]

Thank you for the input.

I will keep counting kilometers and note when I get stuck. This seems to be a variable number. I noticed that when it's cold out the battery seems to have less power and the orange and red light come on quicker...

Live and learn..

Have a fine day

Wolfgang

 

[George S.]

http://www.amazon.com/gp/product/B00EYZS6R6?psc=1&redirect=true&ref_=oh_aui_search_detailpage

This is a cheap version of a Watt's UP, and the price reflects indifferent quality. There are others on the page. The Watt's UP is around $60.

It will accumulate watts and show watts, as you ride. If you know the total watt hours, or amp hours, in the battery, knowing how many you have used since a full charge is very precise. A lot depends on access to wiring. The Cycle Analyst uses a shunt, this kind requires cutting at least one wire and running the meter in that loop of wire. So basically there are two wires from the battery to the motor, you cut both and have four ends. The meter goes to all four ends, plus on one side, negative on the other. The meter has to go from source to load.

This is the only way to get a precise reading on the battery, or what has been discharged from the battery. It works flawlessly, in my experience, around 5 months. I use a Watt's Up, but have two of these.

 

[Wolf krannich]

This sounds great. I checked out the link and the gizmo is around 25$ ??

I will browse around some more and I think get one of these - way cheaper than a Cycle Analyst, which at this point, is total overkill for me.

thank you again!!

Have a fine day!

Wolf

 

[Wolf krannich]

actually I stand corrected: Following the link gets me to the 20$ item - when I go on Amazon.ca and type in watt's up as you suggested I get the 60$ item.

Thank you again!

W.

 

[Wolf krannich]

http://www.amazon.com/gp/product/B00EYZS6R6?psc=1&redirect=true&ref_=oh_aui_search_detailpage

This is a cheap version of a Watt's UP, and the price reflects indifferent quality. There are others on the page. The Watt's UP is around $60.

It will accumulate watts and show watts, as you ride. If you know the total watt hours, or amp hours, in the battery, knowing how many you have used since a full charge is very precise. A lot depends on access to wiring. The Cycle Analyst uses a shunt, this kind requires cutting at least one wire and running the meter in that loop of wire. So basically there are two wires from the battery to the motor, you cut both and have four ends. The meter goes to all four ends, plus on one side, negative on the other. The meter has to go from source to load.

This is the only way to get a precise reading on the battery, or what has been discharged from the battery. It works flawlessly, in my experience, around 5 months. I use a Watt's Up, but have two of these.

 

[Wolf krannich]

Hello again.
So I bought a cheap version of the Watt's-Up meter. Installed it, and so far, so good.
Thank you again for the tip and the link.
I hope the gizmo doesn't fry itself soon, other than that, this is great. It gives me the voltage ongoing, and the Ah used per ON cycle. So I can get a more accurate sense of what's going on.

Best regards
Wolf