Knowing your battery range,

[Amish David]

Was wondering what would be a good LCD volt meter for Li-Po for under $100.00 for a 48v battery, I have a cheesy green,yellow, red lights which you all know is kinda worthless and you can not get the full use out of the bike.
Thanks.

 

[harryS]

You can get any digital voltmeter to check your ebike battery voltage and also to use around the house, if that's OK for you. Mine range from the Centech units that are often on sale for under $4 at Harbor Freight to better quality models such as a $20 Craftsman from Sears.

It is somewhat difficult to assess an ebike battery via a voltmeter. For example, a 48V battery made with 18650 Li-Ion cells will come in at 54.6V when fully charged. If it shows 48V, it's about half capacity. Your controller probably shuts the bike off when the battery goes under 42V. At that point, there might be 10-15% charge still left.

I prefer to use a wattmeter like the Ternegy in the picture. They only cost $12-13 on ebay, and will give you the voltage (usually off by 1/2 volt, but it's consistent). It connects between battery and controller, or between battery and charger.

They also show the total watthours used, but I found that also inaccurate. The info that seems to be good is the amperes being drawn as well as the amp-hours (AH). This is the same AH as advertised on your battery.

 

[Bruce Arnold]

For $12, that Tenergy might be OK. For a full featured but pricey unit, there's always the Grin Tech Cycle Analyst. I'd like to convince myself I need one.

 

[Amish David]

You can get any digital voltmeter to check your ebike battery voltage and also to use around the house, if that's OK for you. Mine range from the Centech units that are often on sale for under $4 at Harbor Freight to better quality models such as a $20 Craftsman from Sears.

It is somewhat difficult to assess an ebike battery via a voltmeter. For example, a 48V battery made with 18650 Li-Ion cells will come in at 54.6V when fully charged. If it shows 48V, it's about half capacity. Your controller probably shuts the bike off when the battery goes under 42V. At that point, there might be 10-15% charge still left.

I prefer to use a wattmeter like the Ternegy in the picture. They only cost $12-13 on ebay, and will give you the voltage (usually off by 1/2 volt, but it's consistent). It connects between battery and controller, or between battery and charger.

They also show the total watthours used, but I found that also inaccurate. The info that seems to be good is the amperes being drawn as well as the amp-hours (AH). This is the same AH as advertised on your battery.


View attachment 22250

I have a Fluke volt meter but I thought this was 12 or 120 only?

 

[Amish David]

For $12, that Tenergy might be OK. For a full featured but pricey unit, there's always the Grin Tech Cycle Analyst. I'd like to convince myself I need one.

@Bruce Arnold thanks for the info, but I would like something a little more simple, the computer stuff is hard to understand I have been using a computer phone for about 6 months and still have a hard time with it. And at. 150 its a bit much. Thanks.

 

[tomjasz]

Ride the bike until the battery hits the BMS cutoff. Now you have a good idea as to how far you can go.

 

[tomjasz]

Was wondering what would be a good LCD volt meter for Li-Po for under $100.00 for a 48v battery, I have a cheesy green,yellow, red lights which you all know is kinda worthless and you can not get the full use out of the bike.
Thanks.

You have LiPo in a case?
There are very inexpensive meters, that are accurate enough, for under $10. Those Ternegy meters break down to quickly IME.

 

[Amish David]

Ride the bike until the battery hits the BMS cutoff. Now you have a good idea as to how far you can go.

Not really I live in the mountains and don't always go the same route, I know I can go 13 miles no PAS "just seeing how far it would go" but the yellow light was still on, some placeses are 40 degree incline for about 1/8 of a mile. My brane tells me I can still ride like I could when I was 20. But my legs say screw this im walking, I may see if I can get a nabor to follow me until the battery quits then have them bring me home.

 

[Amish David]

You have LiPo in a case?
There are very inexpensive meters, that are accurate enough, for under $10. Those Ternegy meters break down to quickly IME.
View attachment 22264thank you.

 

[tomjasz]

????

 

[Amish David]

????

Thank you for the info.

 

[Amish David]

You have LiPo in a case?
There are very inexpensive meters, that are accurate enough, for under $10. Those Ternegy meters break down to quickly IME.
View attachment 22264

They are 18650- I think Panasonic NCR brand.

 

[tomjasz]

They are 18650- I think Panasonic NCR brand.

Relieved....

 

[harryS]

Flukes are good meters. Show us a picture of the front panel, and the forum readers will tell you if it has the right range for your needs.

Battery capacity does not track linear with voltage. What I meant to say is that it's hard to look at a voltage on your 48V batter and say ..."ah, I have 44 volts, I have 20% left." WIth some experience, you might know that 44 volts gives you 2 more miles or whatever. It might turn out that the display designers made 1-2-3-4 Led bars more representative of 25/50/75/100% than a numeric display.

Your battery has an amp-hour (AH) rating. You can convert that to watt-hours (WH) by multiplying by the nominal voltage. Your bike (1000W motor) probably uses between 15-25WH per mile. My bikes, with smaller motors and slower riding, only use 6-12 WH/mile.

We did a 30 mile ride yesterday. My wife used 5.8AH. Around 200 WH at 36V, or 7WH/mile. It's a 9AH battery, so she had 30% left. I got this by measuring the AH back into the battery when I recharged it. You can flip a Ternegy meter around and measure power out and power in. I find it interesting, being an electrical guy. Of course, she just looked at her display and it said one bar, so that was good enough for her. Maybe having a bike that still worked was good enough. When I checked it, the display also said she was down to 35 volts (on a 40V battery).

 

[Amish David]

Flukes are good meters. Show us a picture of the front panel, and the forum readers will tell you if it has the right range for your needs.

Battery capacity does not track linear with voltage. What I meant to say is that it's hard to look at a voltage on your 48V batter and say ..."ah, I have 44 volts, I have 20% left." WIth some experience, you might know that 44 volts gives you 2 more miles or whatever. It might turn out that the display designers made 1-2-3-4 Led bars more representative of 25/50/75/100% than a numeric display.

Your battery has an amp-hour (AH) rating. You can convert that to watt-hours (WH) by multiplying by the nominal voltage. Your bike (1000W motor) probably uses between 15-25WH per mile. My bikes, with smaller motors and slower riding, only use 6-12 WH/mile.

We did a 30 mile ride yesterday. My wife used 5.8AH. Around 200 WH at 36V, or 7WH/mile. It's a 9AH battery, so she had 30% left. I got this by measuring the AH back into the battery when I recharged it. You can flip a Ternegy meter around and measure power out and power in. I find it interesting, being an electrical guy. Of course, she just looked at her display and it said one bar, so that was good enough for her. Maybe having a bike that still worked was good enough. When I checked it, the display also said she was down to 35 volts (on a 40V battery).

@harryS. Fully. Charged is showed 52.22 but I would like to have something to monitor on a long ride though hard to gage here in the mountains. I would feel safer with a good led monitor on my handlebars. This is the cheesy monitor I was talking about, oh and i avrege 15mph.

 

[christob]

One thing to try out just in general (unrelated to meters you can buy) -- spend a little time riding your bike without the assist at all -- ie, just use good old fashioned gear changes (assuming your bike has, for example, 10 gears or similar -- and that it can actually be ridden without the assist/battery.) That way you won't be totally caught off guard (you'll know what you're in for) the first time you're out riding one day and happen to exhaust the battery entirely...

 

[Amish David]

One thing to try out just in general (unrelated to meters you can buy) -- spend a little time riding your bike without the assist at all -- ie, just use good old fashioned gear changes (assuming your bike has, for example, 10 gears or similar -- and that it can actually be ridden without the assist/battery.) That way you won't be totally caught off guard (you'll know what you're in for) the first time you're out riding one day and happen to exhaust the battery entirely...

I guess you mean "motor alone"? The motor only has one gear. Human power is 10 speed MTN. Bike. I did give it a try one day, went 10 miles no peddling but it appeared there was plenty left also.

 

[christob]

No, I meant the opposite -- ride the bike purely under human power for a spell, relying on changing between the 10 gears as necessary -- just to know what to expect in the event of a surprise loss of battery power.

 

[Amish David]

No, I meant the opposite -- ride the bike purely under human power for a spell, relying on changing between the 10 gears as necessary -- just to know what to expect in the event of a surprise loss of battery power.

I did that for 2 months when I first moved here it almost killed me, so to speak. A bad back and 50yrs old I just can't do what I use to, any way that is why I bought the kit, to help me getting up all the big hills. There's almost no flat areas unless I go to town and even there its pretty hilly.

 

[christob]

I agree -- the assist is wonderful and the reason we get ebikes / conversion kits... I just was suggesting that you be familiar with human-power on the bike -- but it sounds like you've already taken care of that!