Watt Meters

[Ykick]

You're not making it easy on us brother JTL, where are you located? That might have a lot to do with offering "sources" for items?

You only need to enter a general location once in your profile/avatar and then we won't have to guess or type all this nonsense out instead of merely providing the info you want/need.

Unless you're capable of crimping APP's and PROPERLY soldering XT family of connectors you'd better served buying appropriate adapter dongles through RC vendors to convert between the discharge and charge port. 'Noticed tons of 'em on eBay as I was shopping some 4mm bullets the other day.

 

[JTL]

You're not making it easy on us brother JTL, where are you located? That might have a lot to do with offering "sources" for items?

You only need to enter a general location once in your profile/avatar and then we won't have to guess or type all this nonsense out instead of merely providing the info you want/need.

Unless you're capable of crimping APP's and PROPERLY soldering XT family of connectors you'd better served buying appropriate adapter dongles through RC vendors to convert between the discharge and charge port. 'Noticed tons of 'em on eBay as I was shopping some 4mm bullets the other day.

I fixed the location, no one brought that up before. I just figured that someone has a favorite place online to purchase connectors, no big deal. eBay is not always the best quality (ie knockoffs) and I only need a couple of them. I looked before but I will look again. I can solder very well. I planned on changing out the APP's, not a fan of crimping.

 

[Ykick]

I fixed the location, no one brought that up before. I just figured that someone has a favorite place online to purchase connectors, no big deal. eBay is not always the best quality (ie knockoffs) and I only need a couple of them. I looked before but I will look again. I can solder very well. I planned on changing out the APP's, not a fan of crimping.

I buy a lot of wire, connectors and power stuff from Buddy RC - http://www.buddyrc.com/ However, ‘don’t see XT90’s there.

Luna has a page with XT90’s - http://lunacycle.com/batteries/connectors-and-wires/

Crimping has it's place since solder wicking into stranded cable can often make it more susceptible to fatigue and breaking.

 

[motomech]

These days, I'm only using name brand 4 mm bullets like Crazpony. They are expensive, but I'm tired of the genaric ones with their hard and brittle shields. The good ones go on so much easier.

 

[JTL]

I fixed the location, no one brought that up before. I just figured that someone has a favorite place online to purchase connectors, no big deal. eBay is not always the best quality (ie knockoffs) and I only need a couple of them. I looked before but I will look again. I can solder very well. I planned on changing out the APP's, not a fan of crimping.

I buy a lot of wire, connectors and power stuff from Buddy RC - http://www.buddyrc.com/ However, ‘don’t see XT90’s there.

Luna has a page with XT90’s - http://lunacycle.com/batteries/connectors-and-wires/

Crimping has it's place since solder wicking into stranded cable can often make it more susceptible to fatigue and breaking.

Thanks!

 

[JTL]

I purchased a GT Power watt meter. I don't have it yet but as I was considering what gauge wire I need to extend my motor controller wires I got to thinking about the wire size of the watt meter. I believe the BBSHD uses 10 AWG (not marked like most wire) I know the tails on the xt90 connectors use 10 gauge. Assuming that the cheap watt meter use a higher AWG ie smaller wire does anyone have concerns about resistance when using them in line with the controller?

 

[JTL]

I purchased a cheap watt meter (GT Power) and put connectors on it so I could monitor my new Em3ev battery and the charger. I just completed my first total run down of the battery ( 50v 15Ah). Fully charged it was 58.6 and it cut out at 37.3 according to my multi-meter. I connected my watt meter in line but doesn't even light up, probably too low voltage. Doesn't this seem low? I am going let it rest for an hour and measure it again, but I don't understand why this would make a difference. I just want to be sure I am not over discharging. I got a little over 55 miles, some pedaling, but a lot of throttle only all on flat ground.

 

[docw009]

I connected my watt meter in line but doesn't even light up, probably too low voltage. Doesn't this seem low? I am going let it rest for an hour and measure it again, but I don't understand why this would make a difference. I just want to be sure I am not over discharging.

Wattmeter doesn't light up when battery is down? I've never checked mine to see where it stops working, but it's probably good down to 10 volts.

Or is it that the wattmeter never lights up? Do you have the "load" side pointing to controller? I never checked mine backwards, as my connectors make that hard to do. If the connections are right, probably a bad meter. It doesn't add any significant load on your bike, so it could be dead and the motor still works fine.

 

[JTL]

I connected my watt meter in line but doesn't even light up, probably too low voltage. Doesn't this seem low? I am going let it rest for an hour and measure it again, but I don't understand why this would make a difference. I just want to be sure I am not over discharging.

Wattmeter doesn't light up when battery is down? I've never checked mine to see where it stops working, but it's probably good down to 10 volts.

Or is it that the wattmeter never lights up? Do you have the "load" side pointing to controller? I never checked mine backwards, as my connectors make that hard to do. If the connections are right, probably a bad meter. It doesn't add any significant load on your bike, so it could be dead and the motor still works fine.

I have it hooked up correctly. It works from the charger to battery, when charging.

 

[Ykick]

I have it hooked up correctly. It works from the charger to battery, when charging.

But it doesn't work when connected only to the battery?

 

[JTL]

I have it hooked up correctly. It works from the charger to battery, when charging.

But it doesn't work when connected only to the battery?

That is correct. The battery still had about 38v in reserve but that was not enough to activate the watt meter. Interestingly, when I put it in line with the charger, which immediatey, jumped the voltage reading to 44v from 38v it worked. There is a small variation from my multi-meter vs the watt meter but that is of no concern. At the higher charged voltage it works. It is charged to 52v and I put it line and it works. Chinese electronics. Go figure.

 

[Ykick]

I have it hooked up correctly. It works from the charger to battery, when charging.

But it doesn't work when connected only to the battery?

That is correct. The battery still had about 38v in reserve but that was not enough to activate the watt meter. Interestingly, when I put it in line with the charger, which immediatey, jumped the voltage reading to 44v from 38v it worked. There is a small variation from my multi-meter vs the watt meter but that is of no concern. At the higher charged voltage it works. It is charged to 52v and I put it line and it works. Chinese electronics. Go figure.

If the battery pack uses a BMS I would venture to guess that BMS was in fault/protect mode thus unable to deliver a few mA's GT Power meter needs?

 

[JTL]

If the battery pack uses a BMS I would venture to guess that BMS was in fault/protect mode thus unable to deliver a few mA's GT Power meter needs?[/quote]

It is one of Paul's batteries so it has a BMS. I actually tried it twice. I put a small charge into the battery and rode it down to the LV threashold and it did the same thing. Something about the voltage under some level. I just hope the BMS isn't defective.

 

[Ykick]

It is one of Paul's batteries so it has a BMS. I actually tried it twice. I put a small charge into the battery and rode it down to the LV threashold and it did the same thing. Something about the voltage under some level. I just hope the BMS isn't defective.

Quite the contrary. I believe the BMS is doing exactly as it should. 38V is roughly 2.7V/cell for 52V (14S) battery pack. It’s protecting cells from OD (over discharge) and not allowing the BMS to power anything until the pack has been recharged to some extent.

FYI - unless you connect an external battery to power the GT Power meter, any measurements will be lost when it turns off. This can be frustrating when attempting to measure the amount of power Ah/Wh delivered from the battery.

Standard RC servo connector for the external 5V battery connection.

 

[docw009]

You have the wattmeter between the controller and battery, right. And it doesn't light up. You're not getting any data on watt-hrs, instant amps, or voltage?

Between the charger and the battery, don't know that there's any useful info there, other than voltage.

 

[JTL]

It is one of Paul's batteries so it has a BMS. I actually tried it twice. I put a small charge into the battery and rode it down to the LV threashold and it did the same thing. Something about the voltage under some level. I just hope the BMS isn't defective.

Quite the contrary. I believe the BMS is doing exactly as it should. 38V is roughly 2.7V/cell for 52V (14S) battery pack. It’s protecting cells from OD (over discharge) and not allowing the BMS to power anything until the pack has been recharged to some extent.

FYI - unless you connect an external battery to power the GT Power meter, any measurements will be lost when it turns off. This can be frustrating when attempting to measure the amount of power Ah/Wh delivered from the battery.

Standard RC servo connector for the external 5V battery connection.

The watt meter must shut down at something under 38v which to me seems strange. I understand that the bms has a lvc as does the controller, but the batt meter is independent of those. The battery still showed 38v which should have been enough to power the meter.

 

[Ykick]

Meter power is NOT independent of the BMS lvc. Don’t take my word for it, rig a meter connection to perhaps a car battery or some other 12-38VDC source to verify that the meter indeed works below 38VDC?

Every GT Power meter I’ve owned works to down around 4VDC…

Do you have a link to the vendor where you purchased your meter? Perhaps it’s different specs or defective?

DMM volt meter doesn’t apply a load to the battery pack BMS the same way GT Power meter does.

 

[e-beach]

.................Between the charger and the battery, don't know that there's any useful info there, other than voltage.

You can track how much amp hours it takes to recharge your battery. If you know your miles, terrain, weather and riding habits, you will learn how many amp hours it takes to get there and back.

 

[docw009]

.................Between the charger and the battery, don't know that there's any useful info there, other than voltage.

You can track how much amp hours it takes to recharge your battery. If you know your miles, terrain, weather and riding habits, you will learn how many amp hours it takes to get there and back.

Yes, but if it's hooked between the charger and the battery, it's connected to the charging port isn't it?

 

[lionelt]

Mine, intégrated in Vector, 18S40Ah, max Amps actually : 70 (5KW) with ctl Lyen 18FET (5KW)

 

[JTL]

Meter power is NOT independent of the BMS lvc. Don’t take my word for it, rig a meter connection to perhaps a car battery or some other 12-38VDC source to verify that the meter indeed works below 38VDC?

Every GT Power meter I’ve owned works to down around 4VDC…

Do you have a link to the vendor where you purchased your meter? Perhaps it’s different specs or defective?

DMM volt meter doesn’t apply a load to the battery pack BMS the same way GT Power meter does.

When I said "independent" I meant the meter doesn't care if is wired to a bms or not so therefore it should work at 39v DC. It may be defective, it was only $10 shipped from China. It works fine at higher voltages just not at 39vdc. Anyway, the battery works and I have my trusty multi-meter. The problem is that I won't be able to use it to take any measurements after the lvc kicks in because the meter will turn off and lose the data. I am still a novice at this battery stuff but if I understand correctly the controller will shut down at its cut off unless the lvc is lower than the battery lvc. If so, and the battery is still delivery enough current for the motor to run even though it hits its lvc, why does the motor stop. When we know there is still 39v left in the battery yet nothing will run. Obtw. Thanks for all of your helpful comments and Merry Christmas.

 

[amberwolf]

The watt meter must shut down at something under 38v which to me seems strange. I understand that the bms has a lvc as does the controller, but the batt meter is independent of those. The battery still showed 38v which should have been enough to power the meter.

No, because it's a "floating" 38v, that can't deliver any significant current (which the wattmeter requires to operate).

A DMM still works becuase it is not powered by the source it's measuring, so it's high-impedance inputs will still register a voltage on the BMS output FETs even when they are shut off.

The wattmeter will work down to very low voltage, around 5v-ish for the ones I've used, but only if there is enough current available to power it.

If you need it to operate even when the BMS is shut off, you must power it from a separate battery, as another poster described.

 

[JTL]

The watt meter must shut down at something under 38v which to me seems strange. I understand that the bms has a lvc as does the controller, but the batt meter is independent of those. The battery still showed 38v which should have been enough to power the meter.

No, because it's a "floating" 38v, that can't deliver any significant current (which the wattmeter requires to operate).

A DMM still works becuase it is not powered by the source it's measuring, so it's high-impedance inputs will still register a voltage on the BMS output FETs even when they are shut off.

The wattmeter will work down to very low voltage, around 5v-ish for the ones I've used, but only if there is enough current available to power it.

If you need it to operate even when the BMS is shut off, you must power it from a separate battery, as another poster described.

I won't pretend to understand the technical details but thanks for the bottom line answer. So, if I use the meter to measure battery performance white I am riding the data will be lost when I hit the lvc or 39v in my case. Correct?

 

[Ykick]

Depends which lvc you're talking about? If the battery pack BMS lvc? Then yes, accumulated data of the meter will be lost.

If the controller lvc, the meter should never lose power.

But the easiest solution (other than just using a CA) is to power your cheap power meter with an external battery. As I mentioned it's a standard RC servo connection: Pos (+) is the middle pin. You'll need to connect a small battery of course. Your meter should have instructions for external power?

You've never confirmed which meter you have but if it's the GT Power meter you can view the manual here: https://hobbyking.com/media/file/209708403X517200X7.pdf

I do appreciate the thanks, sorry I'm not a better writer. Good luck.

 

[docw009]

Now I understand the problem. When the battery LVC kicks in and shuts off the battery, JTL loses all the data. Can't do much about that, except add a external battery like Ykick suggests.

I have the cheap meters too, and they seem to run with my 36V and 48V batteries. WIth a 52V battery, the voltage reading becomes inaccurate above 56 volts and reads low. I recall reading that the cheapos blow up on a 72 volt battery,