Questions about installing an LED voltmeter between my battery and its charger

[Planet Indigo]

I was looking to hook up a little LED display voltmeter on my battery to monitor voltage as it charges, and also as I use it.
I was thinking the most convenient place to wire it would be on the charging connector, so it can always stay attached to the battery, even when I remove it from its craddle when I park my bike.
Can I safely connect it to the charging plug (in parallel) while that plug is also used by the charger to charge the battery? Basically I'd make a male coaxial plug that goes in the battery charging connector, run thick wires to a female coaxial plug where the charger would connect, and in that thick wire Id connect the small wires of my led voltmeter.

Questions:
1) Can I safely do that while the battery is charging?
2) Say my battery is low at 45v and the charger outputs 54.6v, what would my voltmeter display? 45? 54.6?
3) Can I safely keep it plugged in the battery charging port (with the charger disconnected of course) while I ride the bike to observe the battery voltage in real time?

 

[Feliz]

I was looking to hook up a little LED display voltmeter on my battery to monitor voltage as it charges, and also as I use it.
I was thinking the most convenient place to wire it would be on the charging connector, so it can always stay attached to the battery, even when I remove it from its craddle when I park my bike.
Can I safely connect it to the charging plug (in parallel) while that plug is also used by the charger to charge the battery? Basically I'd make a male coaxial plug that goes in the battery charging connector, run thick wires to a female coaxial plug where the charger would connect, and in that thick wire Id connect the small wires of my led voltmeter.

Questions:
1) Can I safely do that while the battery is charging?
2) Say my battery is low at 45v and the charger outputs 54.6v, what would my voltmeter display? 45? 54.6?
3) Can I safely keep it plugged in the battery charging port (with the charger disconnected of course) while I ride the bike to observe the battery voltage in real time?

Yes, 54.6, yes. Keep the connections well insulated from one another.
I've done that and put in an inline ammeter as well.

 

[jwt355]

just get a Luna Cycle charger They are on sale right now as well https://lunacycle.com/luna-charger-52v-advanced-300w-ebike-charger/ They have a meter right on them and the ability to charge your battery to 70% 80% 90% with a switch which makes the life of your battery twice as long. I definitely recommend one of these to anyone who wants to take care of their battery =)

 

[harryS]

Here's my answers.
1) Yes. Providing your wiring is secure.
2) Voltmeter should show the true battery voltage, not the charger voltage when connected. It might go up maybe a 1/2 volt when charger is connected.
3) Yes.

After a while, having a meter attached will be of little interest. You'll know it hits 54.6V when fully charged. When the display says 2 bars out of four, the voltage will be around 48V. When you don't have enough charge to run the bike, it will be 42-44V. You could derive that off the bar display, but some people like to know the volts,

You could also put something like Tenergy wattmeter inline with the charging cord. These are $10-14 on ebay/amazon. It measures volts, watts, amp-hour (Ah), watt-hours. . I find the voltage somewhat inaccurate, but the amps and AH are good info. IT will tell me how many AH flows back into a battery when charging, so I can assess how much AH is used in a ride. If I charge an nearly empty battery, it tells me how many AH my battery really had. Here's a photo of one connected to one of my chargers. I also used to connect to my battery output to directly measure AH used during a ride.

 

[Feliz]

Actually the voltage will be whatever volts the charger is putting out to supply the necessary amps, 2 or whatever. V= I/R. to charge the battery. Voltage will rise as the battery charges, using a LED display is no different than just putting a multimeter (set to read volts) across the two charger leads.