Favorite battery capacity meter.

[tomjasz]

I'm in my 5th year using these meters. Cheap and reliable. Also can be used on a range of voltages.

 

[6zfshdb]

I used this same gauge for a couple of seasons and it works well for the most part. I particularly like the 10 segment display which beats the 5 segment on my bike's handlebar meter.

The only complaint I have is it is voltage based and not linear. If you ride out until 5 bars remain (50% used), you never have enough juice to get back. This problem exists with any voltage based gauge.

To compensate, I ride out until 4 bars are used and save the remaining 6 to get back. This works ok but it requires some guesswork. Even so, it's still better than the one that came on my bike.

 

[PedalUma]

@tomjasz, would you please post this on 'Show Us A Tool'? Explain how you hook it up, when to use it and why. Also show your own photos. Looks nice, useful. Thank you.

 

[tomjasz]

@tomjasz, would you please post this on 'Show Us A Tool'? Explain how you hook it up, when to use it and why. Also show your own photos. Looks nice, useful. Thank you.

The dog ate my homework.

 

[PedalUma]

We had a dog that ate baby socks. We had evidence.

 

[ronaldrodgers]

Thank you for your post.

 

[PCeBiker]

I have been using this gage for about six months now,.

Prosport 48 Volt Golf Cart Battery Meter-state of Charge Meter https://a.co/d/cuTW9Lp


I'm really liking it but it has the same issue that @6zfshdb mentioned in that it's voltage based, and the needle movement isn't linear.
The needle picks up speed as the battery drains, but the printed scale isn't quite linear either which helps to offset the imbalance.
The half way point is roughly when the needle is in the middle of the "C".


I am in the middle of installing an analog ammeter to go along with it,..

I've also got a digital Watt hour meter, but I'm going to try the analog ammeter first.
That might be all that I need, and I prefer a needle gage.

CAMWAY Battery Monitor 8-120V... https://www.amazon.ca/dp/B088RG27LS?ref=ppx_pop_mob_ap_share

 

[Rome]

There's a lot on your handlebars like the compass. You can buy display that shows all the features such as battery voltage or percent and distance.

 

[PCeBiker]

There's a lot on your handlebars like the compass.

I've got a windshield and mirrors hanging off the handlebars too,..

The windshield is kinda useless but my ebike sure looked stupid without it,..

I'm usually function over form, but I had to do something about the form.
So the windshield and compass is my artistic touch.

You can buy display that shows all the features such as battery voltage or percent and distance.

I'd prefer to have no gages at all, but I have range anxiety, so I kinda want the voltmeter and ammeter.

I have a HUGE hate on for digital and prefer analog.
I want NO robots or AI on my e-bike.

The analog meters (including the compass) give raw data without being processed by algorithms or analyzed by a computer.

 

[6zfshdb]

If you read my past posts on this subject, you'll see that these cheap voltage based, non linear, e-bike battery gauges are a pet peeve of mine.
The displays on many more expensive bikes incorporate the same accurate gauge technology used in electronic devices like smartphones and electric vehicles. How much extra would it cost to use this superior gauge technology in ALL e-bikes?

 

[Gionnirocket]

If you read my past posts on this subject, you'll see that these cheap voltage based, non linear, e-bike battery gauges are a pet peeve of mine.
The displays on many more expensive bikes incorporate the same accurate gauge technology used in electronic devices like smartphones and electric vehicles. How much extra would it cost to use this superior gauge technology in ALL e-bikes?

I believe those rely on past/current load as a basis and that has its flaws as well, especially when the remaining future use is not equivalent.

 

[6zfshdb]

I have been using this gage for about six months now,.

View attachment 167086

Prosport 48 Volt Golf Cart Battery Meter-state of Charge Meter https://a.co/d/cuTW9Lp


I'm really liking it but it has the same issue that @6zfshdb mentioned in that it's voltage based, and the needle movement isn't linear.
The needle picks up speed as the battery drains, but the printed scale isn't quite linear either which helps to offset the imbalance.
The half way point is roughly when the needle is in the middle of the "C".


I am in the middle of installing an analog ammeter to go along with it,..

View attachment 167087

I've also got a digital Watt hour meter, but I'm going to try the analog ammeter first.
That might be all that I need, and I prefer a needle gage.

View attachment 167088
View attachment 167090


CAMWAY Battery Monitor 8-120V... https://www.amazon.ca/dp/B088RG27LS?ref=ppx_pop_mob_ap_share

If you haven't already purchased that 500A Camway gauge, which is way overkill, there is a 50A version available:

Amazon.com

The shunt is much smaller and easier to place in a controller housing.

The downside to these gauges is the cable is shielded with connectors on both ends. It's very difficult to cut & splice which means the slack needs to be coiled and stored somewhere. It also requires a 5/8" hole for the connector to pass through.

 

[PCeBiker]

I believe those rely on past/current load as a basis and that has its flaws as well, especially when the remaining future use is not equivalent.

That's the part that I don't like.
I am being studied by the computer and it tries to predict my future.
If I happen to ride on a windy day or decide to ride faster, the predictions are useless and would leave me stranded without enough battery to get home.
I prefer to monitor my batteries myself.

 

[PCeBiker]

If you haven't already purchased that 500A Camway gauge, which is way overkill, there is a 50A version available:

Ahh, crap!!
I didn't know that. I've already got the 500A version.
The 50A version is $10 cheaper too.

The shunt is much smaller and easier to place in a controller housing.

I've been thinking about how and where to install the shunt.
I was thinking inside the frame in the hollow space above the upper battery bracket where the power cable connects to the battery bracket.

The downside to these gauges is the cable is shielded with connectors on both ends. It's very difficult to cut & splice which means the slack needs to be coiled and stored somewhere. It also requires a 5/8" hole for the connector to pass through.

I've already got two holes with grommets coming out of the hollow space. I should be able to fish the cable through the grommet?

I was wondering if I could wrap the shunt with foam rubber to protect and isolate it?
It would be difficult to screw it down or glue it to the inside of the hollow space.
I could then remove the heavy acrylic bracket from the shunt as well.

I figure that the shunt would generate very little heat because it's only seeing 20 amps and it has a resistance of almost 0 ohms.

Do have any advice on that?

I did buy a cheap 20A shunt for $4 but it might not be accurate, and it's kinda big itself at 4½" long.

I want to use the shunt that came with the digital meter because I'm pretty sure that I can plug both the digital meter and my analog ammeter into it at the same time.
I'm pretty sure that I would just connect the ammeter to the B- and P- terminals, and the digital meter would plug into the connector?

That way I can tuck the digital meter away somewhere and have it set to monitor my battery's total capacity while I have the ammeter on the handlebars for quick reference.

 

[m@Robertson]

If you read my past posts on this subject, you'll see that these cheap voltage based, non linear, e-bike battery gauges are a pet peeve of mine.

Yeah but that was because you weren't happy with the graphic meter's accuracy. I have had one of these that was built into a battery I bought in 2017 (my very first) and it measures to be dead-on-accurate versus a quality voltmeter. All I use is the voltage readout so I don't care about the graphic. Which means for my uses its small and perfect. This thread reminds me I have one more that is unused and I need to figure out how to plug it into my Bullitt, which has a battery built into the bike, along with a charger, and I have no decent voltage readout other than to use the display on the handlebars... and I know that is high by 0.9v (when the charger is disconnected, so iuts even worse when connected).

I have tried many of the inline wattmeters that are common (and much larger) and its never a question of whether they are off or not, but by how much. So I end up labelling them. This one is off by 0.4v and I made a note to my daughter/son-in-law (its on a charger I made for them) that an 80% charge is actually 55.8v.

Interestingly, the newer models of these meters seem to have some sort of self-correcting mechanism inside them now. Plug them in and they are WAY high, by like 1.2v. But sit and watch the meter over a span of about 5-10 minutes and you will see it very slowly auto-correct itself down to a steady reading. This steady reading will still be off by a bit but not so bad… my last two meters were both off by only about 0.20v after this initial settling in (it does not remember itself after you unplug so it happens again each time you plug in).

 

[PCeBiker]

If I put my mind to it, I could take a bunch of readings while I'm riding noting the voltage on my "fuel gage" and the voltmeter on my display and correlated it to my odometer readings to find my halfway point.

But I'm pretty lazy and I don't do my homework or take notes.
I don't have a dog, but I could say that my cat ate my homework??

I do like having an ammeter or Wattmeter though because I can see how much power I'm drawing in real time.

I really like my "fuel gage". I can see the voltage sag as it's happening.
The voltage drops under load, and if I turn up my power (up to 25A) the sag is much more significant.

Then I can kill the motor (by grabbing a brake lever) and watch the needle bounce back and see how long it takes to stabilize at it's maximum voltage.

It's way more tactile and tangible to watch the needle move around.

 

[PCeBiker]

If you read my past posts on this subject, you'll see that these cheap voltage based, non linear, e-bike battery gauges are a pet peeve of mine.

Just to help clarify that for anyone reading,..

I have a 48 volt battery that is fully charged at 54.6 volts.

If I am riding using say, 100 Watts continuously, I am drawing 1.83 amps with a fully charged battery (100÷54.6).

If I am drawing the same 100 Watts from the battery near the BMS cut-off voltage of 40 volts, I would be drawing 2.5 amps to deliver that same 100 Watts (100÷40).
So the voltage drops faster as the battery capacity decreases.

But, the rate of voltage drop over time would be linear (because lithium batteries discharge in a linear way), so the math/programming for battery charge should be quite simple to implement.

Unless of course, you need to feed that information to mission control, and strava, and some artificial data cloud that you have to pay for.
What happens if the cloud or data steam fails?

I prefer to ride alone without being connected or overcomplified with software, especially when a software glitch can shut you down completely.

I like to know what my electrons are doing, not what the software decides needs to tell me about it.

Artificial intelligence is unnaturally stupid by design as far as I'm concerned.

 

[Gionnirocket]

My bad.. I hadn't realized that you guys were planning lunar voyages that require down to the millivolt accuracy.

 

[Rome]

I didn't read all of it. I laughed at the cat.
It probably thinks if I'm gonna put it in the oven.

 

[PCeBiker]

My bad.. I hadn't realized that you guys were planning lunar voyages that require down to the millivolt accuracy.

I don't need that kind of accuracy.
I'm a big fan of "Good Enough".

I just need to do my homework and take some measurements.


My grocery getter is a complete piece of crap, but it's still good enough to get groceries.

It's got analog meters too but the damn speedometer is contaminated with AI.
It's a dummy gage controlled by the computer to tell me what it thinks that I'm supposed to know.

The velcro on top was to attach my multimeter to see if the voltmeter was a dummy gage too.


I prefer my analog wind powered machine with no electronics.
It goes over 65kph.

I was all fun and games until the cops kicked me off the railroad tracks for trespassing.