Lipo Battery Voltage Checker for eBike

cgokey

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Jun 9, 2016
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I was wondering what people are using for a Lipo Battery Voltage Checker for eBikes? Might be nice to have something with a wire that can go from the battery to the handlebars. But these look kind of interesting too:

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https://www.amazon.com/Floureon-Battery-Monitor-Checker-Indicator/dp/B00SCJOITA/ref=sr_1_2?rps=1&ie=UTF8&qid=1467415017&sr=8-2&keywords=lipo+battery+voltage&refinements=p_85%3A2470955011
https://www.amazon.com/Integy-C23212-Voltage-Checker-Warning/dp/B003Y6E6IE/ref=sr_1_3?rps=1&ie=UTF8&qid=1467415340&sr=8-3&keywords=lipo+battery+checker&refinements=p_85%3A2470955011


Chris
 
Also, how do these alarms work, as a little bit of reading I'm doing states that there is "load" voltage and "resting?" (no load) voltage. Under load the V can get down to like 3.3V or something but then after no load, it move back up to 3.7, 3.8, etc. So if there is only 1 alarm, wouldn't there be a lot of false alarms?

Chris
 
I don't care much for those alarms. For one thing, they draw enough current that they can't be left connected when the bike is parked, not even for an hour. So every time before the ride they have to be connected(with the annoying screeching).
For use as a Low Voltage Alarm, they are a compromise, as you pointed out, due to Voltage sag. A "hard" Low Voltage Cutoff(LVC), usually in the controller, is a much better way to go. They are fool-proof.
As far as "displays" are concerned, if that is what you are asking about;
Although I started off with a Cycle Analyst, all I run these days is a Volt meter and my fav. is this one';
http://lunacycle.com/batteries/gauge/luna-voltage-meter/
It is very flat and draws so little, it can be hooked up all the time.
It's flat form factor works very well for me because it fits inside the little clear plastic pouch that most sm. "over-the-frame saddle bags have. Here are a pair;
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motomech said:
For use as a Low Voltage Alarm, they are a compromise, as you pointed out, due to Voltage sag. A "hard" Low Voltage Cutoff(LVC), usually in the controller, is a much better way to go. They are fool-proof.

What is the LVC set to in the controllers? Is it pretty standard and therefore protect the lipo battery from reaching too low of voltage?
 
I just use one of these for pack voltage.
http://www.ebay.com/itm/RED-DC-Voltmeter-15-120V-Waterproof-Dust-proof-Shockproof-Panel-Meter-DC-24V-36V-/321405804645
 
http://www.ebay.com/itm/100A-60V-DC-RC-Helicopter-Airplane-Battery-Power-Analyzer-Watt-Meter-Balancer-EA-/262015279643
 
For a decently accurate checker of all the cells in your pack, get the Cellog 8

This is used at the house, to see if packs are balanced. Pretty accurate compared to the alarms.

Once you know which pack in your whole assembly has the lowest capacity, then you can put one of those cheap alarms on just that pack, when you think you will need it. Not all the time, but when you will beat that pack like a bad dog.

You may be out on the road, and need to wring 99.8% of your capacity out of the pack, or maybe you meant to return sooner, and are now worried about making it home. Once you are in limp home mode, the beeping will tell you to ride slower, and slower, and slower as you get into that last 1% of capacity.

So what I'm saying, when the voltage under load gets low enough, it start cheeping, you slow down, and it stops for a bit.

Set the thing for pretty low, when used like this. Like 3v per cell.

Another way to use one, just set it to 3.7v or so, so you get a warning that you are near the end, under load. When it keeps cheeping when stopped, you are now at 3.7v resting, and should be home if you want to leave some capacity in there.

But once you get a watt meter, or whatever bar mounted pack voltage meter, you can just watch that for the voltage that is 3.7v per cell, for the whole pack.

I love the cycle analyst, and have 4 of them. But that luna cycle meter looks great for just a voltmeter.
 
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