Battery Too Good To Be True?

Heat84 · 2025-02-08T21:39:48+00:00

I wanted to put this in the electronics section here, but that doesn’t exist here. I have an electric bicycle and the current battery is 24V and 24Ah. I rode it for at least 5 more miles than I should’ve a week ago and discharged the battery too much and it won’t recharge anymore. I get enough of a charge to go about a quarter Mile😭. I found a new one. But it seems too good to be true. Its 30Ah and it costs about half of what I paid for the 24Ah battery that I have now and it’s physically smaller than the one I have now. Does it make sense that the newest electric bicycle batteries would have more Ah capacity but are physically smaller and cheaper than the previous ones? Another question I have is about the heat from extra Ah causing the metal part of wire nuts and wire couplers to brittle-ize. The stock battery was 8Ah. There’s nothing wrong with the wire itself. I’m not having this problem any more since I replaced 2 stock wire couplers on the controller wiring with crimp on connectors and replaced 4 wire nuts(2 by the controller and the 2 for connecting the battery). Why would more battery capacity create more heat? It’s not like it’s more volts. Doesn’t more voltage create more heat? As for the brand name, Duracell and Energizer or the car battery brands don’t make electric bicycle batteries, so you have to go with the weird unknown brands. But this is the weirdest brand name I’ve ever seen. It’s not even a name. It’s more like an acronym. It’s sold by Amazon(and only Amazon apparently). That has to be a good sign right?

Heat84

Sparkchaser So, I spent 5 bucks and bought that battery gage. Here’s what it looks like on the inside. Pretty much what I expected.
![](https://i.broadbandbulletin.com/2025-05-17/1747488417-807149-batt1.jpg)

The one LED on the left means it’s about 16V. After it gets above 17V the end light goes out and the next turns on. As the voltage is increased the others start to turn on. If it’s about 23V the middle 4 will be on. Once it gets to full voltage the right 5 LEDs are on, the left one stays off.

The voltages are approximate but for $5 not bad

The product info says it was designed for 24 volts. I thought that meant that each light is 4 volts.

Sparkchaser

Heat84 The product info says it was designed for 24 volts. I thought that meant that each light is 4 volts.

No, the first LED comes on around 16V. I don’t have a good linear variable power supply anymore so I can’t be accurate at which voltage the 4 middle ones come on but the first one does go out. The 4 middle ones are as I described. When it’s at full voltage the right one comes on.

As I said, it’s not bad for some resistors and diode drops.

Heat84

The battery that I ordered was out of stock(They told me after I ordered it) and they asked me if I would wait 2 or 3 weeks. I said I would. I’m in no particular hurry.

I asked them if they’d provide me with a male XT60 connector. They said yes.

Heat84

Sparkchaser

What does uA mean?

Sparkchaser

Heat84 What does uA mean?

microamps so 500uA is .5 milliamps

Somewhat-Reticent

Sparkchaser Substituting “u” for Greek letter μ ( as noted ).

Heat84

Sparkchaser
I have it installed and working now. I meant to ask you, why was it designed the way it was instead of logically(Each LED = 4 volts and the LEDs going off from right to left as the battery voltage gets lower)? That’s the way it’s labeled(The right to left part at least).

Sparkchaser

Heat84 why was it designed the way

As I said previously, I have no experience with electric bikes.

However, I assume that the useable battery range is from 17V to 24V. Just measuring the battery from 17 to 24 provides better resolution in the useable range. You shouldn’t be draining it below 16V.

Somewhat-Reticent

Heat84 How well is it working?

Heat84

Sparkchaser

Can you explain the the voltages that the LEDs represent starting from a full battery? If you had said what voltage 2 and 3 lights was instead of others, I probably could’ve worked backwards. Thanks

Heat84

Somewhat-Reticent

It’s working great, except for the LEDs not indicating the voltage in the logical way that it was labeled to. I believe I’ve only went down to 4 LEDs.

The battery is working great too. I’ll probably be buying batteries from that seller from now on.

Sparkchaser

Heat84 Can you explain the the voltages that the LEDs represent starting from a full battery? If you had said what voltage 2 and 3 lights was instead of others, I probably could’ve worked backwards. Thanks

As I had said, I do not have a good linear DC supply so I couldn’t provide exact measurements. I no longer have the battery gage.

Since it starts at 18V and end at at 24V, it is probably 18, 19.5, 21, 22.5, 24.
Keep in mind, they are doing this with junction voltage drops and resistors, so it is nowhere near precision.

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