Question Blacktip 12 AH Batteries ?

[AustinV]

You know now im curios, the Blacktip has a battery indicator that displays battery level by showing bars but from what i can see it does this by using a relatively simple dot matrix display that's from what i can tell is 12x8 pixels.
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You would think in the firmware there would be an option to set it to show percentage. Perhaps there's something I'm missing regarding how they battery level is measured.

Just to be clear for those without a BlackTip - these two displays are not the battery level. I had an issue once where the 2 with the dot under it kept coming up, I contacted DiveX and told them about it (I described it as a question mark, didn’t realize it was a two), they said those icons displayed mean there is a problem with battery 1 or 2, in my case it was 2. I took battery out and made sure contacts were clean, made sure it seated properly since then and haven’t seen it since. The battery level display is a 1-4 bar graph.

 

[macado]

Measuring voltage on lithium batteries is not a very accurate way to determine actual capacity since the nominal voltage of the cells stay pretty flat until they sharply drop off.

It's great that the Blacktip actually has a battery display albeit 4 bars where a lot of other more expensive scooters like the Piranha or even the Bonex scooters don't nor did the older Gavins or Silent Submersion scooters.

The Blacktip battery meter is a good indicator that you have battery life left but I would not rely on it heavily for mission critical things. It's simple not accurate or granular enough.

I also dont really think the resolution of the display used on the Blacktips has enough resolution/pixels to give a good percentage that would be easy to read.

The BMS on the battery would have to employ coulomb counting which I'm pretty sure the DeWalt batteries dont do.

Coulomb counting is a technique used to track the State of Charge of a battery pack. It works by integrating the active flowing current (measured in amps) over time to derive the total sum of energy entering or leaving the battery pack. This produces a capacity that is typically measured in Amp-hours.

 

[Gone for diving]

Measuring voltage on lithium batteries is not a very accurate way to determine actual capacity since the nominal voltage of the cells stay pretty flat until they sharply drop off.

It's great that the Blacktip actually has a battery display albeit 4 bars where a lot of other more expensive scooters like the Piranha or even the Bonex scooters don't nor did the older Gavins or Silent Submersion scooters.

The Blacktip battery meter is a good indicator that you have battery life left but I would not rely on it heavily for mission critical things. It's simple not accurate or granular enough.

I also dont really think the resolution of the display used on the Blacktips has enough resolution/pixels to give a good percentage that would be easy to read.

The BMS on the battery would have to employ coulomb counting which I'm pretty sure the DeWalt batteries dont do.

I agree, not the best way,

But in practice there tends to be voltage drop as you speed up and that will teach you aprox how much battery is left by the amp draw,

I use a meter with a shunt to measure current and voltage which gives me watts, and watt hrs and that's very useful info,

 

[Jona Silverstein]

It is dependent on the controller or BMS.

On the Smart-DPV ESC, we can pull up a direct readout of Wh used on the datalog.

Some BMS Modules are voltage based and others have an internal shunt and go by capacity. either way, I have found all of them to be accurate forms of measuring their capacity.

The BT uses voltage steps but they are inaccurate unless the dpv is under load as the voltage sag can cause quite a difference on reading. Hence the adjustment setting in the FW for how long to wait before displaying the battery meter after releasing the trigger.

 

[Jona Silverstein]

Measuring voltage on lithium batteries is not a very accurate way to determine actual capacity since the nominal voltage of the cells stay pretty flat until they sharply drop off.

It's great that the Blacktip actually has a battery display albeit 4 bars where a lot of other more expensive scooters like the Piranha or even the Bonex scooters don't nor did the older Gavins or Silent Submersion scooters.

The Blacktip battery meter is a good indicator that you have battery life left but I would not rely on it heavily for mission critical things. It's simple not accurate or granular enough.

I also dont really think the resolution of the display used on the Blacktips has enough resolution/pixels to give a good percentage that would be easy to read.

The BMS on the battery would have to employ coulomb counting which I'm pretty sure the DeWalt batteries dont do.

Your Graph is quite inaccurate. Standard LiMn Li-ion cells while they have an S curve its not nearly as stable as that. and with a proper graph, you can depict what your SOC is very reliably based on voltage after the pack has recovered from the voltage sag of the load.

The graph shows extremes that these cells should never be hitting. All Li-ion cells should never exceed 4.2v/Cell and depending on the cell manufacturer and rating the minimum discharge voltage is 2.95-2.70V/Cell.

LiFePO4 does have a very similar curve to the graph but the endpoints are 3.6V and 2.5V respectively.

 

[macado]

Your Graph is quite inaccurate. Standard LiMn Li-ion cells while they have an S curve its not nearly as stable as that. and with a proper graph, you can depict what your SOC is very reliably based on voltage after the pack has recovered from the voltage sag of the load.

Splitting hairs but you're correct. It was just the first example I found on google. My main point was the 4 bar battery indicator on Blacktip is not going to be as accurate as a percentage or capacity given by an actual BMS either by voltage or internal shunt measuring current and voltage.

Typical curve of a 21700 cell for others who might be curious.

 

[ermaclob]

So after weeks of lurking over a number of webs sites for the Dewalt batteries I was finally able to get lucky enough to get two 12ah batteries with bundled chargers off of home depot. They are still out of stock in general from what I can tell however so good luck to everyone else out there. But looks like my search is over........ for now. Now time to start pimping out my scooter and abusing it.

 

[AustinV]

Congrats on being fast - looks like they are out of stock again. Now time to break in the scooter!

 

[stuartv]

So after weeks of lurking over a number of webs sites for the Dewalt batteries I was finally able to get lucky enough to get two 12ah batteries with bundled chargers off of home depot. They are still out of stock in general from what I can tell however so good luck to everyone else out there. But looks like my search is over........ for now. Now time to start pimping out my scooter and abusing it.

Did you get them from HomeDepot.com, or find them in an actual store?

 

[ermaclob]

Did you get them from HomeDepot.com, or find them in an actual store?

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