Tesla home battery pack and DPV battery pack Technology

[cool_hardware52]

Adding a $100 hobby grade component to a $5-8k scooter that may impact diver safety is not exactly an elegant solution. Not that what the EagleTree logger does is rocket science but it's not what I would consider a tested component when you buy one. Additionally, you need to disassemble your scooter to view the information. I look forward to Jon's solution as it seems a step in the right direction.

As for knowing in advance that a cell is on the way out, even if the pack continues to charge and balance, may make your dive planning more conservative. How is that a bad thing? It is a pity that cells have to be changed en masse when just one cell has gone TU but that is the nature of Li batteries.

So while data logging IS a good thing, no one offers it!

The reality is for the vast majority of users real time battery condition is simply not necessary. Adding it to every scooter just raises cost, and complexity. Data loggers easily fill the need *for those that need it*

Data logger can easily spot a pack with a failing cell. You just need to know what you are looking for.

Tobin

 

[eelnoraa]

Not a Li-ON expert, but I do have some experience with them. As far as I know, if you limit the range of the charge/discharge, you can elongate the number of cycles significantly. That is why Telsa is recommending to keep the battery between 20%-80%. They give 10 years of service for average drivers, which estimated to have about 3000 cycles. But if you are charging/discharging between 0-100% all the time, the endurance is about 500 only.

I don't understand the 5 years lifespan for scooter battery. Since you don't use it everyday, if Telsa can pull off a 10 year service, I would only think the usage of scooter, you can go for much longer. If you make 50 dives a year (1 per week), 500 cycles is 10 years.

 

[cool_hardware52]

Not a Li-ON expert, but I do have some experience with them. As far as I know, if you limit the range of the charge/discharge, you can elongate the number of cycles significantly. That is why Telsa is recommending to keep the battery between 20%-80%. They give 10 years of service for average drivers, which estimated to have about 3000 cycles. But if you are charging/discharging between 0-100% all the time, the endurance is about 500 only.

I don't understand the 5 years lifespan for scooter battery. Since you don't use it everyday, if Telsa can pull off a 10 year service, I would only think the usage of scooter, you can go for much longer. If you make 50 dives a year (1 per week), 500 cycles is 10 years.

^^Pack design.


Depth of discharge is a huge player in battery pack cycle life.

This is a key reason why I've always designed my batteries to provide at least 2x the capacity the typical user requires.

For many battery powered devices the battery is a significant cost and weight element, and that leads to the manufacturer furnishing the smallest battery that will allow the device to be sold.

Given that many consumer electronics are obsolete about the time the battery requires replacement it's a model I predict will continue for a long time.

Tobin

 

[Akoni]

The reality is for the vast majority of users real time battery condition is simply not necessary. Adding it to every scooter just raises cost, and complexity. Data loggers easily fill the need *for those that need it*

Data logger can easily spot a pack with a failing cell. You just need to know what you are looking for.

Tobin

Which is why I specified technical level scooters. Even a simple built in data logger would be an incremental design upgrade that would be welcomed by most anyone dropping $6-8k on a scooter or $2-4k on a new battery pack. Realtime monitoring of some basic metrics would be the next step after data logging.

Not a Li-ON expert, but I do have some experience with them. As far as I know, if you limit the range of the charge/discharge, you can elongate the number of cycles significantly. That is why Telsa is recommending to keep the battery between 20%-80%. They give 10 years of service for average drivers, which estimated to have about 3000 cycles. But if you are charging/discharging between 0-100% all the time, the endurance is about 500 only.

I don't understand the 5 years lifespan for scooter battery. Since you don't use it everyday, if Telsa can pull off a 10 year service, I would only think the usage of scooter, you can go for much longer. If you make 50 dives a year (1 per week), 500 cycles is 10 years.

I am no expert in Li batteries either but I believe cycles are not the only factor in lifespan. The batteries will suffer some losses based on time alone and if not exercised regularly that degradation will occur even quicker. None of the BMC's in current generation designs (that I'm aware of) allow any user interaction to set high and low voltages. So you can only guess at it with runtime and what your user provided/installed data logger tell you. Most packs don't even offer a simple capacity display so that you can easily stop charging at that 80-90% mark.

My comments are not pointed at any manufacturer in particular. They are general comments from a long time Li scooter owner/user. I currently own two Li scooters of varying vintages. Both are fitted with loggers.

 

[cool_hardware52]

Which is why I specified technical level scooters. Even a simple built in data logger would be an incremental design upgrade that would be welcomed by most anyone dropping $6-8k on a scooter or $2-4k on a new battery pack. Realtime monitoring of some basic metrics would be the next step after data logging.

Who is in greater need of a "gas gauge", the driver of vehicle that gets 10 MPG and is fitted with a 5 gallon tank, or the driver of a vehicle that gets 20 mpg and is fitted with a 10 gallon tank? Both operate a route that has refueling stations every 40-50 miles.

I am no expert in Li batteries either but I believe cycles are not the only factor in lifespan. The batteries will suffer some losses based on time alone and if not exercised regularly that degradation will occur even quicker. None of the BMC's in current generation designs (that I'm aware of) allow any user interaction to set high and low voltages. So you can only guess at it with runtime and what your user provided/installed data logger tell you. Most packs don't even offer a simple capacity display so that you can easily stop charging at that 80-90% mark.

The current Dive X electronics allow the user to set the low cutoff voltage for the motor controller. Same net effect, it limits the depth of discharge.

DSS Li-Ion chargers display the charge voltage and the amphours returned continuously. Given the high charge efficiency of Li-Ion returned capacity is a pretty good proxy for capacity used.

 

[Akoni]

Who is in greater need of a "gas gauge", the driver of vehicle that gets 10 MPG and is fitted with a 5 gallon tank, or the driver of a vehicle that gets 20 mpg and is fitted with a 10 gallon tank? Both operate a route that has refueling stations every 40-50 miles.

The longer ranged vehicle has a greater need to my way of thinking. You either want to be more time efficient and minimize the number of refueling stops or will seek more lucrative routes that have longer mean distance between refueling for which the shorter range vehicles cannot compete.

Anyway, seems as if we're running in circles now...

 

[cool_hardware52]

The longer ranged vehicle has a greater need to my way of thinking. You either want to be more time efficient and minimize the number of refueling stops or will seek more lucrative routes that have longer mean distance between refueling for which the shorter range vehicles cannot compete.

Anyway, seems as if we're running in circles now...

So after advocating limiting the depth of discharge (which will increase battery life) you are now arguing that it is best to run them down to avoid extra time spent recharging.

Gotta love the intellectual consistency......


Tobin

 

[Jon Nellis]

Realtime monitoring of some basic metrics would be the next step after data logging.

Ya mean like this...

http://www.scubaboard.com/forums/di...ing-sentry-dpv-dashboard-logic-dive-gear.html

 

[Akoni]

If you were asking about Li scooters, then don't 'disguise' the question and come back and talking trash about intellectual consistency. I thought you had some interesting point to make with your analogy, so I played along. Instead you were just looking for an excuse to display your arrogance. Well done.

---------- Post added May 13th, 2015 at 05:31 PM ----------

Ya mean like this...

http://www.scubaboard.com/forums/di...ing-sentry-dpv-dashboard-logic-dive-gear.html

Precisely. Kudos Jon!

Seismometers on the west coast just detected Tobin exploding...

 

[cool_hardware52]

If you were asking about Li scooters, then don't 'disguise' the question and come back and talking trash about intellectual consistency. I thought you had some interesting point to make with your analogy, so I played along. Instead you were just looking for an excuse to display your arrogance. Well done.

---------- Post added May 13th, 2015 at 05:31 PM ----------



Precisely. Kudos Jon!

Seismometers on the west coast just detected Tobin exploding...

Ah, hardly.

I've designed and sold rechargeable battery powered devices for 30+ years. IMO "gas gauges" are a gimmick that almost no user needs. Far better to start with more than enough battery.

If battery capacity is "mission critical" who starts with less than a full charge?

If battery capacity is "mission critical" who plans on using more than some fraction (1/2's 1/3's) of the known, proven capacity?

If battery failure (exhaustion) is life threatening who doesn't include redundancy in their planning, i.e. spare scooter, back up light etc.?

Determining useful range is of course necessary to plan, but that doesn't require real time display, it's easy to determine via data loggers or even returned capacity at time of charge.

Can detail for me exactly how real time data will change your dive planning in ways that a data logger cannot?


Tobin