Battery selection

I'm planning to buy a couple of scooters near the end of the year and wanted to ask about batteries.

I've read through the forum posts, as well as the Tahoe Benchmark papers and had a question about which type of battery to choose. This would apply to canister light batteries also.

I'm naturally giving consideration to the costs and weight of the different batteries, but I am also concerned with what battery would best tolerate periods of non use.

I travel on a lot of short trips each year, but I also take a 3 month trip. With this period of inactivity in mind, which type of battery would be best for me.

It seems to me that DPV and can light purchase decisions are going to be based on the battery. I don't want to spend a lot of money on something that isn't going to do well over time from not being charged and discharged.

Is this bad for all of them, making cheaper replacement costs the driving factor for me?
Or is the more expensive Lipo battery more tolerant of this, making them the better long term buy?

Any thoughts are much appreciated.

-Mitch

Pullmyfinger:

I'm planning to buy a couple of scooters near the end of the year and wanted to ask about batteries.

I've read through the forum posts, as well as the Tahoe Benchmark papers and had a question about which type of battery to choose. This would apply to canister light batteries also.

I'm naturally giving consideration to the costs and weight of the different batteries, but I am also concerned with what battery would best tolerate periods of non use.

I travel on a lot of short trips each year, but I also take a 3 month trip. With this period of inactivity in mind, which type of battery would be best for me.

It seems to me that DPV and can light purchase decisions are going to be based on the battery. I don't want to spend a lot of money on something that isn't going to do well over time from not being charged and discharged.

Is this bad for all of them, making cheaper replacement costs the driving factor for me?
Or is the more expensive Lipo battery more tolerant of this, making them the better long term buy?

Any thoughts are much appreciated.

-Mitch

Click to expand...

Lithium Ion batteries (which includes Li-Po, Li-Po is Lithium Ion with a slightly different electrolyte) have a pretty low self discharge rate. That means they generally tolerate storage well. Nimh batteries have a fairly high self discharge rate, but as long as they are recharged prior to storage, and not stored at high temperatures 3 months is no problem for NiMh.

Regarding replacement cost; Battery capacity makes a huge difference. With any rechargeable battery deep cycling will shorten the life. If every time you use the device you run the battery all the way down you will realize many fewer cycles than if you discharged the battery ~50%. The effects are non linear, meaning 50 cycles to 100% of capacity will degrade the battery far more than 100 cycles to 50% of capacity. Bigger batteries means not only longer run times / burn times if you need it, but also longer cycle life for the typical user.

A well designed, properly sized Lithium Ion scooter battery should provide years of service, ours have proven to do so. With scooters the sad fact is it's pretty hard to use them enough to wear them out. I expect most will die of old age, not too many cycles.

Keep in mind that if you have a scooter battery that lasts 4-5-6+ years the "replacement" is very likely to be something new and improved, battery technology moves very fast.

Good luck,

Tobin

The difference between LiPo and "classic" Li-ion batteries is for practical purposes a bit more than "slightly"..
For one the LiPo packs does not hold the electrolyte in a solvent but a solid polymer, which means the batteries can be shaped however the manufacutrer like and they are also not generally encased in a hard shell, decreasing their weight.
LiPo batteries also generally have a higher maximum discharge rate and for many applications significantly longer runtime.
The downside to LiPo batteries is however that you should use a charger designed specifically for them and they should not be drained below 3v per cell..

Tigerman:

The difference between LiPo and "classic" Li-ion batteries is for practical purposes a bit more than "slightly"..
For one the LiPo packs does not hold the electrolyte in a solvent but a solid polymer, which means the batteries can be shaped however the manufacutrer like and they are also not generally encased in a hard shell, decreasing their weight.

Click to expand...

That Li-Po's are "lighter" than cylindrical 18650's is a myth. Go compare the watthours per unit weight for Li-Po's and high capacity 18650's

For example: All-Battery.com: Tenergy Li-Polymer 3.7V 5000mAh (7063135) Battery This "Li-Po" offers 18.5 watthours @ a mass of 102 grams. 18.5/102 = .181 watthours per gram

Here is another example of Li-Po's with similar specific energy All-Battery.com: Tenergy LIPO 3.7V 2380mAh (753969) Battery

This 18650 All-Battery.com: Samsung Li-Ion 18650 Cylindrical 3.7V 2600mAh (ICR18650-26F) Flat Top Rechargeable Battery This cylindrical 18650 Lithium Ion offers 9.62 watthours @ a mass of 45 grams. 9.62 / 45 = .214 watthours per gram.

There are now 18650's with greater specific energies available. I've been testing some that are ~.25 watthours per gram.

Tigerman:

LiPo batteries also generally have a higher maximum discharge rate and for many applications significantly longer runtime.

Click to expand...

Again not true. Higher capacity = longer run times and usually higher discharge currents. With 18650's one can build a pack that offers greater capacity per unit weight. Besides for dive lights and scooters discharge rates of ~ 1C or less, usually *much* less are the norm. Of what advantage is a 10C or 15C discharge rate for device intended to operate for 2-4-6 hours? Can you point to a single dive light or scooter using such cells?

Tigerman:

The downside to LiPo batteries is however that you should use a charger designed specifically for them and they should not be drained below 3v per cell..

Click to expand...

Virtually all Lithium batteries, cylindrical Lithium Ion or foil packaged Li-Po's should not be discharged below 3.0 volts per cell, and every Lithium based rechargeable needs the appropriate charger.......

Tobin

---------- Post added ----------

Tigerman:

The difference between LiPo and "classic" Li-ion batteries is for practical purposes a bit more than "slightly".

Click to expand...

I'll also point out that in terms of moderate length storage, i.e. the question the OP asked, the differences between a "dry" solvent Lithium Cylindrical cell and Lithium polymer cell is quite slight, both exhibit low self discharge rates.

Tobin

cool_hardware52:

Lithium Ion batteries (which includes Li-Po, Li-Po is Lithium Ion with a slightly different electrolyte) have a pretty low self discharge rate. That means they generally tolerate storage well. Nimh batteries have a fairly high self discharge rate, but as long as they are recharged prior to storage, and not stored at high temperatures 3 months is no problem for NiMh.

Regarding replacement cost; Battery capacity makes a huge difference. With any rechargeable battery deep cycling will shorten the life. If every time you use the device you run the battery all the way down you will realize many fewer cycles than if you discharged the battery ~50%. The effects are non linear, meaning 50 cycles to 100% of capacity will degrade the battery far more than 100 cycles to 50% of capacity. Bigger batteries means not only longer run times / burn times if you need it, but also longer cycle life for the typical user.

Thanks, that's something I had not considered. I'll make sure to choose a 10 amp battery instead of something smaller.

A well designed, properly sized Lithium Ion scooter battery should provide years of service, ours have proven to do so. With scooters the sad fact is it's pretty hard to use them enough to wear them out. I expect most will die of old age, not too many cycles.

Keep in mind that if you have a scooter battery that lasts 4-5-6+ years the "replacement" is very likely to be something new and improved, battery technology moves very fast.

I appreciate your thoughts on this Tobin, I wanted to considered all of the variables in the decision.

Good luck,

Tobin

Click to expand...

Thank you, Sir!

-Mitch