c500user wrote:But how do you keep the cells balanced?
Burgerman wrote: I wouldn't want them fixed to my powerchair! But at least they could be attached in a way that allows them to be discarded fast in an emergency..
Burgerman wrote:The other thing already mentioned is that I am not sure 12A is enough if like expresso you drive continuously, or if like me you are aggressive and 1 can kill a lead battery in about half an hour clearing up the garden or driveway for eg.
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Burgerman wrote: Although it means a dumb charger can be used. And it will balance the cells to answer c500users question.
You will need to use more cells in series for a voltage regulator to work too?
The other thing is that theres a lot of waste charging LA. The charging below 12.9V is quite efficient. Above this, most of the lithium power will go to waste "topping off" at CV. Wasted as heat, gas recombination, etc. So for it to work, its probably better to use a low voltage like 26V and max 12A. so that most of the energy isn't wasted while sat at a restaurant for eg.
Burgerman wrote:Also, they only have about a 500 cycle life in real terms, if discharged and charged heavily. The only reason companies like Tesla get extended service life from them is by utilizing only the centre 66% of the capacity. Meaning their custom software only charges to around 4.075V, and never discharges down to the lower voltages in normal use. It tells you its empty when theres still 20% remaining. So they are not going to last well..
Burgerman wrote:Well then, try it. Buy a fire extinguisher!
Seems unwise on a wheelchair where we cant run away.
https://www.google.com/search?q=li+ion+ ... 80&bih=618
Can the cells be connected and balanced with a pl8, just as you would with lifepo4, but obviously with different charging parameters.
Burgerman wrote:. This is what Tesla does with very complex computer controlled cell charge and balance systems. Which pretty much removes the advantages in energy density they had to begin with. So yes you can do that. The cost advantage remains, but the fire problem also remains... Unwise in a mobility vehicle.
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Just curious...
How does li-ion compare to lifepo4 £ per Ah (initial purchase price)
Then lifetime cost £ per Ah factoring in reduced cycle life.
Also are li-ion allowed in the cargo hold of aircraft. I.E. Going on holiday with wc or scooter?
snaker wrote: and charging boxes?
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