Repacing sla's with lithium?

[fatts]

Hi,
I have a Izip rear pannier type is there any 24v lithium sets which may replace the older sla's in the case or a low cost one that would fit piggy back on the rack to go with the others.
I prefer to fit in case but not very sure of what to get.
I have seen this link.24V 15AH LiFePo4 Electric Bicycle Battery Scooter EBike 26650 Rechargeable 3.2V | eBay.

same company does have others, anyone used these?
many thanks for any help
Milly

 

[muckymits]

I tried my 12 ah headways in the original cases but just too long, 10ah should about go. What you have shown looks a good idea, but I think there was a problem with cheap A123s? One of the others may tell us more about that.

David

 

[fatts]

Thank you David for your reply. Sorry took so long to reply,
been away doing work at the Green Gathering

regards
Fatts

 

[Pikpilot]

The most readily available is the much better Lithium Polymer battery also known as a LiPo battery. Do not be tempted to use LiPos as they are sensitive about charging and discharging limits. They must be charged to 4.2 vpc (Volts per cell) but no more, and end of discharge at 3.0 vpc (2.7 with shorter life). Over charging can cause a thermal runaway, leading to a fire, or a large reduction in battery life. The charger should be of the balancing type which monitors each cell individually and adjusts its charge current so that the vpc of all the cells track as the battery recharges.

A123 cells can be discharged to zero but not recommended below 2.5 vpc for normal life and cell balance. Charging requirements are similar to LiPos but ending at 3.6 vpc. At 3.7 vpc the A123 can be damaged and life reduced. In long series strings it is easy to get one cell higher than 3.7 vpc if a non balancing charger (such as an SLA charger) has been used, so ruining the battery [I suspect this why service life is so short in electric bikes as some use end to end chargers].

For comparison, SLA chargers have a float voltage of 27.6 V on a 24 V battery, and end of discharge would normally be set just below 20 V for a 24 V battery.

Go with the A123 cells but make sure you have the correct charger. Eight cells will be a little higher voltage when just off the charger but there is probably enough head room in the controller. The end of discharge voltage will not need adjustment as 8 x 2.5 = 20V.

The A123 cells are rugged and do not catch fire (like Lipos) if punctured or mechanically damaged.

 

[fatts]

Thank you for that info I shall research when get chance, just became a Grand father today so away from home at present up Notts