Battery pack - lead to lithium
Posted: Thu Feb 02, 2012 10:23 am
I am working with a friend's EV. It is a warehouse type road legal truck running a 48V pack consisting of eight 175Ah 6V lead batteries.
The current range is 3-4 miles at 15mph stop start use after an over night charge followed by another 3-4 miles after a 2 hour lunchtime charge. The pack is sometimes so low that the truck needs pushing back to base part way through the range.
I took some voltage readings one day to see what was happening.
The readings were taken (A) prior to setting out in the morning with an 8 hour charge, (B) on return after 3.8 miles, (C) after a 2 hour lunchtime charge, (D) on return after 3.8 miles at the end of the day.
A-----B-----C-----D
6.6v 6.2v 6.6v 6.3v *
6.8v 6.5v 6.7v 6.4v
6.7v 5.6v 6.7v 5.7v
6.6v 5.7v 6.6v 6.3v
6.7v 6.4v 6.7v 6.5v *
6.7v 5.6v 6.7v 6.4v
6.6v 6.3v 6.7v 6.2v *
6.7v 6.5v 6.8v 6.4v
* Batteries replaced last August 2011. Rest of the pack new in Jan 2011
The thought is to either replace the whole pack with lead or with lithium.
In theory the 175Ah lead could be replaced with 110Ah of lithium for the same usable capacity. However, given the lead pack is used down to empty would that mean that a much bigger lithium pack is needed? Thoughts please?
Are there any UK lithium stockists where I can get an estmate of cost for the pack?
I guess I would also need to add BMS and charger to the cost too?
Cheers.
The current range is 3-4 miles at 15mph stop start use after an over night charge followed by another 3-4 miles after a 2 hour lunchtime charge. The pack is sometimes so low that the truck needs pushing back to base part way through the range.
I took some voltage readings one day to see what was happening.
The readings were taken (A) prior to setting out in the morning with an 8 hour charge, (B) on return after 3.8 miles, (C) after a 2 hour lunchtime charge, (D) on return after 3.8 miles at the end of the day.
A-----B-----C-----D
6.6v 6.2v 6.6v 6.3v *
6.8v 6.5v 6.7v 6.4v
6.7v 5.6v 6.7v 5.7v
6.6v 5.7v 6.6v 6.3v
6.7v 6.4v 6.7v 6.5v *
6.7v 5.6v 6.7v 6.4v
6.6v 6.3v 6.7v 6.2v *
6.7v 6.5v 6.8v 6.4v
* Batteries replaced last August 2011. Rest of the pack new in Jan 2011
The thought is to either replace the whole pack with lead or with lithium.
In theory the 175Ah lead could be replaced with 110Ah of lithium for the same usable capacity. However, given the lead pack is used down to empty would that mean that a much bigger lithium pack is needed? Thoughts please?
Are there any UK lithium stockists where I can get an estmate of cost for the pack?
I guess I would also need to add BMS and charger to the cost too?
Cheers.