Mr. Mik wrote:I have had an unexpected result: A repeated capacity test after 5 recharge / discharge cycles shows reduced capacity of all sticks in the NHW10 BlueCar HP1 sticks!
What I expected was a capacity increase with a few more cycles, but in fact the capacities of all sticks are reduced by about 5%.
Why is this the case?
Two possible explanations come to mind:
grindz145 wrote:In you're experience are these packs easy to find at junkyards etc? I am assuming they air fairly cheap. I am quite interested in getting some of the commutation inverters and possible even an electric motor out of one... Very nice work!
peterperkins wrote:Interesting thread.
Identical cells are also used in the Honda IMA based vehicles Insight/Civic etc. They also suffer from imbalance issues over time mainly as a result of self discharge variations. Heat in the centre of packs also causes IR and self discharge variations between subpacks (a stick of six cells) The honda cars have no balancing or cycling capability so the imbalance fault is inevitable in the end.
The insight forum have a few members now who have considerable experience with repairing these packs. I repair them in the UK for Insight owners. The subpacks respond well to aggresive cycling on the bench with a decent charger such as the Overloader or similar. It can take upto 10 cycles to restore capacity with apparently poor subpacks. http://www.insightcentral.net
In order to repair packs here in the UK I dissasemble the batteries and cycle/exercise all the sticks noting capacity under charge and discharge until it recovers to an acceptable level. Critical is the self discharge rate which can be determined by leaving the sticks for a week and then discharging them to the cutoff point and working out lost capacity. Then I select/match the closest 20 sticks from my stock and reassemble them into a pack.
The temp sensor strip is a PTC resistor sensor and changes resistance rapidly as temp gets upto 70-90C. The cutoff PTC cell overheat alarm point in the Insight is an amazing 90C. The Insight battery fan which is controlled by four other sensors does not operate until the battery reaches 55C. This is too high IMO and leads to excessive heat in the batteries.
The completed packs respond well to CC low current charging and we use 250-350ma at 170V to charge a 144V nominal pack.
The sticks used in the Insight can deliver 100A or accept 50A regen.
Mr. Mik wrote:Do you know if they are 6.5Ah or 6Ah cells?
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