Replacement of 10KW/H BB600 Wet Nickel-Cad system

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HCT's picture
Last seen: 6 months 1 week ago
Joined: Wednesday, February 7, 2007 - 08:16
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Replacement of 10KW/H BB600 Wet Nickel-Cad system

Received a inquiry to replace a wet NiCad system consisting of 60 BB600 cell assembled into a 72 volts and 35 A/H with a newer and greener chemistries capable of carrying 10 KW/H for at least 10 minutes or more .

Do not know much about the BB600 beside they are wet NiCad and original designed for the
military , have not been able to get specification as far impedance on those cells.

Is any one familar with them and used them ?and also measured their impedance when fully charged ?.

This back up system priority list is as follow

Peak power capability 15 KWH peak surge for a maximun of 10 seconds
and capable of carrying 10KWH for at least 10 minutes
High Reliability
Size & weight
Recharge time 6 hours max ,
1000 Min cycles at 75% DOD .

Debating whether to go with Nickel-Zinc or LifePO4, somewhat concerned since both chemistries required sophisticated BMS, to meet the cycle life.

Would appreciate any suggestions .

Last seen: 6 months 3 days ago
Joined: Saturday, July 7, 2007 - 23:55
Points: 1686
Re: Replacement of 10KW/H BB600 Wet Nickel-Cad system

i might be able to help, but i need more information.

how much voltage sag can the system accept for both the 15kw and 10kw draws?
whats the application? (aside from back up) battery size and weight is rarely a constraint in stationary UPS systems.
whats the max voltage the system can see from the batteries?
whats the budget?
all chemistries can do a 6 hours recharge time.
im guessing from the long cycle life requirement, the application is relatively inaccessable?

Thundersky LiFePO4 can be had for about $2US/AH from everspring, less if your order in quantity (but if you were to order in quantity, the direct from thndersky prices are much much better)
The voltage sags by 0.2vpc per C of load.
so if your minimum voltage is 60v, with 24cells you can draw a max of 2.5C. so you need a minimum of 100AH to give you your 15kw. the closest size of the thunderskys is 160AH (90AH would be slighlty too small, unless you can accept a greater voltage drop).
the 160AH pack would give you 10kw continuous for more than 30mins.

Another option would be to see if you can get a set of the original batteries. that way you know itll just work.


Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km

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