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Old 08-01-2007, 19:02   #1
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Unhappy Valence batteries

Mods - I put this link here to be near the other discussions on electric propulsion rather than the battery forum.

Given all the enthusiasm here for these batteries they sounded like the answer for my situation even considering the slight increase in cost.
However looking at the spec sheets it shows max discharge rate of 30 amps regardless of the amp hour rating of the battery.
http://www.valence.com/pdffiles/U-Ch...DS%20Jan06.pdf
Another site gives a few more clues and reveals that they have a cell equalisation problem. it also shows a bank of cells with some electronics connected to each cell. Maybe this is to counter the equalisation problem?
Custom Battery Chargers, UPS, and power supplies for OEMs in a hurry from PowerStream Sorry can't give the direct link, you will have to look for the basic lith ion page then the 48 volt pack.
This would mean several bats in parralell to gain the required discharge rate.
I hope I have got it wrong
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Old 11-01-2007, 12:30   #2
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You might contact African Cats to talk to them about these issues, they use the Valence batteries on their boats and give a true performance electric catamaran. I also know that Valence has a battery monitoring system to prevent overcharging, which might be the electronics you saw. I believe they are rated for around 2000 cycles, which is more than any other battery. Bad thing is of course, price, price, price but an electric African cat is the same price as their diesel.
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Old 11-01-2007, 17:35   #3
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Schooner
The Valence batteries are an option with the African Cats.
Doing some more reading at the Powerstream link it seems the current limit issue is with the battery managment controls. The table of batteries shows this. They could probably supply a heavier unit but I haven't asked.The battery managment seems needed to manage the charge imbalance as the current drops near full charge so in series the full battery wil stop the charge to the others and must be bypassed. Why this affects the discharge rate is beyond me. If I started to consider them seriously there would need to be lots of discussions

In the setup I am researching, Elect/diesel comparison thread, I would need 48v @ 250 Ah or 12 kWh. This equates to 12 of the 20Ah/48v packs @ $1387 each = $16,644 and 153Kg. The 12 packs to get the discharge rate but this is actually cheaper than 5 of the 50 Ah packs $19,535. ChEEEEEEEP eh
Mike
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