T-Pain Is On A Boat: [Electric Boats] Care and feeding of LiFePo batteries?

Wednesday, August 28, 2013

[Electric Boats] Care and feeding of LiFePo batteries?

I was concerned to see the statement:

"Also they were trickle charged at all times, another no no".

Does that apply to LiFePo batteries?

Can anyone provide a summary of what the do's and don'ts are for these batteries?

This is probably asking wayyyy too much, but wouldn't it be neat if we could make a matrix of FLA, AGM, LiFePo, and show the various properties of each in a side by side arrangement?

I'd really like to see this for a 12V battery:

Property FLA AGM LiFePo

"dead" voltage 9V 9V 14V

"max" charge v 14V 14V 16V

Trickle ch maintain? Yes Yes no(?)

Average cycle life 200? 300? 1200?

Average cost (100Ah) $80 $180 $500+(?)

Maint high - water/acid none none

BMS no no strongly recommended

recovery when dead? yes yes no

Any other traits we can add to this, or other things to be aware of??

Note: by "recovery" - I heard that a Li battery is very good for holding it's voltage until it's dead. But once it's dead - it's DEAD. You can't wait for a few minutes and use it again lightly on the "recovery" like you can for FLA's.

John

From: Steve Dolan <sdolan@scannersllc.com>
To: "electricboats@yahoogroups.com" <electricboats@yahoogroups.com>
Sent: Wednesday, August 28, 2013 7:10 AM
Subject: RE: [Electric Boats] Re: AGM Batteries?

Boeing's Dreamliner was an "international" plane built by contractors all over the world from many countries. As with anything like this it was a coordination nightmare. My understanding of this "event" was the problem was in the BMS system program not the batteries them selves. The system was spec'd to be at 100% charged at all times, something that has been determined to be on the ragged edge of theses batteries, you never want to overcharge them and this is what happened. They simply where over charged causing them to overheat. Also they where trickle charged at all times, another no no. I believe there were some issues with the BMS circuit boards as well on the bats. As for the chemistry, all it takes is someone to push hard from a major supplier from a country that planed to buy the Dreamliner who had an interest in sales first to talk someone into their product.

Steve in Solomons MD

But sport planes don't carry hundreds of passengers. If the amount of weight difference between LiFePO and LiCo is that critical, I am sure that it could be made up by creating carbon fiber drink carts instead of aluminum ones ;-) or reducing the baggage allowance per passenger accordingly.

The Dreamliner packs a total of about 5kwh of lithium batteries. Eric's 8kwh pack weighs 200lbs. So how much weight has been saved by using LiCo?

Using your own 25% lighter than LiFePO figure, that would amount to a whopping 50lbs. The maximum take-off weight of the Dreamliner is about 500,000lbs. So we're talking a 1% of 1% weight savings by using LiCo. Bravo Boeing.