LiFePO4 Batteries - Okay Tear Me Apart ;-)

[S&S]

Originally Posted by jallum

Fair enough. Which size/type did you pick up? Where did you source them from?

700Ah Thundersky's from the guy in California.

Of course. That's why the Genasun product has you route the alternator's field wire through the controller board... attenuating or shutting off the field before or at the same time that it throws the contactor to break the charging circuit. That's a big difference between their's and Elithion's BMS offering, it seems.

That's why I went with Genasun. Even so, if you're running a very large alternator (how'd you like to 500A Niehoff on the other thread? ) You still need to ramp down excitation as you'll get a voltage spike if you just "pull the plug" and allow the field to collapse. Putting a large capacitor in line allows the field to decay slowly while the relay is open.

[jallum]

Originally Posted by S&S

700Ah Thundersky's from the guy in California.

700Ah each? Nice. Did you put them together for 12v or 24v?

That's why I went with Genasun. Even so, if you're running a very large alternator (how'd you like to 500A Niehoff on the other thread? ) You still need to ramp down excitation as you'll get a voltage spike if you just "pull the plug" and allow the field to collapse. Putting a large capacitor in line allows the field to decay slowly while the relay is open.

(That Niehoff is no joke... and is exactly the kind of thing I'm looking into. I want a massive bank to extend periods between generator runs, and a high-amp DC generator setup to keep those runs short.)

So, I take it you're generally happy with their BMS? Do you have anything monitoring it's serial ports, or do you just let it do it's own thing? Did you find it to be a pain in the ass to set up or configure? Any regrets?

[S&S]

Originally Posted by jallum

700Ah each? Nice. Did you put them together for 12v or 24v?

12V. 2 series banks of 4 cells each.

(That Niehoff is no joke... and is exactly the kind of thing I'm looking into. I want a massive bank to extend periods between generator runs, and a high-amp DC generator setup to keep those runs short.)

For REALLY high outputs, there really is no substitute. Mil-Spec and emergency vehicle is most of their business- and those really can't fail. I especially liked the no oil cooling and no slip rings.

So, I take it you're generally happy with their BMS? Do you have anything monitoring it's serial ports, or do you just let it do it's own thing? Did you find it to be a pain in the ass to set up or configure? Any regrets?

Putting it together as we speak but I don't expect much configuration problems.(insert fingers crossed smiley here). At some point you just have to make the call and go with it.
I'm going all analog with the controls- I'm not planning to mess with it after set up if I don't have to. Stay tuned- I'll report in as the install progresses. I'm doing a simultaneous repower so I may run out of cash before it's all in for this season.

[ardoin]

S&S: are you replacing both banks or just the house bank?
Also what are you using to regulate the Alt?

[S&S]

Originally Posted by ardoin

S&S: are you replacing both banks or just the house bank?
Also what are you using to regulate the Alt?

That's the house. Start is a small bank of lead acid AGM's on a seperate alternator. I'll be able to connect the house bank to the starter manually if the need arises.

The stock regulator can be set to 15.5V (3.875V/cell) which is just below "full" (4.0V/cell), so that's set. I'm having a controller made to handle alternator temperature and provide a 200ms slow decay "soft" stop and time delay for restart based on a "cell unbalanced" signal from the BMS. The BMS will toggle as the cells rebound when the charge current is interrupted and I don't want the alt. field clicking on and off. I have quotes out to 2 engineering shops for that part. The controller is in series with the field wire from the regulator.

[OceanPlanet]

Originally Posted by S&S

That's the house. Start is a small bank of lead acid AGM's on a seperate alternator. I'll be able to connect the house bank to the starter manually if the need arises.

The stock regulator can be set to 15.5V (3.875V/cell) which is just below "full" (4.0V/cell), so that's set. I'm having a controller made to handle alternator temperature and provide a 200ms slow decay "soft" stop and time delay for restart based on a "cell unbalanced" signal from the BMS. The BMS will toggle as the cells rebound when the charge current is interrupted and I don't want the alt. field clicking on and off. I have quotes out to 2 engineering shops for that part. The controller is in series with the field wire from the regulator.

Nice...that controller sounds like a good thing. Would love to know when you get that (those?) going; I'm sure that both Genasun and RaceCell would like to know about it.

B

[fastcat435]

interesting new on further development of lithium batteries

Green Car Congress: Stanford Researchers Demonstrate a New Nanostructured Lithium Sulfide/Silicon Rechargeable Battery System with High Specific Energy

[ctsbillc]

It will take a while for this new technology to come online. Meanwhile, the prices of the large phosphate cells has become very appealing. Twice the price is very do-able, and the weight savings are huge.

Are these betteries from Mastervolt and others lots of parallel smaller cells?

[Mule]

West Fl Battery, on US 19 in Port Richie (I think in port Richie, might be Hudson, the little towns run together) T105's $89. each. That sure changes the math.

[OceanPlanet]

Originally Posted by ctsbillc

It will take a while for this new technology to come online. Meanwhile, the prices of the large phosphate cells has become very appealing. Twice the price is very do-able, and the weight savings are huge.

Are these betteries from Mastervolt and others lots of parallel smaller cells?

The Mastervolt, Genasun, RaceCell, etc. are 4 cells in series for 12V, or 8 in series for 24V. The "nominal" charged voltage per cell is usually considered 3.2V or 12.8V for a typical 12V pack. The individual cells are actually 3.6V to 4.2V at max charged voltage (depending on the manufacturer), so actual max voltage of 4 in series is roughly from 14.2V to 16.8V.

For higher voltage systems (EV's or electric propulsion), there is the option to put many individual cells in series to get to the higher voltage, and then put the subsequent larger groups in parallel; or to put as many as possible in parallel first.

A small example of this in a 12V pack:
For a 300Ah x 12V pack, you could do either: 3 x 100Ah x 12V groups in parallel, each consisting of 4 x 100Ah 3.2V cells in series (which is the same as hooking up 3ea 100Ah regular lead/gel/agm batteries in parallel). Or, you could do FOUR groups in SERIES, each consisting of THREE cells in PARALLEL....the net result is the same. Either way you get 300Ah x 12V

[DaveOnCudjoe]

I'm at the other end of the market from most, I have low requirements(40ah/day) and charge with solar(100watt). My interest is mainly in weight savings and cost is not the predominate factor. I was very disappointed at the boat show">Miami Boat Show to find only 1 marketer and they were not marketing to me. I'm so glad to see this thread and it has given me more info than in all my searching to date. Lead/acid will be the predomonate force for years to come but Li ion technologies have their place for those who will pioneer the applications. My trimaran is very weight sensitive so if I can save 50lbs that's 6 ga of water or a bunch of food or another sail or a bigger anchor- I can go on and on. Thanks all! Dave

[ctsbillc]

These really are very large cells. That's good, because reliability is better with fewer parts. It's always a bit painful to be leading edge. Warranty may be the thing that make it bearable. Toyota give a great warranty on the batteries and controller for there NiMH hybrids. Mind you, the brake failures and accellerator issues will probably destroy the vehicle before the batteries have a chance to fail - its all strategy.

Bill

[ctsbillc]

Meanwhile, interesting things are happening with solar cell technology Caltech gurus whip up highly efficient, low cost flexible solar cell -- Engadget

Future looks great. Hope I live long enough to enjoy it.

Bill

[S&S]

Originally Posted by OceanPlanet

Nice...that controller sounds like a good thing. Would love to know when you get that (those?) going; I'm sure that both Genasun and RaceCell would like to know about it.

B

I'll keep you all updated. I'm just surprised that the problem hasn't come up.

[ctsbillc]

Another innovation, and one with a ship date Panasonic's silicon-packin' batteries boast 30 percent capacity boost, hit stores in 2012 -- Engadget

Bill