T-Pain Is On A Boat: Re: [Electric Boats] Going LiFePo4

Thursday, February 12, 2015

Re: [Electric Boats] Going LiFePo4

Little typo there.

You *list* your charge sources...

On Feb 13, 2015, at 00:39, Jason Taylor jt.yahoo@jtaylor.ca [electricboats] <electricboats@yahoogroups.com> wrote:

You will want to avoid cutting the DC side of the charger with a contactor. Instead, put a relay on the AC side. The difference is arcing. The AC current passes through 0V 120 times a second and therefore won't make much of an arc, whereas the DC side will be up around 175v permanently which will arc and damage the contact surfaces.

The BMS will have a pack-full pin which could then be used to disable all charge sources.
This could be done by taking the BMS output and having it activate multiple normally closed relays that would interrupt all charge sources.

You lost your charge sources as the Brusa shore power charger, the (rectified) AC genset and regen.
The genset should have a start/stop control. This needs to be interfaced with the BMS pin. If not, put a relay on the AC output of the genset, before the rectifier.

My Elcon charger has a charge-enable pin which I connect directly to my BMS pin. Your Brusa may have something similar. I not, interrupt the AC side for the above-mentioned arcing reasons.

Maybe contact Bill Sputhworth at Elecyr. They specialize in 380VDC microgrids but they also have a marine hybrid propulsion section on their website. They have a pretty interesting BMS under development (wasn't ready when I was shopping for one last year) that may integrate nicely with your genset and charger.

At any rate, they key for your new system
Will be the BMS. Thank to those vendors about your situation and they should be more than happy to provide integration to your situation.

Cheers,

/Jason

On Feb 12, 2015, at 10:32, Steve Dolan sdolan@scannersllc.com [electricboats] <electricboats@yahoogroups.com> wrote:

I'm going to be switching from an AGM battery pack to LiFePo4s in the very near future and hope I can get some direction from the group. But first some background. My system was designed and built by Solomons Technology back in 2004. Solomons is now out of business, more so for being ahead of the curve than not having a great system. Back then LiFePo4's were not an option so I have to deal with modifying the current system to handle the new technology. This will be to understand how the lithium's will interact with a generator and Regen through the props with the new pack. So for starters here is what I have.
The Boat:
Lagoon 410 (41')
10 tons
The Motors:
Westinghouse (Homewood Group)
144V DC 9kw (twin 4.5kw motors on 1 shaft per side)
Max current draw-64A
Controllers:
Advanced Motor Controller (4)
3 phase (PWM) brushless
Max 250VDC
Existing battery pack:
Northstar NSB-M12-210
12V / 210 AH x 12 running in series at 144V0
These batteries were installed in 2007 with a 2 replaced over the last 5 years.
Propulsion Bank Charger:
Brusa NLG 511 at 240V input
Note: this charger is programmable for LiPo's and has 3 temp sensors.
GENSET:
HFL (German) with a Kabota motor 16KW output
Note: Genst is A/C with a rectifier to DC. Output is variable at the helm through a rheostat.
BMS:
HDM Systems Battery Equalizer (PowerCheq) http://www.hdm-sys.com/products/equalizer.php (Since someone was asking about)
PakTrakr battery monitoring
General system operation:
Shore charging is performed through the Brusa to the Propulsion bank. House bank charging is then performed through a separate 144V to 12V charger.
Once under sail the props then go to Regen and recharge the batteries.
If on a long sail and no wind the genset is energized to charge the batteries and then output to the motors. This is manually controlled by watching the amp draw at the helm for the genset.
Typical usage has me running at a total of 60A @ 144V for 3 hours at 6/7 knots which is projected hull speed.

Other than 1 controller and a couple Northstar batteries this system has performed excellent over the last 10 years. I'm starting to see a degradation in Propulsion pack run time though and figure it's time to take the next step.

WHAT I WANT:
Replace the existing pack with a LiFePo4 pack consisting of 48 (probably) CALB CA180AH Cells. For a pack voltage in series of about 164V.
Note: with the AGM's I bulk charge to 174 volts and tapper off to 164 volts during trickle charge. Once off charger the voltage settles to around 158V.
No changes to the original equipment other than a monitoring system for the Lithium's. The existing PakTrkr and HDM system will not work with the new Bat's.

What I'm not sure of is how to control charging of the Lithium pack from the genset, regen , and charger. I'm planning on using contactors to disengage the charger but not sure of the wiring and haven't found a clear diagram. Since the regen and generator goes through a single point in the control box back to the batteries how would I shut charging off to the batteries once I reach full charge of 3.4 per cell (164V total)? My first thought is an alarm so it annunciates once 164V is reached from the genset. I'm not so much worried about regen since the charge is pretty low and would take a few days on that alone, if at all, since on a along cruise (The Islands) I would be using power all the time with the Nav system but even then I would like to have a warning that I was there (Fully Charged).

So what I need is a clear understanding how a Relay/Contactor system works and how to wire it. In addition I'll ask if anyone knows of a knowledgeable individual in the Maryland area who has worked on a system like this. I am going to contact Sally at Annapolis Hybrid Marine to see if they have any input. To be honest I spent a small fortune trying to find someone 5 years ago to explain some things to me and instead found out how little pro's in the area knew about EB's.

Thanks for any help with this.

Steve in Solomons MD
Lagoon 410 S2E