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Old 04-09-2013, 03:49 PM   #81
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Bob I will say you guys have piqued my interest with this thread. I own a GEM2 NEV that I use for commuting around town at 25MPH and it is a kick to drive. My LA batteries are at the end of their life cycle and was considering upgrading to AGM before reading this thread.

Now you guys have me thinking it's time to research the new lithium battery options for my 72 volt 5 HP application. I cycle my batteries 5 times per week in this application plus weekend trips with the wife to the grocery store. It is nice driving past the gas stations. Thanks for the thought provoking thread.
LFP is a good match for this and "almost" but quite a drop in. Probably 23 or 24 100Ah cells.

1) work out the mechanics of installation and security.
2) bottom balance, that means prior to install fully discharge every cell to 2.5-2.6V.
3) charge until the highest cell reaches about 3.45V, no more than 3.5V
4) make sure all connections are clean and secure

The bottom balancing will eliminate the need for a BMS. When one cell reaches end of charge they all will. You stop, but won't drive any cells below the point of no return. Mote this is for EV, not a House bank on a boat.

After the first couple of charges, the highest cell will remain the same, probably for a long time, but you should double check this every 3-6 months after the installation.

The biggest challenge will be finding a way to end the charge with the highest cell at 3.45 to 3.5V. If your 72V charger is well regulated and adjustable, you can terminate upon reaching the right voltage. It might require adding or deleting a cell to get it right. Or use a Junsi Cellog on the highest 6 cells with the alarm output rigged to disconnect the charger with a latching relay.

See:

http://www.jun-si.com/EnProductShow.asp?ID=96

Good luck! You should end up with snappier performance too. Bob
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Old 04-09-2013, 06:23 PM   #82
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All the above is correct. What ever rating in a-hr of the LA's you will probably have the same range with 1/2 that rating due to how different they are rated. Plus acceleration will be better due to shedding 270 lbs. A lot of folks say you need a BMS, I'm not one and agree with Ebaugh on a bottom to top balance of the cells, then your good to go. For me this was a slow process, first I discharged my pack in series to the knee, then rewired all the cells in parallel for the balance charge from my variable power supply. I was charging at an average of 4 amps @ 3.9 volts, so each pack took close to 100 hours to charge in parallel. If you decide to go with (24) of the 60 a-hr cells, that same bottom to top balancing at the charge rate I used (4 amps) will take 15 days of charging. But after I balanced, I don't need a BMS, and that is worth it to me.

Because I didn't want to un-band my cells I just made up jumpers for the parallel balance charging.


The top charger was built for fast charging 12 volt LiFePO4 batteries, weighs only 8 lbs and puts out 50 amps. The bottom is my lab power supply that I used for the parallel charging.
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Old 04-09-2013, 06:32 PM   #83
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I mean the following question in the most polite and sincere way.

Is there a link to a website you guys can provide that provides a LI tutorial for dummies like me?

I almost understand about every third term you guys use
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Old 04-09-2013, 06:38 PM   #84
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Craig,

Just ask, that would be much quicker than the 2600+ posts on the Cruiser's Forum dealing with using LiFePO4 cells as a house bank.
LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks - Cruisers & Sailing Forums
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Old 04-09-2013, 06:44 PM   #85
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Thanks Bob. I'll post some questions after doing some more research on my requirements.

In the meantime are there any California suppliers for the batteries and chargers?
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Old 04-09-2013, 06:49 PM   #86
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My source has been Balqon in Harbor City, California. Be sure to check their clearance sales on older stock, these prices are better than any other source.
Balqon - Advanced Transportation Solution
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Old 04-09-2013, 07:35 PM   #87
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Thanks Bob. I'll post some questions after doing some more research on my requirements.

In the meantime are there any California suppliers for the batteries and chargers?
I need to retract one of my previous suggestions, using the CellLog in the previous post. They work for a marine house bank, but used as I originally suggested will load the cells unevenly in your 72V application. To shut off the charger, you are going to have to use bank voltage, or monitor every cell, not just the high ones. My mistake...sorry.

The cells are available from Balqon and perhaps Calib Power USA in SOCAL. There is a EV dealer in the Bay Area NORCAL, Thunderstruck Motors and also I think that is where Alliance Renewable Energy is located. In Phoenix there is Elite Power Solutions, and in Flagstaff with another location somewhere in California is Electric Blue Motors. An Internet search will find websites for all mentioned, or I can post one if needed.

Make sure you know your supplier before you send them money, it is not uncommon for them to want cash or a wire transfer for payment. It's one of the Achilles heels of LFP at the moment. I have done business only with Electric Blue Motors, who is a distributer for Elite Power and was very satisfied. I was in Grenada at the time and had them ship 48 cells to me....

If you need a new charger, these dealers may be able to help. But EV chargers are pricy, and there may be some simpler alternatives for a small 72V pack. I will think about it, but you could also join and post a question on the DIY Electric Car forum. There are more knowledgeable guys over there that might be able to offer a suggestion.

If price were no object, I'd use CALB FI series cells. You should be able to get them from Calib Power or via the Internet from EVTV Motor Verks. If Balqon has what you need in stock, they will probably be the least expensive.
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Old 04-09-2013, 07:44 PM   #88
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I mean the following question in the most polite and sincere way.

Is there a link to a website you guys can provide that provides a LI tutorial for dummies like me?

I almost understand about every third term you guys use
Larry posted the link in another thread, but I have a write up on how to use Lithium Phosphate in marine house bank applications. If you look at our blog site at:

http://marazuladventures.wordpress.com/

On the right side of the home page ind Bobs Articles is a link that takes you to short blog post with a link to a 12 page or so PDF file article I wrote that covers my installation and things that need to be considered from a marine perspective.

There is also great information on EVTV.ME and the DIY Electric Car Forum, but nothing exactly like a single overview Im aware of.
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Old 04-10-2013, 10:13 AM   #89
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Pro BMS

Here are my thoughts regarding using LI as your house bank (essentially that is what we are doing).

I like the idea of a BMS - it gives you information on all the cells. The main way to protect your investment is to keep the individual cells within spec this means running them down too low and/or over charging - EACH CELL.

The BMS we installed (custom engineered from Balqon) has a remote display at the helm. It not only shows the pack voltage (total battery, in our case 48 v nominal), but high cell voltage, low cell voltage, charge/discharge rate in amps, cell temp, total amp hours available (and as a percentage), and BMS temp.

Additional pages on the BMS allow for manually connecting/disconnecting the battery from the bus - connecting/disconnecting charging devices - connecting/disconnecting load devices. It also "specks" via CanBus to the Elcon 3kW charger.

But most importantly, it will disconnect charging devices should ANY cell approach its upper limit (in our case 3.8v) AND disconnect the battery from the bus should any cell reach 3.9v - after this, the cell starts to damage itself. It works in a similar manner on the discharge side, with disconnecting loads .1 v before disconnecting the battery itself. This is the only way the battery can keep from damage unattended.

One big surprise to me (not, I'm sure to the EEs out there), was upon connecting the battery to the bus, we kept welding contactors closed, thus preventing the battery from disconnecting from the bus. Turns out the capacitors in the inverters were causing a voltage surge. A simple resistor wired between the contactors and a delay relay to close the on/off solenoid (after the capacitors were charged) solved the issue.

And, on a boat, you are most likely going to have an inverter. And will want some sort of safety mechanism to disconnect the battery. Reading total voltage of the pack will not do the job by itself - all it takes is one cell at 3.0v to keep the reading of a 12v battery at 13.4v even though one cell could be 4.0v while the other two are at 3.2v each. This is not your grandfather's LA battery!
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Old 04-10-2013, 10:55 AM   #90
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BMS would equal Battery Management System?
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Old 04-10-2013, 11:28 AM   #91
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BMS would equal Battery Management System?
Yes
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Old 04-10-2013, 11:32 AM   #92
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Yes
Thanks Bob
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Old 04-10-2013, 06:55 PM   #93
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Here are my thoughts regarding using LI as your house bank (essentially that is what we are doing).

I like the idea of a BMS - it gives you information on all the cells. The main way to protect your investment is to keep the individual cells within spec this means running them down too low and/or over charging - EACH CELL.

The BMS we installed (custom engineered from Balqon) has a remote display at the helm. It not only shows the pack voltage (total battery, in our case 48 v nominal), but high cell voltage, low cell voltage, charge/discharge rate in amps, cell temp, total amp hours available (and as a percentage), and BMS temp.

Additional pages on the BMS allow for manually connecting/disconnecting the battery from the bus - connecting/disconnecting charging devices - connecting/disconnecting load devices. It also "specks" via CanBus to the Elcon 3kW charger.

But most importantly, it will disconnect charging devices should ANY cell approach its upper limit (in our case 3.8v) AND disconnect the battery from the bus should any cell reach 3.9v - after this, the cell starts to damage itself. It works in a similarly manner on the discharge side, with disconnecting loads .1 v before disconnecting the battery itself. This is the only way the battery can keep from damage unattended.

One big surprise to me (not, I'm sure to the EEs out there), was upon connecting the battery to the bus, we kept welding contactors closed, thus preventing the battery from disconnecting from the bus. Turns out the capacitors in the inverters were causing a voltage surge. A simple resistor wired between the contactors and a delay relay to close the on/off solenoid (after the capacitors were charged) solved the issue.

And, on a boat, you are most likely going to have an inverter. And will want some sort of safety mechanism to disconnect the battery. Reading total voltage of the pack will not do the job by itself - all it takes is one cell at 3.0v to keep the reading of a 12v battery at 13.4v even though one cell could be 4.0v while the other two are at 3.2v each. This is not your grandfather's LA battery!
That looks like a nice BMS. I wish they would publish the full specs and pricing online.

All the functions sound spot on, however in my opinion 3.8V per cell is too high a value in general, especially if anything other than the Elcon contributes to the charge. And only then if you are charging near the 1C rate, for example, 200A on a 200Ah bank. At the .5C rates, 100A on a 200Ah bank, or less, then 3.6V per cell will get you 100% SOC. Our house bank rates are normally even lower, mine is 150-200A into a 1200Ah bank, under .2C. At 3.5V, My bank is essentially 100% charged and I limit fast charge to that or less. If my electronics allowed it, which it will eventually, I'd stop charging at 3.45V.

But the biggest issue is "floating". I don't know the exact number, and it might even vary a little from one brand to another, but I've seen maximum safe float values quoted from 3.35 to 3.45V. My personal favorite is 3.38. Any higher voltage maintained long enough will significantly overcharge a LiFePO4 cell, causing reduced life. My own tests have demonstrated that 24 hours at sea, with the cell voltage regulated at 3.35V is greater than 95% SOC. I know this by observing 3.35V underway, then right after dropping the hook, charging to 3.6V in 20 minutes at around 150A. The 3.6V here was a test, but it was about 2.5 minutes from 3.5 to 3.6V. We started the trip at about 3.3V.

I can't do it on my BMS, it just pulls the plug at a non adjustable 3.6V, both charge and discharge paths at the moment. But eventually I will have an alarm set for 3.46 or 3.47V, just above the value I plan to never exceed, with the disconnect set a little higher, somewhere near 3.5V. I may separate the charge discharge paths, but it's hard to do with inverter chargers.

The point is Balqon, and the rest of the EV guys are focused on charging and then stopping charge. That's not what happens on a boat. We have alternators underway, solar chargers, shore power "float" chargers etc that don't ever really shut off. And these guys, in my opinion don't have this well thought out.

The problem you mentioned with cell balance is possible and I agree individual cells need monitoring in a marine installation. At the same time, this is not turning out to be a routine issue with healthy cells. I'm probably getting close to 200 cycles since my final installation balance, and the cells are not showing any tendency to drift apart. This is consistent with many other installations Ive followed. So while monitoring is suggested, the automated "balance" function of some BMS systems is not essential. Properly implemented for marine, I see it as an aid to installation and a periodic maintenance function, which can be accomplished manually.

Ive observed the capacitor surge you describe, but no welded contacts yet. Can you be more specific on the fix for this? Are the resistors always in the circuit? Or only on a new momentary relay that is released after the main solenoid closes?

Thanks, Bob
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Old 04-11-2013, 01:10 AM   #94
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I used to work for the oil industry, and believe me they are not nice people.
Apparently, I am not nice people.

Should I tell my wife?
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Old 04-11-2013, 01:06 PM   #95
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For the "soft" start:

1. 100w/10ohm resister.
2. Wire the resister from the battery side of the solenoid to a relay and then to the bus side of the solenoid.
3. When the BMS key switch is turned on, 12v closes the relay allowing 48v from the battery to the bus through the resister.
4. Install a time-delay relay that starts timing when the remote BMS key switch is closed (turned on). When this relay closes (about 5 seconds after the initial relay), it actuates the solenoid which then closes allowing full current from the battery to the bus.
5. Since I have yet to build in a delay for the DC/DC converters, the resister gets warm but not unduly hot. It stays in the circuit as long as the key switch is on (all the time unless working on the battery or circuits), but the current is flowing directly through the solenoid at this time, not the auxiliary resister circuit.

This "soft" start is working well.
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Old 04-11-2013, 01:37 PM   #96
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Reuben,

Do you have any future plans for extended cruising? I have played with the numbers on Sunshine, and other than its current weight I would think extended cruising of the Caribbean would be possible on minimal fuel burn. Tell me if I'm way off base, but since you were able to get 52 KW-hr into the forward end of one hull, and you were using both hulls for the Odyssey LA, any chance of fitting a 2nd 52 KW-hr bank in the other hull? Going by the published boat review tests, at a stately speed of 4 kts (don't laugh, I've averaged less on a 24 hour run in my sailboat), you could cover nearly 100 nm in a day staying within a 80% DOD. Then your choice would be 3~4 days on the hook before another 100 nm passage or pull into a marina and feel like you get your money's worth from your slip fee when you suck down 85 KW-hr.
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Old 04-11-2013, 09:02 PM   #97
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For the "soft" start:

1. 100w/10ohm resister.
2. Wire the resister from the battery side of the solenoid to a relay and then to the bus side of the solenoid.
3. When the BMS key switch is turned on, 12v closes the relay allowing 48v from the battery to the bus through the resister.
4. Install a time-delay relay that starts timing when the remote BMS key switch is closed (turned on). When this relay closes (about 5 seconds after the initial relay), it actuates the solenoid which then closes allowing full current from the battery to the bus.
5. Since I have yet to build in a delay for the DC/DC converters, the resister gets warm but not unduly hot. It stays in the circuit as long as the key switch is on (all the time unless working on the battery or circuits), but the current is flowing directly through the solenoid at this time, not the auxiliary resister circuit.

This "soft" start is working well.
Thanks, I see how it works!
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Old 04-12-2013, 06:32 AM   #98
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FYI: It's "resistor", not "resister".
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Old 04-12-2013, 08:38 AM   #99
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Bob,

I love your thinking - use up as much energy and then glom onto the grid for a refill!

We actually fit the LI battery on centerline under the master berth. And, since the new battery has essentially the same weight as the original AGMs, we have no more reserve buoyancy forward for another battery.

Of course, the other option is to get rid of the Steyrs entirely and replace with steerable, 10kW pods that weigh almost nothing when you take into account the amount of water they displace. That would free up enough buoyancy aft for another battery and perhaps a small 48v DC genset.

Most of my current thinking for a marketable product uses this approach - steerable pod, LI battery, PV array with wind and generator optional - and parallel hybrid another option. Using only electric propulsion is by far the most simple solution.

Ron: Thanks for the spell check!
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Old 04-12-2013, 12:14 PM   #100
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Well Reuben, here's to you having a product for all the upcoming baby boomers that want to cruise but don't want to learn to sail. From my social interfacing I think it might be a rather large group. When I'm introduced at a gathering, they always throw in what I do, so the conversation is steered to long ocean passages, then it settles down to "I'd love to island hop through the Caribbean".

I'll be the first to admit that I'm a big dreamer, but I believe a boat can offer both, the ability to island hop on stored electrons (your there now) and pull off an ocean passage without the sails and rigging. Have you followed propulsion kites, deployed from the bow? Between a light weight Chris White designed hull like a scaled up Buzzard's Bay 34, hybrid pod propulsion, and the kite sail KiteShip - Innovation in Tethered Flight a lot of re-gen under sail, along with large solar and LiFePO4 energy storage, I believe that a world cruiser is just around the corner.

I've done the sailboat cruising.

I've crossed many oceans in ships.

Now I want to continue on, but with an almost zero carbon footprint. Reuben, will you help me and other baby boomers realize our dream?


For folks that aren't familiar with Chris White's designs, most are sailboats, cats and tri's, but he did a design for the power boat market, that takes the hull efficiency of a PDQ 34 to a whole new level, and no pounding in large seas. As you probably know the PDQ 34 can top out at close to 20 kt with twin 100 hp, and at slower speeds be fuel efficient. The Chris White designed Buzzard's Bay 34 with its knife edge hulls slicing through the water will do 35 kt on about the same power and can also be fitted for outboards, with the larger offerings taking his hull to almost 40 kt.
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