T-Pain Is On A Boat: Re: [Electric Boats] AGM vs. FLA batteries and their usage

Ned,

Thanks for this input! Now I just need another $1000 or so, and I'll be in business... :)

With a $500/$600 charger, it looks like the current output would be enough that I could run that off a small generator for backup, as it sounds like several are doing. Is that correct?

From: Ned Farinholt <nedfarinholt@comcast.net>
To: electricboats@yahoogroups.com
Sent: Monday, October 28, 2013 2:32 PM
Subject: Re: [Electric Boats] AGM vs. FLA batteries and their usage

Steve in Solomons:

Here is Thunderstruck's web: http://www.thunderstruck-ev.com/batteries-ev/lithium-ion-ev.html

I found them very helpful. They are in Calif and I am in Va and the shipping was much less than I expected. I worked with a fellow named Mark. I bought GBS cells. The CALBs were not available at the time. If I were to get more, I would go for the CALBs if for no other reason than the bolted terminals are easier than the four little screws.

Again, I have no commercial interest in any of this. Just want to see the applications move forward.

All the best,

Ned

On Oct 28, 2013, at 3:00 PM, Steve Dolan wrote:

Ned,
Any more info on these slightly used LiPo's?? A web address would be great.

Steve in Solomons MD

John,

I have not found that Li chargers are not "very expensive". For example, an Elcon 1500 w charger with about 1200 watts output is $530. Note that the lithium chargers usually charge the whole bank in series. Mine puts out 18 amps at 60 volts. A good smart LA charger might only cost half as much but puts out less than half the power. I have no commercial interest in any of this.

BTW, if you can be satisfied with slightly used lithium cells, you can get them for less than AGMs, based on useful energy storage. The bankrupt government sponsored solar companies are a source of this availability. Your tax dollars at work!

Ned

On Oct 28, 2013, at 2:29 PM, oak wrote:

Carter,

So the bottom line is that you have BIG batteries (golf cart type, with LOTS of AH), and seldom deeply discharge them.

I suspect my "deep cycle" FLAs would have lasted much longer if I had only used an amp or two for a little while, and then recharged.

But they're RATED at 90-120 reserve minutes - which I have read is a "20A load for 90 minutes". I'm not getting close to that, and certainly not on a regular basis. I won't go so far as to suggest that the battery manufacturers are *grossly* exaggerating their ratings, based on my log book entries, you wouldn't be impressed.

I really, really hope that AGMs do a much better job of supporting their reserve capacity rating!

I'm still saving up for at least one bank of Li batteries. But that will take a LOT more $$, and will take a much better charging system. I'm finding that the charging characteristics are different enough, that you need a very expensive charger to deal with Li batteries.

I'm also finding that inexpensive FLA chargers don't do a good job when the battery is deeply discharged. I'm currently playing with using an Arduino to monitor and control charging. The nice part is that once I have it set up for charging, you pretty much get a poor man's BMS for free.

John

From: Carter Quillen <twowheelinguy@yahoo.com>
To: "electricboats@yahoogroups.com" <electricboats@yahoogroups.com>
Sent: Monday, October 28, 2013 11:47 AM
Subject: Re: [Electric Boats] RE: Hello group

John,

Yes, I've heard bad things about "maintenance free" batteries for electric boat application. They just don't hold up to the deep cycling demands. FLA can give much better performance if you take care of them and don't run them way down too much however you do have to deal with the maintenance and safety issues they present.

I've got an eight pack of Trojan T-125s golf cart batteries and so far they are going strong. We worked them a little last winter with a 250 mile passage, mostly across the pan handle of Florida and they have been providing house power to a 3000W inverter now for almost a year. I really try hard not to discharge them excessively and when cruising match my solar input to my propulsion output as best I can. I have never let the bank drop below 48V and try to keep it above 49V but it is difficult to determine the exact state of charge when there is always some load on the system and I'm constantly passing 30-80 amps thru them from the solar array. I don't have a fancy monitoring system and simply rely on my mppt charge controller to see where the batteries are at.

I have not had to add water yet but I probably will soon and have been monitoring that closely. Since the Arc is more of a solar powered boat and less of a battery powered boat I'm not really working the batteries that hard. Typically the 4 kW main array will have the batteries charged by 10:30 in the morning and then the charge controller floats all day maintaining the house loads. When I am underway in partly cloudy weather I will usually run them down a bit, sometimes more than I should.

Our weather is warm here in Florida but the batteries are deep in the bilge so even in the hot summer I doubt they ever see much more than an 80 degree ambient.

Outgassing has been a big concern for me but the bilge and the boat are well ventilated and I've just been living danerously. So far I havn't blown myself up but I recently ordered a venting system from Germany , http://www.bfsgmbh.de/en/system.html, that should solve the problem and make the system much safer.

I am about to separate the house power from the propulsion and put it on some used AGMs from an old UPS system that someone gave me this summer. I have 8-12V batteries that I will make two 48V banks in parrallel with. My research tells me they are not really the right battery for the job and I don't think they will last that long but they were free so we'll see what they got. I still have a kiloWatt of solar on the stern array that I havn't hooked up for lack of charge control capacity so I will wire this thru the built-in 30 amp charge controller on the inverter. Eventually I plan to get another Flexmax 80 charge controller and separate the solar panels into port and starboard 2500W arrays feeding port and starboard T-125 battery banks for both propulsion and house power together but I just couldn't find the budget for the new charge controller and battery bank this year so using the AGMs will be a decent alternative to give me a little more capacity for now.

The free, used AGMs were only about a year old when the UPS was upgraded and they were surplused so they should be in good shape to start with and hopefully will last until I can configure the system the way I want to later. But for now we should be ready to go cruising in a few weeks and I hope to pass 1500 miles under the Arc's twin keels this winter as we try to circumnavigate Florida on nothing but sunshine and hope to end up in Charleston SC before I have to go back to work again.

Carter

www.shipofimagination.com

PS:While the risk of vent gasses from FLAs is definitely real and should be seriously considered in any application, I think it is often highly exaggerated. Although admittedly, it would only take one explosion to ruin your boat and I'm definitely looking forward to getting my new vent gas management system from Germany .

From: oak <oak_box@yahoo.com>
To: "electricboats@yahoogroups.com" <electricboats@yahoogroups.com>
Sent: Monday, October 28, 2013 10:51 AM
Subject: Re: [Electric Boats] RE: Hello group

Carter,

For least risk, I started with deep cycle group 27 batteries. After a year, I'm giving up on those. They dry out far too fast (esp. for "maint. free"!!!).

Are you using golf cart batteries?

How hot is your climate? (I'm in Texas , and had many weeks where temps below deck would climb over 100 degrees)

How often are you adding water to your batteries?

I'm trying AGM batteries, since they are still a less intimidating investment than Li. And I'm hopeful that they won't need the attention that the traditional FLA batteries did. The location I can put them in is a pain to get to for regular topping off!

John

From: Carter Quillen <twowheelinguy@yahoo.com>
To: "electricboats@yahoogroups.com" <electricboats@yahoogroups.com>
Sent: Monday, October 28, 2013 8:19 AM
Subject: Re: [Electric Boats] RE: Hello group

Val,

I would ad one minor correction to Eric's calcs below. If you shop them hard you can get an eight pack of T-105 for a lot less than $1500. I just bought an eight pack of T-125s for about $1300, (without cores to trade in), and could have gotten T-105s for right at $1000 without cores. The golf cart guys get very competitive with these batteries and often settle for very low margins.

This difference will have a significant effect on the economic analysis. Economics will certainly be affected by the market you are in and you could wind up spending $1500 for an eight pack of T-105s depending where you buy them but you could also spend a lot more for LiIon as well and don't forget that expensive battery management system you better get to go with them to protect your signifcant investment.

I'm not promoting lead acid, even though it's what I have on my boat however, if you have a tight budget, they do work, are a very robust and mature technology, and deserve serious consideration as a battery option even if they are a bit lame when you compare their performance characteristics to Lithium. LiIon is definitely the technology of choice if you want top performance and have the money to spend but lead acid gives you good value with a lot less financial risk. There are sooo many variables when making comparisons between these technologies that I submit it is impossible to definitively say which one is actually the best value.

The biggest downside to FLA is outgassing and maintenance but if you're prepared to deal with these two items properly, I think it can be argued they still deliver a very competative value against any other technology availabe today.

Carter

http://www.shipofimagination.blogspot.com/

From: "ewdysar@yahoo.com" <ewdysar@yahoo.com>
To: electricboats@yahoogroups.com
Sent: Monday, October 28, 2013 12:37 AM
Subject: [Electric Boats] RE: Hello group

Hi Val,

There are numerous posts in this group with information that should help you. Here's some info that has been posted a few times comparing different battery types:

------------------------------------------------------------

Here is a re-run of a post that I made on Feb 21, 2013 that compares the three major options in batteries. You'll notice that I tend to use watts instead of amps or amp hours. Since even this thread has already included three different system voltages, using amps means that you've got to do math in your head to make any meaningful comparison.

The prices still seem to be close enough, the lithium prices include passive BMS modules like the ones in my battery pack (less than $300 for 16 independent modules)

Here it is again:

With all the recent talk about FLA vs AGM vs LiFePO4, I think that this post
(#22145 from Sep 6, 2012), provides a fairly good comparison of battery banks
that can deliver the same amount of work. This is as close as I've been able to
get to an "apples to apples" comparison.

You might want to look at the pics in the group folder "Eric's Serenity".
http://groups.yahoo.com/group/electricboats/photos/album/1967401930/pic/list
The last pic is half of my 160Ah 48V traction bank. Lithium is not only
lighter, it is considerably smaller than either FLA or AGM. Weight and size
were high priority when I designed my system.

Fair winds,
Eric
Marina del Rey , CA

Hide message history

--- In electricboats@yahoogroups.com, "Eric" <ewdysar@...> wrote:
>
> ---------------------------------------------
> This is what I posted on April 20 this year in post #21398
>
> Perhaps you mean something like this post that I made back in Jan 2012
(post#20750) and reposted in this month (post #21237). I directly compared the
weight and cost of the same usable capacity of different battery types.
Peukert's has already been factored in. You can read the whole post here
http://groups.yahoo.com/group/electricboats/message/21237
>
> You said "Additional concerns are that the estimated Puekert coefficients
might be 1.0 for Lithium, 1.1 for AGM, and 1.3 for Flooded. Estimated safe
discharge levels might be 80% for Lithium, 60% for AGM, and 50% for Flooded."
>
> In case you want to check my math, for my calcs I used a PE of 1.03 for Li (no
battery is 1.0), 1.1 for AGM and 1.25 for FLA. And you can see that I used
discharge levels of 80%, 70% and 60% respectively.
>
> -- Excerpt from post #21237 -----------------------------------
> Let's do the math for a battery pack that has a usable 2.5 hour range at 2500W
(6.25kWh used).
>
> FLA 14.25kWh to 60% DoD at 2500W = 2.5 hours = 633 lbs, cost about $1500
> AGM 10.5kWh to 70% DoD at 2500W = 2.5 hours = 520 lbs, cost about $2500
> LiFePO4 8.25kWh to 80% DoD at 2500W = 2.5 hours = 200 lbs, cost about $3500
>
> So now the lithiums are 2.3 times the cost of the T-105 FLAs but they are less
than 1/3 the weight for the same range at this load. So for most boaters, I
recommend AGMs as a good balance of price to range.
> ------------------------------------
>
> Another point to consider is that the math is dependent on the load. Because
of Peukert's Effect, higher load/capacity ratios favor Lithium, but lower
load/capacity ratios make AGM and flooded look better. Aiming for the same
amount of energy consumed, here's a similar chart at 4000W for 1.5 hours (6kWh
used)
>
> FLA 15.1kWh to 60% DoD at 4000W = 1.5 hours = 670 lbs, cost about $1600
> AGM 10.5kWh to 70% DoD at 4000W = 1.5 hours = 520 lbs, cost about $2550
> LiFePO4 8kWh to 80% DoD at 4000W = 1.5 hours = 200 lbs, cost about $3400
>
> Here's the another chart at 1500W for 4 hours (6kWh used)
>
> FLA 12.5kWh to 60% DoD at 1500W = 4 hours = 550 lbs, cost about $1350
> AGM 9.6kWh to 70% DoD at 1500W = 4 hours = 475 lbs, cost about $2350
> LiFePO4 7.8kWh to 80% DoD at 1500W = 4 hours = 195 lbs, cost about $3300
>
> Looking at 6kWh usable at both 4000W and 1500W, we can see that FLA cost 40%
of Li at 1500W and 47% of Li at 4000W, entirely because of Peukert's Effect. You
can see where this is trending.
>
> I haven't even thrown battery life into the mix, but since I'm still working,
I don't put as many cycles into my boat as I would like. With proper maintenance
and charging, I believe that I could get all of these battery banks to last 10
years. But that's just the way that I use my boat. For someone that cycles their
pack more often, replacement cost may need to be factored in.
>
> I hope that this helps.
>
> Fair winds,
> Eric
> Marina del Rey , CA
> -----------------------------------
>
>

---In electricboats@yahoogroups.com, <vechnyak@...> wrote:

My boat is an old 1976 Catalina 30 (tall) and this past weekend we just pulled out the Atomic 4 engine. Over the winter I am planning to work on re-powering it with an electric motor. The boat is used for day sailing in the bay and short trips along the NY/NJ shore.

Information is available online about motors but battery info seems vague at least to me since I know next to nothing about battery types and their advantages. Does anyone know of any formula that would allow to calculate all the variables to achieve say 2 hours of propulsion and have a reserve?