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LiFePO4 for house and AGM for start?
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pcg



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PostPosted: Sat Apr 06, 2019 4:05 pm    Post subject: LiFePO4 for house and AGM for start? Reply with quote

I’m contemplating the use of two batteries – a LiFePO4 battery for a house battery (because I can get far more usable Ahs at far less weight than AGM) and an AGM battery for start battery (because I can’t afford a second LiFePO4). If LiFePO4 and AGM batteries liked the same charging voltage this would be a no-brainer (I think) and I could charge both with my outboard alternator and a solar charger, as well as a shore power charger, and put an ACR between them. But they aren’t and that seems to really complicate things.

I’d like to hear comments from anyone who is knowledgeable in the charging characteristics of both batteries and how I might solve this dilemma. Again, I’m trying to charge with an outboard alternator, solar panel, and shore power charger, as well as use an ACR so both batteries get charged.

Is this possible? Practical?

Thank you.

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thataway



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PostPosted: Sat Apr 06, 2019 5:44 pm    Post subject: Reply with quote

OK you are forcing my hand. I have been reading about boat and RV LiFePO4 batteries for about 10 years. I decided to go with one 100 amp (semi usable) about 7 months ago. It worked well on the Cumberland and Tennessee River trips--but just for the two chest freezer/refers.

We cook with an induction burner in the heat of Florida. We also have a microwave, but no inverter at that time. That meant running the generator for cooking or microwave off the grid. (We have a back up propane cylinder single burner to use in the cockpit if necessary).

We added a second 100 amp LiFePO4 battery in Feb. I didn't get the install completely done before leaving for the Hontoon trip--didn't have the fans to cool the inverter installed.

We have: 2 Battle Born 100 amp hour batteries or a total of 200 amp hours (actually I will not draw them down to less than 10%--and 20% is more prudent)--so probably about 180 amp hours. Weight is 60#. To get this capacity with a lead acid or AGM batteries we would be in the 150 or up# weight, and over 3x the space. We have the 2 batteries under the bunk on the port side. There is a cut off switch and 200 amp fuse on both sides of the 00 cable running between the batteries and the inverter. This was switched. (Mistake #1 was using a Chinese copy of a battery switch--it melted after the second use--we just bypassed it.).
We have a Victron 12/2000/80 inverter charger. This has a remote panel, which reads on or off, and can change some of the perimeters of the inverter output. We had to re-do the "outlets" part of the 110 V circuit to feed thru the inverter. NOT the BATTERY CHARGER, WATER HEATER. No High resistive loads, such as a electric cabin heater. So we have a separate circuit for those. We also have two 12 volt circuits--one only for the two refer/freezers. The other is the start, and remainder of house, including the windlass.

The Victron inverter is a piece of magic--but it is large and fairly heavy. It puts out pure sine wave AC power--better than your mains power. If you have low voltage or over a certain amperage, the inverter will kick in and supply the extra power in synch with the mains or generator power. In other words, it would allow a Honda EU2200 to start an 15,000 BTU Air Conditioner , without an Easy Start. It also works as a interrupted power supply--if we loose AC to the boat--the plugs which are on the inverter circuit are switched to the inverter within several microseconds. The battery charger puts out 80 amps, profiled (programed) to be optimal for LIFePO4 batteries. There is also a small 12 volt charger for the engine start battery if you wish to use it. We have a separate 15 amp battery charger for the house batteries and start battery.

YOU CANNOT COMBINE THE LIFEPO4 BATTERIES WITH ANY LEAD ACID/AGM/GEL ETC. THE LI BATTERIES ARE A HIGHER VOLTAGE. THE RESTING STATE IS ABOUT 13.2 TO 13.4 VOLTS, VS THE 12.6 TO 12.8 OF LEAD ACID. If you were to attach the two batteries there would be a massive rush of current from the Li to the lead acid--and would damage both!

Recently I found the solution to that: The Sterling battery to battery charger. It comes in 30 and 60 amps. Because I wanted to limit the charging to no more than 30 amps, and I only have 44 amps from the Honda 150, I went with the 30 amp model. Again, it has to be fused at the 12 volt start battery, and at the charger. There are two more fuses--30 amps at the beginning of 10 gauge run to the Li ion batteries, and at the Li ion batteries. The Sterling charger can also be profiled for the LiFePO4 battery--and is a bridge to the engine start battery which is the point of take off for the charge.

Sterling 1230 battery to battery charger.

I am monitoring this system with the Victron 700. I also have a BMS monitor for the house bank (and voltage of the start battery. The BMS is a larger monitor, but almost identical functions as the Victron 702. We also have Automatic charge relay between the engine start (A group 24 interstate FLA) and two group 27 FLA house bank batteries. When these batteries die, they will all be replaced with group 31 AGM batteries. There is manual method to use either of the house batteries, or both, house batteries for engine start.

This system is not cheap. The first battery was about $975. The second was $925. The Inverter charger was about $1155. The Sterling was $278. Wire and switches were about another $200. All total, well over $3,000. (I had to bribe Marie by promising her a new car....)

I also down sized my RV in the last 6 months. When I put house batteries in it, I went with AGM golf carts for several reasons, including the lack of a converter for the 200 amp alternator on the Diesel engine for charging the LiFePO4 battery. 6 months later, this has changed--and if doing it now, I might more strongly consider the Li ion batteries, because there is an isolator which will take the 200 amps for between the engine start AGM and the Li ion battery. It costs about the same as the Sterling battery to battery charger, but is not as sophisticated. and probably would not work well for an outboard motor.

I found the people at Battle Born to be quite knowledgable. There are many li batteries going into RV's and many cruising boats, as well as off the grid homes. Technology is rapidly changing and prices are starting to come down.

But there is a huge amount of power in these relatively small batteries--and all of the components have to be robust. I mentioned the issue with the battery switch--I now have a US made switch which handles the 200 amps fine. I also had an in line circuit breaker (40 amps) to the Sterling from the house battery. That is what was called for., It was Chinese, and kept tripping. So again, I will be changing this out for a Blue Seas unit probably 50 amps to be safe. The wiring, and terminals have to be very carefully made. I got a hydraulic swagger for the large terminals. We used a lot of adhesive shrink wrap.

The LiFePO4 battery cell voltage is about 3.4 to 3.7 per cell, thus one has only 4 cells per "12 volt battery". instead of the lead acid battery which is about 2.1 t0 2.2 volts and has 6 cells for a "12 volt battery". Also although the charging voltage for both AGM and LiFePO4 is about 14.4 volts, The profile of charging is much different--and perhaps out of the bounds of this post. Down the line we can go into this--but the Li ion battery can be charged much faster--and the terminal voltage, float voltage (not really recommended) is also higher.

Why LiFePO4 vs other li battery technology? It appears to be the safest. There are very few, if any reports of fire or over heating (if properly used). There is a battery management system in each case (size of group 27) which will shut the battery off, if over charged, or if being drawn down too low. Completely discharging one of these batteries will result in a $1,000 paper weight! Over charging can damage the battery. For our first single battery, I used the old West Marine portable charger with the AGM profile. It worked fine, but would not do the last 10%. So I bought a cheap (Chinese--this one worked) charger, specifically made for LiFePO4. It had a monitor built in--amps, volts, SOC. We used that to top things off. We used Anderson connectors for both the battery chargers or any use of high draw for the first battery, and left them in place in case I have to use that same charger in case of an issue with the Victron.

Although these batteries have a lot of energy--drawing at more than 100 amps can only be for a short time (for a 100 amp hour battery), so a single battery is not to be used as an outboard starting battery. Also we have a temperature probe hooked up to both the Sterling B to B charger and the Victron Inverter charger. If the battery begins to heat up, the chargers begin to back down the amount of current delivered.

More to follow as the discussion evolves.

Bottom line, we were very pleased with the LiFePO4 batteries and Victron system. We never discharged over 50%,, even going once two days without charging. We found that running the outboard about 4 hours a day pretty well brought the 200 amp hour system back up to over 95% SOC. We also found that the Victron 12/2000/80 brought the batteries up very quickly. Once we put the cube electric heater, Microwave, and induction heater on by accident--more than 30 amps, where I had the Victron set. The Victron picked up the extra amperage, for the couple of minutes it took me to realize that we had an over power situation. (The mains power was limited to 30 amps--and an additional about 5 amps was added in synchrony with the Mains power. No breakers blew etc. Not recommended, but a "test" anyway.

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Thataway (Ex Seaweed) 2007 25 C Dory May 2018
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caracal



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PostPosted: Sat Apr 06, 2019 10:09 pm    Post subject: Reply with quote

I am currently in the process of rebuilding a 24 and I am contemplating an all lithium setup. I would really like to keep the weight down. Batteries are a great opportunity to do that. I have an idea, but not something that you see too often. I was thinking about running two starting lithium batteries that are actually motorcycle batteries. 625CCA and 6.5 lbs. Then a house battery. I was thinking the 50AH Battle Born. I will have to do some more research on charging. I will be sure to chime in as I learn more about that system. Thankfully, I am rebuilding the boat with an electrician. I know it is going to cost more upfront, but saving 130 lbs is going to be hard to pass up. The motorcycle lithiums used to be only $225 a pop. Most recently, I have only seen them for $285. That price made me question the need for the old AGMs. Just throwing it out there.
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thataway



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PostPosted: Sun Apr 07, 2019 12:27 am    Post subject: Reply with quote

Clayton,
Most of the sources I have read discourage the larger LiFePO4 batteries as a engine start battery. I suspect it is set up for the deep cycle, use, and that the internal BMS would shut the battery down during a high amp draw. For example the BB 100 amp battery will shut down if the voltage drops below
Quote:
All Battle Born Batteries come with a built-in battery management system (BMS) that protects the cells for long-term cycling. The BMS protects against the following conditions:
High voltage: > 14.7V
If an individual cell voltage exceeds a prescribed threshold during charging, the BMS will prevent a charge current from continuing. Discharge is always allowed under this condition.
Low voltage: < 10V
If an individual cell falls below a prescribed threshold during discharge, the BMS will prevent further discharge. Although the battery is in “low-voltage disconnect” mode, it will still allow a charging current. (Note: many chargers must detect a voltage over 10v to send a charge to the battery).





Quote:
High Current
The BMS will not allow a current that exceeds 100 (+/- 5%) Amps for 30s, or 200 (+/- 10%) Amps for 0.5s. Although these thresholds have been verified with a DC load bank, the 30 second high current threshold may be reduced from 200A to around 150A for certain highly variable loads through an inverter – like a microwave or space heater. After a high current disconnection, the battery will automatically reconnect after 5 seconds.
A passive balancing process is activated by the BMS at the top of each charge cycle, when the battery voltage exceeds around 14V. This ensures that all the cells remain at the same state of charge, which helps for pack longevity and performance.


Often the start load is over 200 amps--and voltage drops to in the 8's and 9's with the FLA battery It is very possible that the motor cycle starting battery does not have the BMS. I have not looked into the use of Li ion for starting. There are some of the other Li ion batteries (more expensive) which are rated for starting, but their characteristics are slightly different than the LiFePO4 batteries. It will be interesting to see how the motor cycle batteries work in parallel. You will have to watch the charge on an un-controled "alternator" from the outboard. The li ions do not like to be overcharged.
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Sea Wolf



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PostPosted: Sun Apr 07, 2019 12:42 am    Post subject: Reply with quote

All of this is very interesting!

Sounds like a fun project for a retired electrical engineer with several thousand dollars to play around with and thereby relieve the post-partum job depression blues.

I knew Dr. Bob would have the best grasp of all the difficulties involved and how to approach them, so I was just waiting for his post. Great job, as usual!

However, for the vast majority of us, it's probably off the deep end to attempt such an installation. I'd much rather wait for the availability of a complete integrated system that would convert the whole boat/motor/house/shore power electrical set-up into a matched system rather than a piecemeal approach with different types of batteries. This could well be a factory option as well as a dealer offering, and as a packaged DIY component set, of course.

The CD-22 and C-Dorys in the line will handle the weight of a few additional batteries relatively easily, and that, for me, plus the addition of any desired electrical components (chargers, inverters, generators, combiners, relays, monitors, etc.) for the time being is not only simpler, but less complex, , less expensive, and less worrisome as well. KISS wins,, again. (IMHO)

Joe. Teeth Thumbs Up

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caracal



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PostPosted: Sun Apr 07, 2019 7:11 am    Post subject: Reply with quote

The Relion 100HP is used all the time as a starting battery for outboards. You can actually find a lot of information about that one online. There are quite a few marinas in Florida that have done many installs with these that could be contacted. 80 usable amp hours and plenty of cranking power at under 30 lbs. Makes me drool. Problem is, that sucker is $1,300 right now. I will look more into the Bikemaster 30 battery. It is a good idea to compare that suzuki charger system to all of the harleys that now have these lithiums in them. Don’t want to bring down that voltage too low like you mentioned, but it is interesting to me that they provide 625cca compared to the 550cca in my Caracal that started that boat for 11 years. Definitely got my money’s worth out of that Interstate.
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caracal



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PostPosted: Sun Apr 07, 2019 7:35 am    Post subject: Reply with quote

The Bikemaster does have a BMS. Definitely worth looking into further, but that is why I picked the Bikemaster over many other options. I will have to find those exact voltage limits.
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caracal



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PostPosted: Sun Apr 07, 2019 7:44 am    Post subject: Reply with quote

They state that the lower limit is 10-10.5V.
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Gene Morris



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PostPosted: Sun Apr 07, 2019 9:35 am    Post subject: Reply with quote

This thread got me to thinking about replacing my 9 yr old 6V golf cart batteries. I looked on line for LiFePO4 batteries I don't know this company, if anyone out there has done business with them please respond. It looks like I can replace my 4 house batteries with 2 of these100AH 12V batteries for about the same price or a little less. What do you think?


https://www.batteryspace.com/lifepo4-rechargeable-battery-12-8v-100ah-1269-7wh-100a-rate-with-bluetooth-option---un38-3-passed.aspx

Gene

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thataway



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PostPosted: Sun Apr 07, 2019 10:43 am    Post subject: Reply with quote

First, I agree with Joe, there is no reason for 98% of the C Dory to use anything other than flooded lead acid batteries. In a few cases AGM are better (inside cabin, or on side/end (which can also be done for the LiFePO4). My use of the Li ion is an experiment. I would have not mixed the types of batteries, until there was a battery to battery charger which fit the LiFePO4 profile.

Gene, I don't know anything about AAA Portable power. The header says "Products are designed , assembled & Quality Controlled in USA. All products are shipped from California." Sam's club Golf carts run from $90 to $110 in FLA. AGM are $180 each--so that is closer to your Li battery for the output.

Many of the battery cells are made in China. There is a difference in quality between the different cell makers. Most all of these are literally hundreds of small cells, soldered together with a BMS in a case.

One of the reasons I went with Battle Born, is that they have a track record in both RV's and Boats. They set up the chargers with the profile for the specific batteries. I got good technical advice, and they use mostly Victron inverters and chargers. I had a problem with the inverter when first installed (I had it programed for the Li ion batteries--and they needed to know some specifics about the first battery I had purchased: How long is service, and some characteristics about charging etc). However when I first installed the inverter and hooked it up---nothing. I double checked voltages, connections etc. I went thru the checks when on the line with Battle Born--still nothing. They gave me the phone number of the head tech rep for Victron. It turned out at some point the DIP switches had been set wrong. He walked me thru re-setting the DIP switches and then it worked perfectly.

There are some cheaper batteries and there are some more expensive batteries. I cannot say what cells they are using: Tesla has used mostly Panasonic cells, which are generally regarded as the best. Victron 90 amp hour batteries are $1255 and about 5.5# heavier. They are probably a better battery than the Battle Born. Relion is $1280. I don't know if they are better or not. The Relion HP100 seems to be a battery designed for starting as well as house use. I have no experience with these--concern would be the high voltage of the outboard charging system after the battery is fully charged. BMS can cut off the battery if too high a charging current, but I don't know if any have a timer function. Certainly people are using them in boats.

Once you get to 12.0 volts on a LiFePO$ battery you are on the last 10% of the discharge curve, and is is close to a straight line down...I would be very uncomfortable letting a battery get to 10.5 volts. That would definitely shorten its life span. If you run a liFePO4 battery all of the way down, many are not recoverable.

Here is a comparison of the various chemistries of the batteries:
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DavidM



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PostPosted: Sun Apr 07, 2019 10:48 am    Post subject: Reply with quote

The numbers don't add up for me. Those 100 AH batteries are $650 each with no communications option, so $1,300 for two. Generic 6V GC2 batteries are about $100 each, so $400 for equivalent usable amp hours.

David
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hardee



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PostPosted: Sun Apr 07, 2019 11:11 am    Post subject: Reply with quote

WOW, This is cool stuff. Most of it way over my head, but it is great info. I spent quite a bit of time looking at the new battery question as I was on the verge of replacement this season.

At the SBS I went to several classes on the subject. A very interesting and persuasive presenter from Pacific Yacht System's in Vancouver BC pointed out the Lithiom Iron batteries (not Lithium Ion). He said that to use those batteries for starting would decrease their life to about a year. (They are great for deep drawdowns and thousands of recharge cycles, but cannot handle the rapid draw for engine starting applications.) His suggestion, for house use, 1 or 2 of the LiFe's and an AGM or FLA for engine starting. BUT there would need to be some accessories: a battery to battery charging system, a smart charger, a monitoring system. All great ideas, a nice plan and somewhere close to the equivalent of another college degree in cost, $$$$ or closer to $$$$$.

Full disclosure: there was no mention of MC starting batteries in the LiFe family. With that possibility, it might work on a 22 but my thoughts were that with all the additional parts, and all needing to go into inside, under cover (not into the cockpit under the splashwell) to meant that I would frankly just run out of room.

I would like more information on the specifics of those MC batteries, (names, maker, where - China?, charging requirements.)

Harvey
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hardee



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PostPosted: Sun Apr 07, 2019 11:17 am    Post subject: Reply with quote

DavidM wrote:
The numbers don't add up for me. Those 100 AH batteries are $650 each with no communications option, so $1,300 for two. Generic 6V GC2 batteries are about $100 each, so $400 for equivalent usable amp hours.

David


The advantages are in decreased weight (by about 50%), in depth of discharge and ability to come back to 100%, and number of charging cycles (in the range of 3000 to 5000 from well below 50%).

Harvey
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thataway



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PostPosted: Sun Apr 07, 2019 2:22 pm    Post subject: Reply with quote

The weight of two group 31's or two of larger golf carts is in the 135# range. (about 68# each)--The LiFePO4 battery weight is 30#. That is about 25% of the weight.

I have the battery to battery charger right next to the start battery under the aft seat in the cockpit in the 25. I put the batteries forward because of the weight distribution and room. Plus I wanted them near the inverter, with the heavy cables kept as short as possible.

Battery monitoring systems, and smart chargers are excellent additions to every boat, but in this case I wanted a separate monitor and charger for the Li batteries. I would not really need the smart charger, because the inverter feed for start battery would take care of that...if I wished.

David M--actually most of the 100 amp batteries are running in the $925 to $1300 each. Two would be from $1850 to $2600. That re-inforces your thoughts .
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journey on



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PostPosted: Mon Apr 08, 2019 2:45 pm    Post subject: Reply with quote

Bob,

I'm curious. You installed 200 a-hr of LiFePO4 batteries for the house and a group 24 interstate FLA battery for starting. Since there are a number of Li battery packs which will start an engine (see lithium starting batteries) why did you decide to use the FLA battery?

You have an 150 Honda outboard which has a small starter; so if Li batteries will start a truck, that Honda should be small potatoes. If you used the Li batteries, there is a lot of hardware of which you could get rid.

Boris
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