Heads up - LiFePO4 and ABYC recommendations

As san juanderer noted, few of the LiFePO4 batteries are rated for engine start--and thus the engine, and other accessories can easily continue working. The other issue is that it is very rare for a BMS (external or internal) to shut down a battery. One could use the same argument for a fuse or battery switch failing with traditional FL:A batteries. In fact that is far more likely to happen in John's scenario than a BMS shutting down the Li bank.

Also we carry a jump start kit (greater use was for powering the inflatable dinghy pump, or charging I pads etc.).

I would agree that for the average boater I would not recommend the LiFePO4 batteries. If you are planning on keeping and using the boat for more than 5 years, is the point where the Li become justified.

There are many boats where the weight can be an issue and greater power density is necessary. For example bass boats and the trolling motors.

Certainly if one is contemplating use of the LiFePO4, read as much as possible. We followed one of the early RV adaptors who had 10 years of experience, mostly off grid, as an all electric coach using the LiFePO4 batteries for house.

Also the cost of higher quality LiFe batteries has been falling, and now is only 2x that of a quality AGM battery. Be careful about what brand you choose.

Will Prowse on teardown of several batteries.. This and a google search will find many articles by Will Prowse. They are somewhat RV and solar power oriented, but those applications are also very appropriate for our boats.
 
I’ll second what Bob says. Also my design includes a battery switch to my DC loads, located at the helm, so in the event of an imminent house battery shutdown I can switch the DC loads over to the start battery before it happens. Extremely unlikely though, as Bob stated, but the switch gives me a Plan B and some peace of mind.
 
Don't get me wrong - I like my 100 amp lifep04. I can run 4 days with the diesel furnace (on low) running almost non-stop, my LED anchor light, power every single piece of electronics on my boat, and pull lots and lots of shrimp pots for 4 days straight with it without ever giving it a charge. I could never do that with my FLA group 27. By then, I am out of water, gas, beer, stove oil, and about everything else. I just switch over to one of the AGMs for the last day. If I end up staying longer and restocking, the AGM and the lifep04 seem to charge ok with the outboards - mine rarely run over 13.5 volts so the BMS doesn't shut off.....not ideal, but works pretty well so far. I'm pretty sure the AGM drains into the lifep04, but with the really long multiple hour trips I take, they both eventually do get charged.....mostly.....no expert - just data from one guy.
 
I'm pretty sure the AGM drains into the lifep04,
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Probably the opposite: The resting voltage of a LiFePO4 battery is about 13.4 Volts Vs the AGM of 12.7V. The Li battery is 85% discharged when it reaches 12.7 volts. There in lies the danger of direct connection of a charged LiFe battery to any lead acid-the Li can sustain a. huge outrush of current, especially when connected to a lower voltage battery. That is what would cause the BMS to shut the battery down.

I suspect you connect the LiFe battery to the AGM as you have already have the engine running and at least 13.3 volts. You don't get a lot of charging of the Li battery at 13.5 volts.

In some RV's they LiFe battery is charged directly without a battery to battery charger, but the current flow has the danger of damage to even a Leece Neville 200 amp high output alternator. Thus there is a timer which allows charger only XX minutes out of an hour to avoid overheating the alternator. Almost all of the applications use a conventional FLA battery for the engine start.
 
Alright, I surrender. I'll comment on using a Li battery on a C-Dory.

First of all, the idea of installing 3 ea group 31 batteries in/on/around a C-Dory 25 is interesting to say the least. One can't fit 2 ea 31's in an aft compartment. Fitting them inside the cabin is a non-starter because of the wiring AND loss of space. I don't know if it's possible in a 22.

We all know that c-Dory 25 loses a lot of speed/performance when it gains weight. Journey on has 2 golph cart batteries in the starboard lazerrete, used for house batteries (and starting the boat, incidentally.) They're Trojan T-105's with 200 ah capacity, allowing 100 ah of use. Journey On also has a starting battery in the port lazerete, which has served as a backup battery. The Trojans each weigh 70 lbs (totaling 140 lbs) and fill the lazeret. I can't imagine getting anything else in there and I had to remove the door to get them in (and out.)

So I bought a Chins Li battery, 100 ah. Got a good review on Utube. Size 31, weight 40 lbs, including the Regony 20 amp charger. Good for 80 ah and I got rid of 100 lbs. Better that even golph cart batteries, 2000 cycles @ 80% discharge. It's easy to fit a single 31 battery in the lazeret and the amount of wiring stays the same. No need to check the water level which is a pain in the rear.

Did mention I got rid of 100 lbs? Judy is getting even better at packing the boat for a cruise, so the only weight savings come from my side. I don't argue with anybody who wants to have 2 engines, crab pots, etc because that's what makes their boat work for them. For me getting rid of 100 lbs is a definite plus and I assume it would be for everyone. Also (we hope) longer battery life and no service.

Boris
 
The Chin's battery (and apparently identical Ampere Time) are as low as $369 on Amazon (plus freight ? and Tax). That brings the cost per usable amp/ hour to less than most AGM batteries. There are also a 200 amp hour and 300 amp hour at even slightly less per amp hour.

Good find Boris!
 
Just remember those Chinns, Ampere, and Zooms don't have low temp charging protection. So a good deal, for the right use cases.
 
croakz":30ms070k said:
Just remember those Chinns, Ampere, and Zooms don't have low temp charging protection. So a good deal, for the right use cases.
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Amazon does have a low temp Chin's battery for $659.99Here on Amazon. You are paying considerably more for the low temp (probably a heater circuit). But it is available.

I would think that most of the use in a C Dory would be in temperature greater than 32*F. (Think of putting the battery inside the cabin.) Thus probably not really an issue for most of our boaters.
 
croakz":3hw9bkkt said:
Just remember those Chinns, Ampere, and Zooms don't have low temp charging protection. So a good deal, for the right use cases.
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My Li battery BMSs will have low temperature charging PROTECTION, as in they won't charge below 32F (battery temperature). Don't you mean these don't have a heating circuit that will heat the battery internally when temps drop low enough that the BMS stops the battery charging? Interesting, the battery can still discharge just fine below freezing. It is the charging that the BMS stops. Given in a C-Dory that the battery case will usually be sitting on a sole that is hopefully sitting in liquid water, dropping below freezing hasn't ever happened in my C-Dory 22 (batteries below sink), even when outside temps drop below freezing. In my camper and in our mountain yurt, the BMS does shut down charging when it gets really, really cold. It'd be nice to have a battery that has an internal heater in that case, which are available but more expensive than what I have now.
 
Well, I'll keep going.

First of all, Chin li batteries are only rated for 100 amps and Honda Accord starters (as far as I know) use at least 150 amps. So one needs to have a lead acid battery for starting. That's one reason for a lead acid battery.

Next, Journey On has a 150 hp Honda engine with 40 amps of output, max. But a li 100 ah battery will take up to 100 amps in charging. This means that the Honda alternator will be putting all it's output into charging the li battery with nothing left over for the house loads, such as the MFD, fan, wipers, etc. Therefore one has to limit the charge current for the li battery. I selected a Regony 20 amp charger, assuming 20 amps would charge the lead acid battery and run the house loads. Regony was the cheapest, without bluetooth. Turns out I installed a Balmar SG2000 monitor which has the option for bluetooth, so if I want I can get a remote reading for the battery state. In a C-Dory, I don't think I'll need anything remote.

Now the battery charger has a li setting, which charges until a fixed voltage is reached (~14.6 Vdc). The battery charger then disconnects, which is kinda a shock on the alternator Indeed, if there are no house loads, it'll blow the alternator. Fortuitously, if the lead acid battery is connected it'll take the surge and everything will continue to operate happily. That's another reason for a lead acid battery.

Now, how does one control to DC-DC charger? Two ways. One there is a line coming out of the charger which has to be connected to a 12 Vdc source in order that the charger will operate. This prevents the starting battery from being drained in order to charge the li battery. One can connect it to the alternator output or as I have, through a switch on the dash. All I have to do is remember to throw that switch and I'm betting Judy will remind me. In addition there's a line coming out of the charger that, when activated, limits the charger to operate at 1/2 the normal charge. Again that's a switch in the dash, used if the alternator is struggling to deliver adequate voltage.

And i live in San Diego County where it never freezes so low temperature charging doesn't concern me..

Wish me luck.

Boris
 
I assume that what you're saying is that the alternator on the motor is rated for 10 amps @ 12 volts. If the load is more than 10 amps, the voltage will drop. Until you remove the load. Is that what you are saying?

In my example above, if the alternator is feeding loads that require more than 40 amps, the voltage will drop and cause the starting battery to supply the extra current. And run down.

Boris
 
Will Prowse just did a teardown of a new "marine grade" LiFePO, although a manufacturer calling a battery marine doesn't necessarily mean it meets one's needs. But at 206 amp hours and $1K each, thats getting really competitive with Flooded Lead Acid (and Mr. Prowse seems to think they are better than Battle Born).

I can't see the application on my little C-Dory, but I'm almost hoping the batteries will fail on my trawler. :D

https://www.youtube.com/watch?v=zJmIS5tmzPU
 
Marco Flamingo":1mntlz9n said:
Will Prowse just did a teardown of a new "marine grade" LiFePO, although a manufacturer calling a battery marine doesn't necessarily mean it meets one's needs. But at 206 amp hours and $1K each, thats getting really competitive with Flooded Lead Acid (and Mr. Prowse seems to think they are better than Battle Born).

I can't see the application on my little C-Dory, but I'm almost hoping the batteries will fail on my trawler. :D

https://www.youtube.com/watch?v=zJmIS5tmzPU
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I love the size of the SOK Marine battery too. 13.4" long, where my Expert Power 200ah is 20.6" long! And the SOK is not even 1" taller or wider.
 
journey on":2k0q4l6v said:
I assume that what you're saying is that the alternator on the motor is rated for 10 amps @ 12 volts. If the load is more than 10 amps, the voltage will drop. Until you remove the load. Is that what you are saying?

In my example above, if the alternator is feeding loads that require more than 40 amps, the voltage will drop and cause the starting battery to supply the extra current. And run down.

Boris
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Yup. It's almost always giving it all it has.
 
ABYC has finalized new recommendations for Li batteries. Here’s an article that discusses them. I don’t see any mention of a requirement that the BMS be external. I suspect manufacturers (including Victron) will be making some product changes before July of 2023, when the new recommendations become effective. The comments are worth reading as well.
https://panbo.com/abyc-ratifies-e-13-th ... -standard/
 
Paul, Thanks for posting about the ABYC "standards". It is also a reminder to me that I got away from reading Panbo after Bell Ellison bowed out to Ben Stein. I will get back to regular reading. Also the reference to Peter Swanson’s “Loose Cannon” website and the standards is important.

Nothing earth shattering about the standards--in fact I am a bit surprised that they are not more stringent. It also seems to emphasize the use of the higher quality batteries to meet the ABYC standards.

The requirement of dual systems, is important. It may just be a starting battery, but needs to be independent--and something which is easily available to take over if BMS cuts off the Li system.

Ventilation is important, as is appropriate fusing.
 
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