Lithium Conversion

kennharriet":1xzsauhr said:
Does anyone see any holes in this setup?
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Not a hole, assuming I am looking at the correct Renogy DC-to-DC charger docs, but I would use 8AWG and 40A fuses for input and output of the charger. That way you only need one spare fuse size and wire size for the charger. 8AWG should be over-sized for the 20A load and distance between the lazarettes, so you should be good.

The lithium and lead negatives can usually be tied together for a non-isolated circuit on our boats. Non-isolated will save you from running an additional heavy gauge negative wire between the lazarettes. My setup has a negative bus bar in each lazarette with a single port-to-starboard 4AWG negative wire connecting the two batteries. Batteries with 4AWG to respective bus bars. Motors, house panel, dc-to-dc charger, and other accessories attached to the closest negative bus bar using appropriate wire gauge.
 
Great points Shad! I’ll incorporate your suggestions. 🙂. I will need to make a custom battery tray for the group 22F lithiums as I don’t see anything commercially available that small.
 
Depending on your usage and need for charging from the alternator, it seems a shame to only get 20A from the alternator. If you look back at my configuration with the 50A (max) charger, you can set the DC/DC charging between 10-50A in 10A increments. Mine is currently set to 40A and it shows no sign of overheating. I earlier set it to 30A and then, with experience, upped it to 40A, nearly the Honda 44A output. The setup with the single DC/DC MPPT unit saves a little money and simplifies wiring a bit. You would also only need to buy one BT2 if you want to monitor charging with a smart phone (a nice touch). The only downside I can see is that if there is enough sun for solar charging, my system won't also charge from the alternator, but that hasn't been a problem that I can see. I have a switch to cut off solar when motoring. With your configuration, I guess you could possible get 60A total charging (40A from solar plus 20A from alternator) when you are running on a sunny day. The downside is that it doesn't appear that your system will use your solar panels to keep your charging battery charged when the boat is sitting unused. You should always run your motor when using the windlass, and mine works fine from the house batteries. I also often use the house batteries to run a bow-mounted trolling motor, which is a heavy load on the batteries when trolling.
 
Mine is currently set to 40A and it shows no sign of overheating. I earlier set it to 30A and then, with experience, upped it to 40A, nearly the Honda 44A output. The setup with the single DC/DC MPPT unit saves a little money and simplifies wiring a bit. You would also only need to buy one BT2 if you want to monitor charging with a smart phone (a nice touch).
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Are you monitoring the output of the DC to DC charger amps as it runs through out the voyage? Does it remain at 40 amps? I set mine to 30 amps with the 44 amp outputs. You most likely have a carburetor Honda 90. The more recent fuel injected outboards require a fair amount of current for the EMC: up to 18 amps.
 
Thanks Rob and Bob. My newer Honda BF90D is fuel injected with 44amp output. Everything I read suggested the dc-dc charger should be rated not more and preferably less than 50% of the alternator output. I may have errored on the side of caution and ordered the 20 amp non MPPT unit. I will have the BT2 for remote monitoring. When motoring, the Alaska series dingy will be on the roof and cover the 200w solar panel. It is true that I will not be able to maintain the start battery with solar but then its only load is motor starting when it is immediately getting charged by the alternator. Worse case scenario the Honda 90 can be started with a pull rope which I have practiced just in case. After this season if not adequate, I may want to upgrade to the MPPT dc-dc charger. I’ll report after I’ve used the system.

Thanks again for the great advice. Interesting stuff. I’m enjoying learning from you all. Good thing I made a living as a wildland firefighter rather than a marine electrical engineer. 😂
 
It will be interesting to see to what the actual output is. With the magneto type of "alternator" it should not overhead, as a belted alternator may. Let us know how it works out!~!!
 
thataway":365lhw02 said:
I may be "technically" over fusing the circuits--but there is a relatively huge amount of current and a short could cause a fire in very short order. Anything going into or out of the LiFePO4 battery is fused within a few inches of the battery. Same for current going from DC To DC charger off the engine--with a fuse before the wire run to the Li battery.
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Saw the title post and came here to say something to this effect. It is not over fussing/fusing. I would strongly suggest fuses directly the battery posts.

Personal favourite style, cube/block fuses. Compact.
https://a.co/d/7YDVYCB

Adequate if line side (between battery and this holder) cabling is short and larger than required AWG.
https://a.co/d/2iRK9Dr

If your batteries only have lead posts I'd suggest this for bolting cube fuse holder. Example
https://www.canadiantire.ca/en/pdp/moto ... #store=488

With these, loose pinch bolt so clamp will spread. Gently tap down so clamp is below top of post. Then tighten pinch bolt. Check threaded bolt size matches fuse holder/cable lug hole size.

https://a.co/d/2RIXfL0
Handy for small, emergency, direct to battery cct's. Bilge, lights, sensors, gas detection and what have you.

Liquid electrical tape is nice for covering/sealing terminations. Removes easier than nailpolish.
https://a.co/d/2RIXfL0
Information sheet (see temp ratings)
https://www.permatex.com/wp-content/upl ... /85120.pdf


Hope this is helpful to some. Stored energy in these batteries is serious business. For reference I'm an electrician, I work in mining in locations that utilize salt to keep drill water from freezing. Salt concentrations can be as high as 15%, fat higher salinity than any ocean.
 
Bob had asked what kind of output I actually see (I read that as amps from the alternator) from the nearly-new Honda BF100, and Ken had cautioned that conventional wisdom is that you shouldn't use a DC/DC rated or set to more than 50% of rated outboard output, which I have greatly exceeded at 40A for my BF100. Since the outboard charging system isn't a belted alternator I thought temperature wouldn't be as much of a problem as with a conventional alternator...maybe a mistake. I'm currently fishing in Brazil, but will put a shunt on my alternator side when I get back to test output. I'll also test the system charging depleted batteries and monitor temperature with my Flir. Normally, you connect a DC/DC between the starting and house batteries, as I have, so alternator output might be "filtered" a bit by the starting batteries resistance (it is standard Pb-acid). I'll put the shunt on the other side to see, and see if I can get temperatures high enough to be concerned. I don't want to dial back (via reduce the DC/DC setting) the potential charging from the engine if I don't have to. I want all of the charging I can get. Ken; I was a forestry professor for almost 40 years, and greatly appreciate the firefighter community. I wish you luck in the future.
 
Just an update on the performance of the new system. I used all Renogy products including 2-100ah Li batteries, 200w portable solar under dingy rack with a 40amp MPPT charge controller and a 20amp dc-dc charger (40 amp Honda alternator).

We camped 4 nights in the boat on the drive from home in ID to Skagway without any charging. We were using the Wallas 1300 heater, minimal lights and electronics including Starlink. The batteries never dipped below 13v and about 85% charge.

Once on the water in Skagway we typically have gone 3-4 days without alternator charging relying solely on solar. Since launching we are now running the Engel cooler which is the largest power draw. Alaska meteorologists are describing the unseasonable weather in terms of atmospheric rivers with day after day of 100% cloud cover and gale force winds which have limited solar and travel with alternator charging.

We are on day three on the dock in Juneau waiting on calmer seas to continue south again. In a moment of weakness and desire to continue marriage beyond the 50 year mark, we plugged into shore power today to recharge batteries and run the electric heater. I am using a 20amp ac-dc charger. We are very pleased with the complete electrical upgrade this past winter. Much more peace of mind when there are plenty of other issues to worry about cruising in remote waters. The Wallas 1300 kerosine heater has been awesome as well. It has been cold with highs in the 40’s and runs continuously except when sleeping. I’m quessing the Wallas consumes a quart or less of fuel per day. I’m running Jet A because it is $6/gal vs $16+ for kerosine.

We are also very impressed at all of the cruising Jay and Jolee have done in these waters. It is challenging but then taking more risk as we age is more fun than paying for long term health care insurance 😉
 
Glad to hear the lithium system is working for you. The Class B campervan we have has 600 amp hours of battery, 300w solar on the roof, and a 260 amp underhood "generator" (actually a high output additional alternator). There is a learning curve in using the system, after 35+ years of dealing with lead acid or AGM batteries on other RVs and boats.

With the 3000w inverter, we can run the air conditioner (about 6 hours or so), induction cooktop, microwave, and other 120v appliances without needing to plug into shore power. I'm impressed with the capability.

What I've learned with the lithium batteries is the voltage vs power remaining is different from the lead acid or AGM batteries we've used in the past. Here's a chart I downloaded...

T1z8nC5.jpg


This shows that at 13v, the batteries are at about 30% - really different from the traditional batteries, where 13v would be a full charge left.
 
Depending on what you have, you'll probably never get much into the yellow and never into the red zones indicated in the post above with LiFePO4. I went for a long trip with my truck camper, and then to Brazil fishing for a month. I had hooked up a 12/24VDC converter to power my Starlink mini through its long cable. It was kludged directly to the Renogy battery, not through the regular fused system, during the trip when I found that you can't use 12VDC directly with the long cable because of voltage drop. I didn't remember to unhook it when I left for Brazil, and I guess it was still drawing slightly when I tripped the breaker and "isolated" the batteries before this trip. Since it didn't draw through my monitoring system, the usage read "0" amps. I came home to apparently dead LiFePO4 batteries, but one click of the startup switch for the Battery Management System (BMS) on the Renogy cells showed I still had 12.8 volts. Looking at specs for the Renogy BMS, it ways it will cutoff when one of the 4 cells drops below 2.3 volts, protecting the cells. If this would have been a system with my old Pb-acid batteries, they would likely have completely discharged, and continued to discharge with any recovery over this long time, probably damaging them. I really like the current systems, and I am really impressed with Renogy products, which I have been using for >5 years now. To be honest, I have 12 LiFePO4 batteries of various brands now, ranging from 100-460 AmpHours, all 12VDC, and all of them are still working well, though I guess some have lost capacity over time. A neighbor replaced his huge (like 2000Ah) flooded Pb-acid system a few years ago with LiFePO4 and has already exceeded his earlier replacement schedule. He did burn up two alternators before he put a DC/DC in between, so you need to be careful. If you are considering replacing house batteries, you probably won't regret switching to LiFePO4.
 
I’m sure glad to see your new electrical systems are working out so well for you. Also good to be able to have Internet at the remote locations with the Starlink. I sure enjoyed your video directly from Fords Terror. The last time, I reached out through a satellite from Fords Terror was in 2004 with a Satellite phone, when JoLee & I had the mishap going out of there, crossing the bar on a strong ebb tide. I can see Starlink on our boat in the future.

We know exactly what you two are experiencing with the mid 40 degree temperatures & heavy rain. Hopefully for you, the weather will improve & not continue to be as cold & wet as it was on our 4th cruise there in 2012, when from mid April to late July, we only had 6 days without some rain & the rare blue sky’s came with wind. The Wallas quit after the first month & we put 784 hours on its replacement during the last two months of the cruise, while like you, not running it when sleeping. Still overall one of our best trips & looking forward to being back next year.

Stay safe as possible, though risk does have it’s rewards & you two seem to have similar risk assessment tolerances as us. I agree the older we get the less we have to lose. My biggest fear is injury that causes suffering & lost good times in recovery.

JoLee & I, along with granddaughter Wrenny are leaving Sunday on a rv road trip to Valdez, Alaska, then ferry to Whittier followed by the top of the world highway to Dawson City, Yukon. We will be keeping tabs on you, while on the way.

Jay
 
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