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Upgrading to LIFEPO4 on a Sailboat - this plan look good?

lwitty

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Joined
Jan 16, 2021
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The AGMs on my sailboat are hitting end of life and looking to make the switch to LIFEPO4. Since I just found this forum, thought it would be good to share my current setup first so I can possible correct issues I may have made in the past.

Here is what is in my current setup:

Charging Sources:
  • 4 - 100W Renogy Flexible monocrystalline panels connected in Parallel (sailboat so possible shading from sail. Parallel seems to perform better)
  • Xantrex C35 PMW Charge Controller
  • 80A alternator
  • 40A Xantrex Truecharge 40+ (manual here) when connected to shore power
Batteries
  • 2 – Lifelife GPL-4DL 210ah AGMs (house bank)
  • 1 – Lifeline starter battery (Isolated engine starting battery)
Other Relevant Equipment Currently installed
  • Victron BMV-700 (pre-smart monitor)
  • Xantrex 3000 PROwatt Inverter
  • Cristec rce/100-1e-2ig Electronic battery isolator (separates house & starter bank when charging via alternator)

Lithium Upgrade Plans:
  • Keep 400W of solar panels connected in parallel
  • Install a Victron 12v DC to DC 30A to protect alternator (continue using isolator to charge starter battery). So would connect the DC to DC charger’s input to the isolator output (house side)
  • Replace the Xantrex C35 with a Victron MPPT 30a
  • Replace AGMs with 2 – 200ah LIFEPO4 drop ins (leaning towards the CHINS currently on Amazon, mainly due to warranty)
  • Purchase & install a Victron Bluetooth dongle for the BMV-700
  • Keep the Truecharge 40+ and set to 2-stage charging (bulk/absorption) and set to 14.4v (Flooded/Warm setting) or 14.6v (AGM/Cold)
  • Leave existing battery fuses and solar fuses unchanged
  • Keep the existing 3000 PROwatt inverter


This plan look sound? If I buy the Victron Bluetooth dongle for the monitor, is it worth spending the extra money for the Victron Smart MPPT Controller versus the BlueSolar?

I was going to build my own batteries, however I decided against it based upon where the batteries will be installed on the boat and the beating and tilting the boat takes while sailing.
 
I don’t know much about sailing, except I like watching YouTube sailing videos?...

I would spend the money for the Victron smart solar mppt over the BlueSolar. The Smart Solar gives me some very great info on iPhone about the charging- history, status.etc.

I don’t know much about that battery. Make sure the discharge amps on the batteries (added together) is enough to fully utilize your inverter - some large batteries use smaller bms’s. Verify the same thing on charging - if all charging sources were all on at once - would it be too much for the batteries bms? (you probably have more control over this one).
Also, contact the manufacturer and verify their battery will be fine in a sailboat- (rocking and movement).

The shore power charger - verify it will work with lithium. (I think this one could be a problem- but I don’t know). Many Lead Acid chargers stay in absorbing mode too long and overcharge the lithium’s, then they float at an incorrect voltage too.

Good Luck!
 
Thanks Rocketman. Will definitely go with the Smart MPPT.

I actually inquired with the battery company about vibration, tilting, etc and of course they said it would not be a problem. Will be a bit of a gamble going with the CHINS batteries, but price and warranty (if they would actually honor it) is quite good. Attached is an image they sent when I inquired).

As for the shore power charger, not sure how to assess the Absorption Mode length. What I did see in the manual was the following: "During the absorption charge, the charging voltage is held constant near the gassing voltage, and the battery gradually reduces the charging current it demands as it attains full charge. Once the current drops below 4 Adc for three minutes, the charger either exits to Float for gel and AGM batteries or charges flooded batteries for one more hour." Not sure I know what Adc is and if this will cause overcharging on the lithium or not. Any thoughts? Not worried about float as I can put it into 2 stage mode (bulk/absorption only).
12V 200AH.jpg
 
No! You need the float! If the float is 13.2v (3.3v/cell) that's kinda like turning off the charging - which is what LiFePo4's need! What are the exact voltages for Bulk & Absorption & Float? (That is super important info). You need much more info on that charger before you can decide to use it to charge lithium's. Focus on AGM/Gel mode - the flooded mode will probably give you problems overcharging during absorption. If the float mode voltage works - that charger may be kinda be OK to charge the lithiums (but i am not sure about that). Your problem will be the charger will not exit absorption mode 14.6v until the charging current drops to 4amps dc. With two large batteries that means the current will need to drop to 2 amps each - which may be very overcharged. (all my knowledge in this area comes from book-learning - it may be fine - I don't know for sure). You may want to contact a couple of different lithium battery manufacturers and ask if that charger set on AGM will work with their batteries?

Photo - is that lid metal? In heavy seas, what is to stop all the cells from flying up and the top of all the bus bars shorting against the lid? Now if they took off something off for the photo or that lid is plastic then OK.

One other smaller issue - this 200Ah battery has a 100amp bms for discharging and charging. - charging - no problem - with all sources maxed you get .5C for each battery. For the inverter - each bms can only provide 100 amps - so you will only have 200 amps * 13v = 2600 watts - that is pretty close to fully powering the 3000 watt inverter - Do you run the inverter maxed out for more than 5 seconds? Those cheaper bms's usually don't like to be ran at full power (100a) for long, Do you run your inverter at more than 50% for long periods? (probably not because you don't have the batteries to support it).
 
Here are the voltages from the current charger:
1612208269415.png

If I set to 3 stage charging, and use the "Gel - Warm" setting (charger has 3 switches 1) 2 or 3 stage charging 2) Flooded/Gel/AGM 3) Hot/Warm/cold), I would get Bulk/Absorption @ 14.2 and Float @ 13.8, these seem to be the best from what I understand. I thought I read where lithium does not like float, that is why I was leaning towards the 2 stage mode (which looks like it may be the wrong approach).

My current behavior is to have the shore power plug in 100% of the time while at the dock during the winter to float the AGMs and just rely on solar in the summer (in the Pacific Northwest). Would this be the best approach for lithium as well, always float?

The metal case questions for the battery is a good one which I will take back to the manufacture. However, it seems they sent me a photo of their low temp battery (which I am looking at their standard 200ah, not the low temp as the battery compartment never dips below freezing), the standard battery may not have that metal compartment, but I will ask.

The CHINS standard 200ah battery has a 200a BMS, so I should be good there. I have never drawn more that 150 amps out of the existing batteries and no not plan to add any additional AC appliances which may push the inverter to its full capacity. So I could survive with 100a BMS, but definitely prefer 120 or greater. Also, I will need to double check my battery fuses as I believe they are 100a (need to ensure I have spares before this project gets started).
 
I think it would be best somehow to turn off the charger, until the batteries drop to 30% then turn it on - raise it 70% and just keep it in that cycle while the boat sits and waits for you to come back and play with it. Then just before you arrive it raises the charge to 100%. (ideal world)

My understanding (which is not great) is the AGM Hot would be best for you. I think the most important piece for you is the float. - most of the time your batteries will just be sitting. So the 13.1v = 3.275v/cell would be best in that case. It may not charge to 100% - but that's not a bad thing either. The Victron mart solar charge controller will allow you to set each stage to .001v. (i.e. 14.45v) so you will want to research the exact voltage you want.

Good Luck in your research.
 
Good news & bad news on my project. Good news is I have the new victron Smart MPPT & DC-DC charger installed and working as expected. Also batteries arrived and installed and working. Bad news is I have just read some testing reviews on the CHINS batteries on a different thread. Will need to figure out if I try to get them returned to CHINS through Amazon or see how they last.

Not too concerned about not having low temp cut off not that concerned about low voltage as I very actively monitor and manage my batteries (just replaced 13 year old Lifeline AGMs which still have good life, just wanted my amp hours). So, I can probably live with the CHINS BMS deficiencies as long as their is no safety issues (having no 12v power really is not a safety issue, a fire is...).
 
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