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Post by Fogg on Jun 4, 2023 19:13:36 GMT 12
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Post by fish on Jun 4, 2023 19:27:01 GMT 12
That is the exact one I've been looking at. The logging and data access, via .csv files appears to be very good. Why do you have two? do you have two different batt banks?
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Post by em on Jun 5, 2023 8:31:44 GMT 12
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Post by em on Jun 5, 2023 8:39:39 GMT 12
Also have the victron Bluetooth on the new boat and it’s great , the start battery also has its own little battery monitor with LCD readout that’s Bluetooth as well . Our batteries at home are LifePo4 and one year in we’ve had no issues actually I’ve stopped monitoring them because they are boringly reliable . The charge profile is simple very much like charging your phone really . When the lead acid bank on the boat has done its dash the next BATTERY will be one LifePo4 , the alternator won’t be up to snuff though LifePo4 take a hell load of current in one continuous blast . Fish buy your victron from here if you go that route , it’s cheaper than “half price “ at marine deals . victronenergy.co.nz/
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Post by Fogg on Jun 5, 2023 11:25:56 GMT 12
That is the exact one I've been looking at. The logging and data access, via .csv files appears to be very good. Why do you have two? do you have two different batt banks? One for each port / stbd solar panel.
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Post by fish on Jun 5, 2023 12:35:49 GMT 12
I see the lead carbon batts are promoted on tolerating a partial state of discharge, but still need to be fully charged at least once per month.
What happens to LiFePO4 batts if they are left at a partial state of charge? Any issues?
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Post by em on Jun 5, 2023 14:11:29 GMT 12
I see the lead carbon batts are promoted on tolerating a partial state of discharge, but still need to be fully charged at least once per month. What happens to LiFePO4 batts if they are left at a partial state of charge? Any issues? No issues , they will hold whatever charge they have for months and that’s the beauty you can leave your boat with batts at 50% and that’s not an issue , try that with lead batteries . On Saturday night it was a toss up on the boat between leaving the diesel heater going or the fridge . Heater won the argument but if we had LifePo4 we could’ve run both , in summer we could run fridge and freezer 24/7 instead of turning freezer off every night . First world problems really
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Post by fish on Jun 5, 2023 14:47:11 GMT 12
Warning: Complex Techo Question:
Whilst I still haven't verified my current batts are dead, I'm off down a rabbit hole and am eyeing up a 200 Ah Lithium batt with BMS and blutooth. (sunnytech, $1400, 8 yr warranty).
Re-programming the solar controller is easy. However, how do you get the alternator to charge an AGM start batt & a Lithium house batt?
The alternator charges both house and our existing 12v AGM start batt. We have a Voltage Sensitive Relay so that that when the start batt is sorted, it opens to charge the house batt. We have a Balmar regulator. It will be fiddly, but I can re-programme that to the required set points for Lithium (set all parameters to max of 14.6v, and the main charge parameter to whatever the lithium requires i.e. 13.8v?) I think this means the start batt would only ever charge in 'absorption' phase, at 13.8v, instead of getting a bulk phase of 14.8v as it does now. Would that matter? My logic is it will charge if batt voltage is less than charge voltage.
Also, when the voltage sensitive relay is open, the charge rate per batt is dependent on the resistance, which is a function of how well charged the batt is (fully charged, high resistance). So the less charged batt takes the most current. With LiFePO4 being completely different chemistry and resistance to the AGM, is there a can of worms using a voltage sensitive relay to charge both batts from the same alternator?
I'm sure there is a bunch of ways to deal with this, but I'm keen to not spend loads of $$$ enabling the install of the new tech batt, the whole point of which is to save $$$ and come up with a robust system.
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Post by em on Jun 5, 2023 15:01:08 GMT 12
I bought two sunnytech LifePo4 batts and spent two weeks trying to get them to work in parallel at home not on the boat .
They were unbalanced so it sent my system haywire . I gave up and sold them on trademe at a loss , they did work ok individually though .
If you seriously consider LifePo4 get the best you can afford as it saves a lot of headaches .
Matt or islandtime has both types of batts on his boat so he might give you some straight answers about how to charge them seperately .
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Post by fish on Jun 5, 2023 15:28:00 GMT 12
I bought two sunnytech LifePo4 batts and spent two weeks trying to get them to work in parallel at home not on the boat . They were unbalanced so it sent my system haywire . I gave up and sold them on trademe at a loss , they did work ok individually though . If you seriously consider LifePo4 get the best you can afford as it saves a lot of headaches . Matt or islandtime has both types of batts on his boat so he might give you some straight answers about how to charge them seperately . Oh, there is always a fish-hook buying the cheapest product. If they were unbalanced, could you not return them on warranty? What size batts did you get? I am eyeing up a single 200 Ah. Still considering lead carbon as well. Currently considering all the technical implications. The dual charging one could rule out lithium by itself if it means spending another several hundred dollars on an item to balance up the charging parameters between different batts.
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Post by em on Jun 5, 2023 15:45:46 GMT 12
I bought two sunnytech LifePo4 batts and spent two weeks trying to get them to work in parallel at home not on the boat . They were unbalanced so it sent my system haywire . I gave up and sold them on trademe at a loss , they did work ok individually though . If you seriously consider LifePo4 get the best you can afford as it saves a lot of headaches . Matt or islandtime has both types of batts on his boat so he might give you some straight answers about how to charge them seperately . Oh, there is always a fish-hook buying the cheapest product. If they were unbalanced, could you not return them on warranty? What size batts did you get? I am eyeing up a single 200 Ah. Still considering lead carbon as well. Currently considering all the technical implications. The dual charging one could rule out lithium by itself if it means spending another several hundred dollars on an item to balance up the charging parameters between different batts. I was offered replacements not a refund but the chances of them not being balanced as well was high . I had 24V 300AH I think ? They ran our house individually no problem it was just the parallel thing that fucked them up , one would reach the fully charged voltage set point before the other and the other would reach the low voltage warning set point before the other .
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Post by em on Jun 5, 2023 16:03:18 GMT 12
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Post by em on Jun 5, 2023 16:13:51 GMT 12
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Post by Fogg on Jun 5, 2023 16:20:13 GMT 12
Worth talking to Matt / Island Time about this - he reckoned it would cost me about $5k to do a full conversion of Fogg from AGM over to all Lithium - but that would include a full switch out of batteries plus adjustments/ replacement of charging controllers plus essential safety controllers (to prevent overheating) plus labour costs (cos Matt knows I always pay for top equipment and get someone else to do all the work).
If you were to do it yourself and makes smarter choices you could probably do it for half of that ie $2-2.5k.
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Post by fish on Jun 6, 2023 11:33:38 GMT 12
The short story is, to combine a Lith house batt with an AGM start and charge off an alternator, you need a DC-DC charger. These are about $400 and are limited to 30 amps charging.
One of the big advantages of going lith was to charge at high rates, a 200Ah lith batt has recommended charging of 40A, and up to a max 100A if you are keen. You can parallel more DC-DC chargers for more current, and a 9 amp model is currently on special for $100 (normally $130) which would get to 39A charging, but cost an extra $500 plus some ancillary fittings and cables. This shifts the economics of going lithium backward somewhat, and brings Lead Carbon into play more acutely.
Lead carbon can accept massive charging currents (more than my alternator if I want). It is also resistant to partial states of charge, as it is highly resistant to sulphation. Design life is 15 or 20 yrs, depending on who's spec's you read, and for good quality (top shelf, top dollar) units the cycle life is equivalent to lith. AND lead-carbon is notably cheaper than lith, esp when considering the DC-DC charger. They are heavy though, and need to be fully charged at least once per month.
So far I've found 250Ah Pb-C batts at between $600 and $900. At a maximum of 80% DOD (intermittently) that gives 200Ah of working capacity. A 200Ah lith is between $1,400 and maybe $2,200, plus $400 or $500 for a DC-DC charger.
The problems with Lith batts on an alternator are as follows: 1) Lith batts have very low resistance, so if you use a dumb alternator, it will produce excess current and cook itself within minutes. So you need a smart regulator to limit the current, then 2) If the BMS of the Lith trips out, you will blow the diodes in your alternator, as it will be pushing amps out and then suddenly no-where for the amps to go. 3) If you use a voltage sensitive relay to seperate your start and house batts, the resting voltage of a lith batt is too high and foxes the VSR. I think resting voltage is 13.8v, and the VSR's open at 13.2v or 13.4, so you can't use a VSR to separate your start and house batts (that is what I currently have onboard, so I would have to bugger around with all the isolating switches and wiring etc which I'm sure will cost more $$$ while I'm installing the DC charger)
The basic set up for a DC-DC charger is to charge off the start batt. This way the alternator is isolated from the lith, if the BMS trips out. These DC chargers allow you to set up the specific charging voltages seperately for each battery. I've looked at the victron ones, and they all have victron's smart app and blutooth, so they all have full data logging and full parameter programming via your phone. Very handy.
Questions I need to resolve if going Pb-C: The Pb-C batts have very low resistance as well, like the lith. I need to understand if our Balmar smart regulator can safely limit the current and protect the alternator (it should be able to). I also need to understand how both batts (AGM and Pb-C) charge when the VSR is open, given that the Pb-C will have loads lower resistance than the AGM. I assume this means that once the VSR opens, the Pb-C house batt takes all the charge current.
I am assuming that as the Pb-C is still a lead acid battery, the voltage charging profiles will be compatible with the AGM. The Pb-C have bulk, absorption and float phases, all of which I am familiar with. Our solar controller will be fully compatible. I see it is important to have batt temp monitoring and voltage de-rating for increased temps. We have that function on both our smart regulator and solar controller. This is because if you are charging at high currents, you have to make sure you don't cook your batt and create a thermal run-away (i.e. a bomb). This is not a big risk, and not as risky as over-charging a lith.
I am going to go and get some professional advice. Right now, I've seen a 250Ah Pb-C batt for $600 (also available at $750 and a slight variation at $900) If everything works, there are no technical fish hooks, and the quality and warranty are OK, I could potentially swap out my high maintenance Flooded Lead Acid batts with about 100 Ah working capacity for this new Pb-C batt, get 200Ah working capacity, between 1000 and 8000 cycles and 15 yrs design life, AND be able to charge them at 40 or 50 amps (giving 24 hrs worth of ergs in the time it takes to motor into an anchorage) all for maybe $600.
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