Simple LifePo swap sense check

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stranded

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Following a recent thread in which I ruled out switching to LifePo I have taken a good look at myself.

I can’t get my head round the technical stuff but then I don’t need a state of the art installation- I don’t need more power, but I am very attracted to the lower weight (our battery box is part of the furniture and the only way I can fit 400+AH of agm is with 2xc.65kg batteries, which are not getting any easier to manhandle) It must of course be safe. Seems to my simple mind I might get away with:

1. Replace 400ah agm service battery with 200ah Renogy drop in LifePo with built in BMS: 12V 200Ah Lithium Iron Phosphate Battery w/ Bluetooth

2. Disconnect alternator feed (via Sterling charge splitter) from service bank and install DCtoDC charger from engine start battery to service battery.

3. Retain 400 watts solar via 2xVictron mppt controllers to LifePo (continuing to use Smartsense?)

4. Adjust charge parameters of Mastervolt Mass Combi smart charger/inverter (non-lfp model) to LifePo manufacturer spec (read something somewhere about switching to one stage rather than 3 stage charging?).

5. Adjust LifePo BMS to 12 - 14.2v range?

6. Install a type t fuse (whatever that is) <7” on consumer side of battery +ve
I am sure it can’t be this easy. But could it. Any complicating factors?
 
That sounds like it should work. But will the starter and house batteries be able to run in parallel? It's not necessarily forbidden but generally you want to keep them separate.
 
Nope, that's about it. You will need to sit down in a dark room after you seen the price of a class T fuse. The alternative is a NH fuse from Bimble Solar plus some spares just in case. We have the 160A version but there are other sizes. Some other fuses to and from the DC>DC charger which needs to be mounted in a well ventilated area btw. Our Victron DC>DC reaches 59.9c mounted on the outside of the nav seat with a 3" hole behind it.

We have the Victron Smart Sense on the engine start battery now but it is a good point worth thinking about. Our MPPTs are next to the batteries so see the same temperature and voltage.

Consider Victron Power In, which with a 4 bolt mod becomes a brilliant fuse box with bus bars, about £130 if the budget will stand it.

You will probably need to make a few new cables up, so £26 for a cheap yellow 8T hydraulic crimper from Amazon well worth the money and despite the naysayers, produces good crimps.

Remove Sterling split charger, no longer required and sell it on here.

Purchase electric kettle and induction hob to save using gas all the time. With 400w of solar potentially halve your gas usage.
 
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Pete7 said:
Nope, that's about it. You will need to sit down in a dark room after you seen the price of a class T fuse. The alternative is a NH fuse from Bimble Solar plus some spares just in case. We have the 160A version but there are other sizes. some other fuses to and from the DC>DC charger which needs to be mounted in a well ventilated area btw. Our Victron DC>DC reaches 59.9c mounted on the outside of the nav set with a 3" hole behind it.

We have the Victron Smart Sense on the engine start battery now but it is a good point worth thinking about. Our MPPTs are next to the batteries so see the same temperature and voltage.

You will probably need to make a few new cables up, so £26 for a cheap yellow 8T hydraulic crimper from Amazon well worth the money and despite the naysayers, produces good crimps.
Click to expand...
All good advice.
My big yellow crimper has done me well. Any poor crimping jobs have been down to the quality of the lugs themselves.
If in doubt, drop a size on one or both dies.
 
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Kelpie said:
That sounds like it should work. But will the starter and house batteries be able to run in parallel? It's not necessarily forbidden but generally you want to keep them separate.
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You see, you’ve exposed my ignorance already! The house and engine (and bow) batteries are on their own switched circuits. I thought by disconnecting the alternator from the house I would be separating them completely. House and bow charged only by alternator (or secondary mastervolt output for engine), house by DC>DC and solar. Could you explain where they will be paralleled - is it that the DC>DC will work both ways - hadn’t thought of that. Anything (diode?) I can (simply!) do about it please.
 
stranded said:
You see, you’ve exposed my ignorance already! The house and engine (and bow) batteries are on their own switched circuits. I thought by disconnecting the alternator from the house I would be separating them completely. House and bow charged only by alternator (or secondary mastervolt output for engine), house by DC>DC and solar. Could you explain where they will be paralleled - is it that the DC>DC will work both ways - hadn’t thought of that. Anything (diode?) I can (simply!) do about it please.
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DC>DC only work one way. Perhaps not connect Mastervolt to engine battery, or there is a risk of creating a loop. Digital VSR (£40) to charge bow thruster battery perhaps?
 
OK - well that sounds doable.

Really pushing my luck here, but would the fact that the alternator is fed through a Sterling ProSplit R:

(0.0V Drop Alternator Splitter Pro Split R)

mean that I could in fact keep the alternator feed to the LifePo - as that should ensure that if the BMS switches the LifePo charging off the ProSplit would redirect the alt output to start or bow?

And is Renogy a tolerably decent LifoPo supplier?
 
I think it would be better to use a DC>DC if the alternator is a secondary charging source, solar being the primary. We use our DC>DC occasionally to put a bit of puff in the LFP but don't bother charging it all the way up, no need. There is a cheaper long wire alternative with the wire providing the resistance to limit charging. However, I wanted great control over voltage etc at the cost of lower current charging. If you go the DC>DC route the sterling Pro Split has no real purpose, in which case remove it to keep it simple (KISS approach).

Renogy are a big company, but not convinced about what will happen if there is a problem or how quickly and easily it will be sorted. Sterling are another option and finally Life Batteries in Falmouth come strongly recommended on the 12 Boating Group on FB. More to the point Mark stands by his business name and has always resolved any problems quickly, as has Sterling who replaced one battery for me without fuss.
 
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lustyd said:
That's an enormous case for a 200Ah and quite pricey too. Check out Lithium Leisure Battery | Fogstar UK which will give you greater power density and lower cost.
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Ah - that’s really helpful, and answers a question I have just fired off to Life batteries recommended by Pete - their dimensions seem to be wrong because their 300 and 460s seem to be the same size box - hadn’t realised there would be room for air in there.

So a 460 is now top of my Santa list - unless the bigger capacity throws up new challenges thus making less simple? I have 200 watts optional extra solar so 600 total to compensate if we get carried away with all that power - should be OK in summer I think.
 
stranded said:
their dimensions seem to be wrong because their 300 and 460s seem to be the same size box
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I asked Fogstar that exact question! Their support was extremely helpful and quick and their batteries highly regarded.

The boxes are standard sizes so yes, the dimensions are identical accross several sizes in the range, I believe Fogstar have 4 physical sizes in the range each with multiple capacity SKUs. If not buying from Fogstar check whether they included the handles in the length - Fogstar now do but didn't before. It was a genuine mistake, they apologised and offered full refund but we compromised and they agreed to honour the full warranty even if I cut off the handles to make it fit.

Worth mentioning that the Fogstar 230, 280 and 300Ah are in a quite a bit smaller case (L-380mm x W-190mm x H-245mm) so you may actually get 600Ah in your space if you already have two lead batteries in there. Their 460Ah is roughly the same dimensions (L-522mm x W-240mm x H-218mm) as the Renogy (L-522mm x W-240mm x H-224mm) you were looking at
 
Thanks lusty. Think we’ll stick to the 460 or I might really get carried away beyond our charging capability.

On a related note - looking at a Victron Orion 30A dc to dc charger. They do isolated or none isolated. No idea which I need but as far as I can see apart from a small price and efficiency premium an isolated one would do either way, whereas an unisolated might not. Do you know if that’s right?
 
stranded said:
beyond our charging capability.
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My 300Ah takes over 10 hours to charge but consequently takes days to discharge with everything running. Don’t be concerned about charging capacity, it’ll eventually fill up. Cost is obviously a consideration though!

Isolated is for when your negatives are not joined between the engine and house. Usually they are joined on the negative on most boats with a common busbar or stud. I have the non isolated 30A and it works well, make sure you get the charger version as there’s also a DC to DC converter that’s just a power supply.
 
lustyd said:
My 300Ah takes over 10 hours to charge but consequently takes days to discharge with everything running. Don’t be concerned about charging capacity, it’ll eventually fill up. Cost is obviously a consideration though!

Isolated is for when your negatives are not joined between the engine and house. Usually they are joined on the negative on most boats with a common busbar or stud. I have the non isolated 30A and it works well, make sure you get the charger version as there’s also a DC to DC converter that’s just a power supply.
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Ah OK, thanks - non-isolated should work fine then. Still sticking to 460 - don’t tempt me!
 
300 was ample for us. Even with Starlink it’s still lasting many days if we remember to switch it off overnight!
 
Pete7 said:
I think it would be better to use a DC>DC if the alternator is a secondary charging source, solar being the primary. We use our DC>DC occasionally to put a bit of puff in the LFP but don't bother charging it all the way up, no need. There is a cheaper long wire alternative with the wire providing the resistance to limit charging. However, I wanted great control over voltage etc at the cost of lower current charging. If you go the DC>DC route the sterling Pro Split has no real purpose, in which case remove it to keep it simple (KISS approach).

Renogy are a big company, but not convinced about what will happen if there is a problem or how quickly and easily it will be sorted. Sterling are another option and finally Life Batteries in Falmouth come strongly recommended on the 12 Boating Group on FB. More to the point Mark stands by his business name and has always resolved any problems quickly, as has Sterling who replaced one battery for me without fuss.
Click to expand...
Thanks Pete - all very helpful and reassuring. I’ll stick to solar and shorepower when available for the LifePo. Think I need to keep the ProSplit to manage the start/bow battery spilt, though I’ll need to check if the 3 output version will still work OK with just 2 outputs - can’t see why not.
 
You can't really have too much battery capacity, the great thing about LiFePO4 is that it's very happy sitting around partially charged. One caveat is that you do want to get them up to nearly 100% every so often for the balancer to do its job, but that's not a big deal and you'll not really notice any imbalance if you're staying around mid charge anyway.

We started out with 270Ah and ran like that for about two years, doing almost all of our cooking electrically, as well as running the fridge and freezer. We recently increased to 550Ah which lets us get through a few days of dull weather.
We do occasionally still use gas, that's our main backup if the battery is low, rather than engine charging. There's also a couple of meals that better suit gas cooking. But cooking off solar power has slashed our gas use. We're still using the same 2.9kg bottle we bought in April, and we cook onboard every night.
 
Kelpie said:
All good advice.
My big yellow crimper has done me well. Any poor crimping jobs have been down to the quality of the lugs themselves.
If in doubt, drop a size on one or both dies.
Click to expand...

I have moved to use Klauke lugs. They are a bit more expensive, but are much thicker material.

One challengette is that all manufactured seem to choose different sized lugs so you might need M6, 8, 10, 12 lugs!
 
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