Replacing house batteries project

[SimonNZ]

Hi everyone

I'm researching battery replacement and interested in any tips or expertise!

Our 40ft Beneteau has five 100Ah ventilated lead acid house batteries in two banks; 3 in primary, 2 in secondary we can switch in and out. Engine battery is 130Ah, also ventilated lead acid.

Inputs:

Shore power charger to house and engine battery
310w solar to house
80Ah alternator to engine battery and house via Sure Power 1203 120A multi battery isolator
Turbine contribution to house not counted, keeping as a 'bonus' energy input until I've got around to figuring out what it contributes.

Everything works fine but the batteries are 10 years old. I want to replace the house batteries, reduce capacity and simplify the arrangement while leaving re-expansion possible later. I'd also like to leave the engine battery for now. I'm working on our energy budget. We're mostly day sailors, fridge is the likely the highest consistent consumer followed by water pump and Autohelm -

I'm ordering a Victron smart shunt to get more accurate detail and hoping to prove 2 x 100Ah will do for now, either in one bank or one battery in each bank so I can still switch it out. I'm also hoping to leave the old engine battery in place for now but it will get replaced at some point.

Lithium batteries are tempting. The extra cost is fine if I can get away with two, five is pushing the project budget!

I don't know if I can charge house lithium and engine lead acid side by side. The shore power charger is a Victron with 3 outputs so I've asked them; it's already split to engine and house but I don't know if they're isolated - one would hope so!

I also don't know what the alternator effect would be but I'm hoping the isolator will take care of that.

Are there any other good tips that people with experience can offer?

Thanks!

 

[Boater Sam]

Without a means of controlling output, a lithium battery will cause the alternator to burn out, FLA to Lithium is not a straight swap.

 

[SimonNZ]

Thanks!

Victron make a DC-DC converter and someone recommended no more than half the output of the alternator. That's 80A, so I could put a 30A converter before the Lithium bank, but after the multi-battery isolator. Will add it to my drawings.

 

[simonfraser]

the victron shunt is excellent
i just spend 24 hrs with the fridge and diesel heater on, used 40Ah out of 200Ah 2 battery Pb setup
so you may not use as much as you think ?

 

[Poey50]

Thanks!

Victron make a DC-DC converter and someone recommended no more than half the output of the alternator. That's 80A, so I could put a 30A converter before the Lithium bank, but after the multi-battery isolator. Will add it to my drawings.

Hi everyone

I'm researching battery replacement and interested in any tips or expertise!

Our 40ft Beneteau has five 100Ah ventilated lead acid house batteries in two banks; 3 in primary, 2 in secondary we can switch in and out. Engine battery is 130Ah, also ventilated lead acid.

Inputs:

Shore power charger to house and engine battery
310w solar to house
80Ah alternator to engine battery and house via Sure Power 1203 120A multi battery isolator
Turbine contribution to house not counted, keeping as a 'bonus' energy input until I've got around to figuring out what it contributes.

Everything works fine but the batteries are 10 years old. I want to replace the house batteries, reduce capacity and simplify the arrangement while leaving re-expansion possible later. I'd also like to leave the engine battery for now. I'm working on our energy budget. We're mostly day sailors, fridge is the likely the highest consistent consumer followed by water pump and Autohelm -

I'm ordering a Victron smart shunt to get more accurate detail and hoping to prove 2 x 100Ah will do for now, either in one bank or one battery in each bank so I can still switch it out. I'm also hoping to leave the old engine battery in place for now but it will get replaced at some point.

Lithium batteries are tempting. The extra cost is fine if I can get away with two, five is pushing the project budget!

I don't know if I can charge house lithium and engine lead acid side by side. The shore power charger is a Victron with 3 outputs so I've asked them; it's already split to engine and house but I don't know if they're isolated - one would hope so!

I also don't know what the alternator effect would be but I'm hoping the isolator will take care of that.

Are there any other good tips that people with experience can offer?

Thanks!

Have you read this from Rod Collins of MarineHowTo?
Drop-In LiFePo4- Be an Educated Consumer

You shouldn't charge LiFePO4 (LFP) side by side with lead acid and the three output Victron mains charger won't deliver separate charge profiles to match LFP and lead acid needs. The simple method that some are using is for alternator charging of the engine battery and then this charges the LFP battery via a 30 amp Victron Orion battery to battery charger. That can be set up for LFP and this also takes care of the load dump and voltage spike when you get an LFP blackout. However, I don't think this is a good safe system. Drop-in LFP has an internal non-communicating BMS so you get no warning of a BMS-inspired blackout which can be caused by numerous reasons as Rod Collins discusses. So, although this simple set-up looks appealing and protects the alternator diodes, you still can have a total domestic bank loss. Imagine dealing with that crossing a busy shipping lane at night. One solution is to keep all essential safety circuits run from lead acid and I see that this is the set-up that Morgan's Cloud is now advocating. For day sailing and short holidays I really doubt LFP is worthwhile for you.

 

[Sandy]

I am not convinced that Lithium are cost effective unless you are doing trips >90 days or have cash to burn, as a Scot I don't.

My solution was 3 * 130 Ah house and a 75 Ah engine AGM batteries. AGM can be discharged to 50% capacity and if the casing is ever damaged you won't have acid sloshing about. They are all charged via 70 amp alternator and shore power with a VSR. Having them all as AGM means that I can use the same charging profile.

I upgraded my shore power, shunt and added a Battery Smart Sense to Victron kit last October and am enjoying the detailed information on usage. Interesting to see that 1.6Ah per day or 11.76 Ah per week is needed just to run the monitoring system.

 

[Tranona]

With that pattern of usage then what you have is overly complicated. - although you don't say whether you have a windlass and/or bow thruster and how it is powered. You don't need an engine start of 130Ah, nor the 2 part house bank. For your house needs a bank of 2-300Ah either lead acid "leisure" or AGMs and the engine start a75Ah lead acid (car battery). The 2 banks should be separately switched with a means of switching to the house bank for engine start in an emergency. Your split charger will take care of the alternator charge (do you use shorepower) and the solar will keep up the house bank.

Lithium is a waste of time and money for your pattern of usage. Lead acid will likely give you 10 years life and AGMs typically 50% more. Of it helps, as a guide Bavaria with similar size boats fit 3*95Ah AGMs for house, and one each of the same size and type for engine start and windlass/bow thruster. The engine start is a bit OTT but I guess they got a good deal on buying thousands of thee same size and type a year. This is what I had on my last boat plus using mains charging after every trip and never had any problems with capacity. Your solar will do the same job as the mains in recharging after a trip if you don't run the engine enough.

 

[V1701]

Next time I need to replace my lead acids I'm planning to have a proper look at lead carbon - more expensive but more cycles and tolerant of deeper discharging...

 

[Poey50]

Next time I need to replace my lead acids I'm planning to have a proper look at lead carbon - more expensive but more cycles and tolerant of deeper discharging...

And greater resistance to sulfation at partial states of charge - the great silent killer of marine leisure batteries.

 

[KompetentKrew]

Next time I need to replace my lead acids I'm planning to have a proper look at lead carbon - more expensive but more cycles and tolerant of deeper discharging...

Victron are offering these now.

 

[goeasy123]

I agonized over Lithium for a long time. Unless you're going for a different usage regime... like cooking all electric it's not a good idea for a number of reasons. We went for lead carbon with a similar capacity to yours (420Ah in 3 house batteries).

Victron are expensive, but mainstream manufacturers now produce good product at reasonable prices. The best I've found is the Leoch LDC range. Apart from having to change nothing in the system the main benefit for us is faster solar charging.

See LDC - Superior Lead Carbon AGM - LDC - Superior Lead Carbon AGM

You can get 500Ah for around £600 - £700

 

[SimonNZ]

This is such amazing and helpful advice, thanks so much every much. Very much appreciated.

Looking forward to digging deeper in the weeds and about to get that shunt ordered!

 

[KompetentKrew]

I agonized over Lithium for a long time. Unless you're going for a different usage regime... like cooking all electric it's not a good idea for a number of reasons. We went for lead carbon with a similar capacity to yours (420Ah in 3 house batteries).

Victron are expensive, but mainstream manufacturers now produce good product at reasonable prices. The best I've found is the Leoch LDC range. Apart from having to change nothing in the system the main benefit for us is faster solar charging.

See LDC - Superior Lead Carbon AGM - LDC - Superior Lead Carbon AGM

You can get 500Ah for around £600 - £700

Thank you - that's about half the price of the Victron ones.

Victron claim that theirs cope well with complete discharge, and claim they'll last 500 cycles @ 100% DoD but specify 1000 cycles at 60% DoD [PDF] - this is the same as Leoch's LDC.

I think I'll proceed on the basis that they're the exact same chemistry and order the Leoch in due course.

 

[Daydream believer]

Victron are expensive, but mainstream manufacturers now produce good product at reasonable prices. The best I've found is the Leoch LDC range.

I would be warry of Leoch
I bought 2 No. 100 amp Leoch AGMs start of covid for domestics. I do not have much elecctrics. I do have a cool box but it is on a cut out at 12.9V & only works under engine & shore power. Other stuff are nav lights, chart plotter Autopilot & instruments. plus cabin lights when under way. I do not moor so shore power goes on every day in port. They are kept well charged. I have a red flash start battery.
I found that they would charge 24 hours on smart charger- I have changed this to a Victron one in case the old charger was reverse draining the batteries when turned off.
They drop from 12.9 to 12.7 within a couple of days of idle. power turned off. Then when used drop rapidly to 12.4. I told Leoch about this when they were 2 months out of warranty & to their praise they collected them, tested & changed for new ones FOC . all I had to do was parcel them up.
However, the replacements are not much better. I have not used them much but I have been monitoring them over the winter & just draining the 100 litre CW tank drained them from fully charged to 12.4 V. They slowly went back to 12.5 after 24 hours. But I am far from impressed
My first set of 2 lead acid Varta batteries lasted 5 years & were used for start & domestic & were used a lot. They performed far better than these leoch are currently doing. So far I have not done a night trip but it does worry me that they will hold up.

 

[Minerva]

I am starting to pay attention to this new battery tech as I will probably look to upgrade our system in the next few years. From what I have seen Lithium batteries the £/ah appears to be 3times that of cheap, generic leisure batteries, and twice the price of branded leisure batteries (used the Leoch as recommended above as the branded).

Battery brand	Labeled capacity ah	max useable discharge %	adjusted ah	price	£/ah
Renology Lifpo4	200	0.8	160	£916.00	£6
Leoch LDC	180	0.6	108	£282.00	£3
Superbatt 120ah	120	0.5	60	£120.00	£2

The question, in my mind at least comes down to how many cycles each battery can reasonably be expected to last in the hands of normal folk? Can you reasonably expect lithium batteries to last 3x that of cheapo generic lead acid batteries or twice that of branded batteries? It's probably not too unrealistic a proposition...

 

[KompetentKrew]

By "max useable soc" I guess you mean maximum depth of discharge, @Minerva?

 

[Minerva]

By "max useable soc" I guess you mean maximum depth of discharge, @Minerva?

yes, thats correct.

I also don't claim to be in any way an expert, these are just my fag packet calcs - shoot me down if I've made a mistake.

 

[Daydream believer]

A mate of mine has bought a battery from China. Not sure if it is lithium or lipo or whatever, But it is smaller than a wet cell battery & 100 Amp. It cost him about £100-00 plus delivery. He wired it straight up to his normal system & spec says that he can flatten it almost right down to zilch. He has not changed anything else. His alternator seems to cope OK & charges it back to full- so he says
He used it for a couple of months last year, so has not used it in real earnest. However, he has deliberately left his fridge on & used his electrics to the full- cooker hob etc & says it has performed Ok. His alternator has not overheated -yet
I have showed him videos about people telling one how these should all be set up in special ways & he says it is b..x & unnecessary. I find it difficult to believe & am waiting for something to go wrong. But so far so good.

 

[BabaYaga]

The question, in my mind at least comes down to how many cycles each battery can reasonably be expected to last in the hands of normal folk? Can you reasonably expect lithium batteries to last 3x that of cheapo generic lead acid batteries or twice that of branded batteries? It's probably not too unrealistic a proposition...

Leoch gives this type of information on the subject of 'how many cycles' (laboratory figures obviously).
As can be seen, it is the actual depth of discharge that they are subjected to that determines the amount of cycles one can expect.

This is for Deep Cycle Lead Carbon.

 

[jaminb]

I am (still) in the middle of this dilemma. I can replace my 3 leisure batteries for £300 or upgrade to AGM's for £450 or upgrade everything spend £1000's on Lithium and new chargers / alternators which may not suit my weekend sailing,.

For the occasional longer trip could I just use an isolated Lithium battery as a booster on the longer trips to top up the cheapo batteries with jump leads / the shore power socket and then charge the Lithium with a dedicated charger when back up when on shore power?

thanks