Which leisure battery?

[Mike Hurley]

10 minutes ago, Alan de Enfield said:

 

 

What happened to the Generator you bought ?

 

(Is this still the wooden-top that you bought and had all the problems with - engine, toilet, cabin water leaks, replacing windows, injector pump, cylinder head replacement, leaking stern gland etc etc)

 

Did you girlfriend ever stay more than that one night when the wooden cabin leaked on her ?

And then there was no power for the hairdryer in the morning.

[rusty69]

1 hour ago, Tony Brooks said:

The abilities of LiFePo4 lithium MIGHT give you a better chance of keeping them charged but the price for batteries and the required charge controller equipment may well cost several £1000.

^^^^^^^^Wot he said.

[Alan de Enfield]

2 hours ago, Tony Brooks said:

The abilities of LiFePo4 lithium MIGHT give you a better chance of keeping them charged but the price for batteries and the required charge controller equipment may well cost several £1000.

 

Irrespective of the type and number of batteries 'you' still need to generate enough 'leccy to replace what you have used (and, to accomodate the losses as well)

No battery actually generates leccy, it is just storage vessel - if you don't put any in then you cannot get any out.

[rusty69]

30 minutes ago, Alan de Enfield said:

 

Irrespective of the type and number of batteries 'you' still need to generate enough 'leccy to replace what you have used (and, to accomodate the losses as well)

No battery actually generates leccy, it is just storage vessel - if you don't put any in then you cannot get any out.

 

Though this statement is obviously true, the type of battery chemistry offered by LiFePo4 cells will allow a greater range of discharge for the same nominal capacity than lead acid can offer, with the addition that they can be left at any (within reason) state of charge without damage. The BMS will then 'allow' you to use the cells if/when capacity is available.

 

Your solar system (alone) is unlikely to provide the daily requirement for your needs most of the time outside the peak solar months without added charging through engine or generator, hence the MIGHT.

 

I don't know what this water distiller thing is, but it seems to be an awfully heavy power consumption. The money saved by turning the thing off would buy a lot of bottled water.

[Alan de Enfield]

1 hour ago, rusty69 said:

Though this statement is obviously true, the type of battery chemistry offered by LiFePo4 cells will allow a greater range of discharge for the same nominal capacity than lead acid can offer, with the addition that they can be left at any (within reason) state of charge without damage. The BMS will then 'allow' you to use the cells if/when capacity is available.

 

No argument here - BUT - what you use you MUST put back, if you take twice as much out of LiPo batteries (compared to FLA)  then you need to put twice as much back into get them fully charged - you cannot keep taking out more than you put back with ANY type of battery.

[rusty69]

1 minute ago, Alan de Enfield said:

 

No argument here - BUT - what you use you MUST put back, if you take twice as much out of LiPo batteries (compared to FLA)  then you need to put twice as much back into get them fully charged - you cannot keep taking out more than you put back with ANY type of battery.

Yes, you must put it back, but the point is, you might not need to do so as soon as you would with LA batteries.

 

Its probably a moot point anyway. I'm sure using the water tank analogy, few people think they can take water out of the tank indefinitely without ever topping it up, do they?

[Tony Brooks]

I would also suggest that as, it seems, lithiums will accept as much electricity as any charge source can throw at it without limiting the charge like lead acids do, then the time to fully charged (or as full as you want) should be sooner given the same rated charger. So with lead acids and solar by noon the maximum charge is likely to have been reduced by the batteries, whereas with lithiums they will still be accepting whatever the solar can supply. I am not sure how much difference it makes, but I would expect it to be a lot for solar and engine charging. I acknowledge he won't get out more than he puts in, but lithiums should get the job done sooner, or to pit it another way, should make maximum use of the available charge whereas LAs make very poor us eof the charge.

27 minutes ago, rusty69 said:

Its probably a moot point anyway. I'm sure using the water tank analogy, few people think they can take water out of the tank indefinitely without ever topping it up, do they?

 

Looking at the posts we get about this sort of thing I don't think that is a sound statement. It seems the OP did/does, and all the scores of other who went before him. I doubt they make such an analogy, and if they do, they simply do not understand it.

[IanD]

9 minutes ago, Tony Brooks said:

I would also suggest that as, it seems, lithiums will accept as much electricity as any charge source can throw at it without limiting the charge like lead acids do, then the time to fully charged (or as full as you want) should be sooner given the same rated charger. So with lead acids and solar by noon the maximum charge is likely to have been reduced by the batteries, whereas with lithiums they will still be accepting whatever the solar can supply. I am not sure how much difference it makes, but I would expect it to be a lot for solar and engine charging. I acknowledge he won't get out more than he puts in, but lithiums should get the job done sooner, or to pit it another way, should make maximum use of the available charge whereas LAs make very poor us eof the charge.

Agreed -- IIRC those analyses posted from the JRC website have a total round-trip loss (charger + batteries + inverter) of about 15% which implies lithium batteries, because that's what most off-grid systems use nowadays.

 

Lead-acid will have worse performance than this especially since they need regular charging to 100% SoC and equalising, as well as having increased losses when charged or discharged at high rates.

 

The system as proposed simply won't work year-round even with lithium batteries, and even more so with lead-acid... 😞

Edited February 13, 2023 by IanD

[TheBiscuits]

1 hour ago, rusty69 said:

using the water tank analogy, few people think they can take water out of the tank indefinitely without ever topping it up, do they?

 

That's what the watermaker is for, to avoid having to go to a tap!

[doratheexplorer]

19 hours ago, Tony Brooks said:

I would also suggest that as, it seems, lithiums will accept as much electricity as any charge source can throw at it without limiting the charge like lead acids do, then the time to fully charged (or as full as you want) should be sooner given the same rated charger. So with lead acids and solar by noon the maximum charge is likely to have been reduced by the batteries, whereas with lithiums they will still be accepting whatever the solar can supply. I am not sure how much difference it makes, but I would expect it to be a lot for solar and engine charging. I acknowledge he won't get out more than he puts in, but lithiums should get the job done sooner, or to pit it another way, should make maximum use of the available charge whereas LAs make very poor us eof the charge.

 

Looking at the posts we get about this sort of thing I don't think that is a sound statement. It seems the OP did/does, and all the scores of other who went before him. I doubt they make such an analogy, and if they do, they simply do not understand it.

I think you're right, but I'd rather spend the few thousand quid on a top notch super quiet generator which would be useful all year round.  In winter, those batteries will be flat whether or not they're lithium, if relying solely on solar.

[jhodgski]

On 13/02/2023 at 13:03, Alan de Enfield said:

 

 

What happened to the Generator you bought ?

 

(Is this still the wooden-top that you bought and had all the problems with - engine, toilet, cabin water leaks, replacing windows, injector pump, cylinder head replacement, leaking stern gland etc etc)

 

Did you girlfriend ever stay more than that one night when the wooden cabin leaked on her ?

I've been unable to reply any sooner, but I went with this battery in the end:

https://www.alpha-batteries.co.uk/12v-290ah-expedition-plus-agm-leisure-battery-exp12-290/

 

Should be enough to run the water distiller on sunny days, which I will settle for.

 

I appreciate the very helpful replies, such as from IanD.

 

Alan de Enfield, for your information, I've never had a wooden-top boat. But maybe you can explain the point of your quoted message (and the Buzz Lightyear one)??