Which is better for extended battery life?

[Moped]

We are on a site in Spain for an extended period as it is low cost and cheaper than paid for aires in the area.

I have the battery charger turned off as there is enough daily sun to fully charge the lead acid battery during the day.

The thinking (rightly or wrongly) that I won’t be using as much of the sites hook up reducing electric consumption and any final electric surcharge over and beyond the daily allowance of 5kw.

Now I could turn the battery charger on and keep the leisure battery pretty much fully charged on a trickle charge. Not sure what the impact of this would be on hook up energy consumption.

But the question is, from a battery life point of view, is it better to permit the battery to discharge to 70% each night and allow solar to fully charge the next day, or to turn the charger on and maintain the battery in a trickle charge state whilst using the 12v system nightly?

And as a supplementary question, what might the impact of leaving the charger turned on 24/7 on hook up electric consumption?

 

[trevskoda]

If its a lead acid battery dont run it down more than 30% or its life span will be short and will die very soon, best halfway are lead carbon batts, but these are not recommended to take down below 50%, if it were me keep it on hookup to charge them.

 

[wildebus]

We are on a site in Spain for an extended period as it is low cost and cheaper than paid for aires in the area.

I have the battery charger turned off as there is enough daily sun to fully charge the lead acid battery during the day.

The thinking (rightly or wrongly) that I won’t be using as much of the sites hook up reducing electric consumption and any final electric surcharge over and beyond the daily allowance of 5kw.

Now I could turn the battery charger on and keep the leisure battery pretty much fully charged on a trickle charge. Not sure what the impact of this would be on hook up energy consumption.

But the question is, from a battery life point of view, is it better to permit the battery to discharge to 70% each night and allow solar to fully charge the next day, or to turn the charger on and maintain the battery in a trickle charge state whilst using the 12v system nightly?

And as a supplementary question, what might the impact of leaving the charger turned on 24/7 on hook up electric consumption?

If I thought I would get enough Solar to prove my daily needs, I would not use the mains charger at all.
Dropping the battery down to 70% is not an issue at all - the only concern (and reason to use the mains charger) would be if you didn't have a reasonable battery capacity to through to the next morning once the sun has gone down.

 

[barryd]

Im gonna say based on no scientific knowledge at all that I dont reckon it will make much difference. Ive been plugged in for weeks on end and sat in one place for weeks on end just relying on solar and my batteries seem to last about the same amount of time. Six to seven years. Jury is out on my new fancy (to me) AGM system as its new but so far so good using the same methods.

I suppose you are being good to the environment though relying on solar when EhU is available.

 

[Fisherman]

I would have thought with plenty of solar that the chargers use of power would be minimal.
Quite frankly I could not be bothered faffing about in order to save what might be nothing or there about.
Regardless of wether the charger is on or off, your solar will probably do most of the charging.
But as Barry says you may have environmental reasons, if so fair enough.

 

[Moped]

My thought is if a battery claims to have 225 cycles and you are partly discharging it daily and recharging with solar you are using up cycles.

If you maintain the battery using the transformer you are not so not using life cycles.

So logically the transformer extends battery life as cycles not being used.

Is this right or wrong?

 

[jagmanx]

Just remember the Beatles song..
"Here coms the sun !"
If you use ehu, in the evening, your battery use will be minimal.
Solar will keep your battery 100%
No need to use the charger at all !
Some are built in and so will charge a bit.
I think you would be ok without ehu dependent on your evening usage !
Your battery(ies) will die anyway in time. So save on the ehu cost and put that in the "battery bank".
We use moho in summer and almost never plug in.
Only do so if it is included in the camp cost.
Daylight in Spain surely now good enuff ?

 

[wildebus]

I would have thought with plenty of solar that the chargers use of power would be minimal.
Quite frankly I could not be bothered faffing about in order to save what might be nothing or there about.
Regardless of wether the charger is on or off, your solar will probably do most of the charging.
But as Barry says you may have environmental reasons, if so fair enough.

It depends on how things are setup. The solar will likely think the batteries are full and go into a float mode permanently and the mains charger will be doing the bulk of the recharging.
However ... there will actually be no recharging anyway as if on EHU, the mains charger will effectively be acting as a 240V AC - 12V DC converter and all the power being used will be from EHU and not the Battery and not from Solar.

Financially, if you could be self-sufficient from Solar and you are paying for EHU - either provision OR useage, you are spending money unnecessarily.

My thought is if a battery claims to have 225 cycles and you are partly discharging it daily and recharging with solar you are using up cycles.

If you maintain the battery using the transformer you are not so not using life cycles.

So logically the transformer extends battery life as cycles not being used.

Is this right or wrong?

The cycles are based on the level of recharge.
e.g. a battery might have 225 cycles if you go from 50% SOC to 100% - so do that 225, and your battery is down to 70% of original capacity. But if you are going from 70% SOC to 100%, you might have 400 cycles, or 500 cycles.

These are all factors to consider though. And Jagmanxs point is well made - "So save on the ehu cost and put that in the "battery bank"". If you do have a battery with 225 cycles, it is likely a fairly cheap battery. And replacing it like for like would not be a very high cost.
Say it costs £100 for a new one? if it does 225 cycles, that works out to be £100/225 = 44p/cycle. So if the cost of EHU each day (which is stopping the battery being used effectively) is more than 44p/Day, you are better off using the EHU. If at 70% SOC, you can get 400 cycles, the cost per cycle would be 25p - so then, EHU over 25p/Day would mean you are paying more for Mains than the battery would cost you over its lifetime.

All theroretical. If it were me and I was getting good solar, I would use that to avoid getting into paying extra for EHU use (or even provision if there is a daily cost to just have it). The only reason to use the EHU in your situation that I can see is if it is "free" (or you have an allowance which is there if you pay for it or not) and you can save on gas by using electric for water heating and cooking.

 

[r4dent]

The thinking (rightly or wrongly) that I won’t be using as much of the sites hook up reducing electric consumption and any final electric surcharge over and beyond the daily allowance of 5kw.

And as a supplementary question, what might the impact of leaving the charger turned on 24/7 on hook up electric consumption?

The daily allowance is measured in kwh (Kilo Watt Hours) not kw.

Most sites have a meter showing usage that is clearly visible so it is worth doing a little objective investigation rather than seeking opinions.
With the charger switched off take a reading; wait a few days (i.e. a number of 24 hour periods) take another reading; take one from the other and divide by the number of days to work out your average usage.

Repeat with the charger turned on 24/7.

This will tell you if the charger use is free.

 

[Moped]

All interesting stuff and a good read. Thankyou.

I was curious what battery lifecycle actually meant. As advised above for a lead acid battery one cycle is from 50% to 100%, not from 0% to 100%. So a 100ah battery has 50ah available. It seems to hit 70% on the Sargent panel when the voltage is around 12.2v.

The voltage decline relative to percentage shown is not linear and it also depends on how much 12v stuff you have in use and the therefore the current draw. Turn things off and the voltage and percentage rise.

And by leaving the charger on the lifecycle allowance is not being used and the battery remains fully charged.

The fact is the 12v systems will not use even 1kwh of power in a day. The battery draw has to be around 25-30ah daily which for a 12v system is 0.36 of a KW x 36p (the excess site charge over the daily allowance included in the pitch price) =13p daily.

So basically turn the transformer on if hook up is available to save money!

(As an aside I have just turned the charger on and the lights have become brighter. Maybe other things might work more efficiently also such as water and heating pumps and Alde heating fans).

 

[wildebus]

.... (As an aside I have just turned the charger on and the lights have become brighter.

Yup - higher voltage = brighter lights. However, if the volts go too high, some things if designed for 12V (and I mean a regulated steady 12V, not a Motorhome battery "12V") can go POP!

Maybe other things might work more efficiently also such as water and heating pumps and Alde heating fans).

I supplied a Lithium Battery for someones Camper Conversion. As you will be aware, a Lithium battery settles for most of the time at around 13.1V or so. a little bit later on, I supplied him with a variable dimmer for him to wire into the Water Pump as he found it was running too fast

Because of these kind of voltage variations and using domestic 12V devices (such as Amazon Echos for example), I have a 12V regulator between the battery and the hab electrics

PS. You might want to check the Leisure Battery voltage with a Meter to compare against the Sargent display - the Sargent usually underread sufficiently to give a fairly misleading idea of the battery level.

 

[Moped]

I do carry a meter with us so at some point I will compare the battery voltage with the reading shown on the Sargent panel.

If it under-reads then this means that the actual discharge percentage is not as low as the Sargent panel suggests. I did suspect this as we have a 100ah battery and the most we ever seem to draw is around 4.2ah with lights, Alde pump, Alde fans and 12v TV and some tablet and phone charging. Over 4 hours maximum at night that’s 17ah out of a possible 50ah which should be 83% not 70%.

The Sargent panel works on battery voltage so if it reads this lower than it actually is then in practice there is more battery juice available than the Sargent panel suggests.

 

[wildebus]

I do carry a meter with us so at some point I will compare the battery voltage with the reading shown on the Sargent panel.

If it under-reads then this means that the actual discharge percentage is not as low as the Sargent panel suggests. I did suspect this as we have a 100ah battery and the most we ever seem to draw is around 4.2ah with lights, Alde pump, Alde fans and 12v TV and some tablet and phone charging. Over 4 hours maximum at night that’s 17ah out of a possible 50ah which should be 83% not 70%.

The Sargent panel works on battery voltage so if it reads this lower than it actually is then in practice there is more battery juice available than the Sargent panel suggests.

correctly summised

 

[Moped]

Yup - higher voltage = brighter lights. However, if the volts go too high, some things if designed for 12V (and I mean a regulated steady 12V, not a Motorhome battery "12V") can go POP!


I supplied a Lithium Battery for someones Camper Conversion. As you will be aware, a Lithium battery settles for most of the time at around 13.1V or so. a little bit later on, I supplied him with a variable dimmer for him to wire into the Water Pump as he found it was running too fast

Because of these kind of voltage variations and using domestic 12V devices (such as Amazon Echos for example), I have a 12V regulator between the battery and the hab electrics

PS. You might want to check the Leisure Battery voltage with a Meter to compare against the Sargent display - the Sargent usually underread sufficiently to give a fairly misleading idea of the battery level.

Turned the Sargent transformer off last night and compared panel voltage reading against actual battery reading using voltmeter.

Sargent read 12.5v with battery at claimed 80% charge - voltmeter read 12.54v

So not too far out at this level and Sargent does round up or down to nearest 0.1V so actually spot on taking this into account. Will compare again when battery down to around 12.1v. I will need to change the panel settings so that solar is charging vehicle battery only.

I suppose a question is that whilst the voltage is about right at around 12.5v is the percentage battery level right at 80% having used a claimed 40% of the available 50ah of the 100ah battery?