On the subject of leisure batteries, which I think are described as "deep cycling" batteries, I am a bit vague about how far down is "deep". I frequently am on electric hookup for up to 3 months at a time, and have a dismal record of battery life. The charger in my van shows a reading of up to 14.45 volts when the battery is charged up, (which it is for extended periods), and I came to the conclusion some time ago that this situation was probably not beneficial to the battery. I therefore started switching the charger off for periods, allowing the battery voltage to drop. When the voltage gets down to 11.7 or 8, I start worrying about it sulphating (whatever that is) and switch the charger back on. How far down can a battery go before it starts damaging itself ? Any suggestions, please.
How deep is "deep" ?
- Thread starter lolo
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- Jan 15, 2011
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Hi LoLo.
firstly I am not technically qualified in battery theory. There are some very knowledgeable members on the forum who I am sure will give you excellent reliable advice. But as a starter I would advise that if your charger is of the type routinely fitted to caravans then I would leave it switched on. I believe they are designed to be used this way. Further the voltmeters fitted in caravans should only be taken as a guide I do not believe they are greatly accurate. You may be told differently by forum experts but allowing your battery to go below 12 volts may be detrimental to it. When the battery is NOT being used ie fans or lights on etc then even if the battery was flat as they say it could very well still show a voltage of twelve volts. Only when the battery was being used in a discharged condition would the battery start to show voltages below 12 volt.
Someone will I'm sure be along shortly and give you much better and accurate information.
regards Brian
firstly I am not technically qualified in battery theory. There are some very knowledgeable members on the forum who I am sure will give you excellent reliable advice. But as a starter I would advise that if your charger is of the type routinely fitted to caravans then I would leave it switched on. I believe they are designed to be used this way. Further the voltmeters fitted in caravans should only be taken as a guide I do not believe they are greatly accurate. You may be told differently by forum experts but allowing your battery to go below 12 volts may be detrimental to it. When the battery is NOT being used ie fans or lights on etc then even if the battery was flat as they say it could very well still show a voltage of twelve volts. Only when the battery was being used in a discharged condition would the battery start to show voltages below 12 volt.
Someone will I'm sure be along shortly and give you much better and accurate information.
regards Brian
hi lolo,lolo said:
(borowed from wikipedia) A deep-cycle battery is a lead-acid battery designed to be regularly deeply discharged using most of its capacity. In contrast, starter batteries (e.g. most automotive batteries) are designed to deliver short, high-current bursts for cranking the engine, thus frequently discharging only a small part of their capacity. While a deep-cycle battery can be used as a starting battery, the lower "cranking amps" imply that an oversized battery may be required.
A deep-cycle battery is designed to discharge between 50% and 80% of its capacity, depending on the manufacturer and the construction of the battery. Although these batteries can be cycled down to a 20% charge, the best lifespan vs cost method is to keep the average cycle at about 50% discharge.http://en.wikipedia.org/wiki/Deep_cycle_battery#cite_note-1 There is a direct correlation between the depth of discharge of the battery, and the number of charge and discharge cycles it can perform. two other things should be noted though, the van charger will only top up the battery to about 80% so periodical boosts via a smart charger is recommended. and for someone who uses EHU for long periods it may be benificial to use a car starter type battery, as these are designed to be on constant charge with only short bursts of discharge.
Thanks for that, gents. Battery theory does get me a bit baffled. I have a voltmeter permanently wired in so that I can monitor the battery state when we are out camping with the solar panel. Do I want an ampmeter instead to indicate the number of usable amperehours remaining in the battery,rather than a violtmeter for the volts, because I'm presuming that when you say 50 to 80 percent you are obviously talking about amps and not volts. How can I tell, then, how many of my 110 Ah are remaining ?
I'm sure that this is kindergarten stuff to you and I do apologise. I have a reasonable grasp of most things but I have difficulty in getting my head round this.
I'm sure that this is kindergarten stuff to you and I do apologise. I have a reasonable grasp of most things but I have difficulty in getting my head round this.
Hi lolo..... have a look at this chart on the link below & it will hopefully explain a bit more, but letting your battery get too low is not really advisable...... Look under terminal voltage ......
I bought an Abbey van in 2001 that was fitted with a switchable charger. It had 3 positions, car, battery or charger. At the same time I purchased a new 110 amh battery as I had a mover fitted to the new van. I could not find any information on what seetings to use for the battery so I decided to use the battery setting and run on the battery until the volt meter on the van went into the red (it had no volts quoted just green, orange or red) when I would then switch to charge until the meter was back into green. The battery lasted just under 3 years before it died. Fortunately it was under warranty and the dealer replaced it. When I got the replacement I left the switch to charge all of the time I was using van. The battery is still working in my current Bailey that has a charger that is on full time when EHU. When the van is not being used and is at home I turn on the hook up to the van once every 3 to 4 weeks and use a Ctek charger before going on a trip. We normally caravan all year round but recent very bad weather and a new 9 week old pup have slowed us down so far this year. My advice therefore is do not allow battery to fall below 50% charge, preferably keep it well charged. Mine will fail sometime soon and I will then have the job of finding a suitable replacement that can go another 9 to 10 years.
If you are seeing a maintained 14.45 volts then I hear warning alarms. You may see this as the battery is reaching charge but it must not continue as when the battery reaches full charge it will rapidly cause gassing and real potential for premature failure.
Once charged the battery should only be seeing 13.8 volts as a maintained level, that is below the gassing level.
Measuring the capacity in a battery, its "State of Charge" [SoC], is notoriously difficult; a guide can be found by the voltage on the posts at a particular current be that positive, negative or zero. However to do that you need all the "maps" of voltages vs SoC at various currents, an d to greatly complicate things further these charteristics vary with the traces of alloying metal in the lead used. It is a minefield.
As an approximation, with no load in or out of a battery, at least 2 hours after charging , a reading of 12.5 VDC indicates no more than 50% SoC. If a current is being taken then things will be different, 5 amps will drop this to about 12.3 VDC.
A dead flat battery is one under 11.3 VDC, again typically.
An Ameter is only of value in measuring SoC in identifying the current for looking up the appropriate voltage vs SoC curve in the "map"
This link gives some good guidence info and typical SoC maps during charging and discharging:
http://www.scubaengineer.com/documents/lead_acid_battery_charging_graphs.pdf
The C 100/C20 curves relate to currents that flatten the battery in respectively 100 hours and 20 hours. So a 100 Ah battery's C100 current is just one amp.
Once charged the battery should only be seeing 13.8 volts as a maintained level, that is below the gassing level.
Measuring the capacity in a battery, its "State of Charge" [SoC], is notoriously difficult; a guide can be found by the voltage on the posts at a particular current be that positive, negative or zero. However to do that you need all the "maps" of voltages vs SoC at various currents, an d to greatly complicate things further these charteristics vary with the traces of alloying metal in the lead used. It is a minefield.
As an approximation, with no load in or out of a battery, at least 2 hours after charging , a reading of 12.5 VDC indicates no more than 50% SoC. If a current is being taken then things will be different, 5 amps will drop this to about 12.3 VDC.
A dead flat battery is one under 11.3 VDC, again typically.
An Ameter is only of value in measuring SoC in identifying the current for looking up the appropriate voltage vs SoC curve in the "map"
This link gives some good guidence info and typical SoC maps during charging and discharging:
http://www.scubaengineer.com/documents/lead_acid_battery_charging_graphs.pdf
The C 100/C20 curves relate to currents that flatten the battery in respectively 100 hours and 20 hours. So a 100 Ah battery's C100 current is just one amp.
Thanks everyone for the inputs. I think I have been barking up the wrong tree. My purpose in switching the charger off was to give the battery some "excercise" through its usable range, but I see that I have been extending the range a bit too far. Is there any advantage in doing that as against just leaving it fully charged on the charger. Many thanks for the reference to the figures on the chart, Sproket.
- Nov 11, 2009
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If your own voltmeter is showing 14.45 v that is too high to be permanently at that level. You might be better having a smart charge installed that will allow the battery to 'float' when fully charged but then goes back on recharge when voltage drops. Something akin to the CTEK but as an installation in place of the OEM unit.
Hello.
Sorry to gate crash this post but I'm confused also about batteries. My van is in storage and would like to bring the leisure battery home to charge on my ctek charger. But when i disconnect the battery my tracker battery runs low which is not a rechargeable unit. So could I just put a cheap car battery in for just winter storage use so my expensive leisure battery could stay at home ready for the new season.
You input would be much appreciated.
Thank you.
Neil.
Sorry to gate crash this post but I'm confused also about batteries. My van is in storage and would like to bring the leisure battery home to charge on my ctek charger. But when i disconnect the battery my tracker battery runs low which is not a rechargeable unit. So could I just put a cheap car battery in for just winter storage use so my expensive leisure battery could stay at home ready for the new season.
You input would be much appreciated.
Thank you.
Neil.
- Jan 15, 2011
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Hi Neil that's exactly what I do and my caravan is at the side of my house. I leave a car type battery on the van during the lay up period say from early December until early March and the leisure 110volt battery in the garage attached to a smart charger.
again I am not qualified to say this is the correct thing to do but my leisure battery is approaching three years from new and my relation who is a mechanic brought home a drop tester only a couple of weeks ago and assured me my battery was in great condition.
regards Brian.
again I am not qualified to say this is the correct thing to do but my leisure battery is approaching three years from new and my relation who is a mechanic brought home a drop tester only a couple of weeks ago and assured me my battery was in great condition.
regards Brian.
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I would modify Clives advice a little.
The OEM power supply fitted to a caravan differs from a battery charger in one particular way. It is large enough to power the 12V systems in a caravan without a battery in circuit. It will typically have a current capacity of 12 to 16A. The CTEK units are designed as battery chargers not power supplies, and consequently they do not have that same level of current capacity except in the larger and far more expensive models.
Rather than replacing the OEM unit, I would fit a CTEK unit to use only when the caravan is in storage, and revert to the normal OEM unit when on holiday.
Something else to check. There are cheaper multistage battery similar to the CTEK models for sale, and they also work very well, I have three from ALDI (they seem to come on sale about twice a year) But they do have an achilles heel:- If there is a power cut, you have to manually reset them when the power comes back on. I believe some of the CTEK models do turn on automatically when power is restored.
The OEM power supply fitted to a caravan differs from a battery charger in one particular way. It is large enough to power the 12V systems in a caravan without a battery in circuit. It will typically have a current capacity of 12 to 16A. The CTEK units are designed as battery chargers not power supplies, and consequently they do not have that same level of current capacity except in the larger and far more expensive models.
Rather than replacing the OEM unit, I would fit a CTEK unit to use only when the caravan is in storage, and revert to the normal OEM unit when on holiday.
Something else to check. There are cheaper multistage battery similar to the CTEK models for sale, and they also work very well, I have three from ALDI (they seem to come on sale about twice a year) But they do have an achilles heel:- If there is a power cut, you have to manually reset them when the power comes back on. I believe some of the CTEK models do turn on automatically when power is restored.
Thanks everyone, one and all. A whole mine of useful information. I think I've gleaned enough to understand the situation better. Many many thanks.
- Nov 11, 2009
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to ensure future readers understand my line the reference to CTEK was principally to recommend fitting an intelligent charger/ power supply that works like the CTEK but replaces the OEM unit. But as John says they are not cheap.otherclive said:
Here is a selection of intelligent chargers ..... there are more out there ..... But how deep are your pockets .... & do you really need one....
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