Leisure battery. Charging
- Thread starter molly 2
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wineciccio
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How long is a piece of string?? It all depends from factors relating to your vehicle battery and the alternator output, if you can get hold of a battery meter, then I suggest you take a reading when the leisure battery and the vehicle are cold, then again with engine running and compare the readings, a good battery should read at least 12.7 /12.8, with engine running it should read 13 volts plus:cool1::cool1::cool1::cool1::cool1::cool1::cool1:
GRWXJR
Guest
Also won't it vary depending on the sate of charge and the draw for the primary starting battery?
The charge alternator has to maintain both.
Anyway the ideal battery charge rate is 10% of the AH capacity per hour. So 10A for 100A battery.
So as long as the alternator can do at least 20A (more likely to be more than less) then it's well up to the job I'd say.
The charge alternator has to maintain both.
Anyway the ideal battery charge rate is 10% of the AH capacity per hour. So 10A for 100A battery.
So as long as the alternator can do at least 20A (more likely to be more than less) then it's well up to the job I'd say.
Steve121
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The only way you'll know is by experimenting.
Deleted member 5816
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Alternator Charging
Hi Molly,.......Proberley say 100 miles or half a days driving, at this time of year it could be longer with heater on lights windscreen wiper etc, then it depends on how the split charging is wired and the size of the link to the leisure battery and the state of both batteries as previous comment how long is the piece of string.
Alf
Hi Molly,.......Proberley say 100 miles or half a days driving, at this time of year it could be longer with heater on lights windscreen wiper etc, then it depends on how the split charging is wired and the size of the link to the leisure battery and the state of both batteries as previous comment how long is the piece of string.
Alf
Tezza
Guest
I'm going to hijack this thread but still on topic lol. Last night I checked my leisure battery (220 amps) and it was 12.96 ....full yes?.after running esparcher D2 and tv for 3 hours and checking battery this morning it was 12. 3 volts. Which means if I am correct those two things took about 110 amps...is that possible. started engine and checked amps going in with the sterling and it showed 24 amps going in to the battery. Does the sound right to you guys?
GRWXJR
Guest
There's so many things that affect the voltage reading that make it hard to be sure. Lower temps, some load still being drawn, the battery not having been rested to give an accurate reading, the fact that the 12.96 may have been artificially high as the set had only just come off charge (which sounds likely due to the volts nearly 13v) so this would have dropped 0.5v instantly, the fact that the voltageY be high cos of charge alternator input from driving but not having driven for long enough to have fully recharged, and so on.
Unless you have strictly controlled conditions and opening charge state, fixed accurate load and duration etc etc - then you won't get more than good idea.
A battery needs to be taken to peak voltage by a 10% charge rate & then maintained by a good intelligent charger ramping down the charge to stay at that voltage for 3 or 4 hours to boost the SG value of the electrolyte. Then let it rest without load for an hour or 2. Then measure it's standing Voltage cos That'll give you a battery as good as it'll be as a starting point.
Deleted member 5816
Guest
Leisure Battery Drain
Tezza No it would seem that either there is a drain on the battery from some unknown source or a battery fault.
If you can disconnect both leisure batteries and charge with a battery charger take note of the readings disconnected over say 48 hours then connect one battery take the voltage reading and run the Eberspacher for 1/2 hour or so and check the reading then repeat with the other battery.
Did you buy the DC clamp meter if so Before anything else is there a current drain from the leisure and van batteries when all switched off
Alf
Tezza No it would seem that either there is a drain on the battery from some unknown source or a battery fault.
If you can disconnect both leisure batteries and charge with a battery charger take note of the readings disconnected over say 48 hours then connect one battery take the voltage reading and run the Eberspacher for 1/2 hour or so and check the reading then repeat with the other battery.
Did you buy the DC clamp meter if so Before anything else is there a current drain from the leisure and van batteries when all switched off
Alf
maxi77
Guest
It all depends on when you took the readings, if the first reading was after the battery had been allowed to rest for several hours disconnected before the reading was taken then yes it was full but if you had just stopped charging then it was most definitely not full. Equally for the low reading to be valid the battery needs to have been resting disconnected for several hours to be valid.
Voltage readings depend on the battery being rsted before they are taken, I would expect a battery just of charge to show just under 14 volts with most chargers, and a battery which has just had a reasonable load disconnected may well show less than 12 volts even when actually quite well charged.
Battery meters which measure the current in and out give a much more accurate idea of the state of charge and the capacity remaining but cost a fair ammount more than a simple voltmeter
Tow Itch
Guest
Started writing this yesterday I see part of my answer has already been given.
I don't know enough to answer this completely but perhaps I can help you refine your question.
Leisure battery at 12.96. Anything above 12.7 V I thinks it's 12.76V is fully charged. When was this measured though? If you measure it just after charging you will have an erroneous reading there is a surface charge on the plates. You are supposed to give it at least 4 hours with no charge or discharge AT ALL before measuring. This explains better
On similar vein how long did the battery have to rest?
I could take a 3 parts ragged battery get it to show over 12.80V and discharge it to 12.30V and have very few Amp Hours out.
This might sound like I'm a pedant. I might be but thats not my intention here.
Basic physics Work = Force X Distance Power = Work/Time
Watts is a unit of Power Work or energy provided is in watt hours. Your electricity bill is in Kilowatt hours Watts = Volts X Amps 110Amps is an instantaneous reading if you were supplying 1,300 to 1,500 watts on a12V circuit.
110Amp hours is indication of the work done by the battery i.e. 110Amp for 1 hour 1 amp for 110 hours (there is a calculated discharge rate for batteries) For simplicity if you could measure instantaneously after finishing using or you used for 11hrs then rested the batteries to get a reading. 11 hrs use 110 amp hours used = 11hrs on 10amp discharge at 12.?? (Discharge voltage) = 125 watts for eleven hours ish . That is some fan motor and ignition circuit. Have I heard Espacher heaters take a big lump of power on first lighting? But of course there may have been nothing like 110 amp hours taken out of the battery.
Notionally measuring acid density is more accurate but not as easy and you have to know at what strength the battery was charged at.Try
Battery voltage and state of charge - Energy Matters
Measuring State-of-charge - Battery University
Why won't a split charge relay fully charge a leisure battery? A split charge diode will be poor at charging because of the voltage drop of the diode but this is a split charge relay. I'm quite a big fan of Charles Sterling but his argument against a split charging relay is quite contrary to a lack of charging and is one area where I'm either mistaken or he is a bit disingenuous. Sterling Power Products: Split Charge Diodes Systems Facts and Figures
If we take this last example about using an inverter with flat leisure batteries. I don't know if I've missed something here but surely by the simple means of fusing either or both of the leads from the split charge relay this wouldn't happen. In actuality on a motorhome both sorts of battery would not be charged through the split charge relay. Yes there would be a connection to either the alternator or the starting battery and with the engine running that would be a live link but as stated a simple fuse set at the capacity of the relay would guard against this massive current.
Yes/No thoughts?
You might want to do something if the alternator reduces voltage once warm as many do because of thermostatically controlled regulators.
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sparrks
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A 60A cartridge fuse to BS 1361 protecting the 70A relay in the previous example would take around 900A to 'blow' instantly (around 0.1s) and could carry a current of 150A for 500s (over 8 mins ) before 'blowing' I can only wonder at the breaking capacities and reliability of cheap auto fuses.
Rodeo
Guest
I doubt if there are any figures.I dont know whether there are different types of auto fuses for different applications, but just use the general rule that the 'blow' point is twice the marked rating.
Tow Itch
Guest
My first thoughts were "Glad I inserted
and
that should give me sufficient room to back pedal." With respect to the stuff written by Charles Sterling. If you do take someones word as a given it's not comfortable when you read a piece by them that you doubt.
Then I was thinking about fast blow fuses and possibly using micro circuit breakers.
Then I thought Knob. It's obvious you're no electrician TI.
Yes you're undoubtedly right sparks but this problem or a similar problem occurs in every single fuse protected circuit. It's the same problem as if you connect up your 16amp EHU through a 13amp plug and try to draw 16amp (which you can do for quite a while) or go bananas and jump in a 32amp commando plug for a hot tub and try to draw about 25amp. A fear is introduced to the reader about a just over 2 times overload but in reality the size of the overload is in proportion to the speed of the break.
The problems vary because of the nature of the equipment used and that some appliances will show a high initial draw but essentially this is a question of how we specify fuses.
What happens to the relay and wiring in this circuit is comparable to components in any other circuit at a point of overload isn't it?
The only thing I know of (or think I know) is that you tend to fuse at one third more than the expected load.
So I think my questions should be:
1) How do we determine the peak demand from the leisure batteries, or is it peak charge offered by the alternator? Then perhaps questions if that charge offered is greater than suitable. Possible case for intelligent charging here.
2) Specing relays. Do we overspec because some are carp(sic) and are never going to handle their marked amperage? Or do we overspec the relay (and the wiring?) because for some reason this situation is unique and fuse to the expected charging amps + 33% rather than to the components used?
3) Basic principles for fusing a circuit. Is there something unique about this case? If not what are general principles. This will be useful for other auto wiring.
I moderate another camping forum and while this isn't relevant to that forum there are a couple of guys who should be able to give an input on this I'll try them.
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ivecotrucker
Guest
An interesting thread. Amazing what you can still learn about an old subject - thanks Sparrks, I never knew the figures on DC fuse blow rates were so poor, quite worrying & certainly food for thought.
I think perhaps the OP, Molly2, wanted a fairly simple answer. The Citroen Despatch has various alternator options, the basic is currently 60Ah up to 150 Ah. So, assuming a 60 Ah alternator, to replace 20 Ah in the leisure battery requires 60/20 = 20 minutes motoring or idling (the alternator output on newer models varies very little with engine speed) - simple, except it is totally wrong !!
.
To recharge a battery as it comes up towards full charge needs at least +30% extra input.
The chemical inefficiency of the battery charging reaction is at least +15-20%.
Cabling resistance & loss of charging voltage between alternator & battery could be at least +15%
Alternator inefficiency, worn slip rings etc. is possibly c. +10%.
A slightly slack fan belt could cost at least +10%.
And that is assuming nil split relay loss (depending on which type), no vehicle heater, brake light, indicators etc. etc. So instead of 60 A the leisure battery may only receive a 'useable' recharging current of 20 - 25 A at very best. In practice a full recharge will need at least 3 hours motoring or 150 miles @ 50 mph, fairly close to Alf 1's '1/2 a day, 100 miles'. All this is assuming a reasonably good condition leisure battery, no cable connection corrosion etc and a warm ambient temperature.
I think perhaps the OP, Molly2, wanted a fairly simple answer. The Citroen Despatch has various alternator options, the basic is currently 60Ah up to 150 Ah. So, assuming a 60 Ah alternator, to replace 20 Ah in the leisure battery requires 60/20 = 20 minutes motoring or idling (the alternator output on newer models varies very little with engine speed) - simple, except it is totally wrong !!
.
To recharge a battery as it comes up towards full charge needs at least +30% extra input.
The chemical inefficiency of the battery charging reaction is at least +15-20%.
Cabling resistance & loss of charging voltage between alternator & battery could be at least +15%
Alternator inefficiency, worn slip rings etc. is possibly c. +10%.
A slightly slack fan belt could cost at least +10%.
And that is assuming nil split relay loss (depending on which type), no vehicle heater, brake light, indicators etc. etc. So instead of 60 A the leisure battery may only receive a 'useable' recharging current of 20 - 25 A at very best. In practice a full recharge will need at least 3 hours motoring or 150 miles @ 50 mph, fairly close to Alf 1's '1/2 a day, 100 miles'. All this is assuming a reasonably good condition leisure battery, no cable connection corrosion etc and a warm ambient temperature.
Steve121
Guest
Your link to Sterling is not what I'm talking about. Using a simple split charge relay means you will be relying on the alternator's regulator to charge your batteries. According to fairly extensive research I did a few years ago standard alternators do not allow batteries to reach anywhere near a full charge. A B2B charger uses advanced electronics, not diodes, to ensure close to 100% charge, presumably using similar techniques to those in sophisticated mains powered multi stage chargers.
See this Sterling link: Up to 5 times faster and 100% more charge
and this Durite link: models 0-52-5x