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battery charging


jondiane

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Hi there just back from skiing trip in the van ,at night we use a honda 1 kva geny to charge the batterys 2x 110 and watch the tely at night,the geny is on for about 5 hours a night. it seems to put in enough charge in but only just to run the heating/ pump/ light, that night and the following day till we put the geny on again at tea time. i think the on board charger is around 8amp (ck200) panel. could i run a 20amp charger plugged in a socket to put more in . what draw does a 20amp charger have would the geny run one. hope that made sence.
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jon&diane - 2011-01-16 6:22 PM

 

Hi there just back from skiing trip in the van ,at night we use a honda 1 kva geny to charge the batterys 2x 110 and watch the tely at night,the geny is on for about 5 hours a night. it seems to put in enough charge in but only just to run the heating/ pump/ light, that night and the following day till we put the geny on again at tea time. i think the on board charger is around 8amp (ck200) panel. could i run a 20amp charger plugged in a socket to put more in . what draw does a 20amp charger have would the geny run one. hope that made sence.

 

I've looked back through your earlier postings in the hope I'd find a clue to what motorhome you currently own - but no luck. :-(

 

I don't know what a "ck200 panel" is, but a battery-charger with an 8Amp output seems awfully low-powered for a motorhome with 2 x 110A batteries.

 

Whatever the case, the current-demand a 20Amps 12V battery-charger would place on a 240V generator would be pretty small - no more than 2Amps taking into account inefficiency.

 

Your plan should work (though I strongly advise you to switch off your motorhome's on-board charger before running the 20A one), but I do wonder whether there isn't something wrong with your electrical system if, despite running a generator for 5 hours, your 220Ah of battery-power apparently has trouble coping with the next day's electrical requirements.

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What age are the batteries as it sounds as if they are not holding their charge because my 2 x 110 ah batteries will last several days and nights without recharging even in winter?

 

Have you checked battery voltage when supposedly fully charged and can we assume that the electrolyte level is good and that all wiring is of adequate capacity, all fuses intact, and all joints and connections - especially the battery connection - clean and secure?

 

 

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My Burstner has 2 x 110 ah batteries fitted as standard and the onboard charger delivers 18 amps. I think this is pretty standard, so I would try to find out exactly what your charging rate is.

 

If necessary, you can have another charger fitted, especially if you use it in cold weather conditions.

 

As suggested, get a battery check done by experts. It is usually free if they think you will purchase new ones from them.

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Hi and thanks for the repleys.ck200 where did i get that from?.sorry we have a bessacarr e795 04.the books are in the van and not at my house,will have to check on the out put of the inboard charger,it came with a 85amp battery and we have upgraded to the 110s.on the panel after turning of the geny it reads 13.4v. running the heater all night on number 5, it reads about 12.8 in the morning,and then i turn the heater down to 3 for the day, it reads about 12.3v,there is us and two teenages, four showers a night. what do you think should i get the batterys tested.
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If you onboard charger is only an 8 Amp model which it may well be, then you certrainly would benefit from using a seperate 20A charger for the batteries, whether the batteries are aging or not. If the generator is running at the time then use a the 240 volt adapter for the TV. This reduces the load on the 12 volt circuit.

 

It does sound like you are flattening the batteries rather fast so well worth checking them. I think 1st thing I would do is check the electrolyte levels and top up with distilled water to just below the level indicators, charge and top up again to max level. If one battery level is signigicantly different from the other then it is probably failing.

 

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Thats the one ec200.ok so er right would the 20amp charger take the volts higher.and put thebatterys at 100%. and just a thought we have a inverter fitted for summer use.could we run a 20amp charger from the inverter when driving between sites.to get the batterys up to 100% full. B to Bs are a bit expensive.
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Depends on the 20 Amp charger.

You need to understand where the 14.8 volts comes from.

 

Usually Pulse width modulated chargers will use 14.8 volt pulses for the final stage of charging. Which is supposed to be good for the battery. It is benificial as it helps to break down any hard sulphation and conditions the battery. Without pulse width modulation then 14.4 volts is used.

 

It is all about a maintentance charge for the batteries and not power really, and getting the cells equalised and stratified acid mixed by causing a little gassing in the battery (flooded only). If you need that last 5% to 10% or so of charge you are working pretty tight on capacity.

 

If you have not got gel leisure batteries then I wil not mention here and confuse. ( Bet you turn round now and say you have gel batteries!!).

 

 

Now to the IMPORTANT nitty griity of Your problem.

 

I am going to jump the gun here, Your batteries are either needing top up or are shot. If they have got that bad they need topping up to boost the capacity then they are shot now anyway.

New batteries are needed.

So top up electrolyte if required and test them after using the onboard charger to charge them 'fully'.

You said your motorhome model is E**** 04. Are your battereis original and now 6 or 7w years old? If so, then they probbaly and lost likely need replacing.

Replace them and then see how you get on with onboard charger and I think you will find it is all OK.

 

 

Yes you can increase charge rate by using a seperate charger powered by the generator but you may not need to. You should certainly not need to keep running the generator all the time or anywhere near as much as you have been.

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I would agree. 220Ah of decent batteries and a 16A charger should be enough.

The only thing I would add, though, is that there hasn't been any attempt to calculate the nightly demand. (though it would take quite a bit to exhaust such capacity).

As we don't know the pattern of use, it would be sensible to calculate the draw on the batteries from the various devices, and the length of time they are on, and calculate the overall demand.

One of the things that is quite often overlooked is that, though modern motorhomes have a large amount of lighting, using all of it together for a significant amount of time will severely deplete any battery(ies).

Add to that the TV, any satellite equipment and anything run through the inverter, and the drain could be significant.

Since the OP says the original battery has been replaced since purchase, I'm assuming the replacements aren't that old? 

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Ta Robin,

I missed the bit about upgrading to 2x110. Sorry.

 

So Jon and Diane, how old are the batteries and Make /Model please so I can check out best charging regime for them?

 

p.s. so we need your power profile as well, and estimate of what you have switch on and for how long. Power rating of TV and lights used.

Also what is yru heater...do you run the fan all the time or is use on convention and for how long is the fan running if so.

This should give as at least a stab at working out yoru power. he water punp is small usage even for showers.

 

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Hi this is great you all putting in time to help.The bats are varta 110ah there are about 4 year old but i havent allways used them on the van, we used them at work for other thinks.i think the first thing is to have them checked. ps. there not gel. As for power useage where do i start lets check the bats. The family we go with is a simular set up but he got new bats 3 years ago and his are getting low after the same amont of time as mine are. Just thinking if the onboard charger is putting 16am in 5 hours is that 80am in at best, not allowing for usage in that time. if we go out for tea or a bear ( not so many at £7) the geny may only run for 2 hours.this could have a knock on effect thought the week. my be a 30amp charger *-)
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You will need to roughly calculate your battery usage because, until you do, no-one, including you, can establish the target you are trying to reach.  However, I will attempt a summary of the main points, as I see them, and invite others to shoot me down!  :-)

You have 220Ah of installed battery capacity (probably now less, due to age). 

If you don't discharge the batteries below 60% of their capacity, which will reasonably conserve their life, you can draw 130Ah from them, assuming they start fully charged, before they need re-charging. 

If you allow them to be depleted to 80% of capacity, you will have 175Ah to play with on the same basis, but you will be beginning to shorten their lives, more so if you do this regularly. 

The maximum re-charge rate you should apply to them is 45Amps, the optimum about 25Amps.

Your minimum re-charge time at 60% discharged, charging at the maximum rate, is thus 3 hours: 6 hours if charged at the optimum rate. 

If you allow the batteries to discharge to 80%, they will need 4 hours to re-charge at the maximum rate, and 8 hours at the optimum rate. 

These re-charge times assume you take nothing from the batteries while you are charging them.  However, from what you say you are not running your genny overnight (can't imagine why! :-)), so you're taking out while you're trying to put back - but you don't know how much you're taking out. 

First conclusion: IMO, you regime of use is progressively running your batteries into the injury zone, and has more or less knackered them. 

Second conclusion: you are using too much juice for your regime to cope with. 

Third conclusion: you will struggle to re-charge the batteries while drawing power from them using any regime/charger. 

Fourth conclusion: IMO, you would be better off using mains to fully re-charge the batteries overnight, at least every other night.

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