# Charging from mains electric on Hymer 544



## 88962 (May 10, 2005)

We have a Hymer 544 C-class. As far as we are aware the leisure battery charges when the vehicle is being driven. We have been topping up the charge using electric hook-up at home. Is there any possiblility that we can over-charge and damage the battery? Is this enough or do we need to remove the battery and use a battery charger? We have been doing this for some time without any problems but have a feeling tht we've read something about it - the old brain cells are slowing down!!

Thanks from Jeanann, going to Dorset, Devon and Cornwall over Easter so if you are in the area will give you a wave.


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## 88905 (May 10, 2005)

Not sure what system the Hymer uses but if it is not fully controlled it is possible to overcook the battery.
Far better to get a good charger from Halfords or similar (electronic controlled type) and then charge the battery direct from that. Don't forget to trip the mains supply fuse to the onboard battery charger first though!!.

nobby


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## dodger148 (May 9, 2005)

If the battery is being charged whilst you are driving then there will be some form of regulator or relay fitted. 
I would have thought that there is an inbuilt leisure battery charger fitted to this van, which you could turn on or off as needed. 
Dont you have a hand book ? Its a pity when people / dealers sell vans they dont do a proper hand over for the new owner, then you wouldnt be in this position
If not look on the web for one or ask another 544 owner there are plenty of this model around of differing vintages


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## 88905 (May 10, 2005)

Any charging regulation used whilst driving will not be used by an onboard mains charger. My own onboard charger boiled off the battery water during prolonged winter power on times which is why I now use a smart charger. 
You might like to consider as an alternative a solar panel (Maplin..£15 about) but do ensure it can "see the light" before you buy one. It will provide a small trickle charge to the battery.
Incidentally, when I had a boat in the Med we used to leave the batteries untouched in any way from late August to mid April and they stillheld a good enough charge to start the engine and in 21 years of ownership I only changed the batteries twice.
nobby


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## crissy (May 15, 2005)

Hi Jeanann,
We used to leave the hook up on to keep the leisure battery charged up when the 'van was not in use, but were advised that leisure batteries are different to engine batteries and need to go from from fully charged to low charge and then be charged up again. I'm no techy but I'm sure someone here can say whether that is correct or not. Now I charge the leisure battery up on the hook up, then take the plug out of the charger so I can still keep an electric heater on to keep the chill off, but not charge up the leisure battery all the time. This seems to work fine and it takes ages for the leisure battery to discharge.
Chris


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## Boff (May 10, 2005)

Hi Jeanann,

there are different models of mains chargers used in motorhomes. Most of them nowadays have electronic control built in which prevents the battery from overcharging. If you want to be sure about your model just forward me brand and model no. of your charger and I will find out.



crissy said:


> ... but were advised that leisure batteries are different to engine batteries and need to go from from fully charged to low charge and then be charged up again. I'm no techy but I'm sure someone here can say whether that is correct or not.


That is not correct.

It would be correct for Ni-Ca-batteries as used in rechargeable torches, power tools and some cheap mobile phones. Leisure batteries are lead-acid batteries like engine batteries. They do not mind to be charged up from any level. There is however a difference in design:

Engine batteries are designed to deliver a very high current for a short time (to start the engine) and then at once being charged again. Discharging them to low levels several times or running them in "cyclic mode" (see below) will kill them.

Leisure batteries are designed for "cyclic mode": "Cyclic mode" means that the battery is discharged for some time with (compared to engine batteries) relatively low current, then recharged. They cannot deliver such high currents as engine batteries.

All kinds of lead-acid batteries (including the gel-types) do not like to be discharged to less than about 50 % of their nominal capacity. Also they don't like to be left alone for longer time partially discharged, especially in winter.

To charge the leisure battery while driving it is normally just switched parallel to the engine battery. No special regulators are used besides the standard regulator for the engine battery. As this turns down the voltage when the engine battery is full and there is always some voltage drop in the cables to the leisure battery, the engine normally cannot charge the leisure battery to more than about 80 %. So frequent topping up with the mains charger is a good idea.

Best Regards,
Gerhard


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## crissy (May 15, 2005)

Thanks for the info, Gerhard,
I probably didn't write it very well - I don't let the leisure battery go flat, just to about the level if I was using the 'van without hook-up for 3 or 4 days. 
Is this right - is this what you mean by cyclic?
I use a charger on the engine battery to keep that topped up.
I've been concerned about this for a while so any help is gratefully received.


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## Boff (May 10, 2005)

Hi crissy,

cyclic mode is exactly what you describe: Discharging the battery for some time, then topping up again. Other than engine (starter) batteries leisure batteries (sometimes called "solar batteries") are built for that. 

What you should avoid is discharging below about 50 per cent: Check your average power consumption and compare with the nominal capacity of your battery. 

For instance: You have lights with all in about 40 watts on for about 3 hours per evening. Divide 40 watts by 12 volts makes about 3.3 Ampere current. This times 3 hours makes 10 Ah ("Ampere hours"). Plus having the Truma heater on (about 2 Amps) for 4 hours makes another 8 Ah. So all in all 18 Ah per day. Makes all in all 54 Ah in 3 days, so that should be the maximum time before recharging. 

Note that when only charging with the engine the battery will not go far above 80 % charge, so only two days in this example.

Don't worry too much about the engine battery. In a properly fitted motorhome it will be auto-disconnected when you shut down the engine. (Except for some car-typical appliances like the dashboard clock.) So it should not be discharged too much.

Best Regards,
Gerhard


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## crissy (May 15, 2005)

Thanks for the explanation, it was very useful.


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## 89425 (May 23, 2005)

More info on batteries here
http://www.uuhome.de/william.darden/

____________________________________________________
*Steve 
aka A very wild....wild camper*
.
Click here for my van website!
.









_I do like a bit of feed back to my posts please_
____________________________________________________


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## lecky7 (May 29, 2005)

*Leisure Batteries*

The young lady with the Hymer does'nt say what year it is, we have a Hymer 574 (2003) with 2 leisure batteries, charged by the solar panel &/or mains, they are kept fully charged, whether at home or on site, we have not had a problem


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## 88962 (May 10, 2005)

Thanks everyone for your help.

Now managed to find the answer by scouring the manual from cover to cover. It's a Hymer 544 coachbuuilt, registered in 2000. It seems that there is no problem leaving it connected to the mains for any length of time, as it cannot overcharge. Was worried as had read horror tales of exploding batteries!! 

Now fully charged and ready for off.

See you on our travels. Shame we don't know who's who when we are out and about, it would be nice to know whether we are parked next to any of you folk. Seems everyone waves and communicates on the net but not so talkative when we meet on sites.

Jeanann.


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## peejay (May 10, 2005)

Jeanann wrote;



> See you on our travels. Shame we don't know who's who when we are out and about, it would be nice to know whether we are parked next to any of you folk. Seems everyone waves and communicates on the net but not so talkative when we meet on sites.


you could always download the mhfacts logo and put it in the windscreen, or may i suggest a sticker be designed, i for one would definately purchase one. Praps a budding artist could knock one up, or have a competition for the best one then have it printed????

pete


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## 89425 (May 23, 2005)

Logos,

Logo files can be down loaded from here http://www.motorhomefacts.com/downloads-cat-5.html

Any problems, take a look here http://www.motorhomefacts.com/postt461.html

____________________________________________________
*Steve 
aka A very wild....wild camper*
.
Click here for my van website!
.









_I do like a bit of feed back to my posts please_
____________________________________________________


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