OK I give in, where did they hide the split charger on my Hymer 660s?

Ian Wood

Guest
I've had enough of this game having turned every 'stone' I can think of. I've heard mention it's under the drivers seat, but I've got swivel seats with nothing apparently underneath. It's not in the battery compartment. It's not under any of the seats. Unless it's the black box (50mm x 25mm x 75mm) under the bonnet with lots of wires going to it with Mercedes written on it, but I don't think so somehow. Or maybe the small relay under the dash behind the Mercedes fuse box? Not sure what that ones for, it's not the headlight one which I can hear operating when I click between the headlight options. So is there a secret 'hidy hole' that Hymer cleverly stash it away in? In case you were wondering why I was trying to find it, my leisure batteries (4 x 90 amp/hr) don't seem to charge from the alternator although the cranking one does.
 
I'm not an expert on Hymers, but I remember from previous threads that all the relays are usually contained in the electroblock box which is usually found in a locker towards the front of the van habitation area.
 
I think that the chargers are usually under the seat, however on my T625 and also a mates down the road has an identical T625 the charge system is under the front dinette seat by the bulkhead. It has a vent cut in the bulkhead for ventilation.
One final thought. You may not be looking for the normal blue box as both of the above are smaller and silver.
There is also a bunch of wires with a few bits and things under the drivers seat by the battery. I have never looked for the actual relay and just assumed it was in one of these two areas.
. If you are still stuck, try to speak to Perter Hambilton at Preston. Hambilton Engineering. W hat he does not know about Hymers is not worth knowing.
 
measure voltage at les battery with engine turned of and with engine running there should be difference in voltage and the relay for my les battery has fuse in it. why does the hymer need a batt charger from alt to charge battery ? surely the alt charges the batterys look at some of my post on here for goat boy site give you a quick trouble shoot guide to help you.
 
just a thought. On our old Hymer we had a problem. The fridge sometimes would not work while driving, in other words no power from the alternator.
I telephoned everybody I could think and the consensus was the it was a faulty relay.
Peter Hambilton told me that Hymers in their wisdom fit one blue scotchlock to take power to or from the relay and this would be my problem.
He was correct. It was fitted to the rear top of the engine compartment, left hand side looking from the front and about one foot to the right of the battery.
Maybe this is your fault
 
Is the red key by the drivers right leg turned on. This isolates the interior from the vehicle electrics. There is a relay K1 on the wiring diagram for my S700 it could be located behind the panel with the fuses also between the drivers left leg and the door.
 
oldish hippy said:
measure voltage at les battery with engine turned of and with engine running there should be difference in voltage and the relay for my les battery has fuse in it. why does the hymer need a batt charger from alt to charge battery ? surely the alt charges the batterys look at some of my post on here for goat boy site give you a quick trouble shoot guide to help you.
Click to expand...

That confused me. I assume he meant the split charge relay, unless the some Hymers have those boxes of tricks which modify alternator voltage to give optimum charging regime. I thought those were after market fits though.
 
Now, with the engine off, check the voltage at the leisure battery.

Should get a reading of 12v.

Now fire up the engine , The meter should now read just over 13 volts again.

hope that make it clearer
 
oldish hippy said:
Now, with the engine off, check the voltage at the leisure battery.

Should get a reading of 12v.

Now fire up the engine , The meter should now read just over 13 volts again.

hope that make it clearer
Click to expand...

Another bit of clarity for those without a Hymer.

The old style Hymers on the Merc 410D chassis ( 660 & 700 ) has a blue box battery charger (mains) mounted at the rear of the vehicle near the mains input. It then has a panel above the cooker with switches and gauge for water & battery voltage and a separate one for amps. There are no electronics here. The leisure battery was originally mounted adjacent to the starter battery under the floor beside the drivers seat. Just wires in there. Further forward on the bulkhead below the dash is panel of fuses and an isolation key which disconnects the battery from the system. Any relays would be in here or under the bonnet. The wiring diagram shows relays K1 & K2 attached to each battery.

I have a pdf manual for the 1988 to 94 S700 sent to me by Hymer showing wiring diagram. Basically the vehicle is the same as the 660 only a different body layout. If the OP PMs me with an email address I can let him have a copy.

John
 
thanks

oldish hippy said:
measure voltage at les battery with engine turned of and with engine running there should be difference in voltage and the relay for my les battery has fuse in it. why does the hymer need a batt charger from alt to charge battery ? surely the alt charges the batterys look at some of my post on here for goat boy site give you a quick trouble shoot guide to help you.
Click to expand...

thanks to everyone who replied to my question, what a great response. I've been a way for a few days in my Hymer getting it sized up for a small woodburner, yes a woodburner in a Hymer! Why you might ask and it"s a hard one to answer. I'm basically living in my Hymer on the forecourt of a workshop I own. The heating and insulation of the van is the best I've had in any home (with wheels or not) ever, by a long way, instant (cheap LPG) heat really. But I was in bed thinking I don't actually 'hang out' in the van reading books like I did last winter in a rented 'boat house' (a house not a boat) that had a roaring fire that failed to heat the place, as it happened, but it looked good and made me want to stay in. So I was thinking how could I get a woodburning stove in my Hymer, which bit of space did I really not value now? Well, and this says a lot about me, the wardrobe started looking like a lot of wasted space especially when I imagined a woodburner in it's place. So I had seen 'Windy Withy Stoves' displayed at various festivals (Buddha Fields, Big Green Gathering) and then a friend in 'The Bell Inn' Bath wholeheartedly recommended them to me. So I jumped in the Hymer and flew like the wind (like a very big thing at 48mph!) to the beautiful Blackdown Hills in North Devon. Their small workshop was in an old pigsty and they had a wide selection of very small wood burners their speciality subject. So I'm now the proud owner of a 'Louis' stove which is the second up from their smallest. So the Hymer now has a whole in the roof and hopefully by the end of today I will have the burner fully installed.
So back to my charging issues, I did measure the voltage across my leasure batteries with engine running & when idly on this trip. 13.15 & 12.70 respectively. Also I noticed that my solar charger 'state of charge' reading had gone up from 78% to 80%. A small change for a long journey of 60miles.

When I plug into the 240v, there is a Halfords automatic charger hard wired in that is putting out 3.8 amps. This very slowly brings up the 'state of charge' level.

Also my 120w panel is trickly charging at between 0.2 amps & 2.0 amps in this low level light.

So I'm a little confused about what is going on, these are the possibilities as I see it:
a) everything is just fine and the reading from the solar regulator of 'state of charge' is miss-leading me into thinking I've got a problem.
b) I am getting a small charge from the alternator but it is no where near as big as it should be from what I believe from another 'thread' is 15amp alternator on these old Hymers.
c) the bank of (4 x 125amp/hr 'Rolls') leisure batteries is quite large and is taking a lot of input to charge up.


So I'm feeling a little bit more relaxed about my 'leasure' systems, still would like to know if that alternator is really bringing something to the party. Still don't know where that 'split charge' relay is, but maybe I don't need to know! Anyway thank you all for your helpful replies any further thoughts would be appreciated
 
a) everything is just fine and the reading from the solar regulator of 'state of charge' is miss-leading me into thinking I've got a problem.
b) I am getting a small charge from the alternator but it is no where near as big as it should be from what I believe from another 'thread' is 15amp alternator on these old Hymers.
c) the bank of (4 x 125amp/hr 'Rolls') leisure batteries is quite large and is taking a lot of input to charge up


well it a case of all three ok you need to check amperage output of alternator to rule out the low amperage side of alternator and you do have large battery bank

ok had quick browse through net look on here under tech support this give you some timings to look at

Operating Tech Electronics, Inc.
 
oldish hippy said:
a) everything is just fine and the reading from the solar regulator of 'state of charge' is miss-leading me into thinking I've got a problem.
b) I am getting a small charge from the alternator but it is no where near as big as it should be from what I believe from another 'thread' is 15amp alternator on these old Hymers.
c) the bank of (4 x 125amp/hr 'Rolls') leisure batteries is quite large and is taking a lot of input to charge up


well it a case of all three ok you need to check amperage output of alternator to rule out the low amperage side of alternator and you do have large battery bank

ok had quick browse through net look on here under tech support this give you some timings to look at

Operating Tech Electronics, Inc.
Click to expand...

The standard alternator is 55 amps.

John
 
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