charging Problems

Jul 29, 2007
4,775
9,217
Ipswich
Funster No
32
MH
RV
Exp
30 years
Hi on the way back from holiday recently I noticed the engine was no longer charging the coach battery's, after some investigation today, I found its the Battery Mode solenoid which is knackered.

Just thought I would post some details how this system works, might save someone some time, as its taken me 3-4hours looking at wiring schematics to find it out. I assume all RV's are wired in the same way, but don't quote me.

The emergency battery switch is powered by the coach battery which when you press it energises the Battery mode solenoid joining the two circuits together, so you can start your RV from the coach batteries in the event you have flattened the starter battery.

It also has another function, as soon as you turn the ignition on it is energised from the starter battery joining the two circuits together continuously, allowing the alternator to charge both sets of battery's. It would make sense to me if either a time delay or voltage dependant relay was in the circuit, to make sure the starter battery was charged up first, but the winnie doesn't appear to have either of these.

Because of the way its wired, if you flatten your coach batteries enough, the battery mode solenoid won't work when you press the emergency start button, I found this out when I tried to start the genny to recharge the batteries, the only way I could do it because the solenoid was u/s was to start the engine and use jump leads from one battery to the other.

I do wonder that if your coach batteries were really flat as mine were, whether this could cause problems starting the engine, as the starter battery would immediately try to charge the coach batteries, and with a big coach battery bank as I have (540Ah) there would be a significant voltage drop. Maybe it drops out when you engage the starter? haven't traced the wiring schematics that far. (And don't intend to)

Olley
 

johnsandywhite

Free Member
Jul 29, 2007
2,339
18
Doncaster/Spain
Funster No
31
MH
'A' Class RV &
Exp
11
:Sad: I had exactly the same problem in the USA when we bought our Newmar. It shortened our tour of Florida somewhat. Our Solenoid does not kick in until the Alternator kicks in and starts charging the Motor battery. Sometimes on cold or damp mornings. It would need a few revs for it to kick in. There are several different ways in which they are wired. None of the 4 RV's we have had have been wired the same. Even when they start off with the same chassis. :RollEyes:
 
OP
olley
Jul 29, 2007
4,775
9,217
Ipswich
Funster No
32
MH
RV
Exp
30 years
Hi just fitted the new relay and took the opportunity to cut the old one open, its pretty basic just what looks like a washer pulled down onto the ends of the brass connection bolts, the washer has been overheating, caused no doubt by the small area of contact on the bolts.

I would imagine I will have to change it again in a few years, if I do it won't be with another of these ones.

Olley
 

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hereford bull

Free Member
Jan 18, 2008
76
0
HEREFORD
Funster No
1,250
MH
A CLASS
Exp
6 YRS
olley you seem to be up on things electric can you tell me or show me some pics on how to link up the leisure batts to the engine batts so that the engine batts can be charged sometimes when hooked up to shore power what size wire or can i just use jump cables , as you can tell im no leccy
 
OP
olley
Jul 29, 2007
4,775
9,217
Ipswich
Funster No
32
MH
RV
Exp
30 years
Hi HB the simplist way is to connect a wire between the positive battery terminals, you negatives are already connected together via the chassis.

You need to know your charger size to determine the size of wire, and it needs to be fused. Vehicle wiring products list carrying capacity next to the wire sizes here: VWP - thinwall cable

For 10-20amp charger I would use 3mm wire fused at 30amp, fit the wire with crocodile clips at each end, this is for a temporary connection only, the fuse is there incase you forget to remove the wire before starting the engine, which could result in a heavy current flowing down it and causing a fire. So you may need some spare fuses if your memory is anything like mine. :Doh:

You could use battery cable for the connection and dispense with the fuse but either way if you forget to remove it when off EHU you run the risk of flattening both batteries and being unable to start the engine.

Olley
 
OP
olley
Jul 29, 2007
4,775
9,217
Ipswich
Funster No
32
MH
RV
Exp
30 years
Hi HB assuming you are using 3mm wire for the connection then yes 30amp.

Olley
 

nahnotme

Free Member
Sep 23, 2007
239
0
Funster No
336
Hi Olly
I think I have charging problems and am wondering that it is the solenoid that is at fault here.
My emergency battery change over button on the dash no longer works and the charger doesnt seem as effective as it was.
How did you know it was the solenoid ? where is it ?
I see there is one on ebay
AMERICAN MOTORHOME RV SOLENOID, H/DUTY 3 AND 4 TERM. on eBay (end time 04-Dec-09 09:53:13 GMT)
Is it a job for a pro ? if so can you recommened anyone up norf ?
I emailed star spangled spanner to arrange a check over a week ago but have heard nothing ?
 
OP
olley
Jul 29, 2007
4,775
9,217
Ipswich
Funster No
32
MH
RV
Exp
30 years
Hi winnie is it just your house batteries that aren't being charged, or the engine batteries as well? If its just the house bats then relay could be at fault, its a cheap bit of crap.

Mine is under the step near the batteries, lift the step so you can see the batteries and further in is a panel with two turn catches, twist them and the panel comes off and the relay and a load of other wiring is exposed. Yours may be different though.

Olley
 

GEOFFs125

Free Member
Sep 14, 2007
43
0
Salisbury, Wilts
Funster No
295
MH
C Class RV
Exp
8
My relay failed causing a fire, details of which can be found at :

http://www.motorhomefun.co.uk/american-rv/10588-fire-lucky-escape.html

Mine is located inside the engine compartment. It should be quite easy to test. Once the engine is started within a second or two you can hear the relay click in. Alternatively check the output at the terminal which is connected to the leasure batteries. You should see arise in voltage from engine not running to when the engine is running.

I would strongly recommend that if you are having any doubts about its performance that you replace it, as can be seen from Olley's photos, it would'nt take much for the relay to fail. As for running cables between the two batteres, I think this is asking for trouble, can I suggest you try this little device:

Ultra TRIK-L-START Starting Battery Charger/Maintainer

This is my next project when I can find a supplier in the UK who will not want an arm and a leg for it.

HTH Geoff
 

johnsandywhite

Free Member
Jul 29, 2007
2,339
18
Doncaster/Spain
Funster No
31
MH
'A' Class RV &
Exp
11
Hi Olly
I think I have charging problems and am wondering that it is the solenoid that is at fault here.
My emergency battery change over button on the dash no longer works and the charger doesnt seem as effective as it was.
How did you know it was the solenoid ? where is it ?
I see there is one on ebay
AMERICAN MOTORHOME RV SOLENOID, H/DUTY 3 AND 4 TERM. on eBay (end time 04-Dec-09 09:53:13 GMT)
Is it a job for a pro ? if so can you recommened anyone up norf ?
I emailed star spangled spanner to arrange a check over a week ago but have heard nothing ?
:Cool: Easy peasy job to do. I did it with the basic tools I had in Forida in 1.5 hours BTW, the 3 point is the same as fitted to ours.. :thumb:
 

IanH

Free Member
Apr 6, 2008
158
3
Cornwall
Funster No
2,072
MH
5th wheel
Exp
4
Those solenoids look very similar to the ones we use on the 12 & 24v winches on our recovery trucks.

We used to get ours from Lucas but they are long gone so i will find out where we get them now and post the details
Ian
 

nahnotme

Free Member
Sep 23, 2007
239
0
Funster No
336
I've had the step up and looked in the battery compartment and cant see any thing that looks like this and there is no additional door in there. I've also looked around the engine and again cant see anything like that.
I have found a wiring diagram and found the relay start solenoid on there but still cant find it. Do they all look the same ? Im thinking I need some help with this one ? anyone know of someone in the northwest ?
 
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