Hymer Exsis-i Split Charge Relay

John H.

John H.

Free Member
Joined
Apr 2, 2021
Posts
181
Likes collected
104
Funster No
80,147
MH
Hymer 578
Exp
A long time
My new project is to put Lithium batteries in a Hymer Exsis-i 2014

I have done a fair amount of reseach and reckon the place to start is install a batttery2battery charger, but before doing that I need to disconnect the Hymer split charge relay.

So, simple question for those more knowledgable than me, Where is it? and how do I identify it?
 
It is inside the Elektroblock, disconnect the cable going into terminal 3 on the back of the EBL.
 
Alternatively use a Votronic B2B ( up to 50A charge) which is designed to work with the EBL.
 
You are right that you need to overcome the problem of the split charge relay. How you do that is in some ways specific to the make and model of distribution box (EBL etc), and what the amps output of the B2B is.

If the B2B output is not more than the maximum starter battery amps input, then one option is, as Lenny HB says, to insert the B2B in the EBL starter battery input wire. Disconnect the starter battery input at the back of the EBL, connect the wire to the input of the B2B, and run a wire from the B2B output to the EBL starter battery input connection. The B2B might need a D+ signal to activate it, which can be found by tapping into a D+ signal to the EBL front connectors.

What B2B output are you thinking of? What EBL model number is it?
 
Sounds promising.

The EBL29 on the Exsis-i does not have numbered teminals on the back.

It only has 3 connections (all heavy duty cables)
- Ground
- Engine Battery
- Leisure Battery

Subscribers  do not see these advertisements

 
Sorry, I made my previous response in reply to Lenny HB withou checking fo other nswers.

I will check out the Voltronic B2B - sounds an easy option, if I understand you correctly.

I was looking at the Sterling 30amp B2B, with an option to use 2 of them latter if I add more Lithiums, so Autorouter's suggestion would be a problem later.
 
I just sorted mine out on the same van.

Link to thread is in my signature.
 
autorouter said:
If the B2B output is not more than the maximum starter battery amps input, then
Click to expand...
If on the other hand the B2B output is more than about 40A, then it needs to be wired directly between the starter battery and the leisure battery. The existing wire to the connection on the back of the EBL from the starter battery should be disconnected, which disconnects the split charge relay path. The wire can be used as the B2B input, but may well not be thick enough. The existing connection from Leisure battery to EBL can be left untouched, and everything will function as before. Except the % state of charge and the battery amps, which will not account for the B2B contribution.

The starter battery mains charging and voltage measurement will function as before, because it goes through the fridge 12V supply wire not the main starter battery wire.

Be careful of the colour code of the connections at the back of the EBL.
Brown = common negative, Red = starter battery positive, Black = leisure battery positive.
 
Last edited:
autorouter said:
The wire can be used as the B2B input, but may well not be thick enough.
Click to expand...
John H. I had a 2015 Hymer with an EBL29, which was connected to the engine battery via a 50A fuse and a cable suitable for this load. I wired my Votronic VCC1212-45 as shown in the instructions for connection to an Electroblock “EBL” (which is a Schaudt product). My VCC had special settings for use with an EBL that kept it within safe parameters for the device. It all worked very well and I did not need to run a new cable from the engine battery.
 
I am disappointed that you can't just unplug the relay. Another job made ten times harder than it needs to be. I might just give up and leave things as they are.

Thanks for you offers of help.

Subscribers  do not see these advertisements

 
John H. said:
I am disappointed that you can't just unplug the relay. Another job made ten times harder than it needs to be. I might just give up and leave things as they are.

Thanks for you offers of help.
Click to expand...

You won’t get an easier install than a 30amp Votronic.

It took me 30 minutes and that included taking the back off the seat and putting the tools away.
 
I am sure you are right.

But I have decided to go for the simple approach. Leave the Hymer electrics just as they are with the Hymer suplied AGM battery. It all works very well as it is.

I really only wanted the new Lithium for the inverter, so I will leave it that way with only the Inverter connected to the Lithium and add a seperate 30amp Sterling B2B to charge the Lithium.

Once again; thanks for the help.
 
John H. said:
But I have decided to go for the simple approach. Leave the Hymer electrics just as they are with the Hymer suplied AGM battery. It all works very well as it is.

I really only wanted the new Lithium for the inverter, so I will leave it that way with only the Inverter connected to the Lithium and add a seperate 30amp Sterling B2B to charge the Lithium.
Click to expand...
That's a good option. I didn't mention it because few people ever do that. Once you've decided on separate batteries, with separate B2B and mains charger, there's no need to stick to 12V. Once the inverter current gets over 100A (ie 1200W) then it's worth thinking about 24V. Over 2400W think about 48V.

I have a 3000W inverter/charger, and have a 48V lithium battery, equivalent to about 300Ah at 12V. I also have a Sterling 12 to 48V B2B. Not suggesting anyone does this, but it works for me.
 
I have been doing a lot more research and also remembered my main reason for going Lithium - to lose the 26Kg weight of the AGM Leisure battery.

So, here is what I did:-
- Replaced the AGM battery with Sterling Power Lithium batteries. connecting them in parallel)
- Disconnected (cut) the yellow D+ (engine running) lead going into the EBL. (on my Hymer this wire is conveniently marked D+)
- Connected the freshly cut D+ Wire to terminal 4 on a Sterling Power BB1230 Battery to Battery Charger.
- Connected the Common Negative, Engine Battery Positive and Leisure Battery Positive as directed in the BB1230 User Manual
- Set the battery type to Lithium as directed in the BB1230 User Manual. (Needed to read the manual a few times for that)
- Set the BB1230 to "Pure ignition Feed Mode". (needed to study the manual even more for that!)

So far, So good the B2B now charged the leisure battery whilst driving (with the EBL only used to charge/float on hookup)

However, the more experienced members will have noted that the fridge no longer worked on 12 volt whilst driving.

So, the next step is simple in concept, but needed a little more thought to implement: -.
- Identified the D+ output wire from the EBL to the fridge and cut that.
- Connected the D+ input wire to the D+ output to the fridge (leaving the EBL isolated from the D+ signal.
- Purchased a 12 volt relay and connected the coil between the D+ wire and battery negative. (Relay now operates whilst driving)
- Identified the 12 volt positive output from the EBL to the fridge and cut that. (blue wire on Exsis-i is much heavier than the D+)
- Connected one relay contacct to a 20 amp fused positive battery terminal.
- Connected the other relay contact to the cut blue wire going to the fridge.

The fridge now operates on 12 volts whilst driving and when the engine is turned off the fridge has its own delay circuitry to stop the gas lighting whilst filling up with fuel etc.
 
Glad you have got it sorted. I think there might have been easier ways to do this without so much cable cutting.

Subscribers  do not see these advertisements

 
Ah, my fuse is 50amp hence why I thought mine was 50.
 
If you had connected the B2B at the EBL starter battery input (as in post#4), the fridge etc would have continued to work as before. The D+ for the B2B could be found by splicing into the EBL D+ wire (5way pin3 or 4way pin 2). The B2B is 30A, which is well within the capacity of the EBL split charge relay (labelled Battery cut-off relay on the EBL wiring diagram).

Probably the starter battery will not now be topped up while on hookup.

Subscribers  do not see these advertisements

 
Last edited:
Why would the starter battery not be topped up? With the engine not running (no D+ signal), is the wring not all the same?
Certainly, the Hymer control panel shows the voltage at the usual top of the range..
 
John H. said:
Why would the starter battery not be topped up? With the engine not running (no D+ signal), is the wring not all the same?
Certainly, the Hymer control panel shows the voltage at the usual top of the range..
Click to expand...
Sorry, misread your post. You cut the EBL output to the fridge. I thought you had cut the fridge supply wire from the starter battery to the EBL. This is used to top up the starter battery from the hookup charger. Also used to measure the starter battery voltage.
 
EuroTrotters said:
May I ask why not a 70 amp
?
Click to expand...
The Votronic 50A is certified to be used with the Schaudt EBL as is. If you look at the installation instructions there is one method of fitting for the 50A model and a different one for the 70 and 90A models. You can buy a relay from Votronic to fit the larger models. If I remember correctly it means that the current doesn't all go through the EBL presumably to prevent overloading/ overheating. You might get away with using the larger models without the relay but I suspect that if there were warranty problems it would be difficult...
I just went for the biggest B2B that I could fit without additional hassle so went for the 50A version. This can in fact be downrated to a lower current by flipping some switches on it. I think Pausim went down this route, perhaps because of long cable runs or inadequate cable?
 

Attachments

EuroTrotters said:
May I ask why not a 70 amp
?
Click to expand...
When I had a Hymer I stuck to less than 50A because that was the rating of the fuse on the existing wiring and without knowing more about the internals of the EBL29 I did not want to risk it or the existing wiring. The relay may, or may not be, rated at 70A but there are also the internal pathways within the EBL to consider.

My Votronic instructions also gave 4 current settings, 3 of which were marked as suitable for use with an EBL. The highest setting given for use with an EBL was 49A. This charge level is fine for my purposes and a comfortable charge level for my LiFePO4 battery.

Subscribers  do not see these advertisements

 
Pausim said:
When I had a Hymer I stuck to less than 50A because that was the rating of the fuse on the existing wiring and without knowing more about the internals of the EBL29 I did not want to risk it or the existing wiring. The relay may, or may not be, rated at 70A but there are also the internal pathways within the EBL to consider.

My Votronic instructions also gave 4 current settings, 3 of which were marked as suitable for use with an EBL. The highest setting given for use with an EBL was 49A. This charge level is fine for my purposes and a comfortable charge level for my LiFePO4 battery.
Click to expand...
Agh okay.

I was thinking of going to 70ah and bypassing the EBL99.

Though I think the alternator is only 110amp so not sure how that will work
 
EuroTrotters said:
Agh okay.

I was thinking of going to 70ah and bypassing the EBL99.

Though I think the alternator is only 110amp so not sure how that will work
Click to expand...
If you bypass the EBL and go directly to the leisure battery you will need to disable the relay to avoid creating an electrical loop.
 
EuroTrotters said:
Agh okay.

I was thinking of going to 70ah and bypassing the EBL99.

Though I think the alternator is only 110amp so not sure how that will work
Click to expand...
If the alternator is only 110a you will probably burn it out.
Are you sure its only 110a most Hymers are 160 to 180 amp alternators.
Pausim said:
If you bypass the EBL and go directly to the leisure battery you will need to disable the relay to avoid creating an electrical loop.
Click to expand...
Just need to disconnect the input to the EBL its 25 mm sq cable so should be able to use it for the connection to the B2B.
 
Lenny HB said:
Just need to disconnect the input to the EBL its 25 mm sq cable so should be able to use it for the connection to the B2B.
Click to expand...
That is what I did and then fed the B2B output back into the EBL at that point. It worked well. Far less obvious what was needed on my Carthago with a CBE distribution system.
 
Lenny HB said:
If the alternator is only 110a you will probably burn it out.
Are you sure its only 110a most Hymers are 160 to 180 amp alternators.

Just need to disconnect the input to the EBL its 25 mm sq cable so should be able to use it for the connection to the B2B.
Click to expand...
It’s an old Hymer 2.8tdi 2000 model year. My sprinter is 180amp. My last two sprinters motorhomes were 240amp.

what do you suggest as the highest I use with 110ah ?

Subscribers  do not see these advertisements

 

Join us or log in to post a reply.

To join in you must be a member of MotorhomeFun

Join MotorhomeFun

Join us, it quick and easy!

Join us

Log in

Already a member? Log in here.

Latest journal entries

Back
Top