Battery to Battery installation

Anybody fitted a battery to battery charger between the engine and leisure battery. Is there a cable route from the leisure battery in front of the passenger seat to the leisure battery?

I'm interested in this question too...... what model of Broadway do you have?

What I've learned from the Fiat Convertors Manual (2017) there seems to be a cable that runs from a fuse on the battery, under the floor behind the seats to the pillar on the drivers side. This is limited to 50A.

My assumption is that to get more than 50A to a B2B then you would need to run a new cable from the battery, however, 50A may be sufficient for your needs?

I fitted a voltronic standby battery charger, same as a battery master but half the price.
The reason we went this way rather than a dual solar charger is that is will charge the vehicle battery while on mains without switching the 12v on in the winter. 
Rather straight forward a wire goes from each battery through a 10a fuse to the charger and it trickle charges the vehicle battery once the hab battery is near full.
The cable run in ours is easy, mostly hidden under the carpet.

J

gpilky wrote:I'm interested in this question too...... what model of Broadway do you have?

What I've learned from the Fiat Convertors Manual (2017) there seems to be a cable that runs from a fuse on the battery, under the floor behind the seats to the pillar on the drivers side. This is limited to 50A.

My assumption is that to get more than 50A to a B2B then you would need to run a new cable from the battery, however, 50A may be sufficient for your needs?

We have 2011 Autosleeper Broadway EK.

I have just installed a lithium battery and a Victron B 2 B it rated at 30 amp.

I can get from the Liesure battery across to the other seat with a small piece of trunking. Come out of the behind the drivers seat. Would like to hide the cables for the last run across the walk way and into the battery compartment. 

I have the cables being delivered soon, will have go then.

I was told buy a  knoligable person that the problem fitting a BTB on my nuevo is the sargent 328, it  controls the  LB charging ,fitting a BTB then you could have 2 charge systems  at the same time  causing a loop that could flatten the LB ,if you cut out the sargent charger you would loose power to the fridge and step.  any comment from our experts ?.

I can't think of a reason why you would have the B2B charger and the power supply in the EC328 running at the same time. Why would you do that?

Roopert wrote:I can't think of a reason why you would have the B2B charger and the power supply in the EC328 running at the same time. Why would you do that?

How would you stop it , LB is charged via sargent when running  engine , adding a BtB would add a second charge system running at the same time ,not when charging from 240 power ,

The Sargent charger/power supply operates only from 240V. Unless you are on EHU while the engine is running, the Sargent charger won't be doing anything. Even if you did have 2 power supplies running at the same time (e.g. accidentally starting the engine while on hookup) it should cause no harm.

[Edit - perhaps you are thinking of the split charge circuit, as discussed in another thread? You can't allow both the split charge circuit and the B2B to operate at the same time - for obvious reasons.]

Time to stop digging  ,

Roopert wrote:The Sargent charger/power supply operates only from 240V. Unless you are on EHU while the engine is running, the Sargent charger won't be doing anything. Even if you did have 2 power supplies running at the same time (e.g. accidentally starting the engine while on hookup) it should cause no harm.

[Edit - perhaps you are thinking of the split charge circuit, as discussed in another thread? You can't allow both the split charge circuit and the B2B to operate at the same time - for obvious reasons.]

I am too looking into installing a B2B (i.e. Victron Orion) and I just had a talk with a very kind Sargent engineer that mentioned the loop problem. It was over the phone and lot´s of details but basically a solution was to install some kind split relay in the battery connection between the EC40 (the unit behind the driver seat) and the EC500.
I need to dig deeper into this, I will publish on our main van modification thread when we get to that point

Johnuready wrote:J

gpilky wrote:I'm interested in this question too...... what model of Broadway do you have?

What I've learned from the Fiat Convertors Manual (2017) there seems to be a cable that runs from a fuse on the battery, under the floor behind the seats to the pillar on the drivers side. This is limited to 50A.

My assumption is that to get more than 50A to a B2B then you would need to run a new cable from the battery, however, 50A may be sufficient for your needs?

We have 2011 Autosleeper Broadway EK.

I have just installed a lithium battery and a Victron B 2 B it rated at 30 amp.

I can get from the Liesure battery across to the other seat with a small piece of trunking. Come out of the behind the drivers seat. Would like to hide the cables for the last run across the walk way and into the battery compartment. 

I have the cables being delivered soon, will have go then.

Very interesting, that is the setup we would like to have.
Did you had to do some modification in the Sargent unit to prevent the mentioned "loop"?

Regarding the loop, I've done the following sketch based on what I know (or at least think I know)!

My understanding is that, when driving, the EC500 provides some charge to the Leisure Battery (LB) but at no more than 20A because this is the fuse in the EM40 and the inline fuse to the LB. However, the B-Pillar connection rating is approx 50A (i.e. capable of delivering 50A) so somewhere in either the EM40 or the EC500 there must be a resistance that limits the current through those units.

The connection to the B-Pillar has a fuse at the battery limiting the current to the B-Pillar so I've used 50A in this example - if you want more the connection will need to be made directly to the battery. 

Now, basic physics determines that the current is given by I=V/R - i.e. for any given resistance the current is proportional to the potential difference. So logically, if more current can flow through the B2B than can flow through the EC500, the B2B has effectively a lower resistance than the EC500 (given that the potential difference in both circuits is the same - approximately).

So when driving, current would preferentially flow through the B2B.

When not driving, if the B2B is 'dissconnected' there will be no flow from the LB via this route, and the normal route through the EC500 will apply. Most B2B's or VSR's will not allow reverse current flow if there is not sufficient voltage from the Vehicle Battery (VB).

The question remains if 50A can travel through the EC500 if there is a fault. Perhaps the fuses will take care of this, but also a relay can be used to disconnect this route when the engine is running (which is when the 50A will be present).

I'd be interested in comments on the above. Please feel free to shoot holes in it - its my understanding at present but I'm sure there are some gaps / errors, so comments to close these and get closer to the reality are welcome

Gary