Technical Solar, leisure batteries and more for Knaus on a Ducato

[AlexGR]

Good evening to the community from Greece!

as many others I am in trouble in planning my electricity autonomy in my motorhome.
I recently purchased a 2014 Knaus Skytraveller 650DG based on a Fiat Ducato 2.3 130. The vehicle is Euro5.

I am planning to upgrade the electrical autonomy of my motorhome using a solar system. However, I am really concerned to protect every other part of the vehicle such the alternator.

My solar plan will be somehow the following: Mono solar panels around 300-350watt connected in parallel, 2 x 100-120 Ah AGM leisure batteries, MPPT controller, pure-sine inverter 500-700 watts.
The vehicle comes currently with an 80Ah leisure battery, which I assume is the factory one. The vehicle is currently charging its batteries either through the alternator or through 220V motorhome built in socket (not aware whether the 220V socket charges also the starter battery). I am not aware whether the alternator is a smart one or not.
My target is to install a system that the solar panels could also provide a maintenance charging current to the starter battery just to maintain a healthy state when vehicle is parked for some long time (e.g. a month). So far, I have been offered by local dealers (mainly motorhome dealers) with either the solution of a dual charge controller (EPSOLAR Duoracer) or with a relay from leisure battery to starter battery (like Cyrix from Victron energy). To be honest, I would like to go overall with Victron energy since they seem higher quality products, I am not clear though whether Cyrix is the optimum option. Appreciate your thoughts.
Here comes though my second concern. I 've read here and there regarding the risk of charging the leisure batteries through the alternator. Even more concerned while I am going to add extra load with in total 200-240 Ah leisure batteries, which is something that is not planned by factory. I am not really aware whether Knaus is using a B2B charger or just a relay to charge the leisure battery. Local dealers insist that the alternator will have no issue with extra load since it's constantly generating same amount of amperage (probably factory one generates 120-130 A). However, from what I have read on the web this is not correct. Appreciate here your arguments so as to be able to explain to the dealer. So I would like your thoughts whether a B2B charger is suggested to be installed in order to avoid damage on the alternator and the leisure batteries. Don't know whether I should consider to remove the factory method of charging (e.g. the relay) by installing a B2B charger.

Appreciate your comments since I have reached a point that even though I want to install a proper quality system I am willing to proceed with just a diesel power generator, instead of a solar system, due to the obstacles I have met from local dealers.

Cheers.

 

[theoneandonly]

In creating a solar system we have the choice of going all singing all dancing from the start (mega bucks) or build a system that can be added to /upgraded in a cost effective manner.
1: Solar. ok
2: AGM in the UK they have a poor reputation and FLA, EHB or GEL are preferred type
3: Dual charge controller, I use Votronics duo 250 and 350 models (german). With Victron Votronics regarded as the best. (a good place to get best from start)If you go Victron you will need alternative starter battery maintenance charging. Connect directly to Battery not via EBL or CBE.
4: B2B, you have not got a smart alternator nor Lithium so not neccessary from beginning, surprisingly the dealers are not wrong. This is where difficult choices have to be made 30A,50A,60A. Size physical and Current. Some 60A allow you to specify less if not needed.
The Votronics 30A is compact and configured such that you can start with one and add another in fullness of time (my route when i went Lithium). Do not remove existing Split charging system until a B2B is installed. What size relay is fitted, 30,100A?

 

[AlexGR]

Thanks for your response
2: For the type of batteries I am not quite sure that I have concluded. AGM is mainly suggested by local dealers due to its durability in different weather conditions that a motorhome might get into and due to the fact that AGM could provide a boost amperage in starter battery in case needed. Is it GEL the preferred type due to i.e. safety for gas emissions?
3: Nice to know about Votronics (didn't know about this brand before). It seems that the 350 model is more suitable for 300-350 watt panels. I guess also the monitor Votronic LCD Computer S Solar is also a must have.
4: In what terms the B2B is not needed for GEL/AGM batteries? Is it that such batteries do not drew too much amperage from the alternator? Even if let's say they are not at 20% of its capacity?
For the currently installed relay from alternator to leisure battery I am not currently aware since I will be receiving the motorhome by middle of Jan.

Thanks!

 

[theoneandonly]

2: batteries all down to price. I was all set to go Gel but get went up and Lithium down, so went Lithium. Gel are the preffered Lead batteries for motorhomes due to safety and ability for lower usage threashold 20-30% gel 50% FLA. FLA best price EFB more cycles than FLA. any lesuire Bat could provide a back up charge for SB. But much better to use Votronic s duo charger to always ensuire a charged SB. for the paranoid for the SB (ebay Battery monitor BM2)
3 i have (100&120 ) 220W on a Duo250 and a 330W on a 350W no problems for 4 yrs (350) with Pb and Li. For SOC monitoring with Pb I used a cheap Chinese monitor (ebay search Battery monitor tr16) with Lithium need more capability, I use a Victron BMV712 a display type model that can control a relay based on SOC that i use with 2 SSRs ( more complexity that not needed with Pb) A Victron Smartshunt (bluetooth only) or Votronics also good choices.
4: if no current method for charging with alternator Votronics 30A B2B a good choice.