Brave New World - How much of my Electrical system is worth keeping

[Hughmer]

The connections on my solar panel have failed / corrosion. It was 20+ yrs old / inefficient and I need new one(s). When I started looking for replacements I began to realise that things have moved on a bit in the last few years, - loads of new initials to cope with DoD SoC MPPT, EFB, AGM and B2B.

 

I’ve done my reading and understand what the initials mean and what the technologies do, (and that LiFePO4 is unaffordable). But I now have serious doubts about whether my vehicle electrics are fit for the brave new world and [blue]what I need now is for someone to tell me what to buy and what, if anything, could I retain from the existing set up. [/blue]

 

Existing Set up:

My Bosch S5 LABs (Lead Acid) are 7 yrs old now. General wisdom is they should have been shot 4 years ago but a recent drain test puts one at 97% efficiency (26 hrs to drop from 13.1v to 12.1v at 1.88amp) and the other at 93%. It sounds too good to be true so I’m re-doing the tests.

I have an EBL 99 and a separate10A pwm basic solar regulator connected to Block 6 (Solar)

 

A Battery Mate is connected to spare 4+/- on EBL Block 5 and SB+ on EBL Block 2, but I’m wondering [blue] what does the Battery Mate do that the EBL 99 doesn’t do? [/blue]

 

Considerations:

Replace solar panels & regulator.

Possibly replace Batteries & EBL.

Possibly invest in B2B

Possibly discard battery Mate.

Try to avoid extra meters in favour of retaining the Hymer/EBL interface to show charge/discharge current and voltages of LAB & SB

 

Pattern of use:

3-4 months away once or twice a year. Touring and camping au savage. Campsites/service points 2 x weekly for fresh water & dump. My solar has not been very productive for a while. Generally the alternator replenishes batteries for evening use. We might dwell fro a night or 2 then move, seldom do more than 100km / day. All lighting LED, Absorption fridge, Heater used principally for water

 

Our biggest problem is charging the laptop. We use it for work, - and live streaming TV rather than carry a separate monitor. The charger says 1.8A at 240v. If I’ve got my maths right, this is about 30A at 12v. I don’t believe it ever uses this much power because the inverter runs from EBL Block 5, which is fused at 25 Amp and has never blown. The Hymer control panel (fed from the EBL) only registers 4 or 5 amps discharge when the Inverter is on.

BUT the inverter causes LAB volts to drop like a stone and it doesn’t take long for the inverter’s LV warning siren to start. Maybe the short answer is to buy a more efficient laptop. Ho-ho.

 

Battery & EBL

I haven’t read every thread on the forum but [blue] am I right that the majority view still favours L/acid over gel? If so, - should we go EFB … and will the L/acid setting on the EBL be OK?

 

Are the Molex connectors on the EBL big enough to pass the enormous charging currents that I will enjoy with my new setup? [/blue] (I’m teasing of course) The reason I ask is that one thread mentioned new EBLs have beefier plug/sockets with higher current carrying capacity. But it looks to me that Schaudt allow for 25 Amps per Molex pin on Block 5 of the EBL99. I see two 25Amp fuses each of which can support 2 circuits that together don’t exceed 25 Amp, buy there’s nothing to say you cant use all the 25 Amp on just one of the circuits

 

[blue] Will I “really” enjoy charging currents of greater than 18 Amps, and if I do isn’t something wrong with the battery? [/blue]

 

Solar panels:

I think Mono not Poly. Not so keen on raised rigid (safety/windage). More tempted by semi flex glued down. I’ve been told the heat issue is not so much about efficiency; it’s more about hot air expanding and buckling the panel.

But if I was forced to go rigid, then 2 narrow ones rather that one wide. It just feels safer.

[blue] I haven’t decided on size or make, - very much open to suggestions. There is space on the roof 1m front to back x 1.7m wide. [/blue]

 

Solar regulator:

I’m committed to a new MPPT controller. The names I’ve seen most often are Victron & Votronic. The latter’s paperwork is an easier read. But I am puzzled by Votronic’s connection to the EBL. I have pinged customer service and will update if I get an answer, but here’s the question:

 

Taking the MPP 350 wiring diagram, - the charging current could be up to 30A, though more likely 21 Amp. The connection to the LAB(s) is via the BIG terminals on the regulator, using min 6mm2 cable:

 

Alternatively, if I’ve read it right, I could opt to charge LAB’s via the EBL The benefit being that the vehicle control panel would display charging current. But here’s the odd thing:

 

The dedicated terminal marked EBL on the MPP350 is a small screw and the cable is shown as being 0.5-1.5mm2. [blue] This surely can’t be used to pass anything like the anticipated 21 Amps from the main terminals. Am I entitled to be confused?

 

Does the Regulator limit the current from its EBL o/p? [/blue]

OR

[blue] is the EBL connection a signal wire only, - and if so can it be connected to an EBL 99? [/blue]

OR

[blue] do I need a later version EBL? [/blue]

 

B2B:

I can see value in the system but If my trips are mostly in fine weather and long days do I need B2B if I have an efficient solar installation?

 

Puzzle corner:

MPP technology makes fantastic claims for charge rates. I recently enquired about a controller for a 300 watt panel, and was told: You need to connect the regulator directly to the house battery instead of running through EBL…

 

The advice is based on the anticipated supply current of up to 25 Amp and EBL’s published max solar i/p via block 6 at 18 Amp. [blue] BUT is this really an issue? [/blue]

 

I believe it’s true to say that what is running through the EBL's charging circuits is a function of how much current the batteries (and other systems if connected) are demanding.

 

The Hymer EBL repeater panel could show charge/discharge of 30 A. It has never done so in 16 years of owning this truck. The max current I've ever measublue my 2 x LA batteries pulling on full charge is approximately 8A each.

 

My thoughts are that even if a 300W solar panel / MPPT controller could deliver a net o/p of 21 A or more, the current drawn by batteries is unlikely ever to be this high. It should therefore not present any problems if the o/p of the MPPT is routed to the LABs & SB via the EBL

 

The benefit of your wisdom will be greatly appreciated