DCDC Charging

I have the same as Rod. It works very well for me. It is also programmable for different battery types.
Roy G

Separate devices provides redundancy in case of hardware failure. Have a problem with a single devise and loose all charging capability.
The "confusion with the charging algorithms of both devices" is an urban myth. Separate devices will each perform according to their individual settings which may be the same as each other or may be different. Your choice.
I can add direct alternator charging to the solar and they live together quite happily and the total charge achieved is the addition of the two. This is useful in poor sun conditions. I have been doing this for 20 years with AGMs and still do it since changing to lithium.

I am currently building another motorhome. It will have 5 solar panels at 430W each. Each panel will have its own controller. This has lots of benefits including redundancy and partial shade situations. I will still have the capability to add the alternator while driving. All 6 battery charging sources will play together quite happily.
I don't have and won't have any 240V charging capability. Nor do I use DC-DC charging.
Cheers,
Peter
OKA196 motorhome

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Peter, you say ""Nor do I use DC-DC charging." and therein lies the folly in your argument. This discussion was about a system incorporating a dc-dc charger.
The algorithm of a dc-dc charger invariably incorporates measurement of both voltage and current to the battery. If that battery is also being fed from another source (solar), then its terminal voltage may be elevated by that second source and the dc-dc charger will make an incorrect determination of the battery's SOC which will cause error in applying the charging algorithm. It may not be a Big Deal but it does upset things a bit.
Your "direct charge" system does not of course have an algorithm to get "upset".

As for "redundancy". Yes, useful for some things but in this case it does involve the additional purchase cost and space of a second device which is comfortably incorporated in a single dc-dc charger which enjoy a reputation for reliability.

Incidentally, in case I get judged unfairly, the only reason I installed a mains charger in my motorhome is for benefit of later resale. As also the 230vac GPO in the kitchen. Neither are used in our travels but there are potential buyers who must have them.

Allan, my post was simply challenging your claim that multiple charging devices will create confusion to the charging algorithms.

Allan, maybe I don't have a clue how some of this stuff works, but I think you will find that the charging devices stop charging (or change the charge rate) strictly according to the battery voltage that they are set to do what they do, and they will have no idea of the SOC which is calculated by a separate devise using a shunt. That shunt would have no idea where the charging power comes from (or where it goes), and it does not matter.

In my case, when I had AGMs, the solar was set to charge to 14.6V which was higher than the 14.3V that the alternator could achieve. When the batteries reached 14.3V, the alternator would shut down and the solar would finish topping up to 14.6V. I could tell when the alternator shut down because the tacho would stop (it got its signal from the alternator).
Now, with Lithium, I have the solar panels set to 14.0V max, so the alternator continues to charge to 14.3V (which is still fine for the Li).
In both cases, each devise continues to do what it is built or set to do. Neither is a problem for the other and both provide what they are set at to the batteries. The same would apply if a DC-DC was used as well as a seperate solar charger and/or a 240V charger.
I suggest that there will be no "confusion".

Of course, the OP's vehicle will probably have a "smart" alternator that will need to be "fooled" so it can be utilised. I know nothing about "smart" alternators, except that they don't seem to be "smart" enough. :)
Cheers,
Peter
OKA196 motorhome

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Peter, It is really much simpler than that.
Essentially, any 'automatic' charger (see footnote) needs to determine when the battery is fully charged i.e. its SOC is 100%. If it did not, then it would overcharge. There are several ways to achieve this. Car alternators do so by maintaining a fixed output voltage. When the battery voltage reaches this value there ceases to be a difference between alternator and battery so current flow ceases and the battery is considered fully charged. This is known as "constant voltage charging".
In the case of dc-dc chargers a little more sophistication is employed and the charger output and hence the charge rate can be varied to suit the battery type. This variation is governed by an algorithm and controlled by sensing both the output current and battery terminal voltage and essentially is making judgement on the battery's State of Charge. If the battery terminal voltage is also being affected by another source such as a solar array the dc-dc charger will not see the actual battery cell voltage but an elevated value caused by the solar input. This then provides an incorrect value to the charger control function and warps the function of the algorithm. Most dc-dc chargers also use the current value flowing to the battery to make a judgement about the battery charge state. As the battery terminal voltage rises the dc-dc charge current decreases and is information that the battery nears full charge. Again, if the solar input is higher then the dc-dc charger current will decrease prematurely again fooling the action of the dc-dc charger control.
You may "suggest that there will be no confusion" but you would be wrong.
The system does not go haywire but it will not be at its optimum.

When the solar current is fed via a suitable dc-dc charger it is not simply delivered in parallel to the output and hence battery but is used as an input to the charger and subjected to its controller action to deliver a combined and mppt controlled output to the battery.

Of course the "shunt" that you speak of is not employed in the charging control. It is used only by the monitor to display an approximation of battery SOC. The dc-dc charger has its own internal shunt for charge control.

And no, if a "smart alternator" is involved it need not need to be "fooled". The dc-dc charger is not compromised by it.

So chuck out the DC-DC, charge direct from the alternator and get a better charge rate and cheaper result.
A DC-DC charger serves little purpose if the voltage does not need boosting because of the distance between the alternator and the battery.
Cheers,
Peter
OKA196 motorhome

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Yeah, chuck it out….. who needs it?
While your'e at it, chuck out power steering, hydraulic brakes and shock absorbers…. all newfangled
un-necessary gadgets and save even more money. Maybe get rid of those pesky pneumatic tyres too.

I am serious. Great thing for a caravan with lots of voltage drop.
If they were so necessary, why not have one for the crank battery?
Cheers,
Peter
OKA196 motorhome

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Because the crank battery is usually a flooded lead-acid battery (I know, I know, not always) designed to deliver short but high currents and is usually only discharged very little then promptly recharged by constant voltage in a short time. Because of their voltage curve they quickly lap up charge current and self terminate charging inherently. Pretty robust and not too fussy.

Lithiums with their flat charge/discharge curve, and to a lesser extent AGM batteries are a little more fussy and benefit from curated charging profiles. Not absolutely necessary but it does have benefits other than overcoming supply line volt drop. But you make a choice and pay your money. One way or another!! I paid big bucks for my lithium battery and choose to look after it with care. Just don't tell me that I am duped by "urban myths".

The are a few ways chargers could know a Li is full, a smart charger knows a Li is full simply by watching the amps flow out of it at a given voltage for a given duration aided by some absorption master set time determined by the batteries voltage on start, aswell the charger might stop charging every few mins to monitor the batteries voltage-more so with dc-dc, dumb buck boost chargers just stop when the voltage rises to the set point dropping down to a float voltage, solar complicates things with clouds and the algorithms are pretty generic.

If the Li is hungry and the two chargers can be maxed out in amps then the battery will just pull all the amps (assuming the Voltage regulator set point is high enough and there is minimal vdrop in cables)
If the Voltage regulator set point on a constant voltage source isnt high enough and there is some other source of charging say in the latter part of the cycle then the former might just contribute a rather poor amount of amps. if its v set point is high enough then overcharge can occur, overcharge arises as the voltage is too high for too long, so 13.9ish volts for an alternator is the sweet spot, ,may have to raise that as the Li IR increases overtime.

The reason a flooded cranker "laps" up current quickly is due to; it has a higher internal resistance than a good agm, it has a very poor coulombic efficiency overall, the asymptotic reduction comes earlier and is more aggressive. thus it requires a rather high voltage that many alternators cant muster up and limits current badly. instead of getting 10years out one you might get 4-5. the voltage curve doesnt have anything to do with it, some li-ion have very steep curves and pull every amp they can take.

I dont think you can say a Li has a flat voltage curve. On empty under a 0.3C charge rate they typically start out at ~12.8-13V, then that rises to up to 14.6, at least 14ish, which is on average a whole 1.25v to play with. As long as the Li never exceeds 0.5C charge rates and the charger drops down to float ~13.5v once its full (trail amps 0.05% of C), never charges over 0.3C when cell temps are below 5deg C, 0.05C below zero, they are pretty foolproof.






"This has lots of benefits including redundancy and partial shade situations."

then please mention them all, otherwise its just a baseless assertion as per usual.

The redundancy claim is problematic as this greatly increases the foot print, charge bus/infrastructure and raises the odds of appliances failing more which in your careless generalization failed to take into consideration, a problem for many. sometimes a single failure is better to deal with. the odds of a single mppt failing is rather slim and a once in a while event.

When two panels are in parallel to the mppt and one is shaded, for the most part it gets knocked out with minimal leakage current to it from unshaded panel, but the single mppt is hunting for a single Vmp point as its assuming a single IV curve, so the shaded panel could bring down the good panel's Vmp some what, so the good sunny panel will be loaded more but now at less voltage and so less power. again on a flat roof plenty diffuse light will keep the shaded panel's OCV high enough it should be minimal.

More controllers means more conversion losses, assuming mppt, conversion losses can be lousy due to a wide voltage delta between battery and panel or from being feed small power relative to its size.
mppts consume power as they continually track the optimum power point, some worse than others.
Multiply mppts may consume enough standby power to negate the gains of max power extraction from individual mppts per panel.
On a flat roof exposed to consistent irradiance multi controller is easy and by the same token a single controller would work well, but in west vs east type facing arrays they can be bad, as you wanna make sure the controller with the shaded or no light panels doesn't have the task of finishing the charge.

a good reason to use multi mppt is the single unit might have poor heat dissipation due to how awful passive cooling is, victron gear leaves something to be desired for, dunno how those engineers thought plastic body around 5 sides of the charger was a good idea LOL. needs massive heat sink fins with massive surface area that isnt practical, for above reason and made worse by the power density and heat flux considerations at the matting faces of the cooled components are slowed right down by the slow passive dissipation of the heatsink.

I have not used a flooded lead acid crank in the OKA for 15 years. They would fall to bits inside within 2-3 years due to corrugations. Went to AGM cranks and got 9 years out of the first. Second was replaced at 5 years a year ago with a lithium crank as a trial for the new build. It is 800CCA, 30Ah, 4.5kg and starts the Perkins much better than the 125Ah, 36kg AGM.
Just dropped it in. No other changes. Seems to get along with the Li house just fine. So far, so good :)

ps... my solar controller is still the 20 year old PL60. Working fine, but I don't look forward to the day it fails.
Cheers,
Peter
OKA196 motorhome

ps.... Another reason for a direct connection between the alternator and the house battery (or the ability to easily create one) is so it can be used in reverse.
We had a flooded lead acid crank battery fail in the Kimberley. I used the solar to put enough charge into the crank (helped by the house battery) to start the engine. I did that for a couple of months until we got home and I could buy a replacement at a decent price.
It can also allow a flat crank battery to be easily recharged by the solar if you stuff up and leave the lights on.
Cheers,
Peter
OKA196 motorhome

Peter.

What cells do you use to have 800crank amps 30AHand 4.5 KG? Seems a lot for a small cellpack. They must be far better than what I have seen. Thinking of doing similar in a ute. Is the BMS bypassed for starting?

Allan. I use two MPPT chargers to charge some agm batteries for lights at home and other demands too. They run quite well together and one will go into Float when the other is still delivering a small amount to the batteries. I can't see their AL. GORE. rythms are fighting or being confused.
Having two separate chargers is an advantage as I see it. If one fails then the pack still gets charged at a slower rate perhaps. If a combined unit Alt/Solar/240 and it fails = no charge, then it is a sad day! I presume it is the same switchy bit inside which is actually delivering current to the batteries!

.
You are grasping at straws Peter. That feature is not ruled out by having a dc-dc charger.

My system, with dc-dc charging, incorporates a high-current switch that can connect between the house battery and the cranking battery. A simple function for emergency that has nothing to do with the dc-dc charger or anything else.
It also provides for supplying the house electrics from the cranking battery/alternator in the very improbable event of house battery failure. I hope to never need it but it is available at the turn of a knob.
The operating knob is removable to avoid irresponsible activation by the service apprentice.

I bought one of these.
Lithium crank battery
Paid $500 for it.
Frankly I don't know much about it. It is prismatic cells and I am guessing there is no BMS.
I must ask a few questions..... like how to use the winch without blowing it up. I am guessing that there might be another advantage with the direct connection to the house and maybe I can winch by connecting everything together?

In the meantime, it works well as a crank. Sits at 14.3V (alternator voltage) while driving and drops back to about 13.5V when parked up (which is very close to the house volts).
Cheers,
Peter
OKA196 motorhome

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RMD,
I was not talking about having two solar controllers inputting to a battery in parallel connection.
I was talking about a solar controller in parallel with a dc-dc charger. Similar but not the same.

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Peter, that Lithium crank battery looks good. I would give one a go if need arises.

The spec. sheet for the one you linked states that it has an "intelligent BMS" but if it is marketed for cranking duty there is a chance that it may be OK for winching.

Just had a chat with SSB.
They did not actually say, but I suspect that the BMS does nothing except report voltage and SOC via Bluetooth.
They did suggest that winching would be OK provided the battery did not get hot or let the smoke out which means max 15 seconds of high load followed by a 15 minute cool down.
Running the engine and hooking up the house (which is good for 250A) would have to take a lot of load off it. I can also connect the winch to the house battery, so there is a bigger problem there because of the 250A BMS limitation.
I guess if I need to winch it will be a case of gently, gently and taking lots of time for batteries and BMSs to recover?
These questions were never an issue with AGMs........
Cheers,
Peter
OKA196 motorhome

According to the specs it has over and under voltage protection so would appear to have a BMS and therefore most likely cell balancing etc.

What worries me is the max amp charge rate 90 amps

I have an 85A alternator so 90A max charge is more than ever required.
There are larger versions with higher charge rate capacity.
Cheers,
Peter
OKA196 motorhome

Leigh.
Does it matter if there are two solar controllers or a DC/DC unit? Mostly we are talking about something and multiples of it, which has a switch mode energy output and a controlling algorithm. You said they are similar so how does it matter? All of these are in parallel to the battery section. ???

My preference is to have at least two seperate forms of charging systems available. I'm actually running three types of charging systems in my van, a DCDC which has car and solar inputs. Another solar controller that takes care of the portable panels. Then there is the AC charger and I also have a Methanol fuel cell. All different brands and most have been used in combination with each other apart from the AC charger which usually runs by itself.

In caravan parks etc AC is generally used but any of the others can take over if the AC fails. When out and about the DCDC and Solar mostly do the job, the DCDC has the campers roof top panels connected to it so mostly does all the work, if additional solar is or the DCDC should fail then I ahave a seperate solar controller that poratabl panels can be connected to. If parked up in inclement weather without access to AC the fuel cell is put on line.

Never had any issues running them in combination, they all play happily together but then they are not bargain basement units either.

Personally I prefer to have multiple charging sources as we do a lot of remote travel. Having all your eggs in one basket is not good if your relying on the unit to run freezers and fridges, if the unit fails and you have to cancel your trip and return before your food goes off. If you have a freezer full of frozen meat that spoils it can be an expensive mistake.

I see more and more of one stop electronic solutions where one unit runs everything which doesn't make sense to me, even the manufacture of my camper has gone to a one stop solution in a van that is renouned for its off road reliability, if the smarts fail you loose everything from turning lights, water heating and charging batteries etc. Doesn't make sense to me to have one point of failure being able to kill everthing.

We owned an EFOY for a couple of years in Europe 10 years ago.
I bought it second hand to cover bad weather situations as we were free camping and relying on solar for our power. As it transpired, the solar was usually fine, but the EFOY saved the day when the batteries failed.
Sold it after the trip and got our money back plus.
Great bit of kit. It was just 75W output which does not sound like much, but when it can run 24/7, it can made a lot of power. Make about the same noise as a compressor fridge and can be safely operated inside the vehicle.

Cheers,
Peter
OKA196 motorhome

My understanding is two or more MPPT controllers will play nicely.
Two or more PWM, or a combination of MPPT and PWM will not.

Peter g28
A tree felling terms is " one fell swoop", ie, Felled the tree with one swoop of the axe. Not sure what a "one fail swoop" is though!
In the case above it is more, a two fail.

After the fail swoop.. he may have had to jerry rig a solution.

Reality is it a DCDC/MPPT is two charger sections in one unit. Many think they are just one charger with one input from the car and one from the solar panels. This usually is not the case as an MPPT functions differently to a DCDC charger and they tend to be two seperate units in one box controlled by the micro processor. This makes sense as there are a few specialty micro processors available that specifically designed for MPPT functionality and to control DCDC charger functions. So you may actually end up with three micros in the box, one controlling the DCDC part, one controlling the MPPT and anthor micro that decides which charger to use and control the I/O fuctions user controll etc. Failure of any of the micros can bring the others down too.

If your lucky and the failure is only a minor issue that only affects only one of the chargers, but even then if camped up somewhere for a few days and the MPPT part fails it is not going to be good to have to run your car for hours a day to charge batteries. If your reliant on solar providing most of your power then it is a good idea to have a back up solar controller if often travelling remotely and you can't just pop down the road to get a replacement unit. Myself I prefer not having to make repairs or jury rig equipment to keep it working when on the road where I don't have access to my work shop. I prefer to have inbuilt redundancy and have at least to seperate systems normally sharing the load between them. If one fails then the other takes over till I return home do a proper repair.

"Reality is it a DCDC/MPPT is two charger sections in one unit. Many think they are just one charger with one input from the car and one from the solar panels. "

That's interesting. Which manufacturers produce those? I have not looked at the details of these units for 18 months or so. The ones I have studied in detail have one power path and there is an ignition wire or similar to change that charger over from a DC-DC unit to a solar regulator.

Leigh W
I tend to agree with Peter D. I would think the units which have a DC DC function and an MPPT function BOTH direct their output to the output stage and IT sorts the charge profile. I cannot see manufacturers designing, (they are not silly) TWO separate power output stages/systems. Pretty easy with electronics to turn on the DC to DC OUTPUT to the final stage if Ign is ON. and also OFF if solar ONLY. I don't know that depth of ID of the circuits in the units, but it seems logical and economic to do what Peter D indicates.

Things change peter, has been a long time since the enerdrive units for instance come on the market. From First version of the enerdrive units from memory gave preference to solar charging if both solar and alternator power were available. Current version gives preference to alternator but checks the voltage level at regular intervals and if it drops below at certain volage will switch to solar if available and then keep check to see if the alternator voltage has improved if so will switch back to the alternator ie checks wich source is providing the best charging and use it.

Other makes can use a combination of both alternator and solar to get the highest output.

If you have an MPPT charger you can't connect it to an alternator for example as the MPPT charger will try and load up the panels and pull the voltage down to the MPP which is not going to happen if your feeding it from an alternator. Having said that you can actual connect one to an alternator as I have done similar to check a unit is working by feeding a DC power supply into one and it does work somewhat but not going to operate at its maximum efficiency as it keeps trying to find the MPP and gets confused as the input voltage doesn't change.

I have a friend with an Enerdrive (I think) unit. It always chose solar if it is available, even if the solar is 2A and the alternator is 50A.
Pretty silly.
He had to modify his system to force it to use the alternator if it was available.
He installed an ignition activated switch to turn the solar input off.
Cheers,
Peter
OKA196 motorhome

It was this personal experience that I had remote camping that brought home to me that my own 12v system had to be:

1/. Simple to diagnose issues initially without calling in professional help...ie know and locate which circuit was faulty, have the ability to isolate that circuit without effecting the bulk of the rest of the 12v charging system.
2/. Able to "swap out" troublesome components without pulling half of the 12v system apart to get at it.
3/. Select components that are decent quality, easy to get, simple to use, relatively inexpensive and have a good history of reliability.

From the manual for the current version;

" When the battery is charging through CH3(Alternator) with normal operation (not through Ignition
or override setting), the charger will charge for 3 minutes, it will then rest for 5 seconds to
verify the Input voltage.

During the 5 seconds rest period, if the measured voltage is >12.8Vdc on a 12V System
(>25.6Vdc on a 24V system), the unit will continue the charging cycle through CH3.

If the measured voltage on CH3 is 13.2Vdc on a 12V System (>26.4V on a 24V system)"

So acording to the user manual the Enerdrive units defaults to alternator if it is providing sufficient power ant that is what my unit does. From memory the earlier model may have defaulted to solar if it was available most likely as a petrol saving feature.

One would think as the unit has the smarts it would default to whichever is providing the most charge output or use a combination of both but alas no with that particular brand.

.
Perhaps even more specifically, Enerdrive support notes state…………..

"The DC2DC has the ability to charge from either an alternator linked to a vehicle start battery or from solar power using the built in MPPT Solar Controller. It cannot charge from both sources simultaneously and will automatically switch between the two as necessary. Therefore, if your DC2DC is connected to both solar and vehicle inputs while the vehicle is running, the solar will not be charging until the vehicle is shut off. Please note that the automatic switching between these sources may take a couple minutes as the DC2DC waits for the vehicle start battery voltage to drop."

"RMD

I tend to agree with Peter D. I would think the units which have a DC DC function and an MPPT function BOTH direct their output to the output stage and IT sorts the charge profile. I cannot see manufacturers designing, (they are not silly) TWO separate power output stages/systems. Pretty easy with electronics to turn on the DC to DC OUTPUT to the final stage if Ign is ON. and also OFF if solar ONLY. I don't know that depth of ID of the circuits in the units, but it seems logical and economic to do what Peter D indicates."

An MPPT operates fundementally differently to a DCDC charger. It converts the high voltage fairly constant current output of the solar panel to a lower voltage higher current output while keeping the solar panels at their maximum MPP point range which is all controlled by a dedicated micro processor which controls the whole process by adjusting the frequency of the output stage to acheive the desired result.

A DCDC charger on the other hand just boosts the voltage, again handled by a purpose built micro.

One output stage is designed to lower the voltage and increase the current the other to increase the voltage .

You could no doubt design one output stage to do both functions but then you would need to switch components in and out to tune the circuit but this may become more complex than simply having two output stages. They may have indeed opted to have a controller down stream controlling the charging too. Would be easier though to simply control the micro's doing the switching functions ie MCU tells the micro what profile to use or simply what charge voltage is required.

When considering the number of breakdowns you get in modern equipment, go the combined charger, that will save a bit of weight and expense. The only pieces of equipment I have had collapse on all my trips over the last 30 years that have affected my travels were two batteries. Apart for the batteries, I have had two mains powered chargers go, but they did not affect my schedule.

Spend your monetary savings on a good battery monitor if you don't already have one.

.
I totally agree with Peter, Provided you don't buy rubbish. Good quality modern electrical products are very reliable. It is more likely to be peripherals such as connectors & switches that give trouble.
Furthermore, These accessories are often not vital to your mobility. Sure, your beer may get warm but are you so feeble to allow that to ruin your day? ( I know some would say "yes" to that but they are not around my campfire! )
Some people carry all manner of things that they considered crucial yet had a statistical history of reliability provided that they were maintained. Yet it may have been the very thing they did not carry that stopped them. The ever-present Mr Murphy is your unseen passenger.
I was not disposed to carry heaps of spares so limited myself to a set of wheel bearings on the concept that I could not even be towed without wheel bearings. And I never needed them as it happened.
What did almost stop me on two occasions were suspension failures although even then I was able to continue moving with care. Mind you, there was always fencing wire and gaffer tape in the toolkit.

I just remembered, I did carry a spare pair of shockers for a while and did need to use one. I solved that issue by changing all my shockers to Koni's and never again had a problem. Good quality has its merits.

Yes Allan, Whilst a little “off topic” with regard to chargers, my issue has been the high tensile bolts that hold the shockers in place. Single axle van, twin shock independent suspension for each wheel, four bolts have broken in the 8 years we have had the van. Resulted in not only having to replace the bolts, but also one of the shocks had dropped and dragged along the ground, wearing down the “eye” socket. I now carry 4 bolts washers and nuts, along with a spare shock absorber.

Macca.

Hi Macca, I have sent a Member Message.

After a few changes to our power system, I’ve ended up with, in our canopy, an Enerdrive DC2DC 40A charger(alternator only), a Victron 100/30 solar charger & a Victron BMV712 monitor, charging an ATG 300Ah lithium battery. Solar panel is an LG 375w until from Springers Solar.
The Victron products can be monitored on phone/ipad. One way to get one’s Cook off side is to monitor aforementioned Victron units, and announce regularly, the increase in SOC, and/or battery charge percentage.
Our 2nd hand caravan was fitted with a Redarc 1240 dcdc/MPPT charger, which favours solar input, but I was pleased to learn that it will also use alternator input if the batteries require it. This system is also monitored by a BMV712, and has almost 800w of solar on the roof.

Bob

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Bob "One way to get one’s Cook off side is to monitor aforementioned Victron units, and announce regularly, the increase in SOC, and/or battery charge percentage." ….. Yep, Boring,boring.
It's also not smart to remark that the toilet cassette is full!!!…. Just do it!

Allan B,

I replied to your Member Message, let me know if it came through.

Macca.

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No sign of it Macca. That facility seems a bit shaky.
Try using email. My address is in 'My Profile> About Me'.

Much of the cost of this electrical stuff is proportional to the power that it can handle.
In my new build I will have 5 @ 430W panels each with a 100/30 Victron controller costing $177 each = $885.
I could instead have a single 150/100 Victron controller which costs $701 (with some different features) --both prices are list from Solar4RVs.
In this case, redundancy protection with multiple components has relatively low extra cost.
There are other plusses and minuses with each choice, of course.

Cheers,
Peter
OKA196 motorhome

EDIT... Looking again, that 150/100 Victron is too small. :(

I will be going to an auto sparky for my purchases but will feel a little more comfrtable having a bit of an idea as to what may suit me best.

As some of the comments in this post indicate, there is a rang of opinions as to the best course of action.
This diversity no doubt extends into the professional ranks.

Solar for the vehicle is for when the tent is in use, or to maintain the battery when parked away from 240v (or is it 230v?)

Thanks though for reminding me not to implicity trust anyone who has an opinion.

Paul

If anything other than confusing you even more, this thread will have made you more aware of your variables.
Approach more than one professional auto sparky ( as apposed to a company like renogy or enerdrive who each would have unarguably the best solution in the world) in writing and expect their recomendations in writing then get whichever you feel comfortable with to do the install as well.
Don't at any stage mention internet forum advice or they won't even bother wasting their time replying.
I doubt there are any practising professionals on this forum that's willing to put their money where their mouth is.

qldcamper posted:
If anything other than confusing you even more, this thread will have made you more aware of your variables.
Approach more than one professional auto sparky ( as apposed to a company like renogy or enerdrive who each would have unarguably the best solution in the world) in writing and expect their recomendations in writing then get whichever you feel comfortable with to do the install as well.
Don't at any stage mention internet forum advice or they won't even bother wasting their time replying.
I doubt there are any practising professionals on this forum that's willing to put their money where their mouth is.

"I doubt there are any practising professionals on this forum that's willing to put their money where their mouth is."..WTF are you on about???

I asked a Professional once, and he was THE MAN at Pirahna

RMD ,
and......?

QLD
Something went wrong there, sorry. Some Professionals from companies simply do not tell the truth. The Piranha MAN, the man himself, told me I needed a Bigger alternator for a Dual system. he stated NO Land Cruiser has more than 60 amp alternator.Mine delivered over 100 amps while holding 12.7 volts. Absolutely not true from the top executive!

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Always bear in mind that ANY business exists to make a profit. That is undeniable.
So any advice from them is weighted by that. Even the most honest dealer will recommend the product he sells and it may not be the best for you. Listen to what he says but temper it with independent advice.

RMD,

Hence the reason to talk to an actual auto sparky.
You mention he was a professional, but professional what?

As a side note, what was your alternator rated at, unless it was a 160 amp or higher I doubt very much it could sustain 100 amps output for very long.

QLD
The Denso units don't have an amp rating just a code. Not sure what output it was because I never loaded it higher than 105 amps. The stator was WAY thicker than a a 60 amp alternator, about double.
From what I know, an alternator able to hold 12.7v while under a 100+ amp load is probably able to deliver more than that. I didn't see any point in a destruction test!

The issue was, the well respected industry man was telling me porkies. I knew it was nonsense. Any alternator can probably be driven to destruction but that wasn't the issue here.

RMD,
It is mind boggling what they can put out these days.
As an apprentice I remember upgrading my Escorts 28 amp alternator to the high output 32 amp one.

While all the theories are being worked out we will just continue using our original 100A rated Mitsubishi Canter alternator to charge our LiFePO4 house/engine starting battery bank.
No DC-DC charger involved.

Typical starting current that will slowly temperature self regulate to nearer 75A until the battery is full.
Despite all the naysayers the alternator has not yet released all its smoke in 10 years of full-time travel.

The solar can add another 50A on a good day.

That's an awesome effort for a 100 amp unit.
Battery taking 109 amps and I assume whatever load the vehicle was using would not be showing in that.

SCUBADOO did say he had solar charging as well. That would be contributing somewhat to the 109 A.

Solar charging and all house loads were isolated for the test.
A front cab clock/thermometer, daytime driving lights (800ma) and the engine electrics remain as permanent connections.

The 109A was the alternator output on engine start from cold.
It slowly drops to c75A over about fifteen minutes until the battery is at 14.0V and about 98% SOC according to the Victron SmartShunt and Junctek battery monitors then rapidly drops over a couple of minutes as the the battery terminals reach the alternators maximum 14.1V output.