Leisure Battery Charging system

jace_da_face

jace_da_face wrote: »

Looks good but look at the price . I would like to see a unit that also distributed all load power. This would cut out the need to to install a shunt.

Have you seen what they charge for featureless, under-wired battery killing Ziggybloks?

A distro is an entirely different kettle of fish. You couldn't integrate it, everyone will want something different. Just add yer own fuseblock.

Yeah looks intimidating but it's got:
{15A examples the 30A Manager is only £150 extra}
MPPT solar controller: €300
A Battery Monitor (with a cheap a$$ shunt, but low light solar input will never be confused for end of absorption because it's an integrated unit, which is the single greatest nuisance of auto-syncing jobs): €150
A Quality Mains Charger: €200
An intelligent combiner: €150
A boosted battery to battery charger for smart and dumb alternators: €250
Installation cost for all of the above as a modular kit: ~€350
+€500 for all of the above in 30A

Add to this the claim that it charges to 100% I have never seen a mains charger do this which is why I don't run any.

autumnalcore wrote: »

Looks like a nice package especially if you get a friensly expat to hike it home for you. Certainly more attractive than the sterling offerings for the money.

Yurp
Sterling :rolleyes:
Different league.
Redarc are making the best product they can. Sterling are making the cheapest (and charging the most for it).
Ever notice how ProMariner have a much lower failure rate than Sterling?
ProNautic have a 5 year warranty, ProCharge Ultras have a 2 year warranty. Hazard a guess why! It's the same looking exterior, same board layout.
Edit* [5 year warranty on ProCharge Ultra since 2016 (red terminal cover)]

autumnalcore wrote: »

Submersible spells potted to me though which always makes me hesitate as its basically irreparable if anything fails wonder what the aftersales is like.

Indeed, there's a lot to be said for modularity.

autumnalcore wrote: »

Speaking of reparable, the redarc stuff never seems to show up for parts or repair on ebay going by the forums they seem to have a policy of replacing failed units well outside warranty. Which sounds like a major plus to me.

They are contracting them to the military that ranks them beside Merlin & Xantrex for me.

Don't get me wrong I can do better but I can't do cheaper. It's not programmable although I'd not be unhappy with the presets for the first time ever.
It's got the same 12V solar panel only problems as every other offering...if I was flying two solar panels I'd want two solar controllers because shading.
It's a single point of failure to take out the entire charge system.
I'm pulling 40A-50A (after load compensation) off my alternator these days with low SOC, sticking electronics in the middle will only reduce this and make it less reliable.
Seems like 10mm² is the max cable aperture...meh, fix that with a barrier terminal strip.
I don't run teeny little +12v wires to my shunts.

I heart the solar priority assist feature, I was working on this but was advised against it as it may cause MPP Tracking issues.

12 element

Ring RSCDC30 looks a nice alternative to the CTEK. Thinking about using it in my Van Conversion.

http://www.ringautomotive.com/uk/products/Workshop+Tools/Battery+Maintenance+Tools/SmartChargePro/RSCDC30

Looks good for the money. My preferred MPPT solar controllers cost more.

I haven't used ring products but they're a bit like Durite to my mind. Every-expense-spared, Chinese built jobs.

I'd be very skeptical about the rating/performance.
I wouldn't fit one without a battery monitor.

Temp. compensation is 10mV too low. 14.8V ceiling means temp comp doesn't work for Calcium/AGM/Lead Crystal unless the manual is mistaken which is not unusual for Ring.

Here's something similar from Projecta.

jace_da_face

So my solar charge controller does in fact keep my split charge circuit closed after engine stops. The charge controller will not close the relay once open. But it does mean my starter and leisure battery will remain connected if the engine stops and there is enough solar charge to exceed the VSR threshold.

This would be bad if:

(A) My 12V fridge was left on and I didn't realise, as my fridge would continue to run on battery power instead of alternator power once parked up.

(B) I didn't want solar charge to be directed to the starter battery. I mean why would I unless my starter battery was flat? It should just go to the leisure battery.

(C) I didn't want the two batteries left in parallel anyway, as they are not designed to be and are not matched.

This is not a major problem as long as I remember to open the split charge circuit once parked up, by knocking of the PV panel for a few moments and allowing the relay to open.

It is a nuisance if I turn off the engine and restart it again without needing to get out and without isolating the leisure battery, as now the leisure battery is supplying some cranking amps.

A longer term solution is to eventually wire up a switched ignition signal to the VSR. An even longer term solution is to invest in a smart battery to battery charger/ MPPT combo similar to CTEK or one of the other ones mentioned in previous threads.

jace_da_face

jace_da_face wrote: »

(A) My 12V fridge was left on and I didn't realise, as my fridge would continue to run on battery power instead of alternator power once parked up.

The fridge will create voltage sag and the VSR will disconnect.

jace_da_face wrote: »

(B) I didn't want solar charge to be directed to the starter battery. I mean why would I unless my starter battery was flat? It should just go to the leisure battery.

If you maintenence charge the starter battery it might last a decade

jace_da_face wrote: »

(C) I didn't want the two batteries left in parallel anyway, as they are not designed to be and are not matched.

They are both lead acid?
Just add water as needed they'll be fine. You can charge them together. The problem is in discharging them together. Having said that the engine battery will pull down available solar charge to service battery

jace_da_face wrote: »

This is not a major problem as long as I remember to open the split charge circuit once parked up, by knocking of the PV panel for a few moments and allowing the relay to open.

I've never been a fan of automatic split charge. My setup has always been manual with a sophisticated intelligent relay for storage only.

jace_da_face wrote: »

It is a nuisance if I turn off the engine and restart it again without needing to get out and without isolating the leisure battery, as now the leisure battery is supplying some cranking amps.

Unlikely because the drop will open the relay and besides you won't pull more than 30A across that relay with that cable.

jace_da_face wrote: »

A longer term solution is to eventually wire up a switched ignition signal to the VSR. An even longer term solution is to invest in a smart battery to battery charger/ MPPT combo similar to CTEK or one of the other ones mentioned in previous threads.

Manual + meters. Works for me.

jace_da_face

All plausible points Liam which had occurred too me too. But, with the engine turned off having just been running, and split charge engaged and remaining engaged as the solar controller tries hard to maintain a charge, the VSR will eventually flip-flop like a mad man. At this point the voltage is oscillating within the low and high voltage set points of the VSR. I think it could potentially stay that way for a long time, until the sun goes in :eek:.

Turn the adjust pot fully clockwise.

jace_da_face

Sir Liamalot wrote: »

Turn the adjust pot fully clockwise.

Arghhh! Have adjusted it several times already. The last adjustment was to stop the fridge cutting out when driving due to the a battery loading voltage being pulled down. Unless there is a pot for lowering the “hysteresis” band, I’ll give it a go. It’s a real compromise.

I’m gonna get me a switched ignition signal. That’s all there is to it!

..or a better fridge.

jace_da_face

Now that is not even funny. My fridge keeps my beers cool! That is no laughing matter.

At this point I should digress and refer people to what is, or was, a very influential experiment. A recording of an important event that took place by a man in his shed. One that would inspire me to be believe what is possible.

This is an old link, but it’s importance should not be forgotten. Link

I'm not being funny. A domestic fridge uses ~ one sixth the power, for the same cooling at one sixth the price.
It doesn't bog your charge system and your beers would still be cool.

Alternatively, you can throw copper, contactors, time and money at it and feed the losses. Absorption fridges have never been a clever idea, used to be they were the only practical way to do things if you wanted autonomy. That stopped being true a long time ago. There's no excuse to fit them these days other than they are a cheaper install but come with an insanely expensive legacy.

I spend ~£250 a year powering mine. Yes, my stoopid camper fridge eats two equivalent domestic electric fridges every year in upkeep. Before you count all the wasted food it's lack of regulation ruins...just saying.



Anyone who really uses their vessel will tell you the same.

autumnalcore

Absorption fridges in practically every hotel room too because of the lack of noise but my crappy beer fridge is under the bed now and compressor doesnt bother any of us.

Sound insulation is a one time purchase. Hotels are environmental terrorists. I'm sure the lecky bill is included in the room fee.

jace_da_face

What wattage is your fridge Liam?

120 Watt rated on redundant 12V. 135W Actual.
125 Watt rated on mains. 127W including MSW Inverter. Contrary to popular opinion MSW inverters are more efficient than sine inverters for resistive loads.

Let me put that another way.
My unmodified compressor fridge runs for 25Ah a day.

My active cooled absorption lump.
12v = 260Ah per day and it'll freeze everything/
230V including inverter = 170Ah per day.
Gas = 5kg butane every three weeks.


...Garbage! Some cheek charging what they do for those lemons. :mad:

jace_da_face

But can you replace 25Ah with solar all year around?

Nope. No amount of solar you can fit on a motorhome roof will do that.
My PWM 150W PV hybrid diesel-electric system of old could deliver that most of the year and I ran degenerative 3 week deep discharges between November to February with Mains maintenance charging to buffer.

150W PV Solar alone can deliver that from March to October.
However, I'd want another 25Ah daily for habitation loads like lights and boards.ie.

Current system can provide that April to October, with another 115W, I reckon March to October won't be a problem.

Notwithstanding that a stock 25Ah day fridge has a lot of room for improvement with cooling and insulation so less is more.
My absorption used to use 25% more powah above 15°C before I added active cooling.

With just a 220Ah battery you can run a compressor fridge and resonable hab. loads for 2 days.
Add 100W of solar gives you 4 days in Spring and Autumn and 9 days in Summer.
Fix the alternator charge circuit and you can offset this with between 10A or 60A depending on how well you fix it.

Some people turn to battery to battery chargers...I almost did myself, this will make stock cables work like good cables for 3 times the cable and routing upgrade costs (plus downstream B2B cables)
I wouldn't go fiddling with smart alternators though. For those, I'd be recommending a second alternator which is the best answer by far...I'd expect 60% rated under heavy load, or a B2B.

If you want to Mad Max it stick a series 50Ω wire-wound pot on the D+ and you are the alternator regulator...just remember not to hard start it or melt yer windings.

Another good thing about manual control when you want to pull real powah from an alternator is you can engage it at high RPM after the starting battery hits it for 10s of amps, considerably reducing wear.

jace_da_face

Sir Liamalot wrote: »

Nope. No amount of solar you can fit on a motorhome roof will do that.

That's what I figured and that is the point I want to make. I don't really care that much if my fridge draws 10 Amps from 12 Volts. It only does this from the alternator. Never from the leisure battery. I have the gas option when parked up.

I don't see a downside here. Fuel costs for running the fridge from alternator, back of the envelope calculation here but I would need to drive for about 80 hours for my fridge to burn 1 litre of diesel. A more average and realistic journey of 2 hours, would cost me 3 cent in diesel. I can stay parked up for weeks and keep fridge running on gas.

I wouldn't need EHU to charge a battery to run a fridge, providing solar was enough to replenish other appliance usage. And without 25Ah going to the fridge daily, that is a real possibility. For half the year anyway. If and when EHU is necessary, I'll run the fridge from that.

Now I'm sure I wouldn't want to do it this way if parked up for a year. Replacing a gas cylinder every month would get expensive. But for mostly intermittent and casual use, a 3-way fridge makes sense to me.

Absorption fridge powered from an automotive alternator = 31.5 hours per litre of fossilised sunlight. €0.32 per kilowatt hour.
Compressor fridge = 325 hours per litre of diesel.

Conversely, if I need to go to a campsite to charge a battery and only charge a battery, in Ireland it's €25 for pitch and €5 for EHU. At maximum DOD I'll use 2kWh so I pay €15 per kWh(which the ESB will supply for €0.35).

Bottled gas costs me €0.30 per kWh.

The downside for me is there's less overhead left to charge a battery, the cooling is unregulated, prone to failure, inefficient with a much higher environmental impact & expensive to run.

If I spend, €200 on solar, €120 on a good solar controller & €150 on hardware I can power an efficient fridge for 8 months a year for the lifetime of the fridge. Say 10years? €0.007 per kilowatt hour.

I'd rather stay for months powered from sunlight. Same Sun everywhere I go. I don't need to change bottles & regulators to tour on the mainland.
Definitely less hassle for me, in the long run, to go electric.

My point is only that if you changed your fridge you'd improve your charge system.

On the face of it, it will cost roughly the same to install either system but electric can synergise with hab electrics.
For instance if I design a system that can power a fridge year round I can power a small workshop in the Summer due to seasonal solar gain.
The legacy costs of compressor electric are far less.
It's reliable.
Humans are not good thermostats.

Most caravan split charge cables are so long and thin the habitation battery is running at discharge maintaining an absorption fridge.

There's an interesting design of DIY fridge I reckon could do 10 > 15Ah p/d

Jaden

Sir Liamalot wrote: »

If I spend, €200 on solar, €120 on a good solar controller & €150 on hardware I can power an efficient fridge for 8 months a year for the lifetime of the fridge. Say 10years? €0.007 per kilowatt hour.

Do you have a Bill of materials for that, and rough specs?

Jaden

Jaden wrote: »

Do you have a Bill of materials for that, and rough specs?

That sounds like a commission. :P
I could make one if that's what you mean...

Above are rough figures.
Costs vary depending on system requirements, how good you want it to perform, how well you want it installed, how upgradable you want it, how safe it is, how much control you would like over it's parameters and how much redundancy you feel it requires.

Every system is unique.

jace_da_face

I'll stick with me absorptionator for now Liam. It's not just a matter of me buying a new compressor fridge. I'd also need to add a new solar panel, a new charge controller and a new battery to offset the additional load. Shaving off cents per kWh is all very well but sometimes pragmatism wins out.

Sir Liamalot wrote: »

Absorption fridge powered from an automotive alternator = 31.5 hours per litre of fossilised sunlight. €0.32 per kilowatt hour.

More realistic figures than my rough calculation. So even at €0.32 per kWh, it would cost me 8 cent per 2 hour drive. I can live with that.

Sir Liamalot wrote: »

Humans are not good thermostats.

I have no problem turning a dial if the fridge is too cold/ warm.

Incidentally, your compressor fridge is running 25Ah a day. Is it really drawing just over an amp? A 12 Watt fridge? I presume you keep it running 24 hours. Is that on 12 or 24 Volts? What model is it?

Scandanavian guy's D.I.Y fridge is good but Kiwi bloke's jet powered beer cooler blows it out of the water.

autumnalcore

Absorption is ok

1.  if you have a big enough gas locker to fit cheap gas or have lpg / gaslow. I see people with bongos and t4s spending a fortune on camping gaz bottles
2. If the ambient temperature is not too high like ireland most of the time. South of France, Spain is a different story. 
3. If youre only putting reasonably cold stuff in them - thay can keep stuff cool if ambient temp is not too high but due to the terrible effiency thay are very slow at cooling stuff so if you put room temperature stuff in there it raises the temperature of everything in the fridge for a long period of time. 

jace_da_face

autumnalcore wrote: »

Absorption is ok

1.  if you have a big enough gas locker to fit cheap gas or have lpg / gaslow. I see people with bongos and t4s spending a fortune on camping gaz bottles
2. If the ambient temperature is not too high like ireland most of the time. South of France, Spain is a different story. 
3. If youre only putting reasonably cold stuff in them - thay can keep stuff cool if ambient temp is not too high but due to the terrible effiency thay are very slow at cooling stuff so if you put room temperature stuff in there it raises the temperature of everything in the fridge for a long period of time. 

Yeah I agree. Like I say, if I was living year round in the van, changing gas cylinders every couple of weeks would get old. I would be looking into a gaslow type system. And too bad lucky for me I don't live in a warm country

jace_da_face

Alternators are 40% efficient, a good belt is 98%. That's if you are driving, if you run the engine only to charge then the efficiency becomes a decimal.

To me it's more a case of people don't want the hassle of changing fridge, if they came electric as standard they there'd be fewer converting electric to gas than gas to electric.

jace_da_face wrote: »

I have no problem turning a dial if the fridge is too cold/ warm.

Beer is more tolerant of this than chicken.
I'd recommend having a remote fridge temp display...cheep and cheerful solution fix bodge.

jace_da_face wrote: »

Incidentally, your compressor fridge is running 25Ah a day. Is it really drawing just over an amp? A 12 Watt fridge? I presume you keep it running 24 hours. Is that on 12 or 24 Volts? What model is it?

12V Inlander

It runs ~ 4.5A and 25% duty. 25Ah over 24hours.
We'll see if wrapping it in 10mm closed cell insulation and adding condenser cooling helps reduce that any.

I've €60 of food in my stoopid fridge. Haven't stirred all day, I just relit it again because the wind is blowing out the pilot. Third time today!


At least the chicken fillets in the fridge compartment it froze over-night are helping to maintain temp...

Every time I have to check it I let the cold air out. What a lemon...for sale!

jace_da_face

You mean keep actual food in my fridge? But .... but what about the beer?

jace_da_face

The Zig clapped out again. They don’t make it easy to get in to. No screws. Just some weird hexagonal rivet nut type fasteners. Or was it a unicast case with no panel to prise off? I can’t remember. Anyway the zig might not be a fully fledged charger, but it is still a useful power supply. It will power my appliances and save on battery.

So I got thinking about replacing it with my Maypole multistage charger. But not being fully comfortable about running a multistage charger while loading a battery, I contacted Maypole technical to see what they say.

“The 7428 should not be used as a power supply. A method of disconnection between charger and battery should be implemented whilst the battery is under load.”

Well that answers that. Now I’m thinking I might install the Maypole to charge the battery alongside an ATX P.S.U from an old PC to power appliances. I would put in a relay to break the connection from battery to loads when mains is available.

Sounds like something I'd do. Yeah I have a drawing somewhere for such a system. Most people are turned off by the complexity and to be honest I'd usually recommend keeping it simple and getting a fit for purpose load compensating charger.

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