Solar Install; the on-going saga

My alternator charge to the leisure batteries is feeble. It'll just about run the fridge producing about 10 amps max. with a voltage drop of ~0.4v idle & ~0.8v laden.
However it's a 65ah alternator.
I've been tinkering, swapping the regulator gave me an increase in volts but not amps.

I was having notions of installing a zero centre ammeter in the dash to monitor affairs. Shortfall/generation.
[EDIT: Shortfall = battery discharge with engine running or starter battery charging with engine off and solar generating while battery link switch is closed]





oooh shiney!

The TM tells me when I run the fridge, auto-electrics, wipers, 220watts of dipped lights (yes I could just clean the old lenses but it was easier to install aux. lights) that I'm running at discharge. I believe this to be a shunt bypass related anomaly because my clamp meter says it's all good.

I've gone off the idea now as if I just remedy the problem then I won't have to monitor and compensate.

Back when I was initially installing my leisure battery alternator charge do-fer, I hadn't a clue how to wire a relay so I just butchered a few sets of 400 < 200 amp jump leads and wired direct from the starter +ive to dash switch back to leisure battery +ive & common ground.
This has grown to be a 6 - 8 meter round trip with an assortment of (double fused) cowboy connections.
Now add another 1.5m to install an internally shunted ammeter and you see where this is going.

[EDIT: in defense of VDO pictured, that's a proper externally-remote shunted ammeter,...I was looking at cheap and cheerful versions]

400 amp jump leads are not the same thing at all as 400amp cable. If anything there's a decent amount of copper in them and 400amp insulation for instantaneous loads. The stranded cores themselves are only about 4mm-6mmØ which is actually 70-100amp continuous, and ferociously expensive.

Bare in mind cable ratings are for max allowable temperature not min. allowable voltage drop.
Eg. 10 amp cable = 1.5mmØ
Cable required to carry 10A @ 12VDC 10meters with less than 3% voltage drop = 4mmØ
This is why electrical wholesalers think I'm mental .
A point worth noting in regard to this is that inline fuses are more often than not on unsuitable cable.


So I dug out some real 125 amp cable on a 1m run between batterys and load tested the circuit. I decided the alternator was in fine working order and it was time to stop before I melted something with heavy loading at idle at ~+30 amps.

I couldn't be bothered stripping out most of the old cable so I'm putting a 30A relay in, with the jump leads as the signal live.

Another problem with my current set up is the classic; solar voltage is confusing main charger chestnut.

If I run the fridge on 12volt with the alternator, on a cloudy day with the solar on I hit shortfall; batteries are discharging with engine running. Solar isn't giving me any significant amps, just volts which is telling the alternator regulator to reduce electron production.

In defense of my soon to be decommissioned alternator charge link, the cable is so long it's acting as a natural resistor preserving my sealed batteries from overcharge, how and ever there are better ways to proceed.

I've also been belligering Elecsol to publish their charge parameters. No reply.
The website is down.
I suspect old Steve may be going down with his ship.
I found this thread quite amusing regarding Elecsol Corp.

Welding cable only comes in single core though. Harder to keep neat although highly noteworthy.

http://www.demesne.ie/cablecablecleats.html
http://www.jdcables.com/index.php

For super-serious inexpensive cable Hugh Piggott recommends making it by filling a copper pipe with strands gleaned from cheaper 3 core. I wonder how he insulates it though.

I bet Steve goes online under pseudonames as the voice in the wilderness declaring he got his warranty honoured.

paddyp wrote: »

re; welding cable You generally only need single core in a vehicle though as the chassis is ground.

I always amaze myself how I can overlook the obvious. Now that you mention it there's probably close to 100m of superfluous cable in here. AC habits die hard.

paddyp wrote: »

Are you thinking of doing a piggot turbine? I looked into it before I recon you'd want to be making at least a 2kw version to make it worthwhile as even in windy areas like mine you'll average 1/3 of that , I did find a free souce of neodynium magnets though at the council tip lately - magnetic resitance excercise gear rowers etc have enough for about 1/4 - 1/3 of a rotor, if you live somewhere populous you could probably pick up enough of them for free between gumtree, adverts, munster free ads, buyandsell, donedeal etc.

Yeah I reckon at least a 3kw, I've an anemometer up on one site about 6 month's and it's not looking too hopeful. I'm hoping eventually to build an off-grid workshop and expand from there if that's feasible.
I won't be erecting one unless I can find a site averaging 7m/s @ 9m (You don't need planning permission for a hub <10m once you have no structures within that horizontal radius IIRC).
I could be anywhere between the midlands, Dublin and the UK these days. It's unlikely I'll have anytime for new projects between here and January though. Old projects are still looking at me all sad eyed and neglected.
I'm still on the lookout for a smart drive washing machine motor to tinker with.

I'm thinking of going down the 48v road. I'd be more inclined to put the investment in a hydro rig if I can get the right site, but considering the fickle nature of renewables 'tis best have as many sources as possible. Battery shenanigans! Hahaha, bring it! .

Off-grid really doesn't really make a lot of cents apart from the challenge unless you are very remote, it usually costs more to cycle a battery than grid charges, coupled with lack of generation when batteries are full and replacing the batteries every 7ish years it's not viable for most.

I'd probably consider grid-tie further down the line, when I'm in the mood to have certifiable equipment.

Those free inverters are all gone now, and the feed-in tariffs have dropped to less than half what they were in good 'ole near-sighted Éire. I'll more than likely be moving to the UK for this, they've far superior schemes.

Finally got a chance to work some more on the system. Feckin' work is always ruining my life.

I've some fresh new impressive numbers.

Temperature 14°C
Batteries fully charged and idled 20 hours

Battery #1
Battery Voltage 12.9v


__________Specific Gravity_____S.G. @ 20°C_____Voltage
____________(± 0.010)______________________________
Cell #1________1.215____________1.214___________2.2v
Cell #2________1.235____________1.234___________2.1v
Cell #3________1.235____________1.234___________2.2v
Cell #4________1.215____________1.214___________2.2v
Cell #5________1.230____________1.229___________2.0v
Cell #6________1.215____________1.214___________2.2v

S/G at new 1.250 per cell

Average Cell S.G. = 1.223
16% DOD

84% of 125Ah
Present Capacity = 105Ah

Battery #2
Battery Voltage 13.1v


__________Specific Gravity_____S.G. @ 20°C_____Voltage
____________(± 0.010)______________________________
Cell #1________1.225____________1.224___________2.5v
Cell #2________1.235____________1.234___________2.2v
Cell #3________1.230____________1.229___________2.2v
Cell #4________1.235____________1.234___________2.2v
Cell #5________1.230____________1.229___________2.2v
Cell #6________1.230____________1.229___________2.0v


Average Cell S.G. = 1.230
11% DOD

89% of 125Ah
Present Capacity = 111Ah

New Bank Total = 216Ah
28.5Ah recovered

Sir Liamalot wrote: »

Agenda #1: does PWM recover lost capacity

Yes

Sir Liamalot wrote: »

Agenda #2: Can Elecsol Batteries be left depleted and not get damaged as the manufacturers claim

Hard to argue with those numbers....yeah why not! Although I still reckon they're soft shorting.....maybe I'm using more electrons than I used to because I know where to find more now.

Given that the weakest battery is now the strongest I swapped them around so Battery #1 is closest the solar controller now.

paddyp wrote: »

re; welding cable You generally only need single core in a vehicle though as the chassis is ground.

I found an argument against this method which if anyone else asks I'm going to pretend I planned all along....

Galvanic corrosion .

D'oh

It just dawned on me; I only want 20A ~ 25A @14V, not 20A @24V so I only need a 350 watt traffo...Wa-hey even cheaper :cool:.

Life would be so much easier if I only had one type of battery onboard. Really I ought to be open lead acid all the way. In fact now that I know I can pop off my sealed battery caps at will I'm tempted to raise absorption set point to 14.7v and be done with it.
If I replaced the starter battery for a sealed battery I could also achieve the same but this would be taking a step backwards IMO, even though I could potential save a few bob in the long run and avoid much shenagigans.
Replacing my sealed leisure bank is not viable while they're on the recovery. ...Unless anyone wants to make me an offer for some previously loved like-new-ish never been abused...ahem...super-bling carbon-fibre amaze-o-pants technology batteries...one previous eldery lady owner????:)

Meanwhile I came up with this which I may or may not implement depending on whether there's any of those 3.8A battery chargers left in Aldi when I call in next week.

It's the same circuit as the TS as mains charger with a separate fisher-price charger running to the starter to boost it to 14.7v (I'd almost be willing to bet the temp. compensated TS on a 14.4v set-point would do a better job without it...separate voltage sensing leads make a huge difference) or a CTEK MXS5.
Still I foresee the need of a back-up charger so it may be interesting how they compare.

For what it's worth;
TS45 as Mains Charger with Separate Starter Charger.JPG

Cwaor, full-traction? Can you pm me a contact please Paddy, do you know what make/size they are?
Thanks for the heads up, sounds like the Aldi jobbie is pretty pointless then for my purposes. I may just ramp up to 14.7v all round so. Or do you have any better ideas how to split charge the two banks to separate set-points without spending more than a 75Ah starter battery costs?

Sir Liamalot wrote: »

you could make it a lot simpler by using a regulator and dumping the potentiometer for a simpler on/off setup.

I found a neat little PWM DC motor speed controller while looking for something else, typically after I've ordered the less ideal thing. This can't be regulated, so it will need a resistor in the circuit and/or fans with wide voltage tolerances...or you could skip the resistor and just remember to never set it above 70% while charging the batteries.

For those willing to argue over mA

Whadya mean finished..
mmmm...gizmos...

holyhutzpa wrote: »

Your main drain on power must be the laptop/whatever else you run from the invertor?

I don't use my inverter, it's just there to look at. Sometimes it runs the surround sound (should be 12v) and an aux. monitor.

Lighting about 12Ah p/d
Laptop 10 - 72Ah p/d depends on whether I'm looking at boards and leckytrons or playing computer games watching educational movies about climate change.

holyhutzpa wrote: »

I was just surprised that you were putting so much time/energy into solar and running your fridge on gas!

I'm not specifically putting so much into solar per say as a charging system that works as it should. I need a system that can go a month between EHU's.

I pulled out all my undersized cable, swapping 1.5mmᴓ and 2.5mmᴓ for 4mmᴓ stranded, broken down to 2.5mmᴓ stranded for local regulators to give me a voltage drop of 2% at the the fridge and the 12v outlets.

I gutted my 7.5A 12v. cig socket for the ports and reconnected it on 4mmᴓ.
I installed the switch to link the starter and leisure batteries for solar charge complete with Idiot Light. I wanted the light to switch on automatically when I linked the batteries but realised that a switch between battery +ives is on on both sides. I'm fresh outta single pole, double throw 25A DC switches so I had to switch a spur instead. Idiot switches on idiot light when he links the batteries. Idiot sees idiot light after sunset and remembers to switch off battery link. Idiot switches off idiot light.

I have a split charge relay in a box somewhere, I might eventually swap this out but it could also require some protection from the alternator.

I'm still waiting for a resistor and speed control for the fridge fans. They're very quiet though. Inaudible if there's any background noise...except for the one with a gimpy bearing :mad:. On the bright side they're only 125mA each to run not the advertised 180mA.
They're on two parallel 50°C Normal Open thermostatic switches tied to the upper condenser heat sink. This enables the fans when either thermostat is >50°C. They work great, they don't run very long in this weather unless the fridge is at full whack. Great craic just watching them auto blasting.

Baffles are holding well, mosquito nets are shredded...I'd better recruit some more spiders. The gas hob igniter wire assembly was bouncing on it's wires after popping it's rivet...scary things you find behind a fridge sometimes.:eek:

The fridge has gone from running at 9.5A to 10.5A my shunted ammeter tells me, I seem to have made it more effective but less efficient...bugger.
This sounds very high to me; a 100watt element running at 125watts.
It's alone on a 10amp circuit breaker and not tripping though.
And my RMS clamp meter tells me it's drawing 5.5A from the furthest battery and 3.6A at the nearest .
The inverter can run the AC element for 10.5A -11A IIRC (I'll check cast-away notes at a later date). This would eventually be better as the thermostat on the AC element would reduce running consumption.

I extended a mains socket to where my traffo/charger is going to live.

What's the consensus about AC earthing to the chassis? I'm pro local earthing via the EHU earth, but not entirely convinced it's any benefit to extend to the chassis. Would it not be a potential hazard for DC if it was? How are coach builds earthed?

I spent 3 hours chasing a short circuit on the main consumer circuit breaker, pulled out the fridge again :rolleyes: and all my new wiring to check for meltage. Tracked it down to the overhead lighting circuit. Dropped the ceiling single handed and tried all that wiring for ground faults. Then realised it was a pair of incandescent bulbs.

Net savings;

Striplight LEDs are consuming 15% to 45% less with the greatest saving on the highest intensity.
Laptop 12v power is ~20% reduced and no longer getting hot at the outlet. I opened up the Halfords cheapo charger looking to salvage some gubbins. I'm entirely unimpressed, that contraption was made to fry.
13A fuse protecting 6A cable on a 500mA device with no protection on the DC side. The regulators are looking kinda toasted. The effin' thing is made of resistors must be 200 of the blighters...would it have the one I needed? ...of course not!

I learned quickly when tackling a job of this magnitude that it's impossible not to lose your screwdriver...the trick is to lose a screwdriver in every location you are working!

Field tests are complete. The alternator charge circuit is much improved on what it was, but still crap. I don't like the way is runs at shortfall, only 300mA or no. Discharging starter batteries die young.

The diode is interfering with the alternator's ability to voltage sense and up the ante. With the leisure bank at 75% alternator was dishing out 12amps to the bank, I jumped the diode and it made a run for 20A....ker-ching!
What it's doing at the moment I suspect is watching the starter lose amps like there's no tomorrow and under-compensating.

The diode needs to be change-over relay instead, before the solar module arrives at the solar controller. I'll take 8 consistent alternator amps over solar when they're free any day of the Irish week.

That frees up one diode for a split charge relay. The diode won't fool the TriStar because it has separate voltage sensing leads, [EDIT:] but it will contribute charging voltage drop...now I could compensate for this by customising the charge algorithm and boost the charge set points to 14.8v/15.1v and move the battery sense +ive to the diode input...This is a potential liability though. Hmmm...I'll put that on the long finger beside those tilting brackets what are never going to happen...I just intuitively don't like that particular relay I have...

paddyp wrote: »

A lot of the fridge elements are 125watt.

I'll buy that, I read 100w in an online manual, the dog ate my original.

paddyp wrote: »

What going on with the fridge exhaust where does it go?

Pictured is the exhaust flue shroud, with the right and persistent leverage I can get them to line up and the flue sits into it. Is something amiss? Did I mention the dog ate my manual?

Field Testing results;


Batteries @77% capacity, 42Ah discharged.
Alternator charging amps at leisure bank.

Mk-7 (diode) : 8.7A
with fridge on 0.5A

Mk-8 (Changeover relay):11.4A
...with fridge on: 4.7A

Batteries @81% capacity, 33Ah discharged.

Mk-7 (diode): 6.7A
with fridge on: -1.4A

Mk-8 (Changeover relay):9.5A
...with fridge on: 3.9A

Batteries @87% capacity, 22.9Ah discharged.

Mk-7 (diode) : 4.0A

Mk-8 (Changeover relay):7.4A

I believe I have a clear winner.

I was hunting for more gubbins.
Found a cheaper source for a TS-45.

Looks like I'm down to ~6Ah p/d solar harvest.
Reasonably sunny, light cloud. Roof at approx. 5°-10° declination from horizontal, away from the sun.

First off this is not a serious suggestion I'm just having a laugh looking at logistics.
I do appreciate the physics of 120kmp/h winds and much as I can negotiate a DOE by bringing them back the serviceable parts they make me renew for show and tell, this don't fly...or maybe it will in the wrong sort of way.




:pac:
Actuation;



Requires anchorage, 12v actuator, reduction of horizontal profile to about half what it is from the top of the pole attachment.
Demounting of actuator, folding and road bracing to lock ratcheted flat for travel and storms. Effective ratcheting would probably require module corner supports.


Actuator control link(add limit switches)


Way cheaper and easier just get more cells.

Sir Liamalot wrote: »

What's the consensus about AC earthing to the chassis?

http://www.smartgauge.co.uk/earthing.html

..just pretend "fresh water" = tyres