Redarc BCDC1240 Install

[farqman]

Ummmm, yes it can


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I don’t really understand this. I know that there are recommendations of charging amps, generally around 10% of the battery’s capacity in amp hours, but if the battery is being ‘well looked after’ it will generally be getting charged before it is ‘over discharged’ & consequently the battery will only accept a lower charge rate regardless of the capability of the charger. The BCDC won’t force 40 amps into a battery any more than straight alternator charging would.

I think the problem is if the battery is flat the Redarc pumps a full 40a into the battery. A lot of manufacturers recommend 20-25amps.

I got the Redarc to fully charge an AGM battery, and to account for the different chemistry. Perhaps just got the wrong one. Maybe should have bought the BCDC1225 instead. Too late now I can't return it.

As for heat in the engine bay I was planning to mount it between the grill and radiator like a member from another forum. Will get plenty of airflow here.

[farqman]

I am thinking I may end up going down this path

[threedogs]

I've spoken to they guys at Alco batteries down my way, they will sell me a sealed battery but wont install it for me.
Its all about one battery exploding and the damage it will cause. they aren't going to pay for it. not sure a heat shield is the answer.
They had no problem installing a Vulcan wet cell 115 AH AUX battery for me. Most batteries have explosion caps on them, but if it
starts to swell I'd be removing it.
You just need to look at those Pics NN put up with the turbo glowing, that a lot of underbonnet heat'

[Cuppa]

Uummmm, no it can’t, not unless you have about a 500 watt or larger solar array

Ah yes, you are of course correct. I chose the BCDC1240 because I have 425w of solar in my Patrol , (& many folk I know with rv’s have similar or more). The batteries are Ritar DC series with a max 36 amp charge rate. With the SoC I maintain I have never seen more than around 20 amps coming in, mostly far less.

I did qualify my statement about charge acceptance by saying ‘if a battery is being well looked after’, by which I meant not being discharged to the point of accepting higher than specced charge rates. As I typed it I guess I was thinking that anyone who bought good batteries & an expensive dc/dc charger to go with them would have (should have) put enough thought into what they were doing to have a balanced system resulting in never, or rarely allowing their battery(ies) to become severely discharged. I suppose this might be a rather optimistic thought & upon reflection suppose that many 4wd’ers do only have a single aux battery & don’t buy a BDCD1240 for it’s 40 amp solar charging capacity. Also that many people do not ‘treat their batteries well’ as I advocate. Therefore your advice that they ensure the compatibility of their battery with the charging rate (when severely discharged) is wise. However such use is unlikely to have the benefit of long battery life that a balanced system ensures. Alternatives are to use a lower amperage BCDC or just to rely on solar to do the topping up to full without a dc/dc charger at all. Or to have a set up which allows direct alternator charging up to a pre-set state of charge with a lower amperage dc/dc charger to ’top up’ the battery to a full state of charge. Or a mix of both. Again intended usage patterns would dictate which would suit best.

Thanks for the feedback on the early demise of the Fullriver AGM’s under the bonnet. If your Fullrivers are HGL series (max charge current 20 amps) they should still keep going gangbusters for at least another couple of years, maybe more. Fullriver DC series can take higher charge rates (up to 100amps I think) & importantly also have a construction which withstands vibration better, these if treated well will give a lifespan of 10+ years. I have only ever had DC series Fullrivers. A friend with HGL’s in his OKA was disappointed when they karked it at around 6 years old a couple of years ago (not under bonnet), prior to this he (& I) had thought all Fullrivers were much of a muchness.

[Cuppa]

I think the problem is if the battery is flat the Redarc pumps a full 40a into the battery. A lot of manufacturers recommend 20-25amps.

Will be fine if you get a battery which can accept 40 amps. (e.g.. Fullriver DC series). If you expect to be using a battery until it is ‘flat’ you are probably wasting your money whatever you install. If you intentend to (sensibly) not let your battery become discharged below 40% to 50% SoC then Ritar DC series or others similar (with charge rate of 40 amps or close to it will be ok).

[Cuppa]

I am thinking I may end up going down this path

I guess it really does depend upon what you are wanting to achieve. If, for example, you wanted to run the same loads off both aux batteries in that set up you would need a changeover switch of some sort to allow each to supply te load independently. If that was the intended usage however, then unless space dictates otherwise I can’t see any advantage over having both aux batteries in the rear of the vehicle & not needing the SBI12. However if for example, you wanted one of the aux batteries specifically to provide additional capacity for winch use (paralleled to start battery as shown) this setup would make more sense. If the latter, I would probably still utilise a changeover switch to allow use of both batteries for regular ‘camping loads’ if winch use is generally going to be a rare event.

My vehicle had an under bonnet aux battery when I bought it, set up with an SBI12 but when I installed batteries in the rear I chose to remove the under bonnet aux & instead run heavy cables between start & rear aux batteries which I can manually parallel with the start battery for winch use or in the event that I ever need a jump start. It also enables me to direct charge the aux batteries from the alternator if I were to choose to do so, & means that I can also connect a mains charger to the start battery to charge all the batteries at once (an advantage for me because the under bonnet start battery is easier to access than the rear AGM’s).

Ps. have sent you a PM

[the evil twin]

I am thinking I may end up going down this path

Cuppa has raised some good points above and further to those whilst assuming that the Aux is a Full River DC series or equiv and mounted under bonnet in that diagram...

The DC series is a Deep Cycle AGM rated for Cranking duties so to get the bets use and versatility I would suggest the following

I would use 2 B&S between the Under Bonnet Batteries and the SBI12 with 150 Amp Fuses.
I don't see any point in light gauge wire/small fuse ratings between cranker rated batteries
1. A switch or whatever in the Redarc fly lead will then allow you to start off the Aux at the flick of...
2. Whatever size cable you do end up using determines the size of the Midi Fuses
3. If you have a winch use the 200 Amp Redarc or an Intervolt/Projecta/etc that handles 150 to 200 amp continuous and up the Fuses accordingly.
4. I also prefer the SBI12D or Intervolt equivalent over the SBI12 because the dual sensing comes in handy and simplifies charging of the under bonnet batteries but again no biggee.

If you fuse the power input at the BCDC (no fuse shown on the dia) the 60A Midi at the starter for the BCDC feed should be determined on the cable size running to the BCDC normally it will be around 6 to 8 B&S or so and then a BCDC power input fuse no higher than 40.

If you don't fuse the power input then the 60 Midi should be no higher than 40 Amp.

I don't really understand why the use of the Relay in the circuit is so popular but if you want to use it then OK.
1. The BCDC will isolate the starter at 12.7 volts so it provides no extra protection in that regard.
2. If you connect a power source to the vehicle batteries, say Solar or Charger it cannot power the BCDC unless Ign is on
3. The Solar Panel pictured can't charge the Under Bonnet batteries (I favour feeding the vehicle Aux for Solar and let that power the BCDC if the 2nd Aux is also on board)
4. If you have a Solar array that is always available (hard mounted to your truck for example) it is taken out of circuit if the ignition is on and all loads are now on the Vehicle electrics
5. If you aren't hard mounted and have to deploy your array at Camp or whatever then the vehicle Ign is off anyway.
6. It is another bunch of crimps/connections etc which can fail, cause voltage drop or otherwise be a PIA.
7. If you have on board Solar it makes more sense to have the Relay control blue so it is relaxed to vehicle Ign and powered if Solar is available

None of the above is "you must".
It is just a few thoughts because I like to keep electrics as simple as possible while getting the best performance and most versatility out of any gear

[Cuppa]

I don't really understand why the use of the Relay in the circuit is so popular but if you want to use it then OK.

Just ‘automating’ the switching between solar charging of Aux batteries & alternator charging. Solar only charging if ignition is off. Redarc have a ’thing’ about not mixing charging sources. Probably more to do with simplifying fault finding with some of their other more complex electronics than necessity. The BCDC is either/or, not ‘and’. Having succesfully charged batteries through a combination of alternator charging AND solar charging concurrently for years without problem I must admit I found Redarc’s approach a tad over cautious. (Likewise their non temperature compensated 13.3v float charge on the BCDC1240 but that’s another issue).

[farqman]

Thanks Cuppa for the PM. All I can say is wow.

I purely bought the BCDC1240 because it was top of the range. Figured bigger is better. Learnt that's not so much the case.
The missus got me an ARB battery tray for Christmas (well ordered one, don't have them in stock). So I kind of need to utilise it. I didn't quite realise that charging at 40amp was such a big deal. Originally I was looking at the Optima range which doesn't have a limit, but found out they are quite small in capacity.

At the moment I will only be running a brand new Engel 40l. Plans in the future are to run another engel, inverter, possibly a water pump, and was thinking an Anderson plug in the rear, and one externally on the towbar in case I ever go down the camper trailer route. Also plan on using solar.

[the evil twin]

Just ‘automating’ the switching between solar charging of Aux batteries & alternator charging. Solar only charging if ignition is off. Redarc have a ’thing’ about not mixing charging sources. Probably more to do with simplifying fault finding with some of their other more complex electronics than necessity. The BCDC is either/or, not ‘and’. Having succesfully charged batteries through a combination of alternator charging AND solar charging concurrently for years without problem I must admit I found Redarc’s approach a tad over cautious. (Likewise their non temperature compensated 13.3v float charge on the BCDC1240 but that’s another issue).

Hi mate,

Yeah I agree with you and I guess Redarc could be concerned about bucking power supplies or frying the auto voltage sensing circuit or damaging the MPPT or somesuch.
My best guess is that it may simply be that if the voltage sensing sees a Solar panel it will think it is a 24 volt Alternator so for Solar it must be floating or grounded... who knows

What gets me is why the hell did Redarc design a +$400 bit of kit with an onboard MPPT Solar Reg and then have to rely on people wiring up external switching to select between Alternator and Solar.
1 extra connection and maybe $5 worth of solid state switching circuitry inside at point of manuf and it would have been fully automated in the device, heaps more reliable and easier to use.

It's like designing a car without any plumbing for the fuel tanks and saying "let the customer sort it out whether he wants Main, Sub or ability to switch between both".