Solar via bcdc redarc

Submitted: Saturday, May 28, 2016 at 10:44
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Hi all, quick (maybe not) question about hooking up a solar panel through the under bonnet bcdc1240 redarc charger..
Auxiliary battery under the bonnet is only a 65ah, yes I know it's over kill.. Have another 150ah in the camp trailer, which is connected via Anderson plug. The ct is not always hooked up, as the prado 150 is my daily drive.
I'm soon to replace the aux battery, been doing the job for the past nearly 5 years, would like to squeeze something bigger in there, if I can, due to tight space.
The question is, if I hook up a solar panel through the redarc, what size would do the job, and if parked up with ct, and have the Anderson plug connected.
Run a 50ltr Waco in the prado, and about a 60ltr upright fridge freezer in the ct, also sleep with a cpap machine... Which is my main concern..
We have a 7 week trip coming up, without the ct.. So was thinking if I can get a solar panel, and be able to hook it up, if staying in one spot for a few days, just to run the 50ltr Waco and my cpap machine.. But maybe better to get a panel, which would keep the ct batteries alive a little longer as well, when we do trips with it as well. Basically, need to know how much solar, would the redarc require, to boost the batteries I guess. Love to know your thoughts on the matter, any advise would be helpful.. Cheers Odog
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Reply By: Member - John and Val - Saturday, May 28, 2016 at 12:37

Saturday, May 28, 2016 at 12:37
Odog,

Whole lot of question there and not a lot of detail!

First, the cpap machine. It's first priority, even higher than a cold fridge. How much power does it draw? Guessing about 15Ah overnight unless it includes a humidifier, in which case maybe 25Ah. Will have to allow an extra 10% to cover inefficiency if an inverter is used. Do you have better numbers than these? or maybe you could quote the make and model so we can google for them.

The on-board fridge, again a guess, but say 25Ah per day, more in summer, and a lot more if you run it very cold or as a freezer.

On these numbers, you have run your 65 ah battery down as far as is wise and need to replace about 50 Ah per day, that's about 650watt hours. If all that is to come from solar panels in say 6 hours, those panels must deliver an average of over 100w. They will need to be rated at probably 120w or more to achieve that under a clear sky with a few movements per day to follow the sun.

Now.... what happens when you add the trailer? Guessing, the fridge freezer will call for at least 40 Ah per day, or more in summer. Add a bit for lighting at night, say total 50 Ah per day, same as the above. I think if my guesses are about right I'd use a 150W panel on the vehicle and another with its own MPPT controller on the trailer. I'd also increase the storage capacity in the vehicle.

Hope that's some help.

Cheers

John
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Follow Up By: Member - Odog - Saturday, May 28, 2016 at 13:30

Saturday, May 28, 2016 at 13:30
Thanks John, sorry for the lack of detail, was thinking that the redarc would boost the solar input.. Maybe doesn't work like that?
I'd love to put more ah storage in the prado, air con pipe limits the space, and very risky to move it.. Was thinking maybe just have a spot in the rear, for a sealed battery, which is portable, and can run a lead inside from the Anderson plug, so can make more use on the redarc while driving.. Would that get me out of trouble for a few days, do you think? Thanks again.. Cheers Owen
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Follow Up By: Member - Odog - Saturday, May 28, 2016 at 13:42

Saturday, May 28, 2016 at 13:42
Just dug the cpap converter out.. 12-13.8 volts input 3.1A ... 12 volt, 2.5A output.. If that helps.. Cheers
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Follow Up By: Member - John and Val - Saturday, May 28, 2016 at 15:34

Saturday, May 28, 2016 at 15:34
Hi Owen,

Unfortunately, one of the facts of life is that energy cannot be created - the redarc can change it to a more suitable form, but not increase (boost) it. When operating as an MPPT controller it accepts energy from the solar panel at about 17 volts and converts that to about 13 -14.5 volts to suit the battery's state of charge.

Your numbers for the cpap power supply are very useful. Like the redarc it is simply changing the voltage, in this case to suit both battery and cpap. There will be a bit of a margin built into it, so the actual cpap usage is probably about 25 watts, or about 2 amps at 12 volts. It will require about 16 Ah to run the cpap for 8 hours, which is a bit better than I'd guessed.

I'd stay with the 25 Ah per day figure for the fridge, making a total of about 40 Ah per day, which is about as far down as I'd want to run a 65 Ah battery. I think you'd be wise to add some capacity, maybe in the back of the vehicle, well bolted down and fed with heavy cables from the bcdc. Ideally, I'd move the bcdc so it's adjacent to the bigger battery.

Extra charging options - one often overlooked is that with the big bcdc charger and not a lot of fuel you can put quite a few Ah into your battery. I carry two 100Ah batteries and 150 watts of solar panels which I think would probably be about right for you. Fact is though that a few litres of fuel to cover the rare occasions and I'd need less solar!

Cheers

John
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Reply By: Bob Y. - Qld - Saturday, May 28, 2016 at 15:06

Saturday, May 28, 2016 at 15:06
Bought one of these last year for a temporary fix, Odog, for a desert trip. It's so good it will be used on another trip next week.



Re a solar panel, without using any "science", I'd get the biggest one you can comfortably fit into the Prado. Folding ones would do the job, I'd suggest.

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Reply By: Member - Ross N (NSW) - Saturday, May 28, 2016 at 15:18

Saturday, May 28, 2016 at 15:18
I suggest you check that the model Redarc you have will accept solar input.
Mine doesn't . Sorry I don't have model no. To hand
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Follow Up By: Member - Odog - Saturday, May 28, 2016 at 18:32

Saturday, May 28, 2016 at 18:32
Yes Ross, mine will, but if I have a regulator already on the panel/ blanket I can use it on the camp trailer as well, when/if needed.. So if I go down this path, won't worry about doing it through the bcdc redarc.. Thanks Owen
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Reply By: Member - Odog - Saturday, May 28, 2016 at 18:27

Saturday, May 28, 2016 at 18:27
Been looking at these, a power pack box, and solar blanket 150 watt. Could run a lead from the rear Anderson plug into the back of the car, plug the fridge into that, and run the cpap off the second battery, via the rear Anderson plug, and use the blanket when I need to.. Then the battery box will be portable, might suit me better. Thanks again. Owenhttp://www.supercheapauto.com.au/online-store/products/Ridge-Ryder-Solar-Blanket-150-Watt.aspx?pid=392422&menuFrom=1021381#Recommendations hope that works?http://www.supercheapauto.com.au/online-store/products/Ridge-Ryder-Portable-Power-Station.aspx?pid=368862&menuFrom=1021382#Recommendations
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Follow Up By: steved58 - Saturday, May 28, 2016 at 19:33

Saturday, May 28, 2016 at 19:33
Be wary of the battery they list that fits that battery pack as it is probably not suitable for inside the vehicle a agm or gel battery is better suited a sealed battery can still vent fumes in the confined space of a vehicle This box should be better should be able to take a 100ah agm battery http://m.supercheapauto.com.au/Product/Calibre-Battery-Box-Large-Powered/12358 I had one in the back of my pajero for many years just buy a lead with rings to anderson plug and away you go
Cheers steve
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Reply By: Member - Odog - Saturday, May 28, 2016 at 20:14

Saturday, May 28, 2016 at 20:14
Yep, I agree with you Steve, after taking another look, the ridge Ryder box is maybe a bit on the small size, only take a 75ah battery, would prefer a bit bigger, and also I'd like an agm, rather than wet cell.. And a lot cheaper as well..
Thanks Owen
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Reply By: Ross M - Saturday, May 28, 2016 at 20:23

Saturday, May 28, 2016 at 20:23
If the Redarc is under the bonnet then it will be being heated by the engine bay. That will cause the Redarc to derate ( lessen it's full output) because of it's heat / performance rating.
Therefore, whether it is running off alternator and or solar, it will most likely be limiting it's output to save itself and not delivereing the most from alt or solar while the Redarc is running HOT.

I would not use one under the bonnet until I can ensure a cool environment for it to work in. It may not charge batteries to full capacity because of the limiting which may be occurring.
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Follow Up By: Member - Odog - Sunday, May 29, 2016 at 06:31

Sunday, May 29, 2016 at 06:31
One thing though, you are not going to be sitting at camp, with the solar plugged in... And the car running eh...
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Reply By: Member - Blue M - Sunday, May 29, 2016 at 02:50

Sunday, May 29, 2016 at 02:50
I have a bcdc1240 RedArc mounted under the bonnet on my ute hooked up to 2x120 ah AGM batteries and 2 x 150 watt solar panels on the canopy roof.
Early in the morning, I can start the car when everything is cold and showing in Boost Mode it will give me a Max of 29 to 31 amps at the battery in the back.
After driving it for around 40 to 60 minutes and everything has warmed up/to got hot, it will have dropped back to Absorbtion Mode and puts out around 15 to 17 amps until it goes to float mode.
I have a 40 ltr Engel running as a freezer in the back of the ute.

I have a Phillips CPad machine that runs on either 240v or 12v and it takes around 2.5 amps to run it, and about 6 amps with the humidifier attached.

With the solar, I have seen it put in up to 12 amps on a good day if the sun is in the right place, but most days around 7 to 10 amps at the moment.

The wiring from the unit to the battery is around 2 mtrs.

Odog, when working out your power usage and not driving every day, I would not rely on 6 hours of good charging every day.

I have been on the road for 10 weeks now and only had three days of full sun shine. I never realised how many partly cloudy days there are since I have been relying solely on solar.

Cheers
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Follow Up By: Member - Odog - Sunday, May 29, 2016 at 06:57

Sunday, May 29, 2016 at 06:57
Thanks Blue
I don't think it's a real issue, having the bcdc under the bonnet, mine seems to charge up the batteries (150ah)in the camp trailer quite well, when on the road, despite being about six metres from the unit..
I'm going to go and pick up one of the battery boxes today, think they are on special at present, to go in the rear of the vehicle. Might keep an eye on the solar blankets, see if they come down in price a bit.. If I have the extra battery in the back, I should be right for power, for this up coming trip any way. Sounds like you have your power needs sorted quite well Blue. The cpap machines are a pain, something else to pack and unpack each day when traveling, unless you have a van, or facilities to leave it set up, when on the road. Bit harder when camping, but, do feel better for it I guess... Cheers Odog
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Reply By: carl h2 - Sunday, May 29, 2016 at 11:13

Sunday, May 29, 2016 at 11:13
I have the redarc BCDC1225 charger in my camper we had a problem where the charger would not accept charge from the solar panel via the controller . We had to by pass the controller for the charger to work. rang redarch and that was the answer even thow we had 17.2 volts charge from the solar panel for some reason it would not charge. ran a new cable straight of the junction box put a Anderson plug on and a Anderson plug on the controller so I can swap them around if needed cheers
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Reply By: Malcom M - Monday, May 30, 2016 at 11:43

Monday, May 30, 2016 at 11:43
If you are going to stuff in a replacement battery then the type of battery is worth thinking about. Standard AGM's do not have a very good depth of discharge (DOD) cabability. ie you can only discharge a little bit before the battery is considered flat, 60-70% comes to mind but Goggle will confirm.

Have a look at the Optima Yellow Top range as they allow a substantially higher discharge before problems arise, something like down to 20% without damage.
End result is a lot more useful power before recharge is necessary.

Here's some real world testing of them - http://www.offroadxtreme.com/engine-tech/other-tech/charge-optima-batteries-get-put-through-our-torture-test/
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Follow Up By: Frank P (NSW) - Tuesday, May 31, 2016 at 16:07

Tuesday, May 31, 2016 at 16:07
There are some misconceptions here.

It's never been suggested by knowledgeable people or manufacturers that "standard" AGMs are flat at 60%-70%. It is well recognised that if you take 70% out, you still have another 30% to go before the battery is flat.

I think what you're confused by is the conventional wisdom, well founded, that the less you discharge ANY lead-acid battery in each cycle, the longer it will last.
Keep it at 100% it will last maybe decades.

Discharge it to 0% SOC every cycle and it may last only months.
The conventional wisdom is that the sweet spot between practical useage and getting the maximum cycle life out of AGM batteries is to discharge them only about 50% before re-charging. At 50% they are NOT flat.

I'll give you your due - if the manufacturer says the sweet spot for Optima Yellow Tops is 80% depth of discharge, then they are indeed a better AGM battery than average in terms of the practical use vs length of life equation. But I'll bet they last even longer if you only take 50% out of them each time.

The other thing that begs comment is that test in the link you provided. That "test" proves only that the battery tested withstood abuse a few times and in each case accepted charge and apparently fully recovered. Any battery will do that and will appear to operate normally for some time afterwards. MY OEM battery in my BT50 has been flat at least 7 times in the 18 months I've owned it, due to the quirky design of its electrics. It still behaves like a new battery, but I'll be very surprised if I get another winter out of it - unlike the OEM battery which lasted 5 years in my previous vehicle and which never got flat.

What wasn't tested in the link was the effect the abuse had on both the capacity of the battery and its longevity. It may well be that the Optima Yellow Top will handle that sort of abuse better than some other batteries, but that was not established, just that it could handle it a few times.

The "torture test" was not a test, just a few blokes hooning around in electrical ignorance, abusing equipment and presenting the results in a favourable report - probably to keep the advertising dollars coming into their magazine.

It was rubbish, mate.
FrankP

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Follow Up By: HKB Electronics - Tuesday, May 31, 2016 at 16:17

Tuesday, May 31, 2016 at 16:17
As Frank has pointed out, Optimas can be killed like any other battery, interestingly they do state or at least did on the Australian site that discharging to 0% SOC won't harm them, however if you ask them to supply a life cycles versus depth of discharge they refuse stating that it is commercially sensitive information!

If it is a good as they imply you would think they would be happy to supply the proof?

Figures I last found for an Optima were from memory was something like:

1200 cycles to 0% SoC ( 10.5v ) and 2,000 to 20% SoC ( 11.58v ), like any other lead acid battery they improved dramatically as DOD decreased.

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Follow Up By: Malcom M - Wednesday, Jun 01, 2016 at 06:21

Wednesday, Jun 01, 2016 at 06:21
Not at all sure where you two get the idea that I say they cannot be killed.
I'm simply saying that they handle a much deeper discharge than most other batteries.
Read into that what you will but try hard to take it with the context of the OP?

The review was supplied as 'interesting'. I've never seen a battery survive the sort of problems that were shown in it.
Again Frank read into that what you will.
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Follow Up By: HKB Electronics - Wednesday, Jun 01, 2016 at 11:19

Wednesday, Jun 01, 2016 at 11:19
I haven't seen any hard data that proves Optima's can tolerate deep discharges
better than any other battery. Certainly Optima won't supply anything to back up their claims, if you have hard data I would like to see it?

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Follow Up By: Batt's - Wednesday, Jun 01, 2016 at 20:58

Wednesday, Jun 01, 2016 at 20:58
If this info is correct the following is an interesting read Malcom http://www.aussiebatteries.com.au/deep-cycle-battery-info/
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Reply By: Batt's - Wednesday, Jun 01, 2016 at 21:13

Wednesday, Jun 01, 2016 at 21:13
Odog on another site I was on someone said they took out their small ah aux battery from under the bonnet of their hilux and put a starting battery in it's place which was more than capable of starting the car that allowed them to fit a 105ah deep cycle battery where the original starting battery is which makes perfect sense when your aux battery has limited space. It will cost a bit more because you have to get the wiring swapped over but worth it.
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Follow Up By: Member - Odog - Thursday, Jun 02, 2016 at 16:11

Thursday, Jun 02, 2016 at 16:11
Thanks Batts, yes I have heard of this being done, but the idea of a battery box, which will be portable, I think is a great idea, I can also use it in the tinny, with the electric motor, which will be a big advantage.. Great read about batteries that you put above, appreciate that.. Thanks Odog
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