Redarc BMS with temporary solar

Submitted: Wednesday, Jan 30, 2019 at 17:34
ThreadID: 137742 Views:1096 Replies:6 FollowUps:12
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I have in my vehicle a redarc BMS1215 with a 120ah house battery.
On the roof is a 75watt permanent solar panel connected via anderson plug. This all works well and is a solid set up.

On the days where its a little cloudy or I want to give my battery a boost, I have a second solar panel (foldable) that I can utilise.

How and where do I wire in a second anderson plug to attach a temporary panel when I need it?

Thanks in advance!
Simon
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Reply By: Hoyks - Wednesday, Jan 30, 2019 at 18:00

Wednesday, Jan 30, 2019 at 18:00
I'd wire in a Anderson plug where the solar input connects to the BMS.

As long as you have the polarity correct the BMS should be able to cope with the extra Amps.
AnswerID: 623532

Follow Up By: stoooge - Wednesday, Jan 30, 2019 at 18:02

Wednesday, Jan 30, 2019 at 18:02
Thanks Hoyks.
Just to confirm. I already have one solar panel going to that input. Do you think just having a second line in should be okay?
Thanks.
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FollowupID: 896750

Follow Up By: Hoyks - Wednesday, Jan 30, 2019 at 18:31

Wednesday, Jan 30, 2019 at 18:31
As long as the voltage output from the panels is close, connected in parallel and its within the input rating for the controller, then the BMS's internal regulator should smooth things out and charge.

A total of 175W (on a good day and you are looking at when its a bit overcast) is only the equivalent of an average sized panel really.

I don't know what the BMS input is rated to in Amps, but my understanding and rough calculations, I think with that setup you'd be lucky to crack 17A.


https://hespv.ca/blog/wire-solar-panels-parallel-vs-series/
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FollowupID: 896751

Follow Up By: mountainman - Sunday, Feb 03, 2019 at 15:07

Sunday, Feb 03, 2019 at 15:07
I have seen a anderson plug double adapter piggy back connector online..
Basically one anderson plug goes in one way.
Your second one goes in the other way.
You dont change a thing to your setup now.
Its just a plug in and play when you want another socket.
First time i seen it online
Cheers
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FollowupID: 896842

Reply By: Dean K3 - Wednesday, Jan 30, 2019 at 20:01

Wednesday, Jan 30, 2019 at 20:01
running a second panel in parallel is ok, so long as the watt input doesn't exceed the maximum input allowed by redarc specifications

which is fairly low 250w max from memory

Connection ideally would go into same solar input connectors on redarc unit.

meaning two positive wires attached to redarc unit and negative wherever it required to go.

remember this also means the additional solar panel must unregulated as having to regulators opposing each other will cancel each other out.

The alternative method run a secondary twin core and connector separate to redarc system and then connect directly to battery. This however doesn't allow each "system to see" what each other is doing and over change maybe possible, but cloudy days probably negates this somewhat.

On subject of redarc folks had a alarm going off on a BMS systems for whatever relay it was (solar input or similar), turns out it wasn't fixable according to redarc so at reduced online price had to replace whole unit.

Hopefully you won't be in same situation as they were in.

If in doubt suggest contacting redarc directly they have a tech section n forum and have answered exactly same think I asked them about doing same thing.
AnswerID: 623536

Follow Up By: stoooge - Wednesday, Jan 30, 2019 at 20:19

Wednesday, Jan 30, 2019 at 20:19
Thanks Dean K3.
This is exactly what I was thinking. Thank you for your thorough reply.
I have had the unit for around 6 years, just redoing / remodelling a portable battery box- and had no alarms since purchase...

Thanks again.
Simon
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FollowupID: 896753

Reply By: RMD - Wednesday, Jan 30, 2019 at 22:44

Wednesday, Jan 30, 2019 at 22:44
Stoooge,
The 75 watt panel can be linked to the regulator input using a parallel connection anderson as mentioned above.
If the 75 w and, presumably a 120watt additional panel, will see only around 11 to 12 amps of charge on a good day. Therefore all should be quite ok with a 15 amp regulator of Redarc quality.

The wattage rating of panels is factory ideal conditions and never achieved in normal useage. I have two folding, same same, 120watt panels, ie, 240watts in theory, and on a cooler sunny day with strong sun it will only produce about 13 amps max with a MPPT regulator. The theory says 20 amps but reality is different.

If, and only IF, your regulator can withstand a high input voltage, ie, double the panel open circuit rating, you could arrange a connection using anderson plugs and double the panel voltage by connecting them in series for shady. cloudy days and the panels will then each deliver some usable charge energy when the normal parallel connection isn't going to do much at all, if anything.
A few checks and precautions to be observed to do this though, but it gets charge into batteries where normal systems stall.
AnswerID: 623542

Follow Up By: stoooge - Wednesday, Jan 30, 2019 at 22:58

Wednesday, Jan 30, 2019 at 22:58
Thanks for the reply RMD.
You have answered a few more questions I had. Although not yet purchased, I could potentially get a 200w solar blanket and still remain under the 15 amp recommendation.
I think I know how I am going to wire it up now- but I am open to more suggestions and information to those who are in the same situation.
Thanks again RMD
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FollowupID: 896757

Follow Up By: RMD - Thursday, Jan 31, 2019 at 07:51

Thursday, Jan 31, 2019 at 07:51
Stoooge
With a 200watt panel AND the 75 watt as well, both wired in parallel, you would then be OVER the 15 amp regulator input rating when good sun is available.

Therefore, if still using the same regulator it might be best to unplug the 75w roof one and just use the larger 200w panel. This situation isn't then using all your solar ability though because the regulator safety becomes an issue.

That is the trouble with setting solar things to work, everything you change creates a need for some other item to be required until all is in balance. Maybe a bigger capacity regulator will be needed in future if higher charge rates are required.
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FollowupID: 896760

Follow Up By: stoooge - Thursday, Jan 31, 2019 at 08:40

Thursday, Jan 31, 2019 at 08:40
My impression between the two BMS units (1215 and 1230) is the amperage output. 15amp and 30amp respectively. The input should be regulated and cant be "overloaded"- is this correct?
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FollowupID: 896761

Follow Up By: RMD - Thursday, Jan 31, 2019 at 11:09

Thursday, Jan 31, 2019 at 11:09
The specs you posted does indicate the reg only draws what it can use / accept so you can have more wattage of panel than units 15 a output. This concept is a bit different to some other regs which have less fancy electronics inside. Redarc have made it possible with their inverting stuff inside the reg.
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FollowupID: 896766

Reply By: bellony - Thursday, Jan 31, 2019 at 00:34

Thursday, Jan 31, 2019 at 00:34
We have a BMS 1215 in our KK. I have dual cables from the BMS solar input terminals running to Anderson plugs at the front and rear of the trailer so we have a choice depending on orientation, shading etc. Mostly I run 2 separate sets of panels in parallel attached at both ends, sometimes 3 sets if very overcast (with an Anderson double adaptor). You can put as many watts as you like into the BMS, it is the output that's limited to 15 A.

Panels in series is not an option with the BMS1215. Think from memory the input limit is about 25v and most portable panels are putting out about 20v.
AnswerID: 623544

Follow Up By: stoooge - Thursday, Jan 31, 2019 at 01:02

Thursday, Jan 31, 2019 at 01:02
Thanks bellony.
Thanks for your set up information. As I understand panels in SERIES is a no go.
I like how you have an anderson at the front and rear of your trailer- this is a similar situation that I will be following. Although, I may just use heavier gauge to the BMS unit and then split it once outside the vehicle into two Andersons.
Cheers again.
Simon
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FollowupID: 896759

Follow Up By: stoooge - Thursday, Jan 31, 2019 at 08:59

Thursday, Jan 31, 2019 at 08:59
Thanks Frank P. For some weird reason, Murphy is always camping at the same spot as me!

I agree. So given I already have a 75W panel installed. I shouldn't be looking at something any bigger than 185W for a second panel. Unless of course I can be bothered unplugging the 75Watter and fiddling around with cables.

Simon
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FollowupID: 896764

Reply By: stoooge - Thursday, Jan 31, 2019 at 08:53

Thursday, Jan 31, 2019 at 08:53
According to the destructions.

- In parallel.
- Cant exceed 30V
- BMS will not draw more than 260W

I will install several points in parallel where I can place an extra panel when needed.
AnswerID: 623546

Reply By: kgarn - Thursday, Jan 31, 2019 at 09:10

Thursday, Jan 31, 2019 at 09:10
Use one of these to connect both panels to the BMS:




Available here:

Redarc anderson parallel cable

Ken

AnswerID: 623547

Follow Up By: stoooge - Thursday, Jan 31, 2019 at 09:12

Thursday, Jan 31, 2019 at 09:12
Cheers kgarn.
I am going to make one up myself. I need/want the two inwards at different locations. But its good to know they exist.
Thanks
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FollowupID: 896765

Follow Up By: RMD - Thursday, Jan 31, 2019 at 20:10

Thursday, Jan 31, 2019 at 20:10
Stooge.
If using a few Anderson plugs, go on the net and find a place, Altona vic, Lite Way I think they are called. Buy 20 for around $23. That way you have spares and at just over a $1 each you can make many options for connections and power transfer as required.
I have bought 40 in the last year alone. I use a few.
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FollowupID: 896780

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