Redarc BMS1215 failing to do its job (Help!)

Baz
Nothing worse than a weird fault. Every circuit is different, so I wont even pretend. But you mentioned the solar panels, do they have blocking diodes fitted? Maybe disconnect them in full sunlight and see if they are producing around 17 volts each? If one isnt, check if one of the diodes hasnt blown? Just a thought. One thing, if it worked before, then its not a design issue, its a fault that has developed.

I have an interest in this because I have just dropped off my new Mazda for fit out, and they are installing all redarc gear, I have 2 x 120 panels, the 30 amp battery manager, and 2 x 120 batteries going in, hope it all works well
I am a fan of the RedArc gear, after trying the TowPro, very very good.

Only other thing I can suggest to look at is mounting, is the unit well ventilated?
Good Luck

I had a quick look at the user manual and it states for one 12V panel a bocking diode is not required, for more than on panel use as per manufactures instructions.

The above is a little ambiguos, a solar panel acts like a variable rsistor when shaded, the more voltage you apply to the panel the more "leakage" you get through it, two panels in parallel would have twice the leakage etc, generally with similar panels in parallel this is not an issue, with panels in series parallel combinations it could be an issue and blocking diodes can be used to overcome this, see blocking diodes and solar panels.

Generally there isn't any reverse current flow from a regulator so in most 12V installs blocking diodes aren't required, from what you have written you are getting reverse current flow from the regulator through the solar panels, a blocking diode would prevent this but I'm surprised this would occur as the regulator should isolate the panels from the battery when they are not producing power.

Check the panel wiring and if correct then cover the panels and connect to the BMS through an amp meter, if you see current flow into the panels I would be going back to Redarc and asking them why is this occuring, ie are blocking diodes needed and if so why?

Bit of a mystery Baz! Doubt that I can help you though.

We also have a BMS1215 in our slide on camper, charging 2 x 120amphr batteries, and assisted by a 160w solar panel mounted on the roof. For extended stays have a folding 120w panel too.

In the time we've had it, it has been reluctant to charge using solar. In the mornings, full daylight, one can hear the relays attempting to kick in, but once the sun hits the panel, the BMS has gone to sleep, and usually needs to be manually "invigorated" to start charging. A check of the LCD readout shows the batteries being charged, all parameters perfect, except solar amps at zero.

Spoke to a Redarc tech once about this, and the only suggestion he had was to change from "Touring" to "Storage" mode, to allow the unit to kick in. I've done this numerous times, but it's not a solution, as if one was leaving camp early, the system wouldn't be charging at maximum amps.

Both 12v & 240v charging have been okay. Certainly haven't had the problem that you have Baz. I feel my drama will only be resolved by the unit returning to Redarc for inspection.

Perhaps this might be a legitimate excuse for you to upgrade to the 30amp unit or even the lithium model? :-). Hope you get it sorted soon.

Bob

Baz, I've been running my BMS for 6 years now with no problems. As you know, mine is sitting over 280 AH of Powersonic AGM's and manages 300W of solar as well.

Are the solar panels coming into the BMS "Open Circuit" without a solar regulator between the panels and the BMS? I was told at the time of install that leaving the standard solar regulator connected to the panels affects the BMS. The panels need to be wired direct or openly to the BMS unit with its inbuilt MPPT controller doing the work.

Cheers

Mick

I haven't looked at the circuit for a Redarc device but it if relies on the negative line being switched off to protect the start battery., (similar to solar regultors switching the neg line), You may have a device fitted somewhere which is electrically connected across the switched side of the wiring and it is effectively negating the isolating feature of the Redarc.

I have had this experience with connections on solar regulators and it may be happening to you with your Redarc.

Cheers
RossM

We appear to have identified the problem!

Firstly, there is no underlying fault “within” the product, either BMS or solar panels, which is all Redarc equipment.

Equally, the installation by our auto-electrician is perfect.

Now I am not an engineer or auto-electrician so the least I say the better so I don’t misrepresent the findings as described to me by Redarc and my auto-electrician

It would appear that under certain conditions the BMS will allow a current draw from the start battery even when the vehicle ignition is switched off.

It would appear in very low light conditions, having an implication for the solar panels, and when the house battery is below the charge of the start battery, the start battery may provide some charge back through the BMS – in our case approximately 0.3A/H

In the configuration I have in the vehicle, I continuously run a 60-litre Engel Fridge, but it is an older one without a voltage regulator. Usually it isn’t a problem, but clearly conditions can present when it might become one.

Apparently mine is the first issue that has been brought to the company’s attention, although that isn’t to say it doesn’t occur in other units if the same configuration and conditions exist. I only detected it because the start battery was discharged to the point of not being able to crank the engine after a period of a week or so without use…

One takeaway for me is that wherein I thought the BMS unit worked similar to a smart solenoid and protected the start battery from being discharged when the ignition is switched off – this may not always be the case (under certain configuration and conditions). We have a simple fix for this…

The other takeaway, which is critically important to me is that the entire team at Redarc, an Australian company building products designed for Australian conditions, stand by their product and when problems arise, work hard to resolve.

Cheers, Baz – The Landy