Does the Redarc BCDC offer any benefits over an SBI12 system?

[rwo Advanced Member Find all posts View Profile Close rwo]

I am in the process of buying up for my dual battery system and trying to decide if the Redarc bcdc offers any benifits over the Sbi12 and the alternator diode upgrade, and is it worth the extra $300 odd?

I will be installing a d27 yellow top as the Aux battery (and will replace the main with the same when required), and after reading that plenty of people use dissimilar batteries with this the sbi12 without problems, is there any real benifit to the bcdc? Does a yellow top charge to (or close to) full capacity without a dc-dc charger, using the standard alternator with diode upgrade, as at the end of the day this is the most important factor?

We are also looking at a ct that runs a bms1215 system that will handle charging duties and solar for the trailer, so solar wont be required on the car.

I have searched all over the place but cant find any definitive answers to sway me either way...

[wooley Avid PP Poster! Find all posts View Profile Close wooley]

I've been using a SBi12 and d34m on my 150 (without a diode) for almost a year and it's performed faultlessly. I just couldn't see the benefits of the bcdc, and the extra cost seemed a bit unnecessary.

[Ozpat Advanced Member Find all posts View Profile Close Ozpat]

I am in the process of buying up for my dual battery system and trying to decide if the Redarc bcdc offers any benifits over the Sbi12 and the alternator diode upgrade, and is it worth the extra $300 odd?

I will be installing a d27 yellow top as the Aux battery (and will replace the main with the same when required), and after reading that plenty of people use dissimilar batteries with this the sbi12 without problems, is there any real benifit to the bcdc? Does a yellow top charge to (or close to) full capacity without a dc-dc charger, using the standard alternator with diode upgrade, as at the end of the day this is the most important factor.

We are also looking at a ct that runs a bms1215 system that will handle charging duties and solar for the trailer, so solar wont be required on the car.

I have searched all over the place but cant find any definitive answers to sway me either way...

I have the exact same setup with the diode, D27f and Sbi12 without any issues. Plenty of people on here will steer you away from the dc-dc chargers as a waste of money.

Cheers, Jim

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

I also don't understand why people go the DC charger route, if the alternator can charge one battery without problems it can charge 2 just as well. I have the SBI12 and diode with the Optima blue top and everything is sweet.

Cheers Andrew

[dmclean1313 Lurker Find all posts View Profile Close dmclean1313]

Has anyone used ABR's isolator? seems a bit cheaper than a redarc, just wondering if they were as good?

[pradokit Find all posts View Profile Close pradokit]

The dc-dc units are most useful when it is located in a trailer/caravan. It compensates for the voltage loss that occurs over the 7-10m of cabling involved and ensures you get your 13.2V,or whatever, that is needed to charge the caravan/trailer battery. I wouldn't think this is much of an issue in an under bonnet application. All you need is a system that prevents the main battery being drained by a used up auxillary battery.

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

Has anyone used ABR's isolator? seems a bit cheaper than a redarc, just wondering if they were as good?

If you want to save a dollar then just use a $20 solenoid, activate it off a circuit that only operates with the ignition in the on position and its almost as good as the smart isolators.

Cheers Andrew

[BNEGXL Member Find all posts View Profile Close BNEGXL]

I had ABR's isolator on our 120 for 5 years with no problems. I have now had the Redarc SBi 12 on our 150 for two years, also no problems.

Regarding price, I don't think there's much difference, ABR wants $79.95 + postage and there are ebay sellers with the SBi 12 for $89 delivered.

[rwo Advanced Member Find all posts View Profile Close rwo]

Thanks guys, it seems the general consesus is that a sbi12 will be sufficient for the task.

Now the next question, is a higher rated sbi212 worth the extra and why would someone buy that over the standard sbi12?

[8608 Advanced Member Find all posts View Profile Close 8608]

the SBI12 is a 100A continuous load rated solenoid. they have a inrush/surge rating of about 400A. generally ok for connecting both batteries to start the engine with.

th SBI212 is a 200A continuous load rated solenoid. surge rating of about 600A. Generally used in heavy duty mining and industrial applications, although, if you are planning a lot of winching through both batteries, this may be the unit to go for. some winches can draw over 600A easily on hard starts. you wouldn't want to pull 600 odd amps through the SBI12.

also, try to go a bit heavier in the gauge wiring you use.

[gxl_d4d Advanced Member Find all posts View Profile Close gxl_d4d]

A DC-DC charger will fully charge a battery quicker that an alternator. An alternator putting out 13.8V can take up to 20 hours to charge a discharged battery. The adjvantage of a dc-dc charger is that it initially boost charges the battery before changing over to float mod. If a battery is deep discharged, it may not accept charge if only given 13.8V. I've got a solenoid setup. Every 3 months I still need to top up the deep cycle battery as the alternator can't fully charge it after a slow discharge.

[drivesafe Senior Member Find all posts View Profile Close drivesafe]

Hi gxl_d4d and I don’t know where you get your info from but if you have a low 100Ah FLOODED WET CELL battery at about 30% SoC, it will take an alternator, running at 13.8v about 10 hours to fully charge.

BUT, it will be charge the battery to 90-95% in about 4 to 5 hours.

A 20 amp DC/DC device will take about 8 hours to fully charge the same battery from the same SoC but surprise, surprise, it will also take about 4 to 5 hours to charge the same battery to 90-95%

Now rwo is not talking about a flooded wet cell battery, he is talking about charging an Optima D72 AGM, a 66Ah battery that can be discharged to 0% and, if this flat, can be fully charged from a 100 amp alternator, in 35 minutes ( Optima’s own specs ).

Whereas, you 20 amp DC/DC device 4 to 5 hours to fully charge the same battery.

So why would anybody in the right mind spend hundreds of dollars on something that will take four time as long as at best to do what an alternator can do.

gxl_d4d, if these DC/DC devices are so much better than an alternator, why is it that not one of the pedlars of these devices has a graph showing how their wonder device compares with an alternator, when charging a low battery to a fully charged state.

They don’t show such info because the instant people saw how they REALLY perform, no one would buy them.

The is lots of B/S used to sell the wonder device and in some situations, they can be an advantage, but unlike all the hype, this is in a VERY small percentage of DBS set ups and there are far cheaper and more efficient ways of charging batteries faster than these wonder devices can.

One more point gxl_d4d, contrary to what you and many others think, DC/DC devices will actually charge a low battery at a MUCH lower voltage than what an alternator can do, and it’s only in the final stage of the charge cycle, when the battery is nearly fully charged, that a DC/DC device has the ability to charge a battery at a higher voltage than an alternator does, and the problem here is that most people never drive long enough the allow these wonder devices to get to this final charge stage.

It’s amazing how real life facts can get in the way of advertising hype!

[winniliss Avid PP Poster! Find all posts View Profile Close winniliss]

"It’s amazing how real life facts can get in the way of advertising hype!"

It's liker those ab machine ads. Lose 15kgs in two weeks ansd spot reduce that fat....BS. Get outside and run.

I use a D27F, a redarc SB12 isolator & diode for my aux setup. I also have a CTEK 25amp multi stage battery charger that I can use every now and then if I need to top up my batteries. Once the factory battery goes I will replaqce it with another D27F.

[gxl_d4d Advanced Member Find all posts View Profile Close gxl_d4d]

"It’s amazing how real life facts can get in the way of advertising hype!"

The Centuary Yuasa engineer I used to work with must have had it wrong. His job was design and build battery banks and chargers for power stations and other large industrial installations.

[winniliss Avid PP Poster! Find all posts View Profile Close winniliss]

Yes he did