Redarc Smart Solenoid Confusion

"But everyone believes that one of the advantages of buying a voltage switched solenoid is that it will charge your starting battery FULLY before connecting your auxiliary. "

Not everyone. Not me. I noticed that the RedArc website has this as it's description of it's Smart Start product:
"When the charging system reaches 13.6 volts (27.2 Volts on a 24V system) indicating a fully charged start battery, the REDARC smart start will close the solenoid connecting the auxiliary battery to the start battery and the charging system."

I have a SurePower product which by all accounts does the same thing. I notice that it's description for it's product is:
"When the engine or auxiliary batteries (if 1315 is used), or the engine batteries (if 1314 is used) reeach 13-13.5 volts, indicating charging is taking place, the BATTERY SEPERATOR will engage, joining the two battery banks".

Very important difference in their descriptions as the SurePower description doesn't mention the main battery would be fully charged - only that charging is occuring.

Pete

Thanks for that Mike. I couldnt work out anyway for the device to monitor the voltage in the starter battery unless it could stop or disconnect the altenator which is obviously near on impossible.
I also notice that someone around here says that the dual redarc unit , will disconnect the secondary battery when it is fully charged. According to the Redarc site it doesnt do this and I cant see why it would either.

Cheers

Fil

You're right there too. While the voltage is above 13.5, they will remain paralleled.

The purpose of Dual-Sensing isolators if for situations where either battery may be charged e.g. if a Solar Panel is connected to the Aux battery the Isolator will close to charge the Main Battery

"the engine batteries reach 13-13.5 volts, indicating charging is taking place,"

Pavo - thanks. It gives you confidence in a supplier when their descriptions are accurate.

I just ran the vehicle for an hour or so after jump starting it. But ever since, if I dont use the car for a few days the battery goes flat. So either its tuffed or its not getting enough charge in it while the car is running to bring it back up to charge. Im off right now to pick up a decent charger :) Any other thoughts?

If you dont already have one ,grab a multi meter(cheapie will do) and test to see what volts your alt are putting out and if you got a place close by get them to do a load test on your battery.I suspect your battery is dead.I also take it your aux. battery is charging OK

If your alternator is pumping out more than 13.5 odd volts, then buying a charger isn't going to charge the battery any better. I would have thought 1 hour would be good to charge it. Why not drive to a battery shop and have them test the battery before buying a charger?

Alternator is putting out 14.4v. The starter battery indicates around 12.4v but once you try to crank the engine it does next to nothing. Then when you let it sit for awhile it comes back up to 12.4v. I take it this means its stuffed?

Cheers

Fil

Sure sounds like it's stuffed. Is it old?

If you mean the volts die right off and slowly come back,yep she's stuffed.

Ive had the car for 2 years now and its the battery that came with it. Doesnt seem to be brand name battery either. Now the question is to replace with an AGM or another lead acid....

Can't answer your AGM question...

Ive always used Century batteries and always had a good run out of them.

Check for corrosion at the battery terminals - especially black corrosion at the Positive. Clean both post and terminal so they are shiny metal.

Thanks Pete. I think you're right about the coincidence.

Ive actually already got a switch hooked up in cabin that runs a relay to switch off the redarc solenoid for when I run a Nimh charger in the cabin and dont want the voltage fluctuations from the alternator to stuff it up. I have run the car for an hour last week with the batteries isolated and the next day the car still wouldnt start.

I wouldn't have thought you'd ever need to 'switch off' the RedArc and that anything electrical you run off the battery (be it Aux or Main) would be fine? But I'm not an auto elec or anything so I don't know about this side of things. But I know very well how the product itself operates as my SurePower failed once (years ago, and been fine since) so I became familiar with it then!

I'm led to beleive failures are very rare!

The only reason I need to switch off the redarc (actually just to isolate the two batteries while the car is running) is because of an expensive battery chargerthat I use that runs off of 12v and doesnt like fluctuations in input voltage as it uses a very sensitive circuit to detect when the NimH batteries are fully charged.

Fil

" . . . as it uses a very sensitive circuit to detect when the NimH batteries are fully charged"

- and has inadequate isolation between input and output :-)