observations about redarc isolator
Submitted: Wednesday, Mar 25, 2009 at 00:06
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greybeard
Decided to change out my battery isolator with a redarc smartstart.
Have been observing it's operation over the last few days and have been pondering aspects of that operation.
I'd point out that it is operating as per the specification, apart from the current drain of the actuated solenoid being around the 0.8A mark instead of 13.5V for at least ~ 4 seconds. all good :)
When the engine is switched off it stays actuated until the voltage drops to < 12.5V. Now herein lies the conundum. My main battery is an N70ZZ and my secondary is a 55Ah AGM ( and the camper is a 95Ah deep cycle ). With no load, apart from the actuated solenoid on the smart start, the combined battery voltage takes over 12 hours to drop to < 12.5V
In that time the smart start has used up ~ 10Ah of battery capacity.
Granted it means my fridge ( when connected ) can draw down some power from the starting battery but it also means i'm wasting battery capacity.
And ( i know you need to let the batteries rest for 12 hours but it is a pretty low discharge rate compared to the combined battery capacity ) 12.5V is about 75% charged.
The discharge times and battery capacities don't quite add up but roughly speaking i'm using up nearly half a day of fridge running power just because the smart start won't drop out until the battery volts drops below 12.5V.
I can force it to drop out by leaving the headlights on high beam for a minute or so after i turn off the engine but it all seems counter productive.
I'll have a chat to redarc about it but can anyone, apart from mainey, see anything i'm missing in all of this?
Reply By: Lex M (Brisbane) - Wednesday, Mar 25, 2009 at 00:21
Wednesday, Mar 25, 2009 at 00:21
I agree with all you said. That's how
mine works too.
Pity it doesn't have an override input you could connect to acessories or something to drop it out when ignition is off.
AnswerID:
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Reply By: pop2jocem - Wednesday, Mar 25, 2009 at 00:31
Wednesday, Mar 25, 2009 at 00:31
As one greybeard to another' I've been pondering this same conundrum myself. I to have N70ZZ crankers and 105ah AGM's connected as you seem to have. I had a manual isolator but got sick of forgetting to turn it on or off as required. I have fitted a Matson auto isolator and have been observing a similar situation i.e. a drawdown to below the full charge of 12.8 volts before separation takes place. Most interested to see the responses (if any ;-)))
Thanks for bringing up the subject
Cheers Pop
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Reply By: Krakka - Wednesday, Mar 25, 2009 at 06:05
Wednesday, Mar 25, 2009 at 06:05
Greybeard, I am almost certain that the cut off voltage is adjustable, best bet is to ring Redarc. They are very helpful, and you speak to people who know the product inside out. Maybe the 200A isolator is adjustable, best to ring them.
Cheers
Krakka
AnswerID:
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Reply By: Maîneÿ [wa] - Wednesday, Mar 25, 2009 at 06:06
Wednesday, Mar 25, 2009 at 06:06
greybeard,
here's hoping you will also copy/paste their Email reply to you here also !
Mainey . . .
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Reply By: Member - JohnR (Vic) - Wednesday, Mar 25, 2009 at 06:57
Wednesday, Mar 25, 2009 at 06:57
Redarc will take 0.6 amp every hour it is open on it's own too. So will any other solenoid while it is open, not just your Redarc. They can take a potential 15-17 amp hours a day of battery capacity. If you have the special Landcruiser one it can be down to 12.2 volts that it will remain open. Stop Thief
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Follow Up By: Member - Mike DID - Wednesday, Mar 25, 2009 at 09:32
Wednesday, Mar 25, 2009 at 09:32
Oatley Electronics sell a kit for an Isolator that draws ZERO current while activated.
It can also be used as a Low Voltage Cutout.
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Follow Up By: Member - JohnR (Vic) - Wednesday, Mar 25, 2009 at 10:01
Wednesday, Mar 25, 2009 at 10:01
Mike, if you can give me a pointer link it would be great thanks. Like to see what options to a 4-5% of my better power absorbed over a day by the Redarc. Nearly a fridge extra.
EO has linked draws rather than drawers to Jim Best that looks like a link in your post
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Follow Up By: Member - JohnR (Vic) - Wednesday, Mar 25, 2009 at 10:15
Wednesday, Mar 25, 2009 at 10:15
Is this it?
Oatley Link How many amps will it carry?
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Follow Up By: Member - Mike DID - Wednesday, Mar 25, 2009 at 10:20
Wednesday, Mar 25, 2009 at 10:20
Here is the Oatley Kit - $22
http://secure.oatleyelectronics.com//product_info.php?cPath=35&products_id=270
I haven't used the "Insert Link" option - due to a "feature" of MicroSh*t Software, IE7 crashes totally when I use this option.
I modified the low-voltage cutout so that I can select the dropout voltage in 0.5 volt steps, depending on how much current the load draws and how desperate I am to get as much power as possible out of the battery.
You will need two separate kits to use it as Battery Isolator and as Low Voltage Cutout - but as this price you're still
well below the cost of a plain solenoid cutout.
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Follow Up By: Lex M (Brisbane) - Wednesday, Mar 25, 2009 at 10:27
Wednesday, Mar 25, 2009 at 10:27
I wonder how that latching relay will perform with the vibration in a vehicle.
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Follow Up By: Member - Mike DID - Wednesday, Mar 25, 2009 at 10:28
Wednesday, Mar 25, 2009 at 10:28
The Latching Relay is rated at 80 amps and has serious braided wire welded on the contacts.
You should never exceed this current unless you are winching off the second battery.
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Follow Up By: Member - JohnR (Vic) - Wednesday, Mar 25, 2009 at 10:58
Wednesday, Mar 25, 2009 at 10:58
Mike, thanks for that. It is the Karavan system I will try to protect so no winch.
IE7 problems eh? Try Google Chrome, or even Opera. The hackers are already exploiting IE8
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Follow Up By: Member - John (Vic) - Wednesday, Mar 25, 2009 at 11:05
Wednesday, Mar 25, 2009 at 11:05
Mike here is your
Oatley Link done with IE7 and it works very
well for me, no crashes anytime :-))
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Follow Up By: Member - Phil G (SA) - Wednesday, Mar 25, 2009 at 22:35
Wednesday, Mar 25, 2009 at 22:35
John,
I found a link to the cutout I mentioned this morning. Its 35amps and uses less than 10 mA.
35amp low voltage cutout.
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Reply By: Member - Leigh (Vic) - Wednesday, Mar 25, 2009 at 09:04
Wednesday, Mar 25, 2009 at 09:04
Hi Greybeard. I have similar batteries and I was also concerned about how long it took to disconnect. A flick on high beam for a few seconds seemed to create enough drop to disengage the batteries. When I changed over to another vehicle I decided to place a switch on the earth wire back to the dash to enabe an manual turnoff. The switch has a green LED to also indicate the solonoid is engaged. This, together with a momentary button to join the batteries, has worked particularlly will for me. All I do after shut down is flick the swith off and back to on and it's ready to connect next time I start up. The green led light confirms that the solenoid has engaged. Hope this helps??
Cheers
AnswerID:
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Reply By: ABR - SIDEWINDER - Wednesday, Mar 25, 2009 at 09:05
Wednesday, Mar 25, 2009 at 09:05
Hi Greybeard
Fit an ignition activated relay controlling the black earth wire on the Redarc.
This will switch it off when the key is turned off. Make sure to use + IGN not + ACC if you use the jump start option.
Regards
Derek from ABR
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Follow Up By: Lex M (Brisbane) - Wednesday, Mar 25, 2009 at 10:25
Wednesday, Mar 25, 2009 at 10:25
Thought about doing this.
Had a concern about the spike generated by the solenoid dropping and any suppression circuits in the redarc being disabled because the earth connevction had been removed.
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Follow Up By: GerryP - Wednesday, Mar 25, 2009 at 20:25
Wednesday, Mar 25, 2009 at 20:25
As Derek has indicated, put a relay in the black wire. I know some of the guys at Redarc personally (No - I have no affiliation with them) and they tell me that is a perfectly safe way to control isolation. They also tell me that he next model will possibly have that facility in-built as they are
well aware of some of the concerns people have.
Cheers
Gerry
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Reply By: greybeard - Wednesday, Mar 25, 2009 at 09:25
Wednesday, Mar 25, 2009 at 09:25
thanks guys.
it's a catch 22. if the solenoid ( and it can be any solenoid ) didn't draw so much power it wouldn't be an issue.
if the switch off voltage was, say, 12.8V then it wouldn't be an issue.
as it is, all that is gained by leaving the drop out voltage at 12.5V is for all of the batteries to power the solenoid for a 'half a fridge day' ;)
The only other reason I can see for the 12.5V drop out is to provide some hysteresis to cope with noisey vehicle electrics. There is a time delay in the controller that should do this anyway.
But, I'm not an expert on electrical noise in vehicles :)
One other possible point ( for the electrical/electronic people out there ) is I know with a relay it requires more current to activate the relay than it does to hold it in the activated state. ie reducing the power consumed by the relay once activated. Is it the same principle for a solenoid? If it is then this may be an option to reduce the power consumption of the solenoid.
I'll wait to hear what Redarc have to say.
AnswerID:
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Reply By: Axel [ the real one ] - Wednesday, Mar 25, 2009 at 09:29
Wednesday, Mar 25, 2009 at 09:29
Have you taken into account the draw of the radio /clock ect that all draw some power even when switched off ? Can all add up to the amount of loss over your time frame perhaps.
AnswerID:
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Follow Up By: greybeard - Wednesday, Mar 25, 2009 at 09:42
Wednesday, Mar 25, 2009 at 09:42
the current used by any other load will decrease the time before the battery discharges enough to allow the smartstart to drop out. So having a greater electrical load on the system will actually reduce the amount of power lost in the solenoid. :)
The point about power usage is more to do with the duration and consumption of the ( any ) solenoid after the charging source is removed.
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Reply By: Member - Mike DID - Wednesday, Mar 25, 2009 at 09:38
Wednesday, Mar 25, 2009 at 09:38
It's not that SMART a device, if it doesn't do what you want - and some people even have to put in manual over-ride switches.
Every Battery Isolator manufacturer comes up with some "feature" to make theirs appear than the next one - but in the end all they do is connect the second battery to the Altrenator. Does anyone actually want this "feature" of discharging from the main battery until its voltage drops ?
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Follow Up By: greybeard - Wednesday, Mar 25, 2009 at 09:48
Wednesday, Mar 25, 2009 at 09:48
fair call.
i'm kind of partial to using some of the capacity from the starting battery, just seems self defeating when the extra capacity is consumed by the device rather than by my fridge.
i prefer cold beer to hot solenoids :)
As you state most of these operate the same apart from latching relays ( Oatley kit ) and solid state ( MOSFET ) types.
I've my reasons for heading down the solenoid path rather than the solid state path. So, I'm pondering if the solenoid type devices could be improved to reduce the side effects of their inherent properties.
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Reply By: Member - John (Vic) - Wednesday, Mar 25, 2009 at 10:31
Wednesday, Mar 25, 2009 at 10:31
Why not use a manual solenoid??
Turn it on and off as you need and it draws no current when open (Batteries isolated)
Simple and cheap compared to these so called Smart Solenoids.
I have been through two different models of Smart Solenoids (ARB & Matson) and both don't seem to be reliable over the longer term and too bloody expensive for what they do.
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Follow Up By: Rossc0 - Wednesday, Mar 25, 2009 at 11:43
Wednesday, Mar 25, 2009 at 11:43
Or use a manual solenoid that is automatically actived when the engine is running.
This can be switched by oil pressure or tacho (petrol engines).
Cheers
Ross
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Follow Up By: Member - John (Vic) - Wednesday, Mar 25, 2009 at 12:18
Wednesday, Mar 25, 2009 at 12:18
Yeah or wired into the ignition so it activates when the ignition is switched on or off.
I use a switch on the dash which has a very
bright red led so I see its on soon as I get into or out of the car if I forget to turn it off before coming to a stop.
Clean, quick, simple and cheap. Also easy to trouble shoot if a problem does occur.
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Follow Up By: Member - JohnR (Vic) - Thursday, Mar 26, 2009 at 08:06
Thursday, Mar 26, 2009 at 08:06
Not a switch on the dashboard to switch on, or leave on, then puzzle as to why you have to jump start a few days later. Cor, some people ;-))
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Reply By: Member - Phil G (SA) - Wednesday, Mar 25, 2009 at 21:03
Wednesday, Mar 25, 2009 at 21:03
I agree - its just a waste of power.
I've used 2 solid state isolators in 6 vehicles over the past 20 years. The first Rotronics consumed 30 milliamps. The second one (an MH10) uses 8 milliamps and has a wire going to IGN power, so it isolates and powers down. Costs twice the price of the Redarc though. Derek's solution sounds good if you really like solenoids.
AnswerID:
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Follow Up By: greybeard - Wednesday, Mar 25, 2009 at 23:43
Wednesday, Mar 25, 2009 at 23:43
i'm pondering derek's solution.
one option is to use a 'turbo timer' to provide the earth for, say 90 seconds after ignition off.
bit of a bummer really as I could program a micro to do exactly what I want. Just hoped there was something off the shelf that was pretty close to ideal.
have been researching the solenoid current drain issue and it's pretty common to reduce the current after the solenoid has actuated.
maybe there is still a market for a 'smart solenoid' controller after all ;)
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Reply By: Best Off Road - Thursday, Mar 26, 2009 at 06:58
Thursday, Mar 26, 2009 at 06:58
What I find happens with
mine is this. Once stopped, as soon as the fridge kicks in it puts sufficient load on the system to register under 12.5 and the start battery isolates.
Even in a no/little load situation 12.5 is nothing to worry about. According to all battery charts I have seen, 12.5 equates to 90% charge.
Cheers,
Jim.
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Follow Up By: Member - JohnR (Vic) - Thursday, Mar 26, 2009 at 08:12
Thursday, Mar 26, 2009 at 08:12
Jim, there is a Redarc in my Karavan to protect the batteries from falling to 55%, but the Redarc itself is a thief of
battery power and shuts itself down in days if you don't keep a charge there. It will be replaced shortly. Solar panels are good that way to keep a charge in there
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Follow Up By: greybeard - Thursday, Mar 26, 2009 at 10:05
Thursday, Mar 26, 2009 at 10:05
i think your figure of 90% at 12.5V is a little optomistic Jim.
All of the charts I've seen that give an approximation of charge by measuring terminal voltage ( after resting for around 12 hours, but a light load will give a rough idea ) show that 12.5V is about 75% charge.
Adding load will hasten the voltage drop though.
If your fridge kicking in, say 5A draw, is pulling the battery voltage down to 12.5V as soon as you have stopped, then I'd be concerned about the charge of your batteries and/or wiring to the redarc.
I've found I need to have highbeam and
driving lights ( ~400W or over 30A ) on for nearly a minute to get the voltage low enough for the 12.5V drop out.
I've had a quick
check just now and my redarc is still on after nearly 20 hours.
Don't get me wrong, I'm not saying that there is a problem with the Redarc, I'm just making observations regarding it's operation and applying some maths.
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Follow Up By: Maîneÿ [wa] - Thursday, Mar 26, 2009 at 11:37
Thursday, Mar 26, 2009 at 11:37
Ummm, I think the battery would be receiving Alternator charge prior to vehicle stopping, this charge would see the battery being maintained @ ~13.6v
When the vehicle stops (engine is turned off) it will reduce slowly to ~12.7v
For a fridge drawing 5 Amps to take it to 12.5v (yes, 90% when stated as a SOC percentage) I would think there is a problem with the battery not holding charge or as GB says the system wiring may be suspect.
However I believe Jim's fridge may be a 80 Lt Waeco and it's initial *start-up* draw could possibly be higher than 5 Amps?
As Jim states: "as *SOON AS* the fridge *KICKS IN* it puts sufficient load on the system to register under 12.5v and the start battery isolates"
I believe the INITIAL start current draw will be much higher than 5 Amps.
Mainey . . .
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Follow Up By: Best Off Road - Thursday, Mar 26, 2009 at 11:51
Thursday, Mar 26, 2009 at 11:51
OK, to add some further information.
Cabling from my start batt to Aux is super thick cable, so thick that I had to use 175 amp Anderson Plugs as the cable wouldn't fit in the normal 50 amp ones.
Fridge is a Waeco 80 and is hard wired to the Aux.
Aux is a 100 amp REMCO AGM, 3.5 years old, plenty of use so probably isn't in tip top nick but still holds 12.7 to 12.8 volts. I constantly have a multi hard wired to the batt.
Here's what I just did.
Check voltage, 12.7. Turned on fridge, voltage dropped to 12.4, Redarc went clunk and disconnected. Turned off Fridge and voltage went back to 12.7 after a about a minute. Redarc did not reconnect.
Not sure what this all means, but just offer it up as an observation.
Cheers,
Jim.
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Follow Up By: greybeard - Thursday, Mar 26, 2009 at 12:07
Thursday, Mar 26, 2009 at 12:07
i know i'm going to regret this.
Please read the very first post in this thread Mainey.
1/ In a modern vehicle the regulated output from an alternator is ~ 14.2 - 14.4 V. Therefore a charged battery will not have ~ 13.6V across it prior to vehicle stopping.
2/ State of charge measurement using voltage please refer to this
Car battery FAQ There are multiple other sources with similar information including Colyn Rivers excellent books.
Colyn Rivers battery info 12.5V is approximately 75% SOC provided the battery has rested for a period of time as per documents referenced above.
3/ My experiments have indicated that a load of over 30A for a minute are required to get the battery voltage low enough to reach the 12.5V low cut out voltage. This is with ~ 150Ah of battery capacity. If ~ 5A current draw does this on startup of a fridge then there is an issue with battery capacity and/or wiring.
Please do not use incorrect information to justify and/or confuse an issue. Sit back, look, read and learn.
I'm not playing this game anymore.
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Follow Up By: Best Off Road - Thursday, Mar 26, 2009 at 12:30
Thursday, Mar 26, 2009 at 12:30
GB
Have a look at this link, scroll down to find the SOC table. This is the one I have used as it is supposed to relate specifically to AGM's. Hence my comment 12.5 is 90%. However this conflicts with two links you have put up.
Battery FAQ
Now I'm completely confused LOL
Regards,
Jim.
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Follow Up By: greybeard - Thursday, Mar 26, 2009 at 12:55
Thursday, Mar 26, 2009 at 12:55
cheers jim
the rpc deepcycle reference also describes the variance between different battery types.
in particular both of the references i've quoted have similar discharged voltage of ~ 11.8V, the reference you have shows discharged at 10.5V. big difference.
measuring state of charge with voltage is a black art and subject to a lot of inaccuracies.
apart from the windsun site pretty much all of the online information i've seen matches up ( or it's all been copied from the same site ;) ).
Check out this guys site
smartguage tech regarding all sorts of battery myths.
Bottom line with the state of charge is that with a large capacity battery system in good nick, the design concept of a 12.5V drop out voltage and a solenoid drawing ~0.8A is a noticeable amount of power being wasted.
i don't like warm beer :(
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Follow Up By: Maîneÿ [wa] - Thursday, Mar 26, 2009 at 13:02
Thursday, Mar 26, 2009 at 13:02
GB,
Yes I reread your first post
you say:
"I'd point out that it is operating as per the specification, apart from the current drain of the actuated solenoid being around the 0.8 Amp mark instead of 13.5v for at least ~4 seconds. all good"
Your solenoid drains the battery @ ~0.8 Amp mark *instead* of 13.5v ?
How do you equate 0.8 Amp drain with 13.5v ?
Then you say:
"When the engine is switched off it stays actuated until the voltage drops to <12.5v. Now herein lies the conundum.
My main battery is an N70ZZ and my secondary is a 55Ah AGM (and the camper is a 95Ah deep cycle)
With no load, apart from the actuated solenoid on the smart start, the combined battery voltage takes over 12 hours to drop to <12.5v
In that time the smart start has used up ~10Ah of battery capacity"
The N70ZZ is a Cranking battery.
The websites you supplied state the following for a Cranking battery.
"battery FAQ"
Approximate 12.45v = 75% State-of-Charge
However, the Collyn Rivers battery info site related to DEEP CYCLE batteries, not cranking batteries.
They are the facts - with out any confusion.
Mainey . . .
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Follow Up By: greybeard - Thursday, Mar 26, 2009 at 13:22
Thursday, Mar 26, 2009 at 13:22
please read the last line of the first post in this thread.
I have regretted responding to your earlier post. This game now has only one participant. enjoy yourself.
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Follow Up By: Best Off Road - Thursday, Mar 26, 2009 at 13:36
Thursday, Mar 26, 2009 at 13:36
GB,
This whole 12 volt thing certainly has some Black magic attached to it. The more I read, the more differing opinions I hear.
I've given up trying to understand it anymore. I now just live by the rule of not letting my AGM get under 12.0 volts. If the Solar Panel won't keep it up, I fire up the gennie with 17 amp 3 stage charger attached and bring it back to full.
As long as the beer is cold and the meat stays fresh I'm happy. I no longer have a need to know why.
Cheers,
Jim.
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Follow Up By: Krakka - Thursday, Mar 26, 2009 at 14:01
Thursday, Mar 26, 2009 at 14:01
Gotta agree with you there Jim, as long as the beer is cold and I have the gennie and charger, who cares about why.
Cheers Krakka
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Reply By: Boobook2 - Thursday, Mar 26, 2009 at 07:27
Thursday, Mar 26, 2009 at 07:27
This is one important thing that the Surepower ( marketed here as ARB) isolator has over the Redarc.
The sure power has a connect voltage of 13.2V and a disconnect voltage of 12.8 so it isolates the batteries at close to 100% capacity.
Also the standby current is 10 - 13 mA when disconnected.
The surepower 1314 is the 100A unit and is about $100 delivered from the US. ( or about $180ish from ARB) The 1314-200 is the 200 A unit ( surge of 600A) and is about $150 from the US or $360 from ARB.
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Follow Up By: greybeard - Thursday, Mar 26, 2009 at 12:56
Thursday, Mar 26, 2009 at 12:56
probably a bit closer to what i should have got if i'd thought about the specs before i started :(
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Reply By: Member - Mike DID - Thursday, Mar 26, 2009 at 10:12
Thursday, Mar 26, 2009 at 10:12
Save yourself a lot of money.
Instead of buying an expensive "Isolator" that DOESN'T do what you need without modifications, just buy a Continuous Duty Solenoid and connect the coil to the Ignition wiring. (Do not use a Starter Solenoid - it will overheat)
It will give EXACTLY the same amount of charge into Main and Auxiliary Batteries as the more expensive solution.
All these marketing claims (to convince you to buy their wonderful product) about delaying charging of the Auxiliary until the Main is charged, are MYTH.
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Follow Up By: Member - John (Vic) - Thursday, Mar 26, 2009 at 12:02
Thursday, Mar 26, 2009 at 12:02
Yep!! Agree.
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Follow Up By: greybeard - Thursday, Mar 26, 2009 at 12:15
Thursday, Mar 26, 2009 at 12:15
funny thing is that in previous vehicles i used to use a continuous duty solenoid. thought i'd join the gang and use a smart device.
jokes on me now :)
looking at the specifications of the device it is doing exactly as described. it's just that i didn't pick up on the reality of the amount of energy and the duration that would be wasted under effectively no load apart from the smart solenoid.
oh well, time to put a flyback diode across the solenoid coil and wire it up to the ignition, then enjoy the extra day of cold beer i'm going to get :)
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Reply By: Member - Matt M (ACT) - Thursday, Mar 26, 2009 at 13:10
Thursday, Mar 26, 2009 at 13:10
Greybeard,
I'm NOT proposing this as a solution to your problem, just an interesting observation.
I also have a
Redarc isolator fitted, although I think mine has 12.7V cut out (must be an older model). I also have a voltage booster fitted. What I notice is that the booster continues to draw power from the cranking battery after the car has shut down and charge the auxiliary battery. Once the cranking battery gets to 12.7V, the
Redarc disconnects and charging stops. This usually happens pretty quickly (dependant on the aux battery SoC), but I guess that instead of the cranking battery 'surplus' powering the
Redarc for a period of time, it 'scavenges' power from the cranking battery and stores it in the aux battery.
Again, not a viable answer for you, just an observation.
Matt.
AnswerID:
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Follow Up By: greybeard - Thursday, Mar 26, 2009 at 13:28
Thursday, Mar 26, 2009 at 13:28
there was a change in the operating points on the
Redarc a few years ago to cope with some of the newer vehicles. sounds like you've got an older model.
for my application i'd like to see a similar drop out voltage. I know they can be programmed so i'll give
redarc a call.
cheers
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Reply By: Maîneÿ [wa] - Friday, Mar 27, 2009 at 15:41
Friday, Mar 27, 2009 at 15:41
As I was named in the original post: "I'll have a chat to
redarc about it but can anyone, apart from mainey, see anything i'm missing in all of this"
I think it's time now to put my 'opinion' forward.
I've previously used a 'mechanical solenoid' and noticed it did have a similar Voltage drop as stated by GB, I replaced the 'mechanical solenoid' with an 'electronic charge
isolator' using a Rotronics MH10 because it has a Voltage Drop of just 0.05 Volts.
Obviously the lower the voltage drop the more efficient the charge
isolator is.
Solenoids can drop up to 0.6 Volts.
This voltage drop reduces the amount of charge the auxiliary battery will be able to receive, causing the auxiliary battery to charge to only ~70% in many cases.
Mainey . . .
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