Battery Isolators,Separators, and Switches?

[ridgerunner]

My 2008 SMB Ford E350 V10 van has one Kyocera KC130GT 130W solar panel, a Blue Sky Power Boost 2000e solar power controller, a Surepower 1315-200 battery separator, and two Lifeline GPL-27T 100Ahr AGM house batteries. The van starter battery is pretty much kaput.

I am currently in the process of upgrading the system and have just finished reading this thread all the way through. Excellent thread! Thanks especially to Greg and Dave for all their knowledgeable insights and to others who have shed light on this area which, up until now, was fuzzy to me. I also read Greg's newer updated thread with the same title, but that one seems to have drifted/expanded off into "Lithium chemistry land," so I will post my questions here.

The Blue Sky 2000i solar power controller has gone bad, (intermittent connection at the terminal block,) which resulted in the deadening of the main van battery and weakening of the house batteries (all three of which were replaced 18 months ago.) I have ordered a new drop-in replacement solar controller, the Blue Sky Solar Boost 3000i.

In the meantime, I pulled the 2000e panel from the wall and have it positioned so that the charging circuit is active (the wires have to be pulling on the terminal block just-so to make the proper contacts.) After three days of solar charging under clear blue skies, the two house batteries are now fully charged and are holding 12.8V (measured in the morning.) Yesterday, I removed the bench seat and started poking around all of the electronics that are mounted in there.

I located the Surepower 1315-200 separator and discovered that it was quite HOT, (measured 180°F using a laser temp gun.) I'm guessing that with 13.8V coming from the 2000e on the house side and 0V coming from the van side, (the van battery is disconnected,) the 1315 has decided to activate the solenoid. From this, I assume that the 1315 does NOT have a low voltage disconnect logic state like the 7622 has. I've read that the 1315 draws 1.5A when activated, so 1.5 X 13.8 ~= 21 Watts of heat is being dissipated (and wasted) by the 1315. That's a lot and having a 20 watt heater under the seat in the summer, (yesterday it was 103°F outside,) is not good practice!

My current plan is to ditch the separator and replace it with a simple, rarely, if ever used, "Emergency Jump Start" switch, (i.e. option #1 in Greg's first post on this thread.) Both systems would normally remain isolated, and the van starter battery would be maintained by the "Auxiliary 2A Charge Circuit" feature of the new Blue Sky 3000i controller. This Aux charger circuit kicks in once the main house batteries are charged and the controller drops out of bulk charge mode and has some excess power available. The 3000i will also display the voltage of the van starter AUX battery.

But I *do* like gadgets and I really like the design of the Blue Sea 7622 and would like an excuse to install one of those. So, long story long, here is my first question...

Q: Does the Blue Sea 7620/7622 ever get warm/hot?

I'm guessing not since it only draws significant current while it briefly switches ON or OFF.

Thanks again for this great thread! I've learned a LOT!
Jeff Roberson
Central Utah

Additional: Regarding usage, the van has few 12V house loads, the largest being a refrigerator. The single solar panel can provide all the necessary power when camping in the boonies. It also has 110VAC hookup and InteliPower 9100 charger, but this has never been used. Sadly, the van mostly just sits outside all the time (and gets plenty of sunshine.) I am planning on selling this once I bring it back to 100% (there are some other non-electrical issues that need to be addressed.)

And finally, in the words of Blaise Pascal: "I apologize for the long post, I didn't have time to make it shorter!"

[boywonder]

Originally Posted by ridgerunner

I've read that the 1315 draws 1.5A when activated, so 1.5 X 13.8 ~= 21 Watts of heat is being dissipated (and wasted) by the 1315. That's a lot and having a 20 watt heater under the seat in the summer, (yesterday it was 103°F outside,) is not good practice!



Q: Does the Blue Sea 7620/7622 ever get warm/hot?


It also has 110VAC hookup and IntelliPower 9100 charger, but this has never been used. Sadly, the van mostly just sits outside all the time (and gets plenty of sunshine.) I am planning on selling this once I bring it back to 100% (there are some other non-electrical issues that need to be addressed.)

The Surepower contactor relay types really don't make sense when you are generating say .....20W of solar. Now all of the solar power goes to heating the Surepower relay.

I believe the Blue Sea 7622 has a contactor as well since it handles 500+ amps, but it's also a bit smarter I'm sure. Scalf77 will have the details on how warm they get.

The Little brother 7610 is solid state, so it's doesn't have the relay heat issue, but it's basic and handles 120A. I've used one bypassed with a giant red battery selector switch to combine batteries when a jump start is needed. Blue Sea sells this combo as an "add a battery" kit.

Does your Intellipower 9100 have the charge wizard? The charge wizard turns a dumb converter into a multi-stage smart charger.

Having a battery combiner switch works ..but you have 3 potential downsides:

Forget that the batteries are combined when camping risking draining your starting battery.

If your solar is connected to your house batteries your van battery won't get charged unless you remember to combine the batteries when the van is sitting around.

Forget to combine the batteries when leaving for a trip......then no alternator current makes it to the house batteries while driving.

[ridgerunner]

Originally Posted by boywonder

... Does your Intellipower 9100 have the charge wizard? The charge wizard turns a dumb converter into a multi-stage smart charger. ...

Thanks for the quick reply!
Yes, there is also an InteliPower Charge Wizard installed. (But I have never actually used 110VAC hookup power.)

Originally Posted by boywonder

Having a battery combiner switch works ..but you have 3 potential downsides:

Forget that the batteries are combined when camping risking draining your starting battery.

If your solar is connected to your house batteries your van battery won't get charged unless you remember to combine the batteries when the van is sitting around.

Forget to combine the batteries when leaving for a trip......then no alternator current makes it to the house batteries while driving.

Here's my thinking on my proposed "remove the separator and replace with a switch" configuration...

The new Blue Sky Solar Boost 3000i solar controller has, (in addition to its main house battery charging circuits,) a secondary "Auxiliary 2A Battery Charger" circuit that I plan to hook up to the van starter battery. The 3000i turns this separate (2A trickle) charge circuit on when the main house battery is charged up and there is excess solar power available (which for my use-case, should be often.) Thus, the solar panel will also charge the van starter battery, (assuming I don't over work the house system). The van's starter battery system is otherwise isolated from the house system.

The battery connect switch is normally OFF and intended for "Emergency Use Only." It will never get switched ON except in the unlikely event that a "Jump Start" is needed. Once the jump start is completed, the switch would then be turned back OFF and the alternator takes over charging the starter battery. The alternator is dedicated to the main van battery only. The house batteries get charged by solar (and/or 110VAC hookup) only.

Does this make sense?

[Scalf77]

The 762x versions are latching relays, so power is only used when changing state. So no, it generally won't get hot.

The Surepower gets hot because it is a continuous duty relay, so the power is being consumed. The Surepower does have a disconnect voltage, if it doesn't appear to disconnect it would be broken. It also tends to suffer from build up on the relay contacts (internally), this build up can cause poor connection and makes it get hotter.

Your plan works if you don't want to use alternator power for the house battery. I would ask yourself if you are good with that.

[ridgerunner]

Thanks for the quick response. Yes, I am Ok with not having the alternator charge the house battery, so it looks like I will be good to go.

Once again, thanks for creating this excellent (educational) thread!

[ridgerunner]

So I decided to go ahead and order a new Blue Sea 7622 to replace the Surepower 1315-200 battery separator. I will also be installing a new AGM battery for the Van's starter battery to match the chemistry of the two Lifeline AGM house batteries. As I said before, I'm planning to sell this van, (after taking a few test trips,) and my thinking now is that any potential new owner would likely prefer to have the house batteries charged while driving.

Reading the 7622 manual, the specs say that the disconnect voltage is 12.75V for 30 seconds (or 12.35V for 10 seconds.) But the Lifeline AGM batteries sit at 12.8V when fully charged. So at the end of a sunny day the solar panel output drops to 0V and the batteries will be fully charged sitting at 12.8V - (which is above the 12.75V needed by the 7622 to disconnect.) So the batteries will remain combined even though the charging source (the solar panel) is gone.

I'm guessing this is not really a problem since the 7622 draws negligible power and having three fully charged AGM batteries connected (at 12.8V,) should do no harm. The disconnect would happen some time later when a load (on either side) draws them all down to below the 12.75V threshold. It seems the disconnect voltage would be better if it were above the fully charged battery voltage, (say 12.85V.)

Does this sound about right?

[Scalf77]

Yes, that that sounds correct

[moorefc]

So at the end of a sunny day the solar panel output drops to 0V and the batteries will be fully charged sitting at 12.8V - (which is above the 12.75V needed by the 7622 to disconnect.) So the batteries will remain combined even though the charging source (the solar panel) is gone.

As soon as there is a bit of a load, the voltage will drop and the 7622 does disconnect...If you have a dash switch you see it and if not you hear the relay....Typically in our van the reefer will soon take care of that top charge...