Battery Isolator or auto combiner?

Topic: Battery Isolator or auto combiner? (Read 3224 times) previous topic - next topic

Battery Isolator or auto combiner?

October 04, 2020, 12:48:54 pm

I have been reading that an auto combiner (blue sea) is a better option if you require an isolator to be replaced.
Is this true and if so is the blue sea ML SERIES 500A 12V ACR a good choice?
Preter

Re: Battery Isolator or auto combiner?

Reply #1 – October 04, 2020, 02:00:31 pm

That's the way I'm going when my isolator needs replaced.

Re: Battery Isolator or auto combiner?

Reply #2 – October 04, 2020, 02:00:58 pm

Like this one?
Blue Sea 7622 ML-ACR Automatic Charging Relay with Manual Control 12Vdc 500A

Works OK if you have the same type batteries for start and house. If one side is lithium chemistry the charge profiles and voltages are different enough that I would probably not use one of these.

My solar charges both house and start batteries. My bigger Victron Multiplus will charge both house and start batteries. My Battery to Battery smart charger will charge both house and start batteries while driving. And I have a smaller 40 amp smart charger that will charge house and start batteries when we are plugged in and the big inverter/charger is off. I have no isolator or automatic charging relay devices.

Re: Battery Isolator or auto combiner?

Reply #3 – October 04, 2020, 03:25:27 pm

So Roger all you batteries start and house are Lithium?

Re: Battery Isolator or auto combiner?

Reply #4 – October 04, 2020, 04:58:37 pm

No, AGM Start and Lithium House. Most of the time even while driving solar charger does all of the work. Charge profile voltages are similar, times are different, so I am using LiFePO4 charge profile.. Two weeks in Wyoming and two more in SD and 5 travel days charging only with solar. SOC on LiFePO4 was 100% when we got home. Start batteries are charged by alternator while driving.

Re: Battery Isolator or auto combiner?

Reply #5 – October 04, 2020, 07:54:08 pm

Other than lithium/AGM banks the auto combiner eliminates the chance of dead start batteries if power is applied to the house side.

My mk gels and optima red tops have been perfect since I put in the autocombiner.

Re: Battery Isolator or auto combiner?

Reply #6 – October 05, 2020, 12:00:39 pm

Ok great info...
I will check to make sure the battery types are the same.
Is the unit easy to install, as the isolator is or is it more involved?
Peter

Re: Battery Isolator or auto combiner?

Reply #7 – October 05, 2020, 01:17:28 pm

I changed the original to a new Cole-Hersee 200 amp with agm's in both places. Seems to be fine. I have the original Heart 2500 inverter-charger

Re: Battery Isolator or auto combiner?

Reply #8 – October 05, 2020, 03:25:29 pm

Peter, if you have AGM and AGM or AGM and GEL they are close enough that you can use an isolator or a combiner.

Your alternator may have its normal voltage increased to compensate to the voltage loss in a diode style isolator. If you replace a diode based isolator with a combiner or a zero voltage drop isolator you will want to check to output voltage of the alternator. I think it should be 13.8 to low 14s at the start battery shortly after starting the coach. It will go down as charge comes up.

Re: Battery Isolator or auto combiner?

Reply #9 – October 05, 2020, 03:29:31 pm

My start batteries are Flooded Lead Acid Starting Batteries (Canada Proof G3472) and my house batteries are AGM Batteries (Northstar 8MS-AGM-8DK) so I presume I can not use a auto combiner...
Peter

Re: Battery Isolator or auto combiner?

Reply #10 – October 05, 2020, 03:31:48 pm

I think I may have to replace my start batteries with Red Top 9002-002 to make that work..
Peter

Re: Battery Isolator or auto combiner?

Reply #11 – October 05, 2020, 06:23:00 pm

Naw will work fine. AGM and flooded cells are roughly the same profile as far as my research showed. All new coaches come with combiners

Re: Battery Isolator or auto combiner?

Reply #12 – October 05, 2020, 11:04:02 pm

so if i have my coach plugged into a 15 A outlet and install an auto combiner I do NOT have to put my start batteries on a trickle charger (battery Minder) for storage in CANADIAN WINTERS?

Re: Battery Isolator or auto combiner?

Reply #13 – October 05, 2020, 11:43:58 pm

Correct. See the blue seas description

Re: Battery Isolator or auto combiner?

Reply #14 – October 05, 2020, 11:54:41 pm

Plugging in your coach will not charge the batteries even with a combiner unless you turn on the inverter/charger.

Re: Battery Isolator or auto combiner?

Reply #15 – October 06, 2020, 12:45:33 am

IF the battery charger is temperature compensated as all good chargers are, and if house battery temps are approx. above 90 degrees, with GEL batteries, the charge profile may correctly reduce float below approx. 13 volts, most voltage controlled relay battery combiners will NOT combine, leaving start battery bank not under charge.

Our Blue Sea ACR acts this way often during warm weather. So we also have a diode-based Trik-L-Start that may after the diode voltage-drop, still charge a little with voltages a little above 12.6.

Check Blue Sea specs for voltage close & open preset settings.

Also you may not to use Blue Sea ACR start isolation feature.

We do have a diode-based isolator to handle engine alternator charging that work just fine.

Re: Battery Isolator or auto combiner?

Reply #16 – October 06, 2020, 11:05:40 am

Thanks....The coach will be stored for the impending Canadian Winter, SO high excessive temps will not be the issue.
VERY low temps will.
The inverter (Freedom 25) will be turned on and SET to charge.
I am also considering putting a Lasko "my heat"(plugged in with TC-3 Cold Weather Thermo Cube Thermostatically Controlled Outlets) in both the sewage and manibloc bays to try to keep the temps up.
So plugged in to the coach (plug in's in the bays) will be 2 heaters, and the Battery Minder for the start batteries (UNLESS I go with the auto combiner..)
I guess I should inquire with all these items plugged in, will the 15 A plug in be enough!?

Re: Battery Isolator or auto combiner?

Reply #17 – October 06, 2020, 11:28:23 am

No I do not think so

Re: Battery Isolator or auto combiner?

Reply #18 – October 06, 2020, 03:08:10 pm

One heater on 15 amp breaker would work if nothing else was on. On my last coach I could run one heater on a 30 amp breaker
and if I tried to run 2 heaters the voltage would drop. I had a long extension cord, 10 gage wire so I would only run one.

Re: Battery Isolator or auto combiner?

Reply #19 – October 07, 2020, 07:56:58 pm

Lasko MyHeat are 200 watt heaters drawing about 2 amps of 120volts, so your 15 amp outlet could be ok as long as there are no other loads on the same panel's circuit breaker. Too much voltage drop should be avoided and measured with heaters on.

In very cold temps we run four Lasko 200 watt heaters in bay areas: water pump, water manifold, sewer drain, & fresh water tank. Also have wireless remote thermometers to monitor temps. To help keep heat from leaking out, we have large sheets of Reflectix with sides tucked inside bay doors.

With Lasko 200 watt heaters, nobody should use light bulbs to keep bays warm as they are VERY dangerous.

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