Can I use a flooded and a optima in the same system?

[890man]

I have a interstate battery in the truck which is pretty new and I am installing a dual batt setup this weekend. I have a Optima yellow top laying around not doing anything. Can I run these together with the Hellroaring isolator. I would think not but it would save me from buying a new battery and put the optima to use. I know they have different charging requirements. The Optima would be the backup batt. I will have everything running off of the main and only combine for winching or if I need to jump myself. I have a winch, lights, fridge, cb and a ham radio as draws on the system.

Thanks

 

[Perfect Switch]

You should be able to run two dis-similar batteries with an isolator.

 

[Expedition Key]

I've had this question as well. My truck is less than a year old and the battery that came with it seems great. I'd like to add an Odyssey, for a dual setup but don't want to replace a perfectly good battery.

Perfect Switch, could you elaborate.

Thanks,

Kye

 

[tremors834]

I have a interstate battery in the truck which is pretty new and I am installing a dual batt setup this weekend. I have a Optima yellow top laying around not doing anything. Can I run these together with the Hellroaring isolator. I would think not but it would save me from buying a new battery and put the optima to use. I know they have different charging requirements. The Optima would be the backup batt. I will have everything running off of the main and only combine for winching or if I need to jump myself. I have a winch, lights, fridge, cb and a ham radio as draws on the system.

Thanks

I've been running a dual batt system like that for 2+ years without issue. My main batt is a flooded and my aux is an AGM (diehard platnium). As long as the batteries are isolated from each other when they are not being charged, then you should be good to go.
There have been many articles written on why you shouldn't, and there are some good reasons why you shouldn't use dissimilar batt's. But IMO thats for a perfect world. I was in the same situation and already had new main batt.

 

[890man]

Thanks for the replies. I have a National Luna dual batt monitor on its way to keep an eye on things. I will run it this way and see how things look.

Hey Kye, I just noticed you are in Fairfax. I used to live out in Lagunitas. I'm out in Hamilton Novato right now.

 

[Perfect Switch]

Two batteries, even same brand built the same day, will never be identical. There will always be one where the static battery voltage is slightly different than the other so when you tie them together in parallel, the battery that has a slightly lower voltage potential will pull current from the battery with a higher voltage potential....they'll equalize. With two dis-similar batteries, that voltage difference can be significant and the healthier battery will equalize with the less healthy battery, and this can diminish the lifespan of the healthier battery. Batteries in parallel will "feed" off each other and their lifespan will be shortened verses batteries that are not connected in parallel. Exactly how shortened is tough to quantify, but it's strictly a function of how batteries react when tied together.

When batteries are isolated, then can't dump current into one-another. And because they're isolated, batteries that are different and differing chemistries can be used. At one point, I had a lead acid starting battery and an Odyssey AGM aux. battery. Neither battery could "see" each other due to the isolator. Each battery gets charged my a single alternator. Each battery has different performance characteristics specific to its use.

 

[Expedition Key]

Thanks Perfect switch, I was under the impression that some isolator systems paralleled the batteries when charging and then isolated them when you turned the ignition off.

Hey 890man, yeah, Fairfax, I used to live in Forest Knolls. What kind of rig do you drive?

Kye

 

[wrcsixeight]

There is the possibility that the newer battery, when hooked in parallel with an older weaker battery, can be continually overcharged. The alternator doesn't see 2 batteries, it will see one big battery, and the newer battery with less resistance will absorb more current than the weaker, reach full charge first, and start boiling away electrolyte first.

Since AGM batteries have less resistance, they will pull more of the current than a flooded battery. I don't really see an issue if the AGM battery is for the auxiliary loads, and a greater distance(voltage drop) from the alternator than the starting battery. But if the AGM is the starting battery, it could be overcharged, and since the electrolyte cannot be replenished, damaged.

As said in another post, there are ideal situations, but this is not a perfect world. How much the lifespan would be shortened for the stronger battery would be difficult to quantify. I would want to make sure the AGM battery is not going above the manufacturer's recommended bulk/absorption voltages. Especially if it was new, and 268$.

I once hard wired a new flooded battery in parallel to a one year old battery of a different make to make up my auxiliary battery bank. The new battery was always wet on top, and underneath, and needed more distilled water monthly for the first 6 months. Then it seemed to stop needing so much water, and 9 months later neither would hold a charge.

 

[Rbertalotto]

Two batteries, even same brand built the same day, will never be identical. There will always be one where the static battery voltage is slightly different than the other so when you tie them together in parallel, the battery that has a slightly lower voltage potential will pull current from the battery with a higher voltage potential....they'll equalize. With two dis-similar batteries, that voltage difference can be significant and the healthier battery will equalize with the less healthy battery, and this can diminish the lifespan of the healthier battery. Batteries in parallel will "feed" off each other and their lifespan will be shortened verses batteries that are not connected in parallel. Exactly how shortened is tough to quantify, but it's strictly a function of how batteries react when tied together.

I always understood this to be true. When I was building exotic car stereo systems we would never hook two batteries up in parallel without an isolator for just this reason.

But now I have a 2006 Dodge Diesel PU and it has two batteries simply hooked together with no isolation and it has been fine for four years........Go figure?

 

[Perfect Switch]

Thanks Perfect switch, I was under the impression that some isolator systems paralleled the batteries when charging and then isolated them when you turned the ignition off.
Kye

That's exactly how solenoid/mechanical relay/mechanical switch systems work.....they parallel batteries for charging and disconnect batteries by opening the connection when the vehicle is turned off. It's super easy, innexpensive, and is very common to parallel batteries with an ignition-switched mechanical relay. Conversely, solid-state isolators/rectifiers act like a one-way electrical valve (ala POWER-GATE, Hellroaring, Surepower, etc..), where the electronic(s) control which direction the current can or can't flow.

 

[890man]

Conversely, solid-state isolators/rectifiers act like a one-way electrical valve (ala POWER-GATE, Hellroaring, Surepower, etc..), where the electronic(s) control which direction the current can or can't flow.

This is how I have understood it as well. They seem "smarter" than solenoids. What I am still not clear on is the regulation of the charging between the main and the aux battery. My aux will have no load on it at all, it is simply a backup if my main gets low. Therefore, the aux will always have a full charge and not need much while the main takes a large charge because of the loads. Does the Hellroaring isolator manage the charge rate for the aux batt itself while the main is managed by the stock system?

BTW Kye and others, this is in a 94 FZJ80 Landcruiser.

 

[Perfect Switch]

The voltage regulator regulates the voltage and current output of the alternator. The batteries absorb current as needed. Which battery absorbs how much current is a function of physics, not a function of the isolator/rectifier. So if your backup battery is never discharged, it simply won't draw current of any significance and will ---in theory--- always be there for an emergency jump. The problem is the battery is subjected to months if not years of heat and vibration and if never "exercised" it may not be in stellar shape for that emergency jump. Essentially, you trickle-charge a backup battery with no loads applied......ever.....except that random jump. In my opinion, if I'm buying an Odyssey or Optima to use as an aux. battery, I'm buying it to USE, not to trickle-charge for months on end. Lots of ways to configure and use multiple batteries so pick what works for you.

This is how I have understood it as well. They seem "smarter" than solenoids. What I am still not clear on is the regulation of the charging between the main and the aux battery. My aux will have no load on it at all, it is simply a backup if my main gets low. Therefore, the aux will always have a full charge and not need much while the main takes a large charge because of the loads. Does the Hellroaring isolator manage the charge rate for the aux batt itself while the main is managed by the stock system?

BTW Kye and others, this is in a 94 FZJ80 Landcruiser.

 

[890man]

Thanks for the clarification Perfect Switch. I just ran my fridge for 24 hours and killed the battery. I really wanted to see how long I could go without a recharge. I am going to rethink my setup. It sounds like the better idea may be to run all non stock loads off of the AUX batt keeping the main for starting. The big problem I have with this is the interior lights are a draw to the main that could cause a problem. Led's will be in my future. Do most find this to be a better or more common way to do a dual setup?

 

[wrcsixeight]

I can't say how everybody else does it. But I have everything which can be used with the ignition off, wired directly to the house/ auxiliary batteries. Stereo, Fridge, All Interior lights, inverter, ciggy plugs, air compressor, TV Laptop, H20 pump, Fans, ect...

I use a manual Boat Battery Switch. I have all the loads wires to the number 2 of this switch. Number 1 goes to the stock vehicle engine battery and harness. I can run the engine, start the engine off of either battery bank or both. It is not automatic, but I have only forgotten once, and 3 batteries still had enough.

My usual process is start the engine on number 1 battery, after 20 seconds switch to both, so alternator and solar panel charges both banks. When I stop the engine, I turn switch to 1. Engine computer, starter and door locks and power windows are still wired directly only to the Ignition Feed on the battery switch, but everything else only sees the auxillery batteries, unless I have the switch set to BOTH.

I try never to leave switch set to both without engine running, or strong sun hitting the Solar panel, but 345 A/h leaves me a lot of breathing room, I only go below 50% SOC on the house/ auxiliary batteries if I am trying to do so. And the chassis/ starting battery is always at or above 95%, unless I forget to isolate it and camp for many days without any strong sunlight.

I don't ever worry about needing a jumpstart, I worry about others asking me to move my campsite to jumpstart them. When that happens now I tell them to bring me their battery, and I'll charge it, or push their vehicle to mine. Or if they are really in a rush and cannot push their vehicle, I'll easily remove my chassis battery, and bring it/ send it over, knowing I could still start my vehicle and drive away if they were to steal it, or needed to Buy it, which has happened.

Another thing, I have all LED lighting. All my Lights turned on use only 2/3 the electricity of one incandescent Bulb in one fixture. I don't even consider interior lighting as a major load anymore. Having swiched to LED's earlier might have saved a relationship or 2 along the way.

"Dangnabit woman, turn off the GD lights when your not inside!!!"
With LEDs I couldn't care, and she/they could continue to be blissfully ignorant about the need to conserve anything. Well electrical.

"Are you using drinking water to wash your hair!!!!!!!!!!!"

Logic be danged, relationship over.

 

[mwfish]

I have to stand-up for the parallel battery systems. First, a parallel battery system was created for a reason, engines requiring higher AMP loads at start-up and or large requested loads from start-up. I.E. police cars, fire trucks, ambulances, diesel engines. Second, parallel battery systems without isolators self regulate on their own, not from batt. to batt., as long as the alternator is providing the correct voltage. The lower voltage batt will take more from a properly sized alternator until equalized to its twin. Maint free batteries require 14.4 or 14.6 from the alternator in order to charge. So, if a batt. is feeding its brother or sister batt. than the system either has too much voltage drop and the volts are not returning to the batts., or the voltage regulator from the alternator is not allowing enough volts back to the batt. because of added items. I.E. additional batts and associated wiring, creating voltage drop.

Now with all of that being said. You still match batteries in parallel, because they are essentially one large battery in themselves. Voltage remains the same, amperes are increased. So, if you are using different batts, for different reasons, isolate them. Or, if you are needing higher amp loads, parallel same batts.