Dual Battery or Bigger Battery

CaptainSpalding · Nov 19, 2004

I've just installed the winch bumper and winch, and now it's time to think about the battery.

At first I was considering a dual battery system, with an isolator and all the other attentdant paraphenalia. But I've read about the isolator causing problems and not keeping both batteries in good condition, or the isolator solenoid sticking or otherwise crapping out, and then the second battery isn't there when you need it most.

The solution offered for this is to just wire the two batteries in parallel and double the amperage, with no isolation. It would take a titanic winch effort to run both the batteries down to the point where the car didn't start.

But if I'm going to add a second battery just for the sake of increased amperage, why not save myself the hassle of modifying the battery tray or finding a place to hide a second battery and just get a single battery with more amperage, like an Optima D31T or an Odyssey PC2150.

So, the choice is:
a) two batteries with isolator or switch
b) two batteries in parallel with no isolator or switch
c) one bigger battery with more amps

Thanks in advance for your advice.

- Spalding

eburrows · Nov 19, 2004

The Optima D31T has 75Amp/hours of capacity. The battery that came from the factory in my DII had a 73amp/hour capacity, so that switch doesn't make much sense to me. The PC2150 has the 100amp/hours of my two Orbitals, but I doubt it'll fit in the stock battery compartment.

Ron · Nov 19, 2004

Two batteries, two optimas or two stock size interstates, fit in a DII real easy.

GotRovr · Nov 19, 2004

I recommend two batteries. Redundancy being the most important reason.

I have a yellow top with isolator installed where washer reservior sat using a custom stainless bracket. This deep cycle battery is perfect for my Warn winch, 4 rack hella's, inverter, and cargo utility outlet. I had an in cab switch installed next to mirror control to allow emergency starting. It's a comforting thought having two batteries all alone in the middle of a northern Nevada desert.

JSQ · Nov 19, 2004

I gots 2 yellowtops wired in parallel and a jump box in back just in case.

like Will I do everything with being alone in mind.

CaptainSpalding · Nov 19, 2004

Let me ask you something about your setup please.

GotRovr said:
I have a yellow top with isolator installed where washer reservior sat using a custom stainless bracket. This deep cycle battery is perfect for my Warn winch, 4 rack hella's, inverter, and cargo utility outlet. I had an in cab switch installed next to mirror control to allow emergency starting. . .

This was at first my favorite option. Let me ask you a question though. Say you're in a winching situation. Before you crank up the winch, you flip the switch on the battery isolator, so now the winch and other high amperage accessories are isolated from the other battery and the rest of the electrical system, including the alternator. Isn't it a bad thing to have the winch battery isolated from the alternator? Doesn't the alternator mitigate, at least somewhat, the drain on the battery? Can't the alternator allow the battery to let the winch pull longer before the battery goes flat?

Also, FWIW, I think I read on the Optima site that they recommend that for a two battery system, isolated or not, the batteries be identical in capacity.

DeanBrown3D · Nov 19, 2004

Spalding,

Why don't you give it a try with one battery. I know many people with winches and none of them has a dual battery setup. And we have winched 20-30 times a day (on a good day, that is

) shared between 3-6 rovers. And most of that is by just a couple of winches for the most part.

-D

Eric N. · Nov 19, 2004

CaptainSpalding said:
This was at first my favorite option. Let me ask you a question though. Say you're in a winching situation. Before you crank up the winch, you flip the switch on the battery isolator, so now the winch and other high amperage accessories are isolated from the other battery and the rest of the electrical system, including the alternator. Isn't it a bad thing to have the winch battery isolated from the alternator? Doesn't the alternator mitigate, at least somewhat, the drain on the battery? Can't the alternator allow the battery to let the winch pull longer before the battery goes flat?

Also, FWIW, I think I read on the Optima site that they recommend that for a two battery system, isolated or not, the batteries be identical in capacity.

If you run an isolater I wouldn't worry about that batteries being the same. If you don't run an isolater then yes you're going to want to use the same batteries. Depending on the winch, you can get by with just one battery if your engine is running and you keep the revs up a little. However, if your engine dies or you need to shut it off and then winch you are really going to wish that you had that extra battery. I would get two Optima yellow tops or the like and not use the isolator. But that's just that way I would do it.. Doesn't mean that is the right way. If you get the isolater I would replace the stock battery with a red top optima and then get a yellow top for the winch and such. Red top works better for starting ( well supossed to anyways ) and yellow top works better for the winch.. Red is not a deep cycle where as the yellow top is. Of course I'm not battery expert so take what I say with a grain of salt so to speak..

Runningmule · Nov 20, 2004

I've been running dual red top optima's for almost 2 years now with a Hellroaring isolator. It's been a dependable system, if you get the remote module you can switch batteries from inside the cab, also a LED illuminates to show alternator charging. If your planning on lone adventures, a back-up battrey provides some piece of mind. Relying on your winch is risky business, good luck with your decision.

rpw

Disco Mike · Nov 20, 2004

Your winch will have more available amps. to draw from running two batteries in parrellel and be able to pull harder without overheating. Look at the spec. on your winch, my 9500 HSI has a max draw rate od 400 plus amps. To my way of thinking a 130 amp. alyernator and 2 red tops is the least expensive way to get close to my winchs requirements and not over heat it while reaching it's max pulling power.
You can buy 2 red tops from Costco for $99.00 a piecs, or about $20.00 mor then one yellow top and you get alot more punch for your money.
Mike J.

FIVESPDDISCO · Nov 20, 2004

i use 1 battery and never had a problem BUT i never go out alone and keep a jump box with me. A guy on a run with me did winch till his truck died and i let him use my box. he had no more problems.

antichrist · Nov 21, 2004

Exide XCD for the winch and a Select Orbital for starting.
A schottky diode battery isolator. I think that's a better solution than a seperator (seperators are the ones with a switch to disconnect the batteries from each other). Schottky diode isolaters have less voltage drop. Bill Burke, on his web site, says Optima recommends NOT using an isolator with their batteries. An engineer at Exide told me it's a non-issue with their batteries so that's why I went with Exide. Well, that plus I got a good deal on them.

I also suggest Carol vu-tron welding cable for the cables. Size for size welding cable has less voltage drop (because it has more strands) and the Vu-tron has even less volt drop. You want <5% voltage drop for the complete circut. Plus welding cable is just easier to route.
Anyway, that's my two cents.

FIVESPDDISCO · Nov 21, 2004

tom good idea on the welding cable where do you guys but the other battery?

craig · Nov 21, 2004

FIVESPDDISCO said:
tom good idea on the welding cable where do you guys but the other battery?

Remove the bottle pump, and its plastic housing. Put two optima's in place of the original battery. I will post photos tomorrow if nobody else has. You will need a custom battery tray if you are going to do this. I had mine made locally for $100. You can buy one for $175 from http://www.aedofab.com/ (They have pictures there as well).

--Craig

GotRovr · Nov 21, 2004

Loss of original washer reservior is no problem. Just install two smaller aftermarket washer bottles. One for front other for rear. They can easily be mounted along inside driver/left side fender well. Re-routing plumbing and wiring is easy DIY.

syoung · Nov 22, 2004

What about using a battery separator as opposed to a isolator? The separator will provide a path to charge both batteries, but the starting battery and winching battery never "see" each other. I suppose if your starting battery died, you'd have to jump it from the winching battery though. Is the isolator just a separator with the ability to bridge the two batteries on demand?
The main reason I'm looking at the separator as opposed to the isolator is that the physical size of a separator is WAY smaller than a good isolator... like about 75% smaller.

GotRovr · Nov 22, 2004

I believe an isolator allows for a single point charging system while eliminating cross current draw between batteries. An in cab switch would allow batteries to be bridged in case of extreme draw down, lights out situation.

As for batteries, dedicated starting batteries like the red top are suspect when fully discharging say during a long winch cycle. A better winch battery is a deep cycle type like the yellow top

antichrist · Nov 22, 2004

Steve, you can read the differences at the Surepower web site FAQ section. They have some other good technical information here. But you're right, separators are alot smaller. My concern with a separator (if not well designed) is that if one battery is dead, and then "sees" the other battery you could end up with a very large current flow from one to the other. This may only be a theoretical concern though.

Will, you are correct you only want to use a deep cycle battery for winching. Repeated deep discharges of a "starting" battery will kill it.

syoung · Nov 22, 2004

I killed my regular battery once because I left my lights on (well, the truck was on the driver door and I didn't want to crawl back down through the passenger side window). Although it started, the winching that followed took the will to live from the battery and it was causing all kinda problems.
Anyway- since my winch doesn't get used an awful lot, I got a red top battery. I was thinking that there room for a second battery, which could then be a yellow. I dunno... I haven't heard why they say not to use an isolator with Optimas... Are they saying DO NOT or that it's not necessary? There's a big difference. I typically only do relatively light winch work-

antichrist · Nov 22, 2004

syoung said:
snip
I dunno... I haven't heard why they say not to use an isolator with Optimas... Are they saying DO NOT or that it's not necessary? There's a big difference. I typically only do relatively light winch work-

I don't know either. The quote is cut and pasted from Bill's web site. All I know is I called Exide (because I already had an Exide battery when I saw that and wanted another) and talked to one of their engineers and he said it's not a problem, and he had no idea why Optima says not to. Like I said, that's why I opted for Exide, since they said no problem. They've been in business a very long time, and make all kinds of batteries, so hopefully they know what they're talking about.

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