One Battery or Two?

[JESSE_at_TLT]

I have a couple of Kartek Battery trays that I am in the process of installing in the bed-cage of our Tacoma, but I thought I would ask before putting the second one in. How many of you are running dual batteries in your race trucks/prerunners?

[partybarge_pilot]

Yes, run 2.

[JESSE_at_TLT]

Thanks. Should we just run two regular (red top) Optima batteries, or run one regular Optima as the primary battery and one deep-cycle (yellow-top) Optima as a back-up battery on a selectable isolator switch? I was thinking that a deep cycle back-up battery would be useful if the charging system failed.

[class7s]

I am running just one battery right now but I plan on putting in a second one and having an A/B/Both switch. In case one starts crapping out of the alternator starts to take a dive it should give me enough juice to make it back to the pits and put in another alternator

[FABRICATOR]

Two is nice, but this could be affected by the new roll bar rule. J/K

[partybarge_pilot]

2 yellow tops.

[ZTFab]

Two is nice, but this could be affected by the new roll bar rule. J/K

Absolutely...all batteries must be strapped in with a small 5-point and have a surrounding 1/10 scale basic sample cage made of 4130... :D J/K....

[ChuckH]

Another problem that could be solved by parking on a hill.

Yet no one listens to me :D

[ZTFab]

Another problem that could be solved by parking on a hill.

Yet no one listens to me :D


....I take it everything you own is a stick shift :D

[WannaB-class5]

There is no reason (unless you like the color) not to run dual Yellows. Deep cycles are great in case of charging issues.

[ZTFab]

Like Pahl said, the yellow tops are good for what you may want to use them for.....back-up in case of alternator failure...

They have something like 120 minutes of reserve capacity....that way you can make it back to a pit in time, and being a deep cycle, they handle carging and discharging cycles without killing the cells..

[Ryan_P]

Run all your necesities to run the vehicle/truck to a red top battery, and a yellow top for all your accesories that are more of a convenience than anything else.

-Ryan

[Hemp]

are there any down sides at all to running dual yellows over dual reds?

[partybarge_pilot]

Yellows have more reserve time. If your alternator dies you can go farther.

[ZTFab]

are there any down sides at all to running dual yellows over dual reds?

Yellows cost more.....

[rommel]

are there any down sides at all to running dual yellows over dual reds?

Not only do they cost more, they only have a one year replacement warranty vs. the three year on the red tops.
Hmmmm.... 2/3 the price and 3x the warranty.... Not a real tough choice in my eyes!!!!!

[ZTFab]

Not to be argumentative Rommel...The red tops are great batteries but with the reserve capacity and deep cycle capability of the yellow tops and the fact that getting a battery replaced or pro-rated in the middle of the desert isn't really an option...I'd overlook the slight cost increase of the yellow tops for the added security that you can make it to where you need to go on reserve power from the main and aux. batteries...and if they were both yellow tops, then you would have reserve capacity in both just in case you are really far out and had to rely on the batteries alone.....and yellow tops can be stored for as long as 2 years and still hold a static charge, basically it can sit for two years untouched and still start your car/truck.....

[ntsqd]

Even though it works, deep cycle batteries (yellow tops) are not designed for high current discharges. Like when starting. Using them this way should shorten their life span. I can't say it will b/c I haven't and don't want to do it.

Red tops are designed for high current discharges. They are not designed for cycling like when you play the stereo all night. Ideal useage solution would be one of each, wired to each's ideal application. But that opens up the "Like batteries" argument for charging them.

[ZTFab]

Even though it works, deep cycle batteries (yellow tops) are not designed for high current discharges. Like when starting. Using them this way should shorten their life span. I can't say it will b/c I haven't and don't want to do it.

Red tops are designed for high current discharges. They are not designed for cycling like when you play the stereo all night. Ideal useage solution would be one of each, wired to each's ideal application. But that opens up the "Like batteries" argument for charging them.

I'd have to disagree with the first part of your statement, Thom...at least in the case of Optima deep cycles...
Optima yellow tops are designed as a "dual purpose" battery that are designed for engine start and cyclic applications and for use in vehicles with large accessory loads.
Another benefit of the Yellow top is that it has the ability to hold higher voltage levels while being discharged.....so if you're running off of the battery alone, you'll have a better chance of keeping everything running until you can fix it.....especially important if you're running at night and need to keep all of your lights on until you find a pit...

Running the Yellow top is like running both a red and a yellow together...i.e., dual purpose......Optima batteries with a dark grey body are primarily high amperage "starting" batteries as Thom described...Optima batteris with a light grey body are "dual purpose" starting and deep cycle combined....

[ntsqd]

Used to be that yellow tops were deep cycle only. They cautioned us about high discharge and high charge rates when we put 26 of them into the school's EV. Wonder what they changed?

Optima's own page muddies the water as they do show the yellow top in starting applications. However, the graph of starting current shown on the "starting (http://www.optimabatteries.com/publish/optima/americas0/en/config/product_info/automotive/starter.html) " page shows the yellows to have less discharge current than a red top.
Enough so that I wouldn't use one for starting a big inch high compression engine. Probably be fine for a 4 cyl.

[ZTFab]

I see your point about the graph on the Optima website.....

Also note on the "starting" page, that all of the dual purpose/deep cycle batteries have about 200 cranking amps less than the the red tops...which, IMO, wouldn't matter if you're going to run 2 and wire them in parallel for starting purposes...that would give you about 1500 CCA and a 240 minute reserve capacity....
I just finished a S/C Dragster running a 1000hp, 598ci BB Chevy with 14.5:1 static compression and used two Optima yellow tops...even with just one battery, hooked up, it was plenty to turn the engine over.....
Maybe with the changes to a "dual purpose", the deep cycle is capable of taking a "quick" charge better.....take a look at the "tech. specs." and note that the requirements/procedures are the same for starting and deep cycle."tech specs" (http://www.optimabatteries.com/publish/optima/americas0/en/config/product_info/automotive/deep_cycle/technical_specs.html)

[JESSE_at_TLT]

I was planning to use one red-top for starting because we have had problems running dual yellow-top Optima batteries in one of our other vehicles. I know that the older (didn't know they changed them) yellow-tops were NOT supposed to be in constant-use/constant-charge. If it's OK now, that's cool.
Thanks for all the replies.

[Stephen]

Watch what kind of switch you use, my alt. guy cautioned against the boat switches because of a the chance they could disconnect both batteries while switching, momentarily cutting the alt. off and frying it. Different switches work different ways, you should just know that your switch will keep a batt hooked up at all times.

I've been using a newer (4 years old) yellow top in my recreational K5 as the only battery and it's been great, no starting problems. My understanding is the yellowtop is a blend of the red's fast discharge and the blue's slow discharge to create a battery that can be drained more times and not kill it while still discharging fast enough to start a motor.

My B1K experience last year was a great example of why you need 2 good batteries. We lost one alt and drained the batts completely, then replaced the alt, charged the batteries some and continued on. Then the spare alt. died and we ran on the batteries to the locos mocos pit and tried charging the batteries again but never were able to get back in the race. On the trip out, we had 2 later model trucks charge the batteries for a while and made it about 30 miles before we had to do it again. They were optima red tops. A single battery would have been bad. Dual yellow tops would probably have been better than the reds. Another spare alt. to mount on the truck would have been best.

my alt. guy also said that optimas are "hard chargers", in that context that they take a while to get fully charged. I guess that's just something we have to live with since otherwise the optimas seem to be the way to go.

[movindirt]

Why would disconnecting the battery fry the alt. ???

Tony

[WannaB-class5]

um the 200 CCA that you give up for the yellows means NOTHING to almost any motor. Its still up to 300 CCA more than a normal car battery.

[ntsqd]

If the engine is running the diodes are 'live', when you disconnect the batteries there is a voltage spike and there is another when the battery(ies) are re-connected. Either or both spikes can wipe out one or more diodes. May also affect the voltage regulator, not sure on that. I have a Marine switch on my Suburban. I only switch it when the engine is off. In a racer you may not have that option.

From the graph on Optima's page the starting current of the yellow top is about equal (slightly greater) to what they call a "Normal" battery at the beginning. At the 10 second mark the yellow top is slightly below a "normal" battery. By 30 seconds of cranking the yellow has dropped to below that of the "normal" battery also at 30 seconds of cranking.

[movindirt]

If the engine is running the diodes are 'live', when you disconnect the batteries there is a voltage spike and there is another when the battery(ies) are re-connected. Either or both spikes can wipe out one or more diodes. May also affect the voltage regulator, not sure on that. I have a Marine switch on my Suburban. I only switch it when the engine is off. In a racer you may not have that option.


Good point ntsqd, but any alternator worth putting in your race car should have protection cicuitry to avoid the LOAD spike you are refering to. I also think this would only be if you are talking about doing this with a battery with low charge. Something like a clamping resistor or even possibly a simple inductor should make sure that the rectifier diodes in the alt. don't see a sudden spike in load. Other wise a slip to the off postion on ANY battery switch while the car is running and there goes your big$$$ alt. Sounds lame to me. Kinda funny how the cheap battery chargers you can get from any autoparts store don't seem to have this problem, at least I have never had a problem.

Tony

[JESSE_at_TLT]

I was planning on using dual battery management electronics from Wrangler NorthWest. They make dual battery kits for all types of trucks and the electronics are pretty slick. We have used the universal parts from their kits (isolator relay, switches & wiring, etc.) in one of our other vehicles (rock-crawler CJ7). It's great for isolating batteries while winching for extended preiods of time, etc.

A heavy-duty isolator relay handles all of the battery power and a three-position dash-mounted switch with an LED indicator is used to toggle between modes. You can run-off and charge only the primary battery in the first position, run-off the primary battery and charge both batteries in the second position, and run-off and charge both batteries in the third position.

What do you guys think? These products weren't developed for race applications, but is there any reason why this type of setup wouldn't work reliably?

[ZTFab]

Painless Wiring makes a similar setup to the one you're talking about, Jesse..in fact it sounds identical...I used it on the S/C Dragster I spoke of earlier with Dual Yellow Tops and they have had no problems with it so far...as far as I'm concerned it's the only way to go with a dual battery setup....

[WannaB-class5]

ntsqd,

Thank you and I stand corrected. I was simply going off the CCA numbers on a red, yellow and prostart battery.

[ntsqd]

Good point ntsqd, but any alternator worth putting in your race car should have protection cicuitry to avoid the LOAD spike you are refering to. I also think this would only be if you are talking about doing this with a battery with low charge. Something like a clamping resistor or even possibly a simple inductor should make sure that the rectifier diodes in the alt. don't see a sudden spike in load. Other wise a slip to the off postion on ANY battery switch while the car is running and there goes your big$$$ alt. Sounds lame to me. Kinda funny how the cheap battery chargers you can get from any autoparts store don't seem to have this problem, at least I have never had a problem.

Tony

Uninformed people have kilt their alts doing the "spark test" at the charge terminal testing for alt output. You can get the spike from either direction so I'm not sure that the state of charge matters, the alt will still be dead. I do not know of any alts with such protection devices built in. Such an occurence is not expected in normal service by the alt's designers (OE battery switch?) and being that they are controlled by big corp's a part they can't justify won't be included. It is a good argument for a breaker on the charge wire. Hopefully the regulator ramps up slowly so that a slow trip version isn't needed.

[movindirt]

Uninformed people have kilt their alts doing the "spark test" at the charge terminal testing for alt output. You can get the spike from either direction so I'm not sure that the state of charge matters, the alt will still be dead. I do not know of any alts with such protection devices built in. Such an occurence is not expected in normal service by the alt's designers (OE battery switch?) and being that they are controlled by big corp's a part they can't justify won't be included. It is a good argument for a breaker on the charge wire. Hopefully the regulator ramps up slowly so that a slow trip version isn't needed.

That's to funny!!! But you have to admitt that doing the "spark test" aka shorting the output (OUCH!) is very different than disconnecting and reconnecting a battery. But even that could and should be easily overcome by protection circuitry. I know that most of the newer AC to DC power supplies I have tested have protection on the outputs. Sounds to me like the set-ups mentiond a few post up in this thread are the way to go and I am sure offer the protection I am talking about, or at least they should.... I could sit down and figure out how to build it, just figured someone already has so why waste my time..

Tony

[ntsqd]

The "spark test" isn't shorting to ground, it's 'shorting' to load. Operationally there is no difference, you're still disconnecting or connecting under charge/load.

Note that connecting/disconnecting to the Alt. with engine off doesn't appear to cause issues. It's only doing so while the Alt. is energized that causes problems.

[Junior]

How about closing out this topic with a diagram of how to wire two batteries together and to the vehicle? In series vs ?

Jr

[WannaB-class5]

How about we close this topic with Optima giving us all two yellow tops and they wire all our cars for us! Hey I can dream

[partybarge_pilot]

How about closing out this topic with a diagram of how to wire two batteries together and to the vehicle? In series vs ?

Jr


Wireing in series will give you 24V. You want to run parallel.

[ntsqd]

How about closing out this topic with a diagram of how to wire two batteries together and to the vehicle? In series vs ?

Jr

Jr.,
That can be a can of worms. Some people are convinced that you can only wire two batteries together thru a diode isolator (aka ""diode bridge"). Others are equally convinced that you can simply hook like terminals together (parallel batteries) and be fine.
Then there are the proponents of the bits like the HellRoaring and Painfull Wiring systems for controlling which battery does what. And there are also the marine style systems to consider. Kraz might know more about those.

The only truck I currently own with two batteries came from the OE mfg with them wired directly in parallel. No switches, diodes, or other complicated stuff. I've had a discharge problem with the truck when it sits for long term. Which it does a lot, so I installed a Marine combiner switch mostly as a way to disconnect both batteries when it's going to sit for a while.

I've done the diode bridge thing. Wasn't happy with the voltage loss thru the diodes (called "Cracking Voltage"). At the time I didn't know that the Alt's regulator could be tweaked to overcome this problem. As it was neither battery ever got a full charge, which can be hard on them.

On MISF's Scout we did a diode isolator combined with an Alt with a voltage regulator that was offset for the diode cracking voltage, and put a Ford starter solenoid btwn the batteries for self jump-starting. At the time the Painfull and Hellroaring parts weren't available. Those do essentially the same thing, only with electronics.