How important is it to have 2 same batteries?

[Shaun091382]

Hi i know they say its important to have 2 same batteries..i would just like to know why? i am planning on making them the same as soon as money permits i have a tough time keeping charge in batteries to crank the motor. It is cold where i am with the temp currently fluctuating in between -4*F and 14*F my two batteries are not the same one is 1000CCA/1200CA and the other is 700CCA/840Ca. I plug my block heater in and it helps a bit..I find also that since my truck sits outside for two or three days in this weather without being started is a problem as well, battery grounds are not really corroded and I am using regular Motomaster Diesel 15W-40 just like to hear thoughts on this problem of mine thanks!

[moondoggie]

Good Day!

In my limited knowledge of this subject, everything points to battery matching being quite important, at least in terms of getting maximum cranking performance at the edge of the envelope. I've started my trucks on one battery occasionally, but it was best conditions: summer, etc.

I always change out my batteries in pairs. If one gives trouble, I get rid of both.

Again reaching into my shallow well of knowledge about such things, I've been told that two six volt batteries in series would be a much better solution than two twelve volt batteries in parallel. They didn't build them this way because 12V high-capacity batteries are easily available & 6v almost nonexistent, & the cable from driver side to passenger side would have to carry twice the current it does with the batteries in parallel.

Oh, well

[Dvldog 8793]

Howdy
I have an on board battery charger that trickle charges at 1.5 amps and also cycles the charge on and off. I think I paid $30 at a parts store. I wired it in with my block and oil heaters. When I plug my truck in it starts EVERYTIME very easily.
I've always replaced both batteries because if one failed the other isn't far behind. Also if you have a dead battery in paralel it can drain allot of current if it has a dead cell. I also use synthetic oil in the winter. It costs more and my truck leaks more but it does make a difference
Hope this helps...
Conley

[diesel65]

If you are consistantly running in cold weather, GM recommends you switch to 10W-30 oil.
That is anywhere from 32 degrees F. or colder.
15W-40 has a range from 0 degrees F. to 100+ degrees (ambient temp).

[Bobbie Martin]

I have always (8 years, 125,000 miles) just replaced one battery as it went bad. I currently have one Optima & one Orbital. Never caused me a problem.

[mhagie]

Bobbie, the reason you get away with changing one battery is because of where you live, up here in the great white north recomended procedure is change both at once because of the bitter cold.
Another reason snowbirds flock south in the winter. :D .............Merle

[Marty Lau]

For maxium life change in matched pairs and rotate positions. Even a matched pair one battry will do more of the work because of difference in resistance. First two sets the passenger side crapped out first after 3 years and second set same same. My buddy Major Dork wrench turner supreme say's " you need to rotate them battries you Polock to get extra life from them". So every fall I will with out fail swap battery positions.

[Shaun091382]

So right now i have my 1000CCA/1200CA on my passengers side and the 700CCA/840CA on the drivers side if i get another 1000CCA i should switch the passenger side to driver and put the new battery in the passenger side?

[tswartos]

u need to have both the same...money permits or not...especially in the middle of winter. As a former frozen tundra diesel owner...u have to have matching batteries. Your cranking power will be only as good as your weakest battery...the main problem is the strain your putting on the electrical system. U'll notice at a stop sign idling that your voltage meter is leaning hard and your lights will pulse. Short of good fuel...a decent set of batteries is the highest priority in the miserable frozen cold.

[moondoggie]

Good Day!

Bobbie Martin: If I lived in Jacksonville, FL, I think I

[Diverguy]

Shaun;
Where do you live? Back east or the prairies? If you want to save some money switch to 10W-40 in the winter and it should get you through till April. I drive around B.C. quite a bit so I do not like using 10w-30 in Vancouver when I am down there for a few weeks but it works well for cold cranking when it drops to -15 here. Why are you using Cdn. Cheapy Tire oil? Petro-Canada Duron is better stuff, costs slightly more per liter and is available in all grades nationally.
As for the batteries I am using the Exide version of the Orbital battery on one side and the original A.C. Delco on the other. Having a working block heater really helps but additionally using battery blankets and an oil pan heater is also an asset.

[markrinker]

Rotating batteries? Huh? I think all that does is force you to clean up the terminals once per year, which would be a good idea all by itself, but we usually don't until a problem occurs.

I see no benefit from the rotation itself from an electrical draw point of view. If your batteries are wired in parallel and have good connections and chassis grounding, they both are providing equal power to all loads, even if the lead is run directly to one of the batteries + terminals.

[JCM5]

Shaun,
Having batteries of the same size is not important to the starter or charging system.

It is important to battery life. If this is a temporary issue then dont worry about it.

battery life is loading on the cells. If one is loaded more then the other then the life between the two will not be equal.

More importantly is replacing both batteries at the same time. with the terminals in parrallel, you would not want to run the risk of having a new battery drained or life shortin by an older weak leaking (cells internally)battery.

I like to replace batteries in sets and put in the largest that will fit with no modifications.

[pannhead]

hey BOBBIE MARTIN, how about a pic of the FERRARI

[Bobbie Martin]

That is actually the Scuderia Ferrari logo, which is the race team (its slightly different from the car logo, but only someone with no life like me would know that! :D ). I'm a pretty big Formula 1 and Ferrari fan, so that's why I picked it. But, I don't have a Ferrari road car - but I've had and do have several Mini Coopers and its well documented that Enzo actually had a Mini Cooper and reportedly liked to drive it, so does that count? tongue.gif

[Bobbie Martin]

Bobbie, the reason you get away with changing one battery is because of where you live, up here in the great white north recomended procedure is change both at once because of the bitter cold.
Merle - My Brother lived in Washington for many years. He just moved to Kalona. So I know all about the weather there - thats why I live in Florida! ;)

[TurboDiverArt]

Originally posted by Dvldog 8793:
Howdy
I have an on board battery charger that trickle charges at 1.5 amps and also cycles the charge on and off. I think I paid $30 at a parts store. I just bought 2 of them from Sears, $24.95 each. I have them hardwired into each battery. Power connectors are plugged in together and the chargers and plugs sit very nicely and snug in the square boxed-in area behind the driver side battery. The plug runs to the front of the truck. I bought 2 chargers because I wanted 3 amps of total charging because the oil pan heater pulls 2 amps. I have the pan heater running off a hardwired inverter. The reason for this is that the truck sits in the parking lot all day at work and oil pressure seems to take a few seconds to come up to pressure. I just walk out in the early afternoon and flip the inverter on. Warms the oil for about 4 hours. I tested initially by running the inverter for 13 hours in the cold at home without the chargers on and the truck started right up. I've got 2, 1000/1200 batteries. I figure if the cost of ensuring that the engine gets warm oil in the cold is taking a year or 2 off the batteries, it's worth it. At home the chargers are putting out more amps than the oil pan heater is pulling so should not be draining the batteries. Seems to work for me.

Art.

[ 01-22-2004, 02:42 AM: Message edited by: TurboDiverArt ]

[mhagie]

Bobbie,Is your brothers name by any chance Rick cause if it is I live only two blocks from where he did and we worked together for several years before he transfered to a different shop.......Merle

[Bobbie Martin]

Yes, thats him. I assume you work at the school?

[mhagie]

Bobbie,We both work at the hospital the school got absorbed into the hospital so now we work in the huge main hospital.
Rick is in the electric shop, I am in the plumbing shop, He is a super guy but alas his chev 4x4 is a lowly gasser, at least there is one in the family who knows if its not a smoker its not worth having.he he :D
Small world eh.............Merle

[kowsoc]

What I was told about dual batteries is that the should be a matched pair. I assume this is equal condition also. What happens is the poorer battery (or smaller battery) will "pull" the stronger battery down in its attempt to help out, causing extra stress on the good battery...not to mention less output. This is caused (IMHO) by circulation of current within the batteries (round and round) instead of straight to the starter where it should be.