No, you can run completely different group sizes together in parallel. Why would you think otherwise?
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well, I usually feel like I am Preaching...lol. Ideally, you would want to run identical batteries in a multiple parallel batt set up...but the proverbial no-no is mixing TYPES of batteries...common Wet Cell "Starting", or "Cranking" batteries and the preferred AGM or Dry Cell "Deep Cycle". Running different SIZES of the same type can be acceptable, because the 850 Amp HC600 and the 2000 amp HC2000 are both AGM deepcycle batteries....IMO, the OP would be perfect with something like a XSPower D975 up front, and a big 3 on the 900 watts they are running.
xs power.
the dual batt tutorial thats been on this site for years negates ur mix and match battery advice.. thats all im saying.. do what makes you feel good, unless it's my mom.
If you are running one under the hood and one in back with 15 feet of wire in between and have a "so so" ground for the secondary battery in back how much do you think those "exactly the same batteries" will act the same? There is a difference in battry locations in both wire and temperatures that are dismissed when repeating rules of a battery storage bank vs a traditional 2 battery system in a car or truck.
Not for nuthin bro, but I'll go with identical batts everytime.. noone said it was a 15 ft. run first of all, and/or what gauge wire was being used.. as far as temperature, that has a nominal effect at worst, unless the temp variation is extreme.. using IDENTICAL batts makes a hell of a lot more sense than not. If you disagree because of distance between batts and different temp, and whatever you said about "so so" ground then you need to elaborate.. you're either suggesting it's irrelevant or theres a way to calculate the best batt match thru impedence, etc.. honestly, you're post seemed kinda random and general. Whatever.. wtf do i know. Peeace ya'll
I have a batt thats 2.5 years old and im looking for one to put in the rear. i'm waiting to find a deal on one, or save enough scratch for a new one. one will be old one will be new. i will lose no sleep, as i have done this on my truck (which had two batts) a few times with no problems mixng different sizes and brands. never mixed a wet cell with a agm, but id probly do that too, at least once. lol
True. Batts have a resting voltage. If one is slightly higher than the other, it will try to charge the lower batt. This will cause the higher voltage batt to sulfate quicker, then over time the sulfated batt will become a lower voltage then things will reverse. Outcome is a shorter life batt. That is why people suggest having the same size and age, cause you are more likely to keep the resting voltage the same.
@cat man ;
AGM > Absorbed glass mat
Deep Cycle > A deep-cycle battery is a lead-acid battery designed to be regularly deeply discharged using most of its capacity. In contrast, starter batteries (e.g. most automotive batteries) are designed to deliver short, high-current bursts for cranking the engine, thus frequently discharged of only a very small part of their capacity. While a deep-cycle battery can be used as a starting battery, the lower "cranking amps" imply that an oversized battery may be required.