Using Different batteries?

The concern is that they will charge at different rates, reducing life as the stronger battery will try to charge the weaker one. If the Group 31 is an AGM as well, then you have a higher chance of success. At a minimum, you want batteries that are as similar as possible, different brands aren't as important as different compositions. AGM is a special type of lead acid battery.

 
regardless of how close their specs are, it is never the right thing to do!

If you want to do this practice anyway instead of going with the same type of battery, you will need to invest in a good AGM battery charger.

Sears sells their own, DieHard Platinum chargers are very good for all AGM batteries that are 12v rated.

You will need to monitor and check resting voltage on all batteries separately about once a week and charge when necessary.

Anything below 12.7v needs to be put on charge individually regardless of how strong your alternator is.

You may also need to load test your batteries if you suspect consistent low rest voltage when checking condition.

Failure to do this, you will lose your electrical system down the road.

If you do not lose it, your entire battery bank wil not function as if you had 3 batteries in there...but far less.

It's a fact, not an opinion.

This is why it's best to match everything... Otherwise, a good Solenoid from Oznium will at least isolate via internl relay different batts when car is off.

 
this is why it's best to do it the right way...

And even then, if you had all the same batteries, but didn't have enough of them and are overworking your electrical system, you will still need to charge each batt individually periodically.

Because of the hassle, i install circuit breakers between each group of batts in my vehicle so that i can charge them in small quantities without rewiring everything all the time. My batts are small so i can charge them up as a pair with the current charger i am using.

the way how multiple batteries are wired can cause a big drop in performance too!

If you just typically install a bank of batteries and bus bar or parallel all connections together with wire and run your amp's power all over the place to the batts or bus bar, there is a high chance you are not getting the performance you should.

There are 4 different ways to parallel battery banks for powering devices and out of those 4, there is only 1 proper way. Some methods need to be changed based on product installation but there is no one way that works best for all scenarios.

 
You are talking about banks of batteries. How serious is it when just running 2 batts, one under hood and one in trunk...

I have a yellow top AGM under hood, and plan on picking up one of those C & D AGM batts for the trunk. Should I be okay with that? I do have a batt charger, though. Do I charge it on the lowest setting or what? I will try to get a pic of the charger soon...

 
I wouldn't do it. I have done it in the past, but basically what happens when you mix and average battery with a sealed car audio battery is that the regular battery rests at a slightly lower voltage and is always bringing down the voltage of the good batteries. That happened to me with my batcaps, now I run all batcaps.

 
You are talking about banks of batteries. How serious is it when just running 2 batts, one under hood and one in trunk...I have a yellow top AGM under hood, and plan on picking up one of those C & D AGM batts for the trunk. Should I be okay with that? I do have a batt charger, though. Do I charge it on the lowest setting or what? I will try to get a pic of the charger soon...
Let's say bank in this topic refers to more than 1 battery in vehicle period.

It's best practice to install a solenoid in between them as they shouldnt be paralleled together.

Also, before install C&D, both the front and C&D batt should be charged 100% and installed back into car at the same time with solenoid.

THEN.. you will need to monitor their rest voltage before starting the car to ensure they are both in top notch shape.

 
Let's say bank in this topic refers to more than 1 battery in vehicle period.
It's best practice to install a solenoid in between them as they shouldnt be paralleled together.

Also, before install C&D, both the front and C&D batt should be charged 100% and installed back into car at the same time with solenoid.

THEN.. you will need to monitor their rest voltage before starting the car to ensure they are both in top notch shape.
Ok, well I got a dumb question, what is a solenoid and where can I get one?

 
200 Amp Relay - High Current - Automotive Battery Isolator
This is assuming your alternator is not going to be passing over 200A of current ALL the time.. That is a 200A solenoid.

A solenoid has or should have no measurable voltage drop on output section.

All it is is a massive relay. This is why they do not cost that much.
Ok cool. I will pick one of those up when I get another batt. My alternator is deff not that strong, so it shouldnt be an issue. So I charge both up, then run this between them, then just check the resting voltage on both every week or so? And if it is low then charge them up...

Thanks for your time.

 
Have any pics on ho wto wire them or links??

this is why it's best to do it the right way...
And even then, if you had all the same batteries, but didn't have enough of them and are overworking your electrical system, you will still need to charge each batt individually periodically.

Because of the hassle, i install circuit breakers between each group of batts in my vehicle so that i can charge them in small quantities without rewiring everything all the time. My batts are small so i can charge them up as a pair with the current charger i am using.

The way how multiple batteries are wired can cause a big drop in performance too!

If you just typically install a bank of batteries and bus bar or parallel all connections together with wire and run your amp's power all over the place to the batts or bus bar, there is a high chance you are not getting the performance you should.

There are 4 different ways to parallel battery banks for powering devices and out of those 4, there is only 1 proper way. Some methods need to be changed based on product installation but there is no one way that works best for all scenarios.
 
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