Drawing or Charging From Different Batteries in a Bank?

Almot wrote:

BFL13 wrote:
I am asking what those bad things might be ...

Each battery will age at different rate?

Yup, one battery may become TOO OLD a day before the other one that way, Or a week, but if you do everything exactly as you should, Balance them out and pay strict attention to everything... Well about the only difference is that it might wind up being the other battery that ages faster.

Unless you are sucking major power, Like say a 2,000 watt inverter at full load, often,, Won't make much difference.

Manage with bus bars:

BFL13 wrote:
I am asking what those bad things might be ...

Each battery will age at different rate?

MEXICOWANDERER wrote:
If you can avoid a wire nightmare there is nothing wrong with your idea

That does look a lot like my battery compartment!

Based on this reply and the others in the thread, I have decided, as with many other things, it's ok if I only do it a little. :)

Thanks everyone.

Hi,

That's one reason I have switches. When I'm not being lazy I turn on both banks before I start heavy loads. After I finish the coffee, toast, eggs, and bacon, I should really switch back to one bank at a time. My one bank is getting old.

Mexico.. I truly like your response.

To the O/P... There is a very small resistance in the jumper wires that connect the batteries to one another and in the connections to the battery terminals.

Putting the charger and the load on the SAME terminals means the charger carries a slightly greater portion of the load when it is operating.

Now in practice, it likely won't make much difference, but it can....

One thing when you have multiple batteries in parallel (And for this post a pair of six volt in series is ONE 12 VOLT BATTERY). it is recommended that the NEGATIVE lead (Chassis ground normally) go to one battery and the POSITIVE to the other.. I'm not sure I support that, but that is what they tell me.

pianotuna wrote:
Hi BFL13,

It has to do with small differences in resistance that end up causing much larger imbalances. The terrible thing is that jars on the "ends" of chains never ever get fully charged. And you, of all folks, know exactly where lack of 100% charging leads.
..............

.

None of them gets to 100% while camping, even on solar. I don't care if some get to 98% and others only to 96% that day. They all get to 100% individually for sure when I do their recovery sessions at home.

When just camping no solar and doing 50-90s the 90% itself is not very exact for the bank, and who cares if each battery is a little different in SOC when I stop the gen? What I do care about is getting some Peukert on the way back down to 50% for the extra AH.

What do I get as a benefit in return for losing that Peukert value?

Seems like being penny wise and pound foolish to me, but "everybody says" do it right or else bad things happen. I am asking what those bad things might be and just how bad they are, so I can do a risk assessment that applies to how I do things.

Thanks

Balance them within the reason. I think method #2 on the above mentioned site is a good alternative, it only requires 4 short cables between the batteries. This is what I am using with my 3*12V parallel. Method #3 looks more like a wire nightmare to me.

As to your initial question - yes, I think loads should be applied in the same locations as chargers. There are battery post extenders, or make a bus like in the pics above. Part of the problem is that your chargers and loads are not optimal already - there should be one inverter, one solar charger, and one load wire from the rig. I don't understand where converter comes into play here - it is normally hard-wired somewhere upstream in that "general" DC wire of the rig.

Hi BFL13,

It has to do with small differences in resistance that end up causing much larger imbalances. The terrible thing is that jars on the "ends" of chains never ever get fully charged. And you, of all folks, know exactly where lack of 100% charging leads.

Since, in effect, you have 3 twelve volt batteries, the only way to balance them is method #3 on the smart gauge site. But the three are not equally sized so I suppose one could mess about with extra connections and/or longer wire to try to use increased resistance to over come that issue.

I believe you take better care of your batteries than almost anyone else here, and certainly more care than I do.

I'm no parallel battery expert but common sense would tell me that there isn't that much difference. All the little electrons are lined up and ready to march through the connecting cables. Some of them might have a bit more push because battery voltages might be different but they're all gonna' march. One way to have a more orderly wiring scheme is to use a copper bus. You can install the one lead off the batteries to the bus and connect the devices to the bus. I find it's easier because if you have to mess around with batteries, you don't need to disconnect multiple terminations.

I made these simple ones with a 1/8" copper bar and a 4" double gang box:


The bus bar is glued and screwed into pieces of HDPE, glued and screwed into the box walls. Holes are all 1/4-20.