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lewster · 06-05-2016, 03:12 PM

Should do it.

Lew Farber
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greghoro · 09-01-2016, 04:41 PM

Quote:

Originally Posted by lewster

And BTW, I'm no fan of the automotive type battery clamps that Airstream uses in every trailer they build. Proper deep cycle systems always use solid copper eyelets that can be attached to the battery with either a nut or bolt, tightened to the battery manufacturer's recommended torque.

Any suggestions on any type/style/brand of solid copper eyelets to replace the automotive type battery clamps?

Greg

Mgieselman · 09-01-2016, 06:49 PM

[QUOTE=lewster;1801038]

Quote:

Originally Posted by Papa smurf

To your question; a single connection on each battery as described above will assure you of using all of the battery cells equally during discharge. This will give your battery cells an equal 'workout' during any discharge event and also allows for a single cable connection to a disconnect switch for complete battery isolation.

The Interstate SRM-24 batteries only have a single electrical connection, although they do have 2 ways to attach loads to that connection one threaded and one standard terminal post.

I don't think there is anyway you can wire up a 12V lead acid battery so that the load doesn't travel through all of the cells equally.

Am I missing something?

lewster · 09-01-2016, 07:16 PM

[QUOTE=Mgieselman;1844612]

Quote:

Originally Posted by lewster

The Interstate SRM-24 batteries only have a single electrical connection, although they do have 2 ways to attach loads to that connection one threaded and one standard terminal post.

I don't think there is anyway you can wire up a 12V lead acid battery so that the load doesn't travel through all of the cells equally.

Am I missing something?

Absolutely!

In any 2 battery system, the loads should be split across both batteries in the following fashion: Positive to battery #1 and negative to battery #2.

Regardless of the size of the parallel connection cables, you should not connect both load cables to a single battery.

This is not the case in a series connection between 2 batteries, as the only terminals remaining would be the positive on battery 1 and negative on battery 2.

Mgieselman · 09-02-2016, 12:27 PM

[QUOTE=lewster;1844620]

Quote:

Originally Posted by Mgieselman

Absolutely!

In any 2 battery system, the loads should be split across both batteries in the following fashion: Positive to battery #1 and negative to battery #2.

That applies to 2 batteries connected in series but not to parallel, if you connect them in parallel it doesn't matter were you connect the load or even if you do it in multiple places as Airstream does.

When a load is applied to batteries connected in parallel it draws equally from all the batteries in the bank. This can be proven out using a DC current clamp around the connection to each battery.

Here's how my batteries were connected from the factory.

lightmind · 09-02-2016, 01:31 PM

Not quite. Recommended practice is to wire like fig.1. The reason for this is that the wire connecting the batteries together has a small resistance that will create an imbalance between the batteries charge / drain in a parallel configuration. If you have more than two batteries in parallel as I do it is even more important to wire as in fig. 1 .

There's only one way to wire in series configuration...

lewster · 09-02-2016, 02:01 PM

[QUOTE=Mgieselman;1844935]

Quote:

Originally Posted by lewster

That applies to 2 batteries connected in series but not to parallel, if you connect them in parallel it doesn't matter were you connect the load or even if you do it in multiple places as Airstream does.

When a load is applied to batteries connected in parallel it draws equally from all the batteries in the bank. This can be proven out using a DC current clamp around the connection to each battery.

Here's how my batteries were connected from the factory.

Your batteries are wired EXACTLY as I recommended! The inverter cables are split between both batteries as are the house DC cables.

Neither are connected to a single battery but are spread across both.

In addition, those 6 AWG parallel cables should be significantly larger, as they should be fully compatible with the much larger internal connectivity bus found INSIDE the batteries that physically join the cells.

Connecting both load cables to a single battery in a parallel system will almost guarantee uneven battery draw and charging.

Lew Farber

DaveP · 12-22-2016, 11:42 AM

Hi Lew,

In the upgrade to my electrical system to a ~400 Ah battery bank, would I be better off with two GPL-4DL (lifting weight aside), three GPL-30HT or four GPL-27T. The weight and cost (per Ah) is approximately the same and they would all fit under my front sofa. I am thinking lower internal resistance in the bigger batteries is good (versus external wiring on smaller Ah batteries). I am also thinking the redundancy of the smaller batteries is good. What would be your guidance?

Thanks, Dave

MWBishop · 07-12-2018, 11:34 AM

I know this thread is rather old, but still applicable.
Can someone provide a quick answer for me?

In scenario of battery connections (below as came from factory):

1. What negative wires get disconnected when storing the A/S?
2. Where would a battery disconnect switch be added?

Am thinking the negative jumper?

Snowy · 07-12-2018, 08:40 PM

The two 12v are wired in parallel and then the loads (trailer & inverter) are connected in a balanced configuration. Note the red of one red/black pair goes to the positive on one battery while the black goes the the negative on the other. If you remove the negative jumper as you suggest it should break the circuit between the load pairs.

However, what I don't know is if there is a connection from the black negative(s) to the chassis anywhere. Test it. See if anything stays powered with black jumper disconnected (on the side where it's on its own)

Mollysdad · 07-12-2018, 09:47 PM

One large pair powers the inverter, while the other large pair powers the converter.
Both pairs are split across both batteries.
If it was me, I'd disconnect both negatives. You could leave the jumper, but it won't be bolted down so just set it aside.
On my 2017 I have a black lead with a yellow crimp that goes to the jack, no drain, and a pair of black leads that go to the Zamp connector, also no load. (I wonder why I have a Zamp plug and you don't?)

In theory the jumper breaks the path because the loads are split across both batteries, but the ground goes to the chassis somehow, so there's still a path active.

Zil · 07-13-2018, 05:39 AM

With the cross connections as shown in photo, removing the inter-connecting negative cable would disconnect the system. Your photo; lower right negative. If i were to work on the system I would first disconnect negatives from both batteries.

MWBishop · 07-15-2018, 12:57 PM

Mollysdad - good catch - yes I do have the wires for the Zamp.
This was a photo from an older, previous post that I copied since the wiring is same as mine and a good example to use.
Currently I have a timer on my shore power (charges about 4 hours a day).
But may be moving to a no-power site, thus my questions.
"Damn it, Jim, I'm a software engineer not an electrician!"
Thanks everyone.

uncle_bob · 07-15-2018, 01:05 PM

Hi

The reason to put in a disconnect switch is to shut off the parasitic loads. The inverter (even when off) is one of the parasitic loads. The other negative lead goes off to all of the "other stuff" ( = more parasitic loads).

You need to put the switch in so it cuts off both the inverter negative cable and the negative to the rest of the stuff. The interconnect strap between the two batteries can be left in place.

Bob