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Old 09-07-2016, 03:45 PM   #127
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Hi Ohiobrits,

I just finished reading your amazing journey in reducing the tongue weight and have a few questions.

Did you remove the original battery cables or used them to connect the new wires? Do you have a photo of this?

Why did you downgrade the 12v batteries to 6v?
12V are also lighter 56lbs
6V 66lbs
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Old 09-07-2016, 04:26 PM   #128
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Many of us have upgraded to a slightly larger and taller battery box so we can install two golf cart 6 volt batteries in series.

Gets same voltage with increased capacity. It's not a downgrade.

Paralleling 12 volt batteries is another way to get more capacity, but IMHO is touchy if the batteries don't match exactly.


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Old 09-07-2016, 09:32 PM   #129
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Originally Posted by GenXair View Post
Hi Ohiobrits,

I just finished reading your amazing journey in reducing the tongue weight and have a few questions.

Did you remove the original battery cables or used them to connect the new wires? Do you have a photo of this?

Why did you downgrade the 12v batteries to 6v?
12V are also lighter 56lbs
6V 66lbs
GenXair, the cables from the factory battery box run up through the floor into the front storage locker (on an FB, I assume this is similar for other varients) and terminate on a positive and negative bus bar in this area. The wires to the batteries could be left connected and in place so long as you disconnect the positive from the bus bar so it is not live. I opted to remove them. You will need to extend the positive supply wire from the tongue jack back to the positive bus bar in the front storage locker since this is normally connected directly to the battery. Removing the batteries frees up the battery box for other uses....I now store my Anderson levelers, some pads for the stabilizer jacks, a wrench for my ProPride and can of spray lubricant in there.

On reuse of the battery cables - When you have relocated the batteries you will need to run suitably sized positive and negative cables from the batteries back to the same bus bars to power the coach. Since you will want to use larger wire gauge for this and since the cable runs will be much longer you will want to use new cables. I used 2ga, the original cables were 4ga I believe. Make sure you add a breaker on the positive wire close to the battery to protect the cables in the event of a short.

On the reason for 6V v 12V batteries - Connecting 2 x 6V batteries in series gives you a 12V battery with the same AHr as a single 6V battery (2 x 200 AHr 6V batteries in series = a 12V 200AHr battery). In contrast, 2 x 12V batteries connected in parallel gives you a 12V battery with the sum of the AHrs (2 x 100 AHr 12V batteries in parallel = a 12V 200 AHr battery). The batteries appear to be equivalent but the 6V units will have slightly thicker plates and will in general be more able to handle abuse / heavy discharges than the 12V solution. A battery made of 2 x 6V units is therefore seen as an upgrade although differences are likely not noticeable to the average camper.

Attached is a photo in the front storage locker. The white circle is the negative bus bar, red is the positive bus bar and purple (hard to see) is where the cables come up through the floor from the battery box. The silver box you can see mounted on the side wall is the factory 1000W inverter, the black box is the 7 pin junction box (cable to hookup to your TV terminates here). You can also see the "store/use" solenoid which isolates most of the coach 12V users when in store mode.
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Old 09-09-2016, 09:03 AM   #130
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Thanks for the battery info rmkrum.

And thank you Ohiobrits for answering my questions.

I'm planning to make these mods sometime during the fall, after our October trip, and I'm sure I'll have more questions as I get ready for it.

Thanks again.
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Old 09-25-2016, 06:26 PM   #131
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Originally Posted by Ohiobrits View Post
My battery uses CALB CAM 72 AHr cells (x48, 864 AHr)
Do you really have forty-eight individual cells? Basically twelve 12v banks?

My sixteen cells weigh 110lbs. Impressed your forty-eight only weighs 200lbs. Wonder if that is the difference between my 100aH cells and your 72aH cells.
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Old 09-26-2016, 08:32 PM   #132
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Do you really have forty-eight individual cells? Basically twelve 12v banks?

My sixteen cells weigh 110lbs. Impressed your forty-eight only weighs 200lbs. Wonder if that is the difference between my 100aH cells and your 72aH cells.
Yep. They are arranged as 4 sets of 12 cells (3.2V/864 AHr) connected in series to produce a 12.8V/864 AHr battery - 12P, 4S.

The BMS monitors the four 3.2V, 12 cell batteries and balances them relative to each other. Since the 12 cells in each of these 3.2V batteries are connected in parallel, the individual cells will self balance across the bus bars.

To ensure an individual cell failure is detected, the BMS monitors each 12 cell battery against baseline values such as resistance and other parameters and will give a fault if one of the 12 cell batteries is starting to drift (a cell failure, buss bar loose etc). This is flagged as a "Weak cell" error. You would then need to the inspect the individual cells in the "weak" battery to see where the fault is. This should ensure an individual cell failure will not damage the other 11 cells in a 3.2V battery without some warning.

Relative to weight, the 3.2V cells weigh 4.2lbs each so just over 200lbs for the batteries alone. The hanger is constructed from Aluminum and engineered carefully to minimize thickness and section sizes. Just checked my notes and half of my battery fully assembled with supports and buss bar was 107lbs so 214lbs for everything. The battery is split into 2 sections to ease handling under the AS and the 2 blocks connected with solid copper bus bars. Positioning using a trolley jack is mandatory. No way you would want to even try this with muscle power alone

As you say, this is ridiculously light for the AHr (0.233 lbs/AHr - battery only). This was the lightest I found (but not the cheapest). That honor rests with the CALB CA100 - these are however quite a bit heavier and more bulky at 0.3 lbs/AHr. Weight and compactness (given my installation location and # of cells required) closely followed by cost were my main drivers for battery selection.
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