factory wiring of batteries are all wrong

[Himcules]

so i finally have some time to take a close look at my battery banks today and i'm very disappointed in what i found.

boowho made a post about his battery bank and we determined it wasn't wired up to drain across the entire bank evenly. all draining came across the first set of 12v and filling came into the second set. not balanced by any means...

stock house battery bank wiring:


the batteries also have very short terminal posts so you really can't stack the cables up.

i also moved the battery temp sensor from the magnum inverter to the far side so it gets a more accurate reading across the entire bank instead of only the "top" half.

the battery cables are uneven in length. the serial hook ups are 2 different lengths. about 4-5 inches different from each other. i will need to buy 4 cables to rectify this.

i moved my disconnect switch from the side of the bay to the back. from the original side installation, the positive cable was too short to reach the other side of the battery bank (far opposite of it's negative post). having moved the disconnect relay to the middle of the back wall, i could now reconnect the positive to the far opposite side of the bank.



i was not so lucky with the inverter's wiring. both are the same length, but i need another 16 inches of reach to get to the proper negative terminal on the far side of the bank. i'll have to get new battery cables and replace the factory ones. that makes another 2 cables. at least the inverter was placed right next to the batteries like in some other installations

then i looked at the chassis battery setup. again, this was wired wrong. they are in parallel, but the positive cable is super short and the negative cable is long. way uneven length.

and the connection from the chassis to the batteries were again only on one battery. i did fix this as the correct terminal post was only 2 inches away and there was enough slack in the cable to do this.

Stock wiring:


Balanced hook up wiring. (Parallel wiring still incorrect length)


so i will need to buy a set of cables for the chassis battery to even out the length for the parallel hookup as well.

so in minimum, it's 7 cables (if i can find the correct match on the chassis parallel length otherwise it's 8 cables). thats the whole set of cables... FR should change this so it's correct and not make the owners have to pay to fix something that was poorly implemented.

[drc343]

Hate to say it but the batteries were wired correctly. Now they are also wired correctly just now need longer cables. There will be no change in charging or output. Both ways will work just one uses shorter cables.

[Himcules]

Originally Posted by drc343

Hate to say it but the batteries were wired correctly. Now they are also wired correctly just now need longer cables. There will be no change in charging or output. Both ways will work just one uses shorter cables.

are you sure?

it's my understanding that with the original wiring, the drain is heavier on the 2 on the left (the first "12 volt" battery) and then subsequently sips from the 2nd set.

by placing the negative on the first set (top left most) and positive on the second set (bottom right most), the drain is now even across both "12 volt" batteries. it'll work in both configurations. it's just not an efficient design and will result in shorter battery life is how it was explained to me. also you do not get the true ah capacity ratings since one is drained before the other. equalizing effect has greater negative impact because of this.

what are your thoughts on the cable lengths themselves?

[Herk7769]

While both wire setups "will work;" the way he has rewired will be more efficient and result in even charging and discharging across the bank. The attached article and graphic has more information.

[Himcules]

Originally Posted by herk7769

While both wire setups "will work;" the way he has rewired will be more efficient and result in even charging and discharging across the bank. The attached article and graphic has more information.

well.. its balanced with discharge.

charging is unbalanced and still on the 2nd set of 12v since i have not replaced the cables from the inverter to the battery bank.

i know most factory battery banks last about 3 years while upgrade aftermarket batteries last 10 years. perhaps this has more to do with battery life than simply trojan batteries are better... imo, kinda hard to make that comparison when usually the installation with the trojan batteries are corrected (distance to inverter, amp used to charge, cable size, cable lengths, isolators, etc)

[boowho]

Himcules, what I find more interesting about your pics is the fact that you don't have battery slide out trays. I didn't think that trays are optional but maybe they are.

At any rate I have them on my 2011 390RB-40 for the house batteries. Chassis batteries are fixed like yours.

Boowho??

[Himcules]

none of the 2013 models i toured had a slide tray for the batteries... want a bummer... i wished mine had a battery slide tray

[ernest917]

I thought all Berkshires had battery slide trays.... My 2008 has two.....

[NO3putt]

Ours has two slides trays also with house batteries and coach in the same cabinet.

[Himcules]

i'm jealous that the older models have battery tray slides and the new ones do not

[ernest917]

Doesn't make much sense does it.... You'd think on the newer models, they'd simply add new upgrades and NOT take existing ones away.... Really glad I have an 08'...

[tmmar]

Originally Posted by Himcules

i'm jealous that the older models have battery tray slides and the new ones do not

While my '08 has the slide out trays for both the coach and chassis batteries, as no3putt says, the coach and chassis batteries are staked in the same compartment making access to the chassis batteries very tight.

[ernest917]

My coach and crank batteries are on separate slide-out trays and are not difficult at all to service.... Have a buddy that has a Monoco and he has to stand on his head to service his...