side note besides my issue in my previous post. but my 2000 F350 7.3 has dual batteries -- im sure most do

playing around with solar panels and such I was always told there was proper ways to charge and drain dual battery setups


so to my understanding -- negative on one battery and pos from other thus charging equally

same when loading you want both batteries to drain evenly

so with that said.. why does ford run possitive from driverside over radiator then to passanger side ?
I've tried researching threads on this maybe im missing something, or maybe its not a real big deal, to me it seems the driver-side battery is sorta last priority putting most wear on passenger side battery

the camper has 24v solar panels and batteries hooked up for 24v, i keep the truck / camper seperate because of so, and have done so much research to keep them seperate and how to charge or drain a battery bank lead me to these thoughts

i know it cant be a serious issue, but for longitivity, or cold weather starts there gotta be a better way

i guess what im asking is this... after all that ramble -- is there something serious running off the passenger side negative terminal detrimental? and if so, if i take the passenger side battery negative off the chasis, run good wire over to driverside negative then super ground extra wires from driver side negative to missing points wouldnt that work to equalize the battery load/charge?
maybe simple way leaving the positive wire alone the way it is? hence bringing negative terminal charge to driver side, leaving positive charge to passenger side?
prolly opening up a can of worms, and thou this is on my mind, its not a mod im going to do tommorow or even a month from now but it is something ive been pondering, not sure if every battery has to be grounded directly or if the other battery can snag the ground from the matching battery

prolly not a big deal on dual batteries -- prolly more of deal on solar / or battery banks larger than 3 -- thanks for thoughts and input



thanks to everybody, seriously, thank you

 

More of an issue with larger battery banks, it's to do with the resistance of the cables, larger, shorter cables help.

 

yea, was rambling that in back of my two brain cells --- might just leave it be --- i have drained the batteries a few times noticed driver side just tad stronger, but them resistance thing=of-a-ma=jigs might get me

thanx

 

On our trucks... each battery is grounded with a dedicated cable to the engine, and from there the engine is grounded to the chassis. It's then up to us to maintain the integrity of the individual connections, and we'll have good battery/truck performance.

 

i do like that idea, but still leaves the bridge cables different lenghs where charging negatives differ from possitives supposed to be basic battery 101 but think Shovelheadrob prolly onto something
I'm sure Ford thought of this-- or maybe not -- dunno, some ohm resistance reading might change causing pcm to squirt out blinker fluid if i mess with it



that one thing never hurts and usually always do, add more grounds to engine block


forgot to ask -- ya say dedicated... does that mean isolated to block or just adding more to block

 

with a parallel multiple battery system like our trucks have, it does not matter where the cables are connected, as long as they positive goes to a positive and negative goes to a negative point. and that the connecting cables are good.
the important factor is batteries have to be equal in load capacity. if have you a 4 year old battery and a 4 week old battery, the old battery will draw the new one down. that is why it is very important to replace batteries in pairs, and they must be the same capacity.

 

i charge mine just like ford does, hook up the charger positive and negitive to just one battery, the other battery is conected via the stock cables and charges just fine, just like it does every time your truck is running. you are overthinking it.

 

actually have done this, and charger says charged shuts down, then do same for other battery, its not fully charged so takes more charge

think allot of youtube on powerstroke say while working on electric stuff, disconect batteries from harness and charge seperatly for full charge

yess, i am overthinking this, need to stop, not like i got big bumping stereo thumping out Easy-E Boys in da-hood or nothing. LOL

got 16 small AGM 35ah batteries in camper along with additional six 29 something big deep cycles (bad mix and match) but they seperate and hooked 24v to match solar panels on roof when truck dies i sometimes take out my solar tester to test the batteries in engine, reads the CCA so i can say, atleast on mine charging using stock wires intact does not charge them equally ---

with that said, not sure how the alternator charges them, maybe the alternator charges them more equal than house charger using the stock hookups

but when ya start and crank and start over and over -- the passenger side battery deffently drains faster than driver side,.. again not much, but readable on battery tester

again, yes, overthinking it... need not mess with it, its only two batteries not 16 in a bank like the camper has -- just one of them things ive been wondering and pondering -- but again, i dont know how the alternator charges them or if pcm takes stock wires and hookup into consideration when measuring something,

again, dont want something overcharging or undercharging, and dont want the pcm to spit out blinkerfluid all over my muffler-bearings

so even though i ponder and question, its more curiosity than anything, like others mentioned, not that big of deal AKA if it aint broke dont fix it

lol -- its all good -- thanx everybody for feedback, yes it works fine stock, yes when on house charger i seperate them from harness to get that little extra bit crammed in there

if it is something that would improve it though, drain them more evenly, i might get that extra 1/2 a crank for winter time -- nope ill leave it alone

 

sounds like one of your batteries is going bad

even if you unhook the batteries and charge them seperatly the second you hook them together they will begin to equalize negating the effort of charging them seperate.

 

possiblility though they do check out somewhat even when seperatley put on trickle charge overnight -- atleast as CCA is --- batteries are autozone cheap ones both 11months old, think 100 something peiece, was bought as gift

you can buy same part numbers on batteries or electronics, and no two will be exactly allike -- but if they trickle charge seperatly on house charger, top them off, then just spin wheels with no start but cranks over and over --- till almost dead, then suddenly the driver side battery has noticable more CCA / volts left then when they started out

so atleast by cranking alone, they dont drain evenly, and everybody is right, prolly only get 1/4 - 1/2 crank-over anyways if found a way to do it, -- just not worth it

while running -- both batteries are about equal --- just when no start/ cranks -- over and over during troubleshoot, the majority of drain is on passenger side battery.

 

i agree with pirate. either one of the batteries is weaker than the other, or the connecting cables are going bad and have a Resistance limiting the charge going to the other battery.
a broken jacket on a battery cable will allow corrosion inside the cable where it can not be seen. as little as 2-3 ohms resistance could mean as much as 10% less power going through the cable to the other battery.

 

try this, charge your batteries independently snd then let them sit over night without connecting them. in the morning check the voltage with a Multi meter.

that will be a good indicator.

i am not familiar with CCA testing device so i cant comment on its accuracy but it sounds gimmecky. the true way to load test a battery is with a Carbon Pile tester and those are very uncommon nowadays because of size and cost but sny good shop will have one. the more common handheld restior testers are an ok indicator but to truely know you need a carbon pile load tester

 

just a over-glorified volt mater, originally bought cause of the sixteen 35ah AGM batteries, but has settings for flooded aswell,

would i recomend it? --- prolly not, works good, just feel got ripped off, think i paid $55 for it a few years back, and with that 22 batteries (24 batteries including engine) i am glad i got it, more for solar battery banks tells ya the weak batteries so ya can pair them up better via indidual banks, so if i got 16 batteries, but 4 of them running week at about 251 CA (cranking amps) were the rest are maybe 285CA then i know to put 1 of the 4 in four seperate battery banks (4*4=16 so yes, have four banks of fouur batteries each bank -- trying to keep all bank totals even

so very helpful there, just stretches the battery life a tad bit keeping them even -- like pirate and tjc transport said above -- so yes, over-priced battery tester / volt meter prolly can do the same, but deffinatly a tool i have and use on both solar and truck

again I've tested my batteries, yes maybe wire broken crack under radiator stuff, but when i test i use this tester, and i dont recomend it cause pricy little thing, but the tester never let down so far -- ONLY reason why i started this thread is not to troubleshoot my system, it could be better, stock wires are just that -- stock so i could prolly get improvement by replacing wires and thats on my list for few months down road. i started this thread to ask a curiousity concern for when i do them wire upgrades, anif i should hook them up like recomendation or leave them stock layout

for that I say thank you -- link below only if ya want technical details about the battery tester i use when testing the engine batteries otherwise dont click it -- its amazon and they get 3rd party cookie hungry

thank you all for your input -- i have learned allot, no sarcasm is intended -- thank ya -- everyone


over priced battery tester, bought long time ago when first starting solar battery banks

 

Take a bubble tester and test each cell of both batteries. One bad cell = one bad battery = both batteries will pull down to the lowest voltage when starting = two bad batteries and a hard start..... When your GPR kicks in at the 'wait to start', you will have a lot of voltage pull down and one bad cell will really shoot you in the foot.

 

If the potential problem in paralleling batteries is that Battery B does not contribute the same amount of stored energy to the load as Battery A, causing Battery A to work harder, deplete faster, cycle deeper, what have you.... all because of the resistance in cabling between the batteries, and the unequal distance of the load between batteries, then this potential problem can be solved by either reducing the resistance in the parallel links, or evening the distance of the load. It seems easier to wire in the former than reconfigure the latter.

It has been well established through many user reports logged over many years... that the passenger side battery in these trucks depletes/degrades quicker than the driver's side battery.

Taking the path of least resistance (ha ha) to fix this problem, it was easiest to leave the factory wring in place, and simply add duplicate wiring to reduce the resistance between paralleled batteries



Starting at the battery nearest to the starter, the double up begins...




Another view showing the secondary parallel leg under the OEM leg as it leaves the battery...




Following the siamesed snakes around the corner in front of the radiator...




Landing at the "less utilized" driver's side battery...




But wait, there's more. At the driver's side battery, there are several positive (and negative) cables spidering off the terminals, including ANOTHER paralleling leg through the alternator...




Line A that goes from driver's side battery to the fuse behind the alternator, is joined with another big fat red positive cable that that goes from that same alternator down toward the engine on it's way back to the "main" passenger side battery...




Here's a better look at what's going on back there behind the alternator which is facilitating the reduction of resistance between paralleled batteries...




And even closer view... naming names...




So, not only are there now 3 parallel legs passing between parallel batteries, reducing the resistance between them... there is also a low resistance (but still fused) charging path from the alternator directly to each battery individually. Current produced by the alternator does not pass Go, does not collect $200, but instead goes directly to the jail cells of the batteries. Each of them. As if they were different. But in fact they are the same, as they are paralleled six ways from Sunday.


But that's only half the story. The negative ground side is just as important, and in this installation, just as augmented as far as the effort to reduce resistance between the batteries, as well as between the load and the batteries.


Starting with Ground Zero, the engine block...




Moving from there up to the main alternator... as if the case mount to the front cover in and of itself isn't enough grounding, the cables by pass the front cover, the gaskets and any loosening of the alternator bolts (seen that happen) by providing a fat wad of copper directly to the engine block, and simultaneously, directly to the driver's side battery that otherwise appears to loaf along for the ride...





Sometimes we run into installation issues when draping the engine bay with more cables, like too short of a bolt to hold em all...




This isn't rocket science, but if it is at all possible to make a mountain out of a mole hill, I keep my shovel at the ready...




The following will not apply to everyone, but I gave my secondary alternator the same treatment, adding a ground strap, more as a shade tree attempt to drain EMF noise from radiating along the tubular metal transmission cooling lines that make for inconvient antennas, which attach to the same bracket that retains the passenger side block grounding stud. The transmission has two hall effect sensors that are sensitive to EMI (I have verified this the hard way, which is the only way I learn), so if a diode goes wonky and an alternator starts generating stray AC, I'd like to direct that back to the battery sink for absorption...




Not to be Negative Nelson or anything, but the second alternator's mounting connection to the engine, plus this direct copper path from the alternator case to the passenger side battery, completes the "paralleling" pathways between batteries, and reduces the resistance between charging sources and batteries, as well as between loads and batteries.




Both of my 10 year old batteries, when disconnected from each other (quickly and easily accomplished by the negative terminal disconnects shown in photos above), still measure within 100th of a volt from each other.

All the OEM factory wiring remains in place, untouched by this effort to obtain Equal Battery Rights. An effort that appears to have worked.