Charging house batteries

[luvrbus]

Wow you guys can make something so simple into a engineering feat.Knowing Jack  for several years I am willing to make a small wager he makes what he has on hand work being he is sorta thrifty and smart too.lol he is probably still licking his wounds for the telephone up grade to use Tap Talk that is no longer here Jack I still have my $29.00 ZTE phone BTW.Batteries will self equalize I can charge my starting batteries on the MCI and the battery light will come on if one has more charge volts and only 1 head light will come on. Go back in a couple of hours the head light comes on and the battery light is out and both batteries have the same voltage     

[Jim Blackwood]

Well, there's a charging curve for the batteries between voltage and current. It's a logarithmic curve which just means it gets steeper a lot faster as the voltage drops more and as the voltage gets higher it changes slower. Not that that's a big deal, the important thing is that charging voltage is always a little higher that the battery's static fully charged voltage under normal conditions.

Actually any battery in good condition should at least theoretically read the same voltage regardless of the state of charge. They don't because of internal resistance, leakage and current flow in the testing meter. So it doesn't take a big change in voltage to get lots of current moving. I think that's all stuff that we all mostly understand. The reason we usually see larger differences in battery voltages is on account of the various loads on the battery, and the less internal resistance there  is the less the variation when a load is increased or decreased. So now, no two batteries are going to have the same internal resistance. So if you apply a charge across them one will naturally tend to take more charge than the other. It may not be much or it may be a good bit. Variations in the charging voltage can overcome that and even it out and that's what a top notch charging system which takes current into account will do.

As you get closer to full charge where the current drops off this internal resistance may mean that at a given charging voltage one battery draws a maintenance charge, just enough to overcome minor losses whereas another may draw enough to slowly deplete the battery acid. Again, they both achieve the same full charge voltage, that's based on the atomic chemistry of the dissimilar metals and has to be the same but the internal resistance is what cuts down the current flow and that is based on physical construction and can vary quite a lot. So a really good charger will monitor the voltage as well as the current and reduce current flow to a maintenance level when the full charge voltage is achieved regardless of what the battery internal resistance is doing.

Lesser devices, and the alternator's voltage regulator is one of those lesser devices in most cases, simply provide charging based on the battery voltage and  bring it up to a level that insures that the average generic battery will get an average generic full charge and this works pretty well on the road. But for a full time static installation that's pretty rudimentary and means you have to keep an eye on electrolyte levels and ph. All of which is entirely doable. So it's mostly just a question of whether you'd rather watch your batteries or buy fancy chargers.

Jim

[oltrunt]

Jim that made me laugh good naturedly-never mind the spelling, I am after all "ol trUnt!  At best all I am going to be able to do is try to maximize voltage in and voltage out without cooking my batteries.  I think (hope) BBC is the way to go.  After the $310.10 BBCC purchase ( more here in Kalifornia  because I'm paying for the bullet train and the moon probe (or whatever), I'm still excited by the prospects.

So whats another $300.  The guy at the battery store informed me that my four and a half year old batteries are down to 50%.  Apparently they don't owe me anything so OH WELL.

I talked to wiffy and despite the cost  it isn't any more than a couple of nights at the lodge hotel in Yosemite--and the bed is better in the bus.  Leaving for Yosemite on Oct first---Whoopie!  Jack

[windtrader]

Leaving for Yosemite on Oct first---Whoopie!  Jack

And where do you go in the winter?

[Jim Blackwood]

It's funny really, any of the new Lithium batteries will have an inexpensive and very sophisticated charger *and* a very sophisticated discharge regulator because they don't tolerate any abuse, but can we get that for lead acid batteries? HA!

Jim

[TomC]

Battery wise I have 2-31 starting batteries and 2-8D Lifeline AGM house batteries. Engine has a Delco 50DN 300amp 12v alternator and also have a Trace 2512 inverter charger with 130amp 3 stage charging.
To jump the two banks of batteries, I have 2-150amp continuous relays (look like Ford starting relays) paralleled together with a heavy metal strap. I have an on-off-on switch so the relay can be controlled either by the ignition switch, or manually powered by the house batteries. Then I can either charge my house batteries going down the road, or jump start myself if the starting batteries are low. Simple, and been 100% reliable for 24 years. Good Luck, TomC

[chessie4905]

I have something similiar. Can use house batteries to assist engine start and also coach batteries to assist generator start.

[oltrunt]

Such a fuss in my little bus.  I have 2 group 31 start batteries, 2 Trojan GC house batteries and 1 group 24 battery to run the air compressor and start the genny.  The 24 is linked by a manual switch  to the start batteries so it can be charged by the 110 amp alt if it gets low.

Since I want the house batteries "Smart Charged" while driving I'll spend this weekend installing a Sterling BB1230 unit.  While I'm at it I'm replacing the stationary battery tray with a roll out version--should have done that when I built the bus.  Jack

[oltrunt]

From the nothing is ever simple file:


I read stuff upside down just as easily as right side up--great for parties when I was a teen. Not so great now. I'm working on a roll out system for my battery drawer. I'm getting too old to be lugging golf cart batteries off a tray that sits well inside the body line. I picked up a pair of triple slide drawer slides rated for twice the load I intend to have. I had to weld brackets to the slides to make things work. The tray slides in and out at about a 40 degree angle. I drew up some plans and got to welding. I welded up the right side and it all worked just fine----so I welded up the left side the same way. Ah S*&#! The left side is the mirror image of the right but not when you read things upside down!?! The brackets were where I wanted them. just backwards so I decided to reverse the direction of the slide rather than risk destroying the whole thing with a grinder. I figured out how to get the slide apart. All those TINY ball bearings and two sizes to boot. Six hours later and completely cross eyed I got the slide back together--backwards--it works. Tomorrow I'll finish the installation. I won't draw any plans, I'll just build.
Jack

[Oonrahnjay]

... Six hours later and completely cross eyed I got the slide back together ... 

    Pictures, please??

[oltrunt]

Ha!  they all turned out upside down.  I'll post pics tomorrow.  Jack

[oltrunt]

I got the battery tray finished and tested today--it works.  Jack

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[luvrbus]

Looks good Jack,my 8D's are so heavy I am building mine using the Smith Cam Followers type rollers   

[chessie4905]

OR, just get the factory roll out battery tray from a 4905.

[Oonrahnjay]

I got the battery tray finished and tested today--it works.  Jack

     Nice work - it sure does!  I like that setup.  I was moving my batteries, partly because of some floor/frame corrosion (and also to get them closer to the engine by a lot) a few years ago.  The welder I had hired to repair the floor frame said "I can build you a roll-out battery box".  I turned my back and he had welded up a 60 pound frame with ball bearing rollers built in.  About last year, I looked at that and said "that tray sets the bottom of the battery 3 1/2 inches above the floor -- if I made a pair of simple metal slots that contain 2-3 rollers each, I can cut 45 pounds off the bottom of that tray and make the bottom of the battery 5/16" of a inch off the floor and gain space I need".  (3 Type 31 batts.)  I'm gonna do that when my tuwit arrives.