Storyline
Well-Known Member
I see your system but what happens when one of them is a bit run down ? Surely the good battery will pinch the power from the low one
Battery - Domestic vs starter
- Thread starter viva
- Start date
awol
Well-Known Member
I feel a 2 balloons connected to a compressor analogy coming on.
Hadenough
Well-Known Member
Ahhh go on then, I haven't heard that one!
prv
Well-Known Member
Last time I suggested using a sensible electrical layout, the fans of the Big Round Switch insisted that it was "simple" and "foolproof".
Yeah, right
Pete
Yeah, right
Pete
awol
Well-Known Member
Simple enough. If compressor is alternator, balloons are batteries and you have a 1/2/both valve. Go to "both" and the balloon pressures will equalise, if compressor is running, both will expand. Just takes time for a full battery to equalise with a less full one, but it will. Pressure equates to voltage, mass of air to coulombs.
For prv, simple and fullproof ain't the same. My simple 1/2/both switch can't fry my alternator no matter how stupid I am, allows me to totally disconnect the batteries when I leave the boat and requires a modicum of common sense to ensure the batteries get charged and there is always one unused to start the engine. VSRs, diodes and you still need switches are a good solution but I would never underestimate the ability of a fool to cock things up.
prv
Well-Known Member
Indeed they're not, and when this came up last time I allowed that the Big Round Switch is simple in some senses. But it's definitely not foolproof, not even close.
If it really was simple to use, and foolproof, the OP wouldn't have posted the confused nonsense at the top of this thread. He'd have just got on with using his boat, and not worried about having to fiddle with switches beyond a big "On/Off" when arriving or leaving.
Pete
JumbleDuck
Well-Known Member
When they are on charge it should make no difference, as neither can know or care what the other is doing. 14.4V is 14.4V. I suppose it might cause issues if one partially shorted internally, but I think there would be bigger problems then. Anyway, since both batteries are identical and were bought at the same time I hope that by balancing the use I make of them I can keep them pretty similar.
However, as I wrote, I hope soon to make them into a single 130Ah domestic battery ... I have a newish starter battery from a Nissan Micra I scrapped which should have no difficulty starting a 1GM10 and which is pleasantly small.
JumbleDuck
Well-Known Member
Did you know that the pressure in a balloon initially increases as you inflate it and then decreases continually until it goes pop? If you connect two identical balloons together, one more inflated than the other, the smaller one will get smaller and the bigger one will get bigger.
Sorry, don't know what this has to do with charging systems but I find it interesting.
JumbleDuck
Well-Known Member
That's rather unfair, because the OP's problems lay in not knowing what was there rather than in operating it. A typical "sensible" system with two isolators, bridge, VSR and main switch is really no more intuitive.
Now that he knows how to work it, I expect that the OP will find his system both simple and foolproof.