battery charging

Peter
I like that call... one thing I do, is look at matching up battery's all the time...
Just makes sence to me.. even though you can get away without matching,
(for a while anyway)

Cheers
Bucky

2 batteries are of same make model etc etc

what adoes one do if say a third is not?...does one stick in battery isolators and do it manually?...can it be done automatically?

Member,

when mixing batteries, this advice is for you:

In case the charging is done by a (recommended but dear) multistage system, then the boost voltage setting should be adjusted to suit the one battery with the lowest recommended boost voltage.
Similar goes for the float voltage setting, but these don't differ much from battery to battery anyway.

F.e. three batteries: one has a boost recommendation of 14.4V, the next one has 14.7V, and the third one has 14.2V.

Wire them all in parallel, and have the multi stage charging system set to 14.2V boost (and 13.6V float).

Find out which of the three batteries sits in the hottest spot, and attach the temperature sensor to that one.

In case of alternator charging:

the issue of mismatched charging is moot, and all batteries subject to regular substantial depth of discharge will suffer - alleviate this by applying occasional charge top ups manually (again with the lowest boost voltage setting).
Solar is ideal for this because it can supply the higher voltage and low current required for this. Mains powered charger is cool too, but generator is a waste of petrol for this purpose.

Hope this sums it up.

cheers, Peter

WTH does "what happens when you install a new battery to an existing one" mean?

Sorry Moose will try to make clearer. The question was asked if you could charge two batteries at once which I was under the impression that you could, but Peter replied "if same chemistry, state of charge, and temperature,....." So my question was do I need to do anything to the existing battery if I was to add a second battery. Hope this makes sense. After seeing a previous thread about a battery dropping a cell I don't want to go there. I'm still new to this stuff and trying to get my head around it all.

Thanks Justin.

Justin,

you're under the right impression, yes you can hook 'em up in parallel for charging.

And this works best under the conditions I've stated earlier.

And these conditions are being met easily by leaving them wired in parallel for charging, and discharging.

That way, the batteries will always have equal SOC.

If you only switch them in parallel for charging, but not for discharging, then there is potential for overcharging one battery because the SOCs most likely won't be equal at the moment you switch them in parallel.

Having said this, if they're being 'float charged' by an alternator, then the mismatched SOC can't cause overcharging (but the one battery with the deep discharge will suffer because it's not going to see the required boost charging voltage).

Only in multi stage charging setups, the one battery with the higher SOC (if you allow it to go there by separating them) will get slightly overcharged as described earlier.

cheers, Peter

Behave! LOL

"Can one charge two batteries of equal size simultaneously" -> yes
"and/or is best to install isolators and charge separately" -> yes

Barry, because I believe solar will charge efficiently, is that really ‘miss-behavior’ LOL

Generators must be horizontal to work efficiently, IMO they also really are a pain
Only Solar works in both horizontal and vertical positions without strain or pain LOL
( no further pain information contemplated )

Maîneÿ . . .

dont confuse them Mainey

what you talking about!..lol

and only genorators work with no sun
- so whats your point?

and anyway who mentioned genorators?


In partial answer to the question things can turn to crap if charging 2 batteries at the same time if one has died

a dead battery theives all the charge and runs down the good battery

had this happen with a few vehicles running "dumb" solonoids

go to start and even with dual batteries no go despite one battery still being good

I think you have to get out a bit more and smell the roses LOL"

read what was posted then laugh at it :-)
I answered the "very important question" about *headaches* mentioned by the OP "LOL"

Maîneÿ . . .

Hi Mainey
You surprise me
You do have a sense of humour even if it did go over my head @ first reading .
Now I will have real problems with your posts
Trying to work out if they are tongue in cheek or serious beliefs[ like solar efficiency]


Peter

Peter,

Yes, I believe I've a SOH, so maybe I should just type slower :-) :-)

Yes, I seriously believe in Solar power, even the Australian Government believes in Solar power now.
Wow, that remark should be deleted, it makes a positive statement into a negative one :-)

As for Solar efficiency, well that would be a whole new subject as there are so many ways of stating the efficiency of Solar systems, none are truly wrong, just some are more correct than others, so lets not go there LOL

Maîneÿ . . .

Mainey, I was with you all the way until "even the Australian Government believes in Solar Power"........the Government whether Liberal or Labour believe most passionately in getting re-elected.........lol