Hi
It will not make any difference
All either charger will see is a 300Ahr battery pack
What may happen as the pack approaches full charge is one or the other charger may switch from boost mode .& contribute little to the remaining charge
If the chargers are the same brand /model that may only be a very minor consideration but if different brand or models that change over for one may be much earlier

I suggest you read very carefully what Julian said on another forum.
Your question is different, but he is the only person I know who runs 2 MPPT controllers into the same batteries and he understands better than most what the interactions are likely to be.

Cheers,
Peter

Hi.
You can get all sorts of variables sticking multiple battery's on one charge line.
IF you look around. there are chargers with "multiple" outlets.
My 25a marine unit has three Outlets. IE can connect to 3 battery's at different levels of charge.
and it distributes up to it's 25a max t'ween them to suit.
I also have a 40a 4 phase Commercial unit in rear of Ute for when travelling and topping up 2 x Battery's
when stopped at parks O'nite or when Genny running for aircond (3.8kw)

Those multi's are not the cheapest. But if you working with multi battery's.
they are the best. Specially if your battery's are set up on differing loads.

Look on net. Multi outlet 240-12/24v chargers.

It is a better way of doing it if you starting out. Otherwise you'll get dizzy running round with the Multi.

But don't buy less than 25a if starting out on them. they need that minimum to spread a decent ampage around.

This one was spare from last yacht. she had a 50a built in,(6 battery's in one bank, 2 in other.)

Trace Pot, inverter with several panels. Generator. AC and coupla dumps linked to AC/Engine coolant HWS.

Worked well for the 15 yrs I had her. Only changed banks once and still good when sold her.

-- Edited by macka17 on Thursday 26th of May 2016 10:07:04 PM

Oldtrack.

I said "Variables" not troubles.
Basically if different battery's on different loads and at different levels.
One charger will charge them. BUT can overheat the first one/s finished while trying to top up remainder.
With more in line it's even more so.

You can never get All fully charged without waiting for a long time
especially when there's no trip out of input voltages for the ones already full.
I've seen some well bubbling battery's on some boats.

That's why I said "if starting out and thinking of charging multiple battery's."

A Multi charger does a proper full top up job of all battery's on line within it's capacity,
rather than "Shall I turn it off now, this one is bubbling?."
Although you can install one of those screw on/off battery terminals to each battery,
as we did when starting out. that works. but you have to keep eye on them.

Pricing on several smart chargers compared to one Multi charger shouldn't be that much more?.
Plus this way is completely Automatic. Just check water levels occasionally.

I'm Just basically giving a better alternative is all. with "my" opinions only.
After 50 odd yrs of cooking and flattening battery's in Yachts and power boats,(and caravans) practice.

This system is designed and built to do the job properly as an offshoot of engineering
By Technical electronics engineers working in shipping mainly.

Anything that can improve what we doing both more efficiently, and "Safely" has to be a bonus.

 

My last van had 4 panels.Generator. plug to car alternator, and a wind genny from yacht (when on local static site)   with 2 x 110a AGM.s    That worked well with a good regulator..

But as I said b4. one smart charger, multiple outlet doing all. is better than multiples doing "Maybe" all.

and only another possibility offered to think about.

Regards.

-- Edited by macka17 on Friday 27th of May 2016 01:15:22 PM

scruffy 01 wrote:

---

Oldtrack, that is what I thought. Both chargers are Projecta 15 amp but 1 is fairly new and the other is a bit older. I have noticed that 1 seems to go into standby mode before the other so will keep an eye on them and switch off the one that reaches float mode first. Thank you.

---

 The reason for one to go to float mode (not standby) is that the two chargers will have slightly different set voltages.

The set voltage is the voltage the charger is set to for absorption charging. The chargers go through their charge cycle (bulk, absorption and float) and during the absorption stage the output voltage is set to the steady set voltage. During this stage the charge current will taper off as the battery charge level reaches full charge. When the charge voltage reduces to an amp or three (dependent on the size of the charger) the charger will deem the battery to be nearly fully charged and drop down to float charge.

Because you can not get the set voltages of two chargers identical the one with the lower set voltage will go into the float charge stage first. This is what you are observing. It does not matter how many chargers you have connected to a battery they will all go into float mode one after the other depending on their set voltages. The only thing that matters is that the combined output currents of the chargers should not exceed the maximum charge rate for the battery. In your case your set up is quite OK. Continue operating your system as you have set it up as it is.

Yes and no.

He was talking about two chargers he had.

fair enuff. they will work.

But. if you just starting out. as many on here are.

 

The Multi outlet charger is a more efficient and similar priced way to go than 2 x.

less complex too.

I've run the 2 x chargers, and the single multi charger.

single unit is  the better way to go.

It will fully charge and float each individual battery at whatever float level it set at.

two or three, or multiple on each outlet with  bigger units.(I've run 6 on one 50a comfortably

If three on 3 way unit. they don't even have to be same capacity IE 85a/90a/110 a.

It reads each one individually.

They really are that good. and will extend battery life too.

 

Like I said several times.

This is just another alternative to put on the table, more for people starting out

and don't have the 2 x units with wiring to suit, with multi battery's.

A single (say 40a) will do same job too. not as cleanly but cheaper.

 

If you have multi batt's (more than two)on same parallel circuit,

Don't wire them pole to pole to pole.

Check on net and follow instructions on how to cross wire to even the  loads.

 

Try again.

originally he said basically 3 batt's in parallel on 2 combined chargers. One from each end.
Those chargers are also "Projecta" which don't have a very good reliability record.
Unless they improved them,

Yes. you can charge as many battery's as you like on one charger theoretically but it could take forever.
Plus if one of those battery's charges first it could cause a problem charging the rest.
unless you have a panel or two on roof.

For than money, or a little more, specially if you're just starting out in this game as I said.
And a lot are.

you can have a better system. Which will maintain your battery's at full capacity.

I've said repeatedly over the last three posts. this is just another alternative.
which WILL do a better job

There are a lot of new caravaners on here.
Surely it's a good idea to spread as much info as you can to them.
The cost of this way is minimal even to a second hand caravan. and it will keep your battery's full and on float.
which also means longer life to your battery.

My battery's lasted on average near 7 yrs. regularly. and they were only Exide Extreme's.
My caravans the same.

Cars. I was lucky to get two yrs till I put a coupla old Solarex 40w Panels on carport roof.
(they 35yrs old now and still giving 2.2a each through reg.)

In some ways . Like most elect posts .. Too many variables.. So many different charges and types ..