Parallel chargers

I put four chargers online for additive amperage.

Maybe the next time I do this, I'd better turn around and yell at the chargers...

"Wait A Minute! You Can't Do That!"

Single syllable hint...

As long as voltage hasn't risen to the point of reaching the point of regulation, battery charging amperage is additive, amp hours are cumulative.

But many POWER SUPPLIES cannot be paralleled unless some circuit work is done.

RJsfishin wrote:

2oldman wrote:

BFL13 wrote:
You don't need a combiner first, just hook each one to the battery.

Good. I have a bus bar to which everything is connected.

Like that is going to stop the 2nd charger from raising the system voltage, and lower the amperage on both.
Its called spinning your wheelzs, better known as "P'ing up wind"

2Oldman,

Maybe this is related to

"Don't Eat Yellow Snow"

Thanks bfl.. very thorough.

landyacht318 wrote:
The meanwell, set to 14.7, will start tapering slowly, fairly quickly into the charge cycle, unless I bump up its voltage to ~15.3v,

Neat.. I can't adjust the voltage on this charger.

I think my batts have lost a bit of capacity, and since I spend almost no time hooked up, I need to charge quickly then run an Eq on them.

I have paralleled my 40 amps Meanwell rsp-500-15 and a schumacher sc2500a( 26 amps max) into a single group 27AGM for about 66 amps total into the battery, depending on load at the time.

The meanwell, set to 14.7, will start tapering slowly, fairly quickly into the charge cycle, unless I bump up its voltage to ~15.3v, then they both output their maximum until battery voltage actually hits 14.7v or so which is another 20 minutes or so when depleted to ~50%.

Once amps taper to 40 or less, I remove the schumacher and let the Meanwell finish it off which takes about 4 more hours until amps taper to 0.4a at 14.46v. Absorption time depends on many factors on this battery and likely all lead acid batteries. I've seen it take 8 hours to taper to 0.4 amps at 14.46 after a lot of low and slow solar only, and incomplete recharges

Extra info on the complex part:
-the total amps cannot exceed the battery acceptance rate amps.

If your battery will accept 60 amps at that SOC and voltage, you can put two 40 ampers on it and each will do 30 amps (or if they are at different charger voltages, some combo where the higher voltage one does more amps than the other but the total cannot exceed 60 due to the battery acceptance limit. Might see 40 and 20 instead of 30 and 30.

-once the battery acceptance is down to 40 amps, instead of leaving the two 40s doing 20 each, you can yank one 40 and the other will jump back to its full 40 and go on from there tapering as usual.

-each charger has its voltage 'spread' between its voltage and the battery's. As the battery voltage rises, the spreads get smaller. Once the spread gets really small, that charger's amps will taper then stop as the spread gets down to zero. So that charger is 'squeezed out' and the others which still have some spread continue. Eventually, as each charger's spread shrinks to zip and it drops out, the last charger (the one with the highest charger voltage) will be doing it all. When its spread is gone, no amps flow, and the battery is fully charged

So just because two chargers are "adding their amps" it doesn't mean each one is putting its full rated amps into the battery. You can only get all chargers doing full amps and see the total of that, when
all chargers still have enough 'spread' to be at full amps, and the battery will accept all those amps from all those chargers.

It works best when all chargers are at close to the same charger voltage and that is high 14s.

There is no point in running more chargers when a smaller number of chargers can do all the amps the battery will accept.

-Sometimes one charger won't start if the other one is already on. If that happens, start them in the opposite order. Now most likely, the second one will start so you get both running. You might have to do some trial and error on that for the chargers you happen to be using until you figure out which to start first. Rule of thumb for common case-- start the smart portable first, then cut in your converter and solar.

Between two smart portables, start the lower voltage one first. I found the 14.6v Vector 35 amp 1092A would not start if the 14.8v, 40 amp VEC1093DBD was already on. Turn on the 14.6 one first and the 14.8 one starts no trouble and you get 75 amps total showing on the Trimetric. It takes a little practice to learn how to get them all going sometimes.

RJsfishin wrote:
Its called spinning your wheelzs, better known as "P'ing up wind"

I have no idea what you just said.

2oldman wrote:

BFL13 wrote:
You don't need a combiner first, just hook each one to the battery.

Good. I have a bus bar to which everything is connected.

Like that is going to stop the 2nd charger from raising the system voltage, and lower the amperage on both.
Its called spinning your wheelzs, better known as "P'ing up wind"

BFL13 wrote:
You don't need a combiner first, just hook each one to the battery.

Good. I have a bus bar to which everything is connected.

You can parallel all sorts of chargers on the same battery bank. They don't have to be identical at all. What happens for how much they add their amps and how that changes as battery voltage rises then depends on their respective "charger voltages." That is complex to describe but easy to see as it happens if you are watching.

I had some posts on this a while ago as Roy says.

Lately, I have been using my 100a PowerMax, 40 amp VEC1093DBD, and solar all at once and they add their amps just fine. Also now I can parallel my 100a and new 55a PowerMax plus solar. ( I could add the 40a VEC too, except the Honda 3000 can't run the 100, 55, and 40 at full amps all at once--needs more VA of a generator)

You don't need a combiner first, just hook each one to the battery. If you have a Trimetric though, you need to put each charger's neg on the shunt's end that is away from the battery or the Tri won't "see" the total amps.

I have read somewhere about "stacking" converters and also about stacking solar controllers like that is something special some can do and some can't. Makes no sense to me why not any of them unless they are trying to get exact same "charger voltages" for some reason.

I think I have read one of our RV'ers from up north does this sometimes with two or three B&D VEC1093DBD smart mode chargers in parallel...

Roy Ken