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southsideph avatar image
southsideph asked

MultiPlus Overcharging ?

I have multiplus 1600/70 charging 2 x 130AH AGM batteries in parallel, Twice now I have connected camper to grid and the CO Carbon monoxide detector has gone off - I know these can be sensitive to hydrogen which is worrying if charging is forcing the valve open on the batteries - it just may be coincidence. Batteries had been quite heavily discharged over the weekend


There is no real evidence on VRM as far as I can see. Bulk voltage was 13.8 ish, temperature didn't exceed 28c, Asorbtion was 3.25 hours 14.68v the only thing I could see was 40A initial bulk charge current.

Any thoughts would be much appreciated.

MultiPlus Quattro Inverter Charger
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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·

Do you setup the Multi for your batteries or do you run it with default settings?

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JohnC answered ·

Hi @SouthsidePH

It could be venting. Those charge figures are quite aggressive, and I'd question the need to push that hard. You in a hurry?

A look at the tail current in VRM should show a 'flattening off' of charge (ideally using a shunt or with no loads) when the batts are near/fully charged. Continuing on with a long Absorb or Float at higher-than-necessary V's is risking venting. Those Amps gotta go somewhere..

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southsideph avatar image
southsideph answered ·

Hi

Running with the default settings for AGM

Following shows from VRM, the charge cycle , Error in the post absorption was 5 hours which is the default max. Don't know if this was related state of discharge. Obviously I have concerns now regarding connect to hookups - if the Multiplus is going to overcharge batteries and cause them to vent - it is interesting that charge rate earlier was the same for bulk is from the Orion


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southsideph avatar image
southsideph answered ·

I think I have answered my own question, if anyone has any thoughts:

Batteries are Leoch LAGM-130 (12V130AH)

Maximum charge Voltage/Time 14.7v/2hrs

Maximum Charge Current 27A ~ 4.5A per cell

2 x LAGM-130 in parallel 4.5A x 12 Cells 54A

In my case maximum charge current was 40A, my understanding of battery theory this should equate to 40/12 = 3.33A per cell - well within battery max in this configuration

The Multiplus was set to Curve Type - Adaptive +Battery safe but max absorption was 5 hrs - 3hr overcharge due to, I'm guessing deep discharge.


Rgds







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JohnC avatar image JohnC ♦ commented ·
@SouthsidePH

Bear in mind that 14.7V is listed as "maximum". Does that allow for temp compensation with cold batts? Probably doesn't say.

I thought that the Adaptive setting would have cut back Abs at the ~12.8V it started at, but maybe not with that preset. There is actually another AGM preset with 14.4 Abs, and you could try that. Not so aggressive and should still perform ok.

Just an observation of the current taper in your graphs, maybe 5-6Amps is where Abs could be finished and Float started. That's just me, others may differ.


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