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gabriel

battery charger for agm, what, where, $?

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the quest for a battery charger continues. i stumbled upon this one. if i charge my batteries to near float with the axpert and use the charger i just mentioned to top them up individually, which will mean i have to disconnect them from both the ha02, the bmv and each other and charge until they reach 13.5v each; then reconnect and sync the bmv - will that be the way to at least sync the soc correctly? settings for charge rate and tail charge will then follow.

will it be bad for the batteries if the charger charges to 14.4v at 3.8a whereas the battery spec sheet indicates a 'cycle service' [bulk?] charge of 14.1v?

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10 hours ago, gabriel said:

will it be bad for the batteries if the charger charges to 14.4v at 3.8a whereas the battery spec sheet indicates a 'cycle service' [bulk?] charge of 14.1v?

I think the occasional charge to 14.4 bulk, dropping to 13.5 will be ok.

If your spec sheet recommends 14.1 then why not save the money planned for the charger and do the following;

  • Make sure that Bulk Charge = 56.4 (14.1 x 4 as per spec sheet),
  • Set float charge to 14.1 x4 = 56.4V as well (just for 1 day to give batt's good equalization),
  • Set ICC - USE SOC FOR CONTROL (no time setting during this operation),
  • Set ICC - TO SOLAR SOC = 100% - so it will charge all the way to 100% before switching to Battery mode, allowing your batt's a good charge,

In the evening when PV input is gone then set all back to previous values, this is a 1 day deal to boost your batteries. If your batt's turn to smoke then I apologies in advance (but I think they will be fine).

EDIT: The above is to boost charge from solar, the other option would be to set your system to charge from the grid occasionally (which I personally never do).

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4 minutes ago, pilotfish said:

If your batt's turn to smoke then I apologies in advance

you won't mind if i hang in here for a second opinion ...:unsure:

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Hi Gabriel

I think I am being dim but cannot understand why you need an independent charger for AGMs. If you had Trojans then I would understand but there is nothing that a C-Tek charger can do that the Axpert cannot do.

Chris

 

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36 minutes ago, Chris Hobson said:

I think I am being dim but cannot understand why you need an independent charger for AGMs

no, you are not dim :)

to my mind [now THAT is where dimness might enter the picture] all 4 batteries must have the same charge. ok, the ha02 should accomplish that BUT at present, under load and presumably in float, they measure 13.51, 13.53, 13.53 and 13.53 volts each, power entering at 13.51. the ha02 does not seem to get no 1 battery on par with the rest.

i thought, ok, lets charge all of them to 13.53v or whatever in order to get 100% soc to achieve two things, a- to sync the bmv and b- to teach the ha02 what it means that all are equally charged in order to assist it

g

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2 minutes ago, gabriel said:

they measure 13.51, 13.53, 13.53 and 13.53 volts each

That is pretty good balance, I wouldn't be concerned at all with those numbers.

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4 minutes ago, gabriel said:

no, you are not dim :)

to my mind [now THAT is where dimness might enter the picture] all 4 batteries must have the same charge. ok, the ha02 should accomplish that BUT at present, under load and presumably in float, they measure 13.51, 13.53, 13.53 and 13.53 volts each, power entering at 13.51. the ha02 does not seem to get no 1 battery on par with the rest.

i thought, ok, lets charge all of them to 13.53v or whatever in order to get 100% soc to achieve two things, a- to sync the bmv and b- to teach the ha02 what it means that all are equally charged in order to assist it

g

The HA-02 only starts working when there is a 20 millivolt  (0.02V) difference between the batteries. Your multi-meter readings independently verifies that the HA-02 is doing its job. So are you getting a midpoint deviation alarm on you BMV?

If so then let's look at 2 things:

  1. How big is the deviation? Anything over 1% on a 48V system (2% on a 24V system) is reason for concern.
  2. How long is the deviation present? My big CB Solar batteries took a couple of months to get into balance and stayed in balance until they started failing. They use to be out of balance for about ½ hour or so and slowly the time period became less and less.

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1 hour ago, The Terrible Triplett said:

Every few months I swap the battery sequence.

easier said than done with 70kg dumbbells B)

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8 hours ago, The Terrible Triplett said:

swap the cables around between the poles. 

For one series string I don't really see the point. I still think the reason the battery at the end tends to have issues is climatological and not electrical :-)

And you guys are bickering about 0.02V here. That's two tick for the ADC in many digital multi meters (20V range, 2000 steps), it's on the edge of what it can measure. For all you know, they are close to exactly 13.52V, but half a tick in each direction pushes it to 13.51 vs 13.53. :-)

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52 minutes ago, plonkster said:

And you guys are bickering about 0.02V here

^^^?

The battery balance is about as good as you could ever expect. I reckon any fiddling that you do could only disturb that.

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good morning forumites!
again i have to harvest your knowledge
in an attempt to get 100% soc on my battery bank before i flash my axpert 5kv with coulomb&weber's latest v.72c, i had it charge on utility through the night and isolated it from the axpert&utility by disconnecting the bmv702 shunt and negative pole cable, pulling the fuses, switching the disconnect and disabling the axpert [in the right order though].
although the axpert, on the pre-coloumb [proprierty 2015 axpert] software indicated fully charged the batteries now indicate the following voltage charges, NOTE, the bank is still connected in series with the ha02 battery equalizer connected on all poles, there is no load though [the positive is still connected to the axpert].
13.19
13.19
13.19
13.18
the float charge of my batteries is indicated as 13.5v each, so i will attempt to get them there with external charging per battery [after disconnecting all], which should result in all of them being in float, before reconnecting them and switching on the axpert and synchronising the bmv702 to 100% soc, i.e. fully charged.
would this be the way to proceed?
God bless
g

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11 hours ago, The Terrible Triplett said:

swap the cables around between the poles.

i'll have to work that one out on paper 1st, kophou soos 'n dronk weeluis :rolleyes:

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1 hour ago, gabriel said:

so i will attempt to get them there with external charging per battery

Hells bells dude, I dont know why you insist on creating unnecessary work for yourself!:wacko: Your Axpert seems to be doing a wonderful job of keeping your batteries charged and balanced, but if you have a lot of time to kill and like experimenting with expensive kit like batteries then go ahead!

1 hour ago, gabriel said:

the float charge of my batteries is indicated as 13.5v each

Float charge voltage is WHILE ON CHARGE. As soon as you disconnect the charge source as you have done by disconnecting NEG your battery voltage will slowly drop and settle around 12.8v.

LOS NOU UIT!!!

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1 hour ago, pilotfish said:

Hells bells dude, I dont know why you insist on creating unnecessary work for yourself!:wacko: Your Axpert seems to be doing a wonderful job of keeping your batteries charged and balanced, but if you have a lot of time to kill and like experimenting with expensive kit like batteries then go ahead!

Float charge voltage is WHILE ON CHARGE. As soon as you disconnect the charge source as you have done by disconnecting NEG your battery voltage will slowly drop and settle around 12.8v.

LOS NOU UIT!!!

Agreed. There is no issue here. What would be a better test, is to check voltages between batts before bed, and again in the morning before sun is on the panels. This will show you how they are discharging. AGM has very low IR so they can go out of wack far quicker than FLA. But does not sound like you have anything to worry about here. The float deviation you mention is no issue at all.

Hope that helps.

Livsol.

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11 hours ago, plonkster said:

 For one series string I don't really see the point. I still think the reason the battery at the end tends to have issues is climatological and not electrical :-)

I still think there is something in it. You had a tongue in cheek explanation a couple of months back. But I would like to know how many times battery 1 is the one that starts to fail. My batteries where in odd battery box with battery 1 &  4 having the same "environmental" conditions and 2 & 3 having slightly different environmental conditions.

 

 

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