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by'eck

Member Since 04 Apr 2011
Offline Last Active Yesterday, 09:56 PM
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Posts I've Made

In Topic: Batteries Not Reaching 100% SOC

Yesterday, 09:52 PM

Sorry Richard but your logic is flawed - unless the battery had full capacity, was discharged to 50%, and then suddenly lost half its capacity prior to recharge. In reality loss of capacity is gradual and so whatever is taken out on one cycle, giving whatever SoC reading (it doesn't matter) has to be put back on recharge plus 5% or whatever. Of course the actual SoC prior to recharge won't match the indicated SoC, but that is not the issue in this context.

 

Yes I was waiting for you to find the the flaw in my argument wink.png

 

Nevertheless based on use of two BMV600's I do find that you get such issues if the actual and programmed battery capacity are not at least roughly similar. Indeed I use it as a sign that I need to reset programmed capacity as batteries age. This issue is exaggerated if the BMV is not regularly synchronised by having it reach 100% SOC indication.


In Topic: Batteries Not Reaching 100% SOC

Yesterday, 08:57 PM

Tail current settings aside, I think the most likely reason for the issue in your OP is that the batteries actual amp hour capacity has dropped compared to that which the BMV is set to. This means that when batteries are down to 50% SOC on the BMV on say a 500 Ah bank it expects something close to 250 Ah plus charge inefficiencies to be put into them to bring the reading up to 100% SOC. If the actual battery capacity is only half that then they will be fully charged with approx half that amount, but then gauge will only be reading 75% SOC - just an example, but see where I'm going? This may explain why it was hitting the 100% SOC reading before when the batteries capacity was greater.

 

Bringing the tail current setting back into the equation, the BMV should still theoretically jump to 100% SOC indication when charge current drops to the pre-set tail current. However I suspect the algorithms programmed into the gauge may limit just how far it can jump when there is a mis-match between programmed and actual battery capacity.


In Topic: Studer AJ400 inverter ?

Yesterday, 07:20 AM



I will try connecting to a 12v batt and see what happens.

 

If you have an AJ400 it won't work. Its a 48 volt version however bizarre that sounds on a canal boat. You can see for yourself here.


In Topic: Inline water pressure switch when water tank runs out

21 April 2015 - 01:21 PM

Mine has a built-in buzzer that you can't miss when water tank runs dry. Its provided by the pump motor screeming away rolleyes.gif


In Topic: Electroquest 30 amp battery charger

21 April 2015 - 01:05 PM

 

I don't have the (very poor!) instructions for my Electroquest charger here, I think.  However I can't recall seeing any reference to having to have both positive outputs connected - in fact I can't actually recall any detail on using two outputs.

 

As it only comes with a pair of pre-prepared cables, one red, one black, with a crimp at one end, and a croc clip at the other, rightly or wrongly I assumed it is fine to use just one output, whether connecting to a single battery on the bench, or a whole bank in the boat.

 

How does the two output thing work then?  I can't remember it being specced as a set number of maximum amps per output.

 

I did say earlier "with most multi output chargers". The rationale behind this is that any output without a load on it will show up as higher than any actual battery voltage so the charger sensing this may provide unnecessary voltage control to all outputs, limiting charge current to the ones that are connected. The need for not leaving unconnected outputs is certainly mentioned in Sterling manuals.