question

saba avatar image
saba asked

Charging Issue.

Hello,

I have a motor vessel which has recently been fitted with a MultiPlus 3000/120A with brand new Victron AGM batteries (total 880 Ah). The MultiPlus is fed by shore power plus an Onan 7kva generator. When the vessel is away the batteries are taking an inordinate amount of time to recharge and following my investigations I now realise why. This morning the batteries presented with a residual charge of 55%. I started the generator and shortly after noted a few things

1. The charger was indicating charging at absorption rate and not bulk rate.
2. My monitoring system was indicating that a charge of 90A was being sent to the bank for 1 minute 20 seconds after which the unit temperature light flashed and the charge rate reduced to 4A for 2 minutes 30 seconds.
3. This cycling is constant.

Any thoughts would be greatly appreciated. The system was professionally installed.

battery charging
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3 Answers
Paul B avatar image
Paul B answered ·

Hi, please download the victron tool kit and this has a option that tells you what the flashing lights mean. this may help if you have a unit issue

Also for the unit to switch to absorption then the bulk voltage value must have been reached. could you also advise on the voltage output a well


If the multiplus works fine on shore power, then try turning okk the UPS setting in the multi plus

a MK3 unit would be needed to do this


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saba avatar image saba commented ·

Thank you for your response Paul B. Please see my response to Daniel Boekel.

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Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @Saba

If the system was professionally installed, the first action would be to call the company that installed it and ask them to (help) fix it.

of course the unit should not be overheating after such a short time, first things to check would be:

-ambient temperature

-is the fan working or is it blocked somehow

-check firmware version, flash newest firmware if needed

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saba avatar image saba commented ·

Thank you for your response. The ambient temperature is around 20C. I have awoken this morning at anchor with the house batteries at 55% with 12.42V. Started the generator and the charger went to bulk for 5 minutes (13.42V) and then shut down under a flashing temperature light and reverted to the same cycle as yesterday (absorption). It is a little hard to hear the fan run whilst the generator is running although placing my hand over the top vent indicated no airflow during shutdown. From this I can only surmise that the fan is not operational.

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Paul B avatar image
Paul B answered ·

AS per the victron tool kit if the temp light is flashing this is a internal temperature warning, a solid red light means a temp overheat shut down.

You dont mention the age of the Multiplus just that you have replaced the batteries. but Daniel is correct


try updating the firmware

and as a possible work around place a fan under the unit to create some airflow into the unit from the bottom. then see if you get the issue still.

if this stops the problem then check the fan and make sure it is turning as it could be clogged with dust etc or just jammed.


otherwise take it to a service agent for repair


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saba avatar image saba commented ·

Paul B,

Many thanks. The unit is 8 months old and I have now noted, from research, that this is a common problem with this unit even to the point where some users are replacing the OEM fan unit. I will open it up and check fan rotation.

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