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notjustageek avatar image
notjustageek asked

Pylontech battery charging power limited to 2kw

We have a Multiplus II 48/5000 connected to 5 Pylontech US3000C batteries. These have been functioning as expected since installation (August 2022), but we are experiencing low charging power overnight at the moment - 2kw vs the 3.5kw we normally have. We are on a time of use tariff and want to fully charge the batteries during off peak rates (6 hours), however this isn't working with the lower charging power.

When we first noticed this the battery temperature was under 18c, since then we have added insulation around the battery and introduced a seed germination mat to help increase the temperature when necessary. Currently the battery temperature is 27c and we are still seeing reduced charging rates. Looking in the battery parameters the CCL and DCL are both 185A and none of the modules are blocking.

Could anyone suggest reasons for the lower charging rate? Thank you for your help.

Multiplus-IIbattery chargingPylontech
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notjustageek avatar image
notjustageek answered ·

So, turns out this was caused by a loose electrical contact where the DC connects to the Multiplus II. I'd built a cabinet to house the batteries earlier in Autumn and forgot to tighten the bolts - the inverter/charger was limited power due to the high temperature inside. Thankfully the safety systems in the Multiplus II worked.

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Alexandra avatar image
Alexandra answered ·

@notjustageek

Around that temp usually it is a factor in battery life (ESS) that causes slower charge at lower temps.

Switch it off and see if there is a difference.

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notjustageek avatar image notjustageek commented ·
Could you explain how to switch it off? Is this related to the battery saver options, we are using external control so I don't think that affects us.
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Alexandra avatar image Alexandra ♦ notjustageek commented ·
In the ESS menu on the GX, you have a setting allows you to switch between battery life with or without and keep batteries charged.


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notjustageek avatar image notjustageek Alexandra ♦ commented ·

Great - thank you for explaining. I've switched from external control to without battery life, unfortunately still seeing the same issue.

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Craig Robinson avatar image
Craig Robinson answered ·

or you could place a heater in the cabinet to warm the batteries I had to do that added a temperature controlled heater set to 20 degree I also added a cooling fan so if it gets to warm, the system is working fine its meant to reduce the charge current in cold weather.

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notjustageek avatar image notjustageek commented ·
Thank you for the suggestion, I've added a relay connected heater already and the batteries are now maintaining a temperature of between 22c and 27c. Unfortunately, I'm still have limited charging power. If you have other ideas, I'd be interested to hear them.
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JohnC answered ·

@notjustageek

Having 'Weak AC' selected in the Multiplus can cause a charge reduction like this. Selecting it causes a poor Power Factor to be applied, and by extension there's always the (unlikely) possibility you have that naturally..

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notjustageek avatar image notjustageek commented ·
Thank you for the suggestion - I've confirmed in veconfigure that Weak AC is not selected and have checked my grid power factor is good.
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