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lithiumboatbattery asked

24V / 100AH LiFePo Battery not charging fully with IP67 24Vcharger

I have a 6 month old 24v / 100AH lithium battery that I can't seem to charge fully. I have been through 20 cycles with the Victron IP67 24v charger and the most I can get is around 10 amp hours. Charge mode is always the default Li-ion mode. I should not the first time I charged it took almost the full 100AH after purchase from store. The voltages all look correct but the charger goes into storage mode after about 1-2 hours. At most I get 3-5hrs of use with a draw of around 4-5AH, and then the battery dies. I have even hooked up to portable fridge / freezer, and it also gives out over the same time period. This is the second battery I have had the same issue with. All charger diagnostic looks good but can't get more than 10AH per charge even after leaving on for days.

The battery can take 40AH input ...

Help

battery chargingLithium Batterybatterylife
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kevgermany avatar image kevgermany ♦♦ commented ·
Please give us more details on the battery. Make/model/chemistry. Any BMS?
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lithiumboatbattery avatar image lithiumboatbattery kevgermany ♦♦ commented ·

It's an OEM PowerTechLithium 25.6V 100Ah deep cycle battery. Charging profile is CC/CV Cycle Charge Voltage 29.2V, Float Charge Voltage 29.2V, Recommended Charging Current up to 40A. There is an inbuilt display that looks like the attached. As for the chemistry ... not sure it's LiFePo.

Is there any chance the default Lithium Charge setting is to low during absorption phase as it sits at 0.2 -4 for ages...

Or is this just the battery BMT refusing to take a higher current?

Thanks again for the advice in advance

powertech-256v.jpg

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Alistair Warburton answered ·

Bulk and absorbe settings seem very low to me...

I have Ultramax 100Ah units configured in series parallel to give 300Ah at about 26V...

Each battery contains a BMS, stand alone, and advice from Ultramax is to Bulk and absorb at circa 29V, I don't know exactly without looking, but I wouldn't recommend going that high without checking the BMS requirements for your kit first.

For a Raw cell that is high but the internal BMS needs headroom to work.
Ultramax also recommend absorb at the same level but for no more than 6 mins.

I have mine set lower because the charger I have has a minimum of 1 Hr absorb unless it is a repeat cycle in which case the limit is 15 mins.

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kevgermany answered ·

You'll need to use the Victron connect app to set the battery voltages for you battery. The default lithium settings are lower than you say is recommended -28.4/27 for lithium.

Loooks like max current is 8A, so you may want to increase the absorption period as well.

Set battery to user defined instead of lithium, this gives you access to the voltage settings.

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lithiumboatbattery answered ·

Thanks everyone ...that screen shot was sitting at storage / absorption mode on the IP67 charger. I am going to run it down again and try the advanced settings. Please note this is a single 24v / 100Ah batter not a parallel setup. The charge outcome is the same .. i.e. it won't fully charge and drops out quickly...giving only max 6-9Ah of charge.

So the options / reasons are:

1) The Victron IP67 charger isn't able to charge the battery correctly due to the default lithium settings i.e. somehow the battery BMS is being triggered to show it is full charge...

2) The Victron IP67 charger's default lithium charge settings are too low

3) The battery is faulty ... by all accounts this doesn't seem to be the case as the only constant here is the charger...


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kevgermany avatar image kevgermany ♦♦ commented ·
The charger works by measuring battery voltage. Your battery has unusually high voltage requirements for lithium. Guessing it's because of the way the internal BMS works. To avoid overcharging, sophisticated chargers switch down/off when preset battery voltages are measured.
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