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Old 29-10-2022, 06:33   #1
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24v lifepo4 bank charging

I have my boat in a heated shed this winter. I just discovered my shore power is having an issue yesterday, so I can't use the chargers built into my system. I'm about to leave for a few weeks, and I'd like to hook something up to just maintain the 24v lifepo4 bank I have, preferably without having to disassemble the battery bank.

My house bank is made of 8 12v batteries each with onboard bms, two parallel 12v banks of 4 stacked in series.

Can I just get a 24V 5A Victron Blue Smart Charger and attach the clamps to each end of the 24V bank? while leaving everything hooked up?
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Old 29-10-2022, 07:00   #2
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Re: 24v lifepo4 bank charging

Why not just disconnect the batteries from the system? In the absence of a power draw, leaving them sit like that is actually better than having them on float. You don't have to "disassemble the entire bank", just disconnect the main Battery + wire.
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Old 29-10-2022, 07:05   #3
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Re: 24v lifepo4 bank charging

I'm planning on doing a lot of work on the boat this winter (which is why I'm in the shed), it would be really convenient to not have to disconnect and reconnect everything multiple times. I was hoping for a way to just attach a charger to the existing setup.


My existing Mastervolt 70A charger must be attached to the system at the two ends of the bank, charging the whole setup at 24v, so I feel like I should be able to just clip a 24v standalone charger to the same points.
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Old 29-10-2022, 07:28   #4
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Re: 24v lifepo4 bank charging

If disconnecting one wire is too much trouble, AND the battery charger you are going to use is compatible with the charge and float profile of your batteries, of course you can connect one into the system.

Li batteries (as a general rule) do not like to be stored floating at 100% charge, so exactly how your portable battery charger manages them is important.
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Old 29-10-2022, 07:38   #5
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Re: 24v lifepo4 bank charging

Ok, thanks. I'll take a closer look on monday and see if there's an easy way to disconnect the bank. I think I'll still get the charger, so that I can charge it if I need to before I can figure out what's wrong with my shore power.
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Old 29-10-2022, 08:21   #6
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Re: 24v lifepo4 bank charging

The big question is why your chargers donít work but you think other chargers will workÖ

For parallel cells or batteries, you canít just use the main battery switch to disconnect: you have to disconnect the parallel connections.

If you can find a small charger that will work on the power where you are then you can connect it to the same busbars that the other chargers connect to
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Old 29-10-2022, 08:41   #7
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Re: 24v lifepo4 bank charging

The chargers permanently installed on my boat run off of my shore power circuits. I am getting power at my shore power inlet and ELCI breaker, but there seems to be a problem with my isolation transformer, or possibly the automatic switch that directs the isolation transformer output to my 230V breakers. It's going to take some time to diagnose and fix this. I'm leaving next week for a few weeks. So I was thinking I could buy a 24v 5a victron charger and plug it into a 110V outlet with an extension cord and just clip it to the house bank in the mean time.
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Old 29-10-2022, 08:52   #8
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Re: 24v lifepo4 bank charging

Quote:
Originally Posted by Muaddib1116 View Post
The chargers permanently installed on my boat run off of my shore power circuits. I am getting power at my shore power inlet and ELCI breaker, but there seems to be a problem with my isolation transformer, or possibly the automatic switch that directs the isolation transformer output to my 230V breakers. It's going to take some time to diagnose and fix this. I'm leaving next week for a few weeks. So I was thinking I could buy a 24v 5a victron charger and plug it into a 110V outlet with an extension cord and just clip it to the house bank in the mean time.
I donít think itís a good idea. LFP doesnít want to be fully charged. If you are leaving for a couple weeks only, the batteries should be just fine if you switch the main battery switch off. Disconnected they only discharge a maximum of 3% per month so even if parallel batteries discharge into each other a bit you should still find your batteries at almost the same SOC than when you left.

Do you have a Cerbo with online monitoring?


Put a system for storage mode on the project list. You can switch a charger on/off based on SOC of the battery using a Victron battery monitor.
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Old 29-10-2022, 12:47   #9
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Re: 24v lifepo4 bank charging

The charger would need to be after the bms disconnects. You can’t connect direct to battery.

Tracing ac power from inlet to panel to charger should take 30 mins.,, fix the problem.
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