24v Battery Charging Options

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sbs_59

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Currently have a 24v trolling motor that uses 2 12v batteries with a plug in on board charger. The boat will be docked in a location without shore power available. I'm looking for advice on the options for charging this system the fastest. The main motor doesn't get ran long enough for an alternator charger to be useful. Solar applications? Portable generator? Replace current system with a 24v lithium battery and take home at night to charge?
 
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airshot

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I would consider a 24v lifepo4 battery. I have been very impressed with mine. I get twice the run time from mine that I was getting from two agm batteries. Lighter in weight, less than half of the agm batteries. As for your issue with charging, solar is way to slow so without shore power, a portable genny is the only way. LifePo4 battery is light enough to take home with you, and they charge quickly with the proper charger.
 
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sbs_59

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Any idea how long it would take a generator to charge the 24v system as is? The cost of a good generator and fuel is comparable with the new battery and charger, but I could always sell the original setup to offset cost...
 
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airshot

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All depends how low the batteries are drained. When I was running dual group 31 agm batteries, they would take at least 12 hours if they were low. My Lipo battery will recharge in 6-8 hrs when really low. Also depends on charger charge rate. After two years of running my LifePo4 battery, there is nothing about agm batteries that is better than the Lipo type !
 
dingbat

dingbat

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sbs_59 said:
Any idea how long it would take a generator to charge the 24v system as is?
Click to expand...
Depends on the Ah rating of your batteries and the charger

A fully discharged battery rated at 100Ah will take 10 hours to charge mwith a 10 amp battery charger.
 
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boscoe99

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What is the main motor? What does its alternator output?

One advantage of lithium is how quickly it can be recharged.
 
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sbs_59

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It's a 115 hp Yamaha, not sure about output. From what I've gathered, the main engine wouldn't have long enough run times to utilize an alternator charger...
 
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KD4UPL

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How long is a string?
If you have 100 Ah batteries making your 24 volts and they're down half way that's 50 Ah to put back. If you have a 10 amp charger that's 5 hours. With a 50 amp charger it's one hour.
You can work the math for your particular set up. I'm oversimplifying and ignoring loss, efficiency, charge tapering, etc.
 
dingbat

dingbat

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KD4UPL said:
If you have 100 Ah batteries making your 24 volts and they're down half way that's 50 Ah to put back.
Click to expand...
If you’re at 50% on a 24V system your down 50Ah in each of the two 12V batteries for a total of 100 Ah
 
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