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24 Volt Battery


Dick N

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No. You have a 12V system and while it is very easy to connect 6V batteries in series to get a 12V output, it would be pretty challenging to split one 24V battery into two parts in order to get 12V out. It isn't impossible but it is impractical.

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24 volts is fine in its place, and, of course, could mate up in parallel to two 12's in series, but do you have 24 volt loads??? Its possible to do what you ask subject to load applications. Years ago when there were still mixed 6 and 12 volt applications in order to tap 6 volts from a 12 volt battery they used to drill down through the case to insert an electrode in the middle. Some of the older GMC 4104 etc busses at a Busnuts rally I attended charged at 24 volts but that was into two 12's in series, each of which could still power 12 volt loads (not my ideal method). Also anytime you start coupling batteries I recommend they be of the same age, size, design etc. to achieve better balance in charging and loading, and so one doesn't rob from or cannibalize the other.

 

Short answer yes its "possible" but I don't understand the application.

 

John T

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Short answer yes its "possible" but I don't understand the application.

 

John T

Here is the application. I have four lithium 12v storage battery's and have an opportunity to purchase a 24v lithium battery with double the amp hours for a great price. Alas, will not work.

 

Dick

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Dick, you need to ask that question to some of the fine gents here who are more familiar with Lithium batteries. While my generic answer is I believe basically accurate HOWEVER I was under the impression Lithium batteries are comprised of several cells in series and perhaps you might center tap where 12 VDC is available (you could derive 12 volts that way), BUTTTTTTTTTTTTTTTT still you need to charge the 24 volts, CAN YOU DO THAT????. Sure you can still parallel a 24 with two 12's in series.

 

Sorry, I have to pass on this one but still a good subject

 

John T

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Might do a split DC system, feed 24 volts to the inverter from the big lithium battery and provide 12 volts from the existing 12 volt battery.

 

That makes charging interesting as you need two charging systems to manage the two batteries but it is certainly possible.

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Might do a split DC system, feed 24 volts to the inverter from the big lithium battery and provide 12 volts from the existing 12 volt battery.

 

That makes charging interesting as you need two charging systems to manage the two batteries but it is certainly possible.

 

Hmmmmmmm! Stan, now you have me thinking. We have a residential refrigerator. What if I put in another inverter dedicated to the refrigerator and used the 24 volt lithium battery just for the refrigerator totally divorced from the 12 volt pack. Now, all I have to do is figure out how to charge the 24 v battery. This may get into the "too hard category".

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This may get into the "too hard category".

 

I don't know about "too hard", but it would certainly be cost prohibitive if you're talking a 24v charger (inherently more expensive than 12v chargers), dedicated inverter, additional BMS, dedicated wiring. I would hazard to guess that any savings you might see in the reduced battery bank would be eaten up by the independent charging system. In that case.. you might be better served by simply increasing the size of your existing 12v bank (providing that's even practical depending on the current age of your existing cells.)

 

Depending on your charging method and equipment, it "may" be 24v capable (although not likely.. it couldn't hurt to check). In which case you could rewire the existing bank into a 24v system and then just use a regulator to step down the voltage for house use. There are a lot of "IFS" in doing that. As John mentioned.. charging and discharging across the full bank would be compromised to a degree.. but all told.. you might still be ahead in terms of AH's with the 'give and take' being a shortened battery life.

 

If you're hurting for power reserves.. adding in an additional 12v bank for dedicated use for your reefer has some merit.

 

As far as the 24v cells go though.. personally, I would take a pass.

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As far as the 24v cells go though.. personally, I would take a pass.[/quote

 

 

Yarome, I think you are correct. In spite of the good deal on the 24v lithium battery, I will pass on it. Although, after all the excellent input, I believe I could make it work. Just not willing to take this project on. Thanks everyone.

 

Dick N

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  • 2 weeks later...

Nuke-e who is usually in the HDT forum section, is working on a 48 volt system using a lithium battery out of Volt. Maybe some of the items he is doing can work for a 24v system. You can read up on it at this link:http://rvnerds.com

Dave

 

Thanks a bunch for that link, Dave. That was interesting reading. Yes, it would be possible for me to convert. But will stay with my 12v lithium pack for now. I have too much equity into the 12v side of things.

 

Dick N

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As Yarome noted, you could go to a 24 V (nominal) system by putting the 12 V batteries in series and then in paralle with the 24 V LFP. You would then use a Meanwell 24 V to 12 V converter. Your alternator would not charge the system though.

 

We have four 12 V (nominal) 2.2 kW-hr batteries in series for a 48 V (nominal) battery suite. The voltage from solar panels is 90 V and the controller drops this to 48 V. We have a 508 W Meanwell 48 V to 12 V convedrter. The alternator from the tow vehicle is not used. We do have a 1.5 kW battery charging system which we can use if we want to charge the battery suite (dumped the 50 amp, and then the 30 amp cables) with a 15 amp power cord.

 

We are purchasing a Roadtrek 190 as an alternate RV.. There are to many places in Canada, Mexico, and USA where our 34' 5th wheel will not go. And if it does go, we could probably never get out again (found this out a month ago in San Miguel del Allended - and CHurch's book definitely warned about taking the wrong turn - I have been in the dog house since then as I went with the GPS and Elaine went with memory; she was correct). Son will look at vehicle this next week, and determine solar panel and battery requirements. We will use either one or two of the LFP batteries instead of the four we currently use. He is considering going to parallel 12 V for the smaller Roadtrke but may decide on 24 V if he decides we need the energy storage. Probably can get a maximum of 300 to 400 W of panels as opposed to current 1400; but then it is a much smaller vehicle and we do not plan to run AC on solar/batteries

Reed and Elaine

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I guess you could just put a 24 V to 12 V converter on the 24 V battery and run things in parallel. Mayhaps there are reasons this may not work. Just talked with son and he is looking at a 24 V (nominal) for our about to be purchased Roadtrek

How about this? Dick N

 

http://www.ebay.com/itm/NEW-DC-DC-24V-to-12V-5A-60W-Step-Down-Regulator-Module-50W-Voltage-Converter-/331841744520?hash=item4d434f2e88:g:4yUAAOSwx-9WyOtb

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I went to 24v, then up again to 48v. Victron makes some nice DC-DC converters to keep the coach at a nice steady 12.5 (or whatever you like). Keeps the lights from flickering or burning something up when equalizing.

I guess it depends on your rig...what are you doing about high amp 12 volt loads? Or don't you have any? I'm thinking of the hydraulic pumps, in particular (for slides and levelers). I agree on the Victron, but they only go up to 70 amps/12 volts (if I recall correctly).

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I guess it depends on your rig...what are you doing about high amp 12 volt loads? Or don't you have any? I'm thinking of the hydraulic pumps, in particular (for slides and levelers). I agree on the Victron, but they only go up to 70 amps/12 volts (if I recall correctly).

Yes Jack I remember you do have much higher loads. 360 watts works fine for me for the slide motors.

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A converter for 24 V to 12 V is a simple enough fix. Would not want to dismantle a 24 V battery into componente parts.

 

We have 48 V battery suite (as noted above) in our 5th wheel since the voltage from panels is 90 V. Son is designing a solar/LFP system for our new (2002) Roadtrek and since the run from panel to controllers (one from 315 W panel and one from 100 W panel - there is limited space on a Roadtrek roof) is fairly short, he plans to have a12 V battery suite.

 

LFP fabrication and fabricators have changed in the three years since son fabricated our 5th wheel. Have been checking the web for current LFP and frankly, Manzanita Micro still looks good as far as costs go. Have noted that most RVers are going with Lithionics and Starlight Solar. Son is in contact with SimliPhi and they seem to have some good solutions. Should appreciate any knowledge and/or advice on this subject.

Reed and Elaine

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