1 AH means you get one amp for one hour. Power is amps times volts, so 1 amp at 12 volts is half as much power as 1 amp at 24 volts.
Amp-hours only makes sense when comparing batteries of the same voltage, watt-hours is the same across all voltages. A 225 AH 12 volt lead acid battery an 8D size and is very heavy. It can supply about 120 amp-hours or so for long life in cycling mode. A 200 amp-hour lithium battery is good for maybe 180 amp-hours without damage. Rule of thumb is lead-acid should cycle at 50% and lithium can go to 80%. Joe Della Barba Coquina C&C 35 MK I Kent Island MD USA From: Bill Coleman via CnC-List <cnc-list@cnc-list.com> Sent: Thursday, July 28, 2022 3:35 PM To: Stus-List <cnc-list@cnc-list.com> Cc: Bill Coleman <colt...@gmail.com> Subject: Stus-List Re: [EXTERNAL] Re: Lithium Batteries Oh! For some reason, I thought Ah were constant, regardless of voltage - I guess maybe that is Kilowatts - So with a 200 Ah Lifepo battery vs a 255 AGM, looks like I will lose some capacity, unless that is made up with efficiency from the Lithium - . Does that make sense? Thanks Joe. Bill Coleman On Wed, Jul 27, 2022 at 2:40 PM Della Barba, Joe via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > wrote: A 100 AH 24 volt battery and a 200 AH 12 volt battery hold the same amount of power. Assuming they are using 100 AH cells, the 12 volt will have 2 sets of 4 in series in the case that are then in parallel and the 24 volt version will have all 8 in series. You could literally open the case and change a 12 to a 24 volt or back again, BMS issues aside. Don’t forget the lithium batteries in a standard-size case may not be using all the real estate inside that case either, it isn’t like lead-acid where a certain capacity means a certain size. Joe Della Barba Coquina From: Bill Coleman via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > Sent: Wednesday, July 27, 2022 2:33 PM To: Stus-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > Cc: Bill Coleman <colt...@gmail.com <mailto:colt...@gmail.com> > Subject: [EXTERNAL] Stus-List Re: Lithium Batteries These are confusing, they have a 24 V that looks similar in size to the lifeline 8D, but the 8D is 255 Ah, and the SOK 24V 100Ah LiFePO4 Battery <https://www.us.sokbattery.com/product-page/sok-24v-100ah-lifepo4-battery> is only 100 Ah - are they supposed to be equal, even with that disparity? Blil Coleman Entrada Erie PA On Tue, Jul 26, 2022 at 4:45 PM Joe Della Barba via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > wrote: I think I am going to get 2 of these: https://www.us.sokbattery.com/product-page/sok-12v100ah-lifepo4-battery Advantages I see: 1. Two of them means a dead BMS only takes half the bank offline, not 100% of your power. 2. They have heaters for the very rare times the cabin might be below freezing. 3. They have Bluetooth for access to the BMS. 4. I saved the best for last, if the BMS craps out or you just want a better one, just open it up and replace it! This is NOT possible with most batteries unless you cut them apart. 5. See 4, a dead cell can be replaced. Joe Della Barba Coquina C&C 35 MK I Kent Island MD USA
