Re: [electricboats] Replacing FLA Batteries with Lithium in Duffy Electric Boat

Hi Rob,

No problem, I know there's allmost no info on Duffy's to get by.

I discovered that the so called "problems" of BMS's are mainly mentioned with batteries that are self build. It got me also confused in my search of batteries. 

Remember, each Voltium battery has his own BMS. I was also concerned about the balancing of the cells in perticular in the balancing between the three batteries. I contacted the seller and they said not to worry about the balancing between the batteries, because each of them has his own BMS. So they act like three solo 12V batteries with each having there own BMS. 

At the end of the charging time all three batteries are full, 100 %.

I am charging my batteries, as you can see, connected together in the Duffy, in serie with one Zenith 36V Lifepo4 charger. When the Zenith charges it charges each battery 12V and about 20 A for each battery. After the batteries are full they go in a floating charge state a short time and then they stop getting charged because the batteries are fully charged.

I don't have problems with balancing or disbalancing from the cels in each individual battery. However I do experience some difference in Charging to fully loaded batteries, It differs sometimes in maximum charging percentage of the batteries which shows in the app from Voltium. So like I said, the batteries charge mostly too 100 % but sometimes they are different, so 100%, 99% and 98%. 

I also have another charger, a Victron Energy blue smart Li-ion (see picture) which I use ones in a while to fully charge one batttery at the time on 12V 30A to be sure that all batteries evantually are equaly charged, as in the same percentage. After doing that to each battery, I place the batteries back in my Duffy and connect them in series again and charge them through the Zenith again.

I have these Batteries almost a year now and they have had 20 charging cycles now. I use the, I think original, Curtis 1204 36V controller, which was allready in my boat. I tried, when I bought the Batteries, to switch to 48V but that would require a different type of controller, in this case the Curtis 1205, and offcourse an extra battery .

Now about your range, that depends offcource how much Amperage your motor pulls at maximum throttle. I think you can theoraticly calculate how much range you have. 

For instance, I pull allmost 60AH at full throttle, which, in my opinion, will pull about 60 amp from my batteries in one hour. That is 180 Ah in 3 hours which leaves about 20Ah, after three houres. But I never pull that much Amps during normal trips, mostly between 20 Amp and 40amp, so that's why I have more then enough range.

What kind and year of Duffy do you have? And in perticular, what kind of 48V(?) motor do you have?

Roland

https://www.nocoev.com/product/curtis/manual/1204m1205m_n.pdfV

Mseries text - nocoev.com Curtis 1204M/1205M/1209M/1221M Manual 3 2 — INSTALLATION & WIRING 2 Fig. 2 Mounting dimensions, Curtis 1204M and 1205M motor controllers. Dimensions in millimeters. www.nocoev.com

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Van: electricboats@groups.io <electricboats@groups.io> namens Rob Houston, W0WKO <rahouston@gmail.com>
Verzonden: vrijdag 13 mei 2022 12:21
Aan: electricboats@groups.io <electricboats@groups.io>
Onderwerp: Re: [electricboats] Replacing FLA Batteries with Lithium in Duffy Electric Boat

 

Roland, thanks------this is very helpful!

I've read that having LifePO4 batteries in series is problematic for the individual BMS's.  Are you using a single 36V charger for the batteries?  A LifePO4 charger, perhaps?  Have you had any problems with cell balancing during charge or discharge?  How long have you had these batteries?  Are you perhaps using the older Curtis controller?

Your range is pretty close to what I'm trying to achieve.  I've been looking at one 48V 150Ah to achieve 3-4 hours of cruising with some reserve remaining.   Like you, I have no interest in worrying about being stranded.  

Thanks again for your helpful information!