Battery options for Outboard Motor

[hiphopfred]

Hi All,
I saw an older thread related to electric outboards, but it did not really have the info I needed. I am relatively new to the battery and solar world so I am looking for advice on upgrading batteries for my Torqeedo Cuise 4.0 motor. It is currently running off 6 older Trojan flooded lead acid batteries. I would love to upgrade to lithium, but I want to make sure I get the right thing without spending a fortune. Torqeedo sells a battery that would work, but it cots $5,200. I have looked at general lithium batteries, but would love to get your suggestions, and what else I would need (new charger, anything else?). I came across this battery pack built by Best Go. It looks well build, but I don't know anything about that company, and I am not sure it will work with the outboard. This is a primary motor so will be running continuously.
Thank you all for your thoughts and suggestions!

 

[TKB4]

There are a lot of DIY possibilities that would be much cheaper than that. You could get 16 of these cells bolt together add a BMS (battery management system for about $150 and you would have over 14 Kwhr compared to their about 8 kwhr for about $2300 or maybe less.

Basen Lifepo4 Battery Cell 4 Pieces Lifepo4 3.2v 105ah 200ah 230ah 280ah 300ah 310ah Lithium Ion Batteries Lifepo4 - Buy Lithium Ion Batteries,Lifepo4,Lifepo4 280ah Product on Alibaba.com

Basen Lifepo4 Battery Cell 4 Pieces Lifepo4 3.2v 105ah 200ah 230ah 280ah 300ah 310ah Lithium Ion Batteries Lifepo4 - Buy Lithium Ion Batteries,Lifepo4,Lifepo4 280ah Product on Alibaba.com

offer.alibaba.com

Or you could get180 ah cells and have over 9 Kwhr compared to about 8 Kwhr for even less. You would also want captain tape and a container like plastic storage container etc .

 

[hiphopfred]

There are a lot of DIY possibilities that would be much cheaper than that. You could get 16 of these cells bolt together add a BMS (battery management system for about $150 and you would have over 14 Kwhr compared to their about 8 kwhr for about $2300 or maybe less.

Basen Lifepo4 Battery Cell 4 Pieces Lifepo4 3.2v 105ah 200ah 230ah 280ah 300ah 310ah Lithium Ion Batteries Lifepo4 - Buy Lithium Ion Batteries,Lifepo4,Lifepo4 280ah Product on Alibaba.com

Basen Lifepo4 Battery Cell 4 Pieces Lifepo4 3.2v 105ah 200ah 230ah 280ah 300ah 310ah Lithium Ion Batteries Lifepo4 - Buy Lithium Ion Batteries,Lifepo4,Lifepo4 280ah Product on Alibaba.com

offer.alibaba.com

Or you could get180 ah cells and have over 9 Kwhr compared to about 8 Kwhr for even less. You would also want captain tape and a container like plastic storage container etc .

Thanks for your reply! I have been looking into building my own and actually how I found this forum! This certainly does seem like most cost effective route. I Just know very little about this stuff and want to make sure I do it right. What do I need to look for when considering the load that motor will draw form the battery? They mention input power of 4000 watts on the motor specs sheet. I assume this affects the BMS and batteries I would need. I need some hand holding!

 

[Hedges]

4000W / 48V = 83A
Seems like a BMS rated for 100A should be adequate.

If you got a 100 Ah battery, discharge rate would be 0.83C. Larger battery, lower rate.
Make sure the cells you select are rated for that current or discharge rate.

If you were using LA battery, usable capacity would be lower at such a discharge rate, but not such a problem for lithium.

People here feel no-name lithium batteries have "optimistic" current specs for their BMS and recommending staying under half their claimed rating. Apparently only a few high quality ones are beefy enough.
DIY you should be able select a BMS that is good, possibly select a suitable external relay. Or a control on the motor itself?

 

[TKB4]

Thanks for your reply! I have been looking into building my own and actually how I found this forum! This certainly does seem like most cost effective route. I Just know very little about this stuff and want to make sure I do it right. What do I need to look for when considering the load that motor will draw form the battery? They mention input power of 4000 watts on the motor specs sheet. I assume this affects the BMS and batteries I would need. I need some hand holding!

More basic lithium iron phosphate is considered 3.2v per cell generally for 48 volt pack you would use 16 cells in series for a nominal 51.2 volts total. Most cells come with busbars the metal pieces to connect the posts on the batteries together. Make sure the cells come with the busbars and the screws or studs and nuts for the terminals.
Most use capstan ? sp. tape to hold the cells together then place them in a container.

Next if you currently have lead acid batteries (LA) then you are only using about half or less of their capacity so instead of 8 kwhr you are actually using about 4 kwhr. With LiFePO batteries most use about 80% of their rating so a 6.4 kwhr pack would be about the same power but actually still your boat would go further because the weight of batteries would be about half probably 200-250lbs of weight savings.

So do you want about the same range as your current battery pack or more range ? consider that and the fact that the lifepo battery should last 6-10 or more times more cycles than the LA and maybe 20 years or more if not used often but kept charged every few months.

Next what Amp Hour Cells to use. When he said 1C discharge etc that means at 1 times the amp hour rating (A hr) so a 100 apr cell discharging at 1 C is discharging at 100 amps and since its 51.2 volt pack this is 5,120 watts which is more than your rated 4,000 watt input needed. Many cells can discharge at 2C or even 3C. If you got 120 air cells rated to discharge at 1 c you would have a cushion and you would have 120 times 51.2 or 6.144 Kwhr that should perform about like the LA batteries you have. Anything rated higher should just add more range and remember the range should also stay near new for many years.

I would just search for relatively better buys on the cells on alibabba and ali express. There are some companies that stock chines cells in US etc where you can get them in a week or less but you pay more for this privilege. There are even cells on amazon. CALB is considered a good brand and many here have ordered EVE cells. Also make sure you ask for GRADE A cells that are new.

A 100 amp BMS should work well as he mentioned there are several brands many use Dahli and others Even Battery Hookup sells their own brand now. If you ever use or charge your batteries at or below O degrees centigrade or 32 F you might want to get a BMS with low temp cutoff . You can discharge them below that but you shouldn't charge below that.

I forgot you asked about charger. You Might need a new charger for around $300 or more or the charger you have may work as long as you have BMS. It would depend on the programming etc of your charger. I seriously doubt you would be using a charger that charges too fast. I have used a 48v golf cart charger meant for LA on Lithium with a BMS. Without a BMS you might overcharge and damage the cells. Equalization is another topic to be considered but not as complicated as it may seem.

Sorry this is so long but not sure how much help you need.

 

[TKB4]

4000W / 48V = 83A
Seems like a BMS rated for 100A should be adequate.

If you got a 100 Ah battery, discharge rate would be 0.83C. Larger battery, lower rate.
Make sure the cells you select are rated for that current or discharge rate.

If you were using LA battery, usable capacity would be lower at such a discharge rate, but not such a problem for lithium.

People here feel no-name lithium batteries have "optimistic" current specs for their BMS and recommending staying under half their claimed rating. Apparently only a few high quality ones are beefy enough.
DIY you should be able select a BMS that is good, possibly select a suitable external relay. Or a control on the motor itself?

So look for at least 100 Ahour cells I would prefer at least 120 Amp hour with at least a 1C discharge rating . Anything 100 or above will provide the 4,000 watts at 1C discharge but the more Amp hours the more range etc and the size of the cells will be a little larger and heavier. Make sure and get busbars included and terminal attachments. You will need 16 cells. You can watch some of Will Prowse battery build to get an idea how to build them from you tube. He is the head moderator of this forum also.

 

[Hedges]

Lots of people here buy 280 Ah cells. Not exactly "A" grade, but they are measuring 270 Ah.
I don't think prices are much higher than for 100 Ah. Think what you could do with the extra capacity ... sure beats rowing if you encounter a headwind on the way home.

 

[TKB4]

Yes and that large say 180 Amphours or more it wouldn't really matter if they were Grade A. The problem with non grade A cells of any capacity is they could actually be used cells that have already degraded say 10 % and in my opinion will degrade the next 10% much faster than the first 10 %. so you may get almost the full initial rating they wont last as many cycles but that would be mainly for daily solar use for the boat motor I doubt it would ever matter even using it twice a week or 100 times a year itchy should die of old age and not cycling.

 

[hiphopfred]

More basic lithium iron phosphate is considered 3.2v per cell generally for 48 volt pack you would use 16 cells in series for a nominal 51.2 volts total. Most cells come with busbars the metal pieces to connect the posts on the batteries together. Make sure the cells come with the busbars and the screws or studs and nuts for the terminals.
Most use capstan ? sp. tape to hold the cells together then place them in a container.

Next if you currently have lead acid batteries (LA) then you are only using about half or less of their capacity so instead of 8 kwhr you are actually using about 4 kwhr. With LiFePO batteries most use about 80% of their rating so a 6.4 kwhr pack would be about the same power but actually still your boat would go further because the weight of batteries would be about half probably 200-250lbs of weight savings.

So do you want about the same range as your current battery pack or more range ? consider that and the fact that the lifepo battery should last 6-10 or more times more cycles than the LA and maybe 20 years or more if not used often but kept charged every few months.

Next what Amp Hour Cells to use. When he said 1C discharge etc that means at 1 times the amp hour rating (A hr) so a 100 apr cell discharging at 1 C is discharging at 100 amps and since its 51.2 volt pack this is 5,120 watts which is more than your rated 4,000 watt input needed. Many cells can discharge at 2C or even 3C. If you got 120 air cells rated to discharge at 1 c you would have a cushion and you would have 120 times 51.2 or 6.144 Kwhr that should perform about like the LA batteries you have. Anything rated higher should just add more range and remember the range should also stay near new for many years.

I would just search for relatively better buys on the cells on alibabba and ali express. There are some companies that stock chines cells in US etc where you can get them in a week or less but you pay more for this privilege. There are even cells on amazon. CALB is considered a good brand and many here have ordered EVE cells. Also make sure you ask for GRADE A cells that are new.

A 100 amp BMS should work well as he mentioned there are several brands many use Dahli and others Even Battery Hookup sells their own brand now. If you ever use or charge your batteries at or below O degrees centigrade or 32 F you might want to get a BMS with low temp cutoff . You can discharge them below that but you shouldn't charge below that.

I forgot you asked about charger. You Might need a new charger for around $300 or more or the charger you have may work as long as you have BMS. It would depend on the programming etc of your charger. I seriously doubt you would be using a charger that charges too fast. I have used a 48v golf cart charger meant for LA on Lithium with a BMS. Without a BMS you might overcharge and damage the cells. Equalization is another topic to be considered but not as complicated as it may seem.

Sorry this is so long but not sure how much help you need.

Wow! Thank you for all this detail. I need a lot of help so this is wonderful. More range would be better, but my current setup does not really give me away to monitor how much battery remains, so adding that feature to this new setup would be really helpful. It sounds like som BMS can do that over bluetooth? Thanks for the clarification on the watt input needed. That was one question I was having trouble answering. I will dig in a little more but will likely come back with more questions! Thanks!

 

[Bob B]

If you've got a couple of days .... read thru this thread. http://www.bbcboards.net/showthread.php?t=982657

 

[Terrapin]

Unrelated to capacity is the durability. I plan to use the fortune cells for on the water when the time comes. They are much sturdier at the terminals than shallow 6m screws in aluminum and are built with a case around them to prevent friction rub. The corners of the cases allow steel rods to hold them together. If you do use thee m6 terminal cells Id suggest braided buss bars to keep torqueing to a min..
cells:

buss bars:

EVTV Motor Verks Store:

store.evtv.me