dgadee
Well-Known Member
I have just remembered I saw a neighbour out cutting his grass with a battery powered mower - one made by a tool manufacturer (Lawn Mowers | Garden Tools | Ryobi). Is this the future for outboards, too?
Lithium battery for trolling motor
- Thread starter Kelpie
- Start date
andyj301
Active Member
Same as your 68lb. Current measured with a UNI-T UT210E clamp meter
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andyj301
Active Member
I bought 2 of US $407.68 25% OFF|12v 100Ah Deep Cycle Lifepo4 Lithium Iron Phosphate battery pack BMS Built in for Golf cart EV RV Solar energy storage battery|Battery Packs| - AliExpress to replace the 300ah SLA I had. Was looking at Leoch GTP 12110 but for a fraction of the weight and not much more cost I decided to take a punt. Very much buyer beware and they took about 2 months to arrive, but the site is offering ebay like buyer protection and the company had good feedback on this item. I have had the batteries for about 4 months now, one in my boat and one for dinghy. Although the 20A charger i purchased is actually 10A.
Kelpie
Well-Known Member
Thanks, that's very useful info. So it looks like I could get away with a smaller battery.
JumbleDuck
Well-Known Member
Many thanks. $400 ex-Chana still on the ouch! side for me, but heading in the right direction.
Kelpie
Well-Known Member
$400 for a battery that will have the motor screaming at full power for two hours...
I'm seriously contemplating the Winston 20Ah pack (Shop GWL | Lithium Battery LiFePO4 (12V/20Ah)).
Works out about £160 inc vat and shipping, for the bare pack. Can discharge at up to 60A so enough for my motor, although it will only provide full throttle for 20mins. If it's just for tootling the mooring and back, that's enough. Weighs 3.5kg so I would look at a way of strapping it on to the motor itself. I'd need to budget for a charger, probably something fairly smart since it would be working with no BMS. And preferably some sort of low-voltage cutoff device.
Other packs are available, giving much better Ah/£. But once you move away from the Winston ones you find that they don't have the high discharge rate, so you'd need a 60Ah battery minimum.
I'm seriously contemplating the Winston 20Ah pack (Shop GWL | Lithium Battery LiFePO4 (12V/20Ah)).
Works out about £160 inc vat and shipping, for the bare pack. Can discharge at up to 60A so enough for my motor, although it will only provide full throttle for 20mins. If it's just for tootling the mooring and back, that's enough. Weighs 3.5kg so I would look at a way of strapping it on to the motor itself. I'd need to budget for a charger, probably something fairly smart since it would be working with no BMS. And preferably some sort of low-voltage cutoff device.
Other packs are available, giving much better Ah/£. But once you move away from the Winston ones you find that they don't have the high discharge rate, so you'd need a 60Ah battery minimum.
Poey50
Well-Known Member
Worth noting that these cells appear to need an initial charge of 15 volts. Presumably this is some kind of one-off activation process. (The same was true for my cells - 3.65v being the required figure.) Then 14.8v is the recommended routing charging. However their recommended (5 amp) charger is 14.4v. So as previously said it might be worth getting some clarification on all this from GWL technical department. In general all charging for LFP is the same and simple. You charge to the target bulk voltage and stop. So any charger that can get to the target bulk figure is fine as long as you can stop it. Few chargers do that so buying an LFP specific one that does is useful or an accurate programmable voltage sensing relay. I got a cheap Kavanavo charger on AliExpress that charges to 14.6v at around 15 amps and stops. That might work for you.
Edit: 10 amps is for regular charging (0.5C), 20 amps absolute (i.e. life-shortening) maximum. So I'd be looking for a 10amp charger.
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Kelpie
Well-Known Member
Thanks... I've barely even begun looking in to the whole charging issue.
My lead-acid charger has gone walkies so I need to buy one anyway for bench charging old car batteries.
It would seem to make sense to get something that will not only do that, but also work with whatever LFP I end up getting. I'm not sure what that entails though, prices start at about £20 on eBay for Chinese chargers that claim to work with every sort of battery. I guess it's worth spending a bit more than that though? I'd like to have some control over voltage and timing for different stages of charging.
My lead-acid charger has gone walkies so I need to buy one anyway for bench charging old car batteries.
It would seem to make sense to get something that will not only do that, but also work with whatever LFP I end up getting. I'm not sure what that entails though, prices start at about £20 on eBay for Chinese chargers that claim to work with every sort of battery. I guess it's worth spending a bit more than that though? I'd like to have some control over voltage and timing for different stages of charging.
Poey50
Well-Known Member
If you plan to buy a pair of them, and take home the discharged one to charge, AND you are considering building an LFP pack from cells (and will therefore need to charge to 3.65v to top balance, then a bench top power supply unit would be a good buy. You can set the target voltage on the PSU and know that once the constant current stage is over the target voltage will be held steady. (You don't of course want a long constant voltage (absorption) stage but at least you don't have to manually intervene to prevent the voltage rising.) So you can use that for 15v, 14.8v, 3.65 v - anything.
I have this one after seeing a very strong professional review on it. It's about £10 cheaper now than when I bought it. DC Power Supply Variable,0-30V /0-10A,（precision 00.01V，00.01A）4-Digital LED Display Adjustable Switching Regulated Power Supply Digital,with Alligator Leads UK Power Cord Used for Spectrophotometer: Amazon.co.uk: Business, Industry & Science
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Kelpie
Well-Known Member
Thanks again. That power supply looks a really handy thing to have, much more versatile than any charger.
I'm trying to narrow down my options for the trolling motor battery.
1) good old lead-acid, a 16kg lump would give me about half an hour endurance and cost next to nothing. A pain to lug back and forth from the dinghy though.
2) a 60Ah LFP in a rugged case, about £230 from AliExpress (e.g. US $301.6 20% OFF|Waterproof 12V 60Ah 80Ah 100Ah 120Ah 130Ah 150Ah 180Ah Lifepo4 Battery with BMS for Trolling Motor Solar System+10A Charger|Replacement Batteries| - AliExpress) This is very tempting, it's supposedly waterproof, comes with a charger, has a voltage meter on the side, etc. A third the weight and double the endurance of the lead-acid.
3) build my own pack and put it in a suitable case, e.g.Pela. I'd be more confident that this would actually be waterproof. But a bit more to get my head round, e.g. choosing the BMS (or not having one) and how to charge it.
I'm trying to narrow down my options for the trolling motor battery.
1) good old lead-acid, a 16kg lump would give me about half an hour endurance and cost next to nothing. A pain to lug back and forth from the dinghy though.
2) a 60Ah LFP in a rugged case, about £230 from AliExpress (e.g. US $301.6 20% OFF|Waterproof 12V 60Ah 80Ah 100Ah 120Ah 130Ah 150Ah 180Ah Lifepo4 Battery with BMS for Trolling Motor Solar System+10A Charger|Replacement Batteries| - AliExpress) This is very tempting, it's supposedly waterproof, comes with a charger, has a voltage meter on the side, etc. A third the weight and double the endurance of the lead-acid.
3) build my own pack and put it in a suitable case, e.g.Pela. I'd be more confident that this would actually be waterproof. But a bit more to get my head round, e.g. choosing the BMS (or not having one) and how to charge it.
dleroc
Well-Known Member
In my experience of using a battery operated outboard I would be mostly concerned about it's use in salt water. The one I had corroded very quickly although the golf cart battery was ok for short usage.
JumbleDuck
Well-Known Member
mogmog2
Well-Known Member
That's really interesting, thanks.
What level of discharge do you let it drop to?
How do you recharge it whilst cruising?
RupertW
Well-Known Member
As a Torqueedo user for 6 years (first 3 with a heavy 3m rib with up to six people and luggage) it’s really good to see that trolling motors plus light batteries are getting closer to its performance at a small fraction of the cost (the Torqueedo uses 80amps at full throttle but we rarely use more than half that).
It’s long overdue that somebody produces an integrated trolling motor and battery package to imitate Torqueedo and bring all prices down - or more innovation from Torqueedo to allow them to keep the price advantage.
It’s long overdue that somebody produces an integrated trolling motor and battery package to imitate Torqueedo and bring all prices down - or more innovation from Torqueedo to allow them to keep the price advantage.
JumbleDuck
Well-Known Member
Used cautiously, it has never run out, but we don't have any accurate measure of discharge. Bottom light on the motor, for what that's worth.
I have yet to work out the cruising issue - my crew bought the motor with saved-up pocket money after kind neighbours at Ulva Ferry loaned one last year and what with one thing and another I never got round to making it a home on th eboat. My current vague plan is to give it a shelf in the stern locker and feed it with a VSR off the house battery.
fredrussell
Well-Known Member
having been on Andrew’s elec powered dinghy I have to say it’s a revelation. Hard for me to see why anyone would spend twice the amount on a Torqueedo. My current Honda 2.3 will be the last petrol outboard I own. Just such a faff compared to electric.
Kelpie
Well-Known Member
I've still not made any decisions on powering the trolling motor. The more I learn about batteries, the more it seems you have to spend. Sometimes ignorance is bliss! I think initially I will just use one of my old car batteries, a bit heavy but will get me going while I figure out something better.
GHA
Well-Known Member
Wouldn't dream of an electric outboard on a cruising boat, hard enough as it is to get the batteries charged every day
How do you get to the reef for a snorkel miles away and back?
Oh, remembered, jump in with the yanks anchored next to you and their rib with a 20 horse on the back
mogmog2
Well-Known Member
Thanks. We'd get worse runtimes anyway with a bendy avon + 2 on board, but it's definitely interesting. I was hoping my mercury 2hp would last until electric became viable, but the future is upon us and maybe I should flog it whilst it still has some value!
I'm trying to drag myself up to speed with 12v charging systems as I was stuck in the 80's?. I'm rolling out a small, simple solar setup, possibly 140W total and hopefully that will contribute usefully but also low on detail ATM.
mogmog2
Well-Known Member
That was an approach I'm seriously considering too.
