e-bike battery for hookah dive system

[zeiler]

I live on a sailboat currently in Malaysia and would like to power a Hookah diving compressor made by Brownie with a Li FePO4 battery. The 24v compressor is rated at 0.75HP and normally sold with two SLA Odyssey 28ah 12 v batteries.

Peak current is 25 amps and avg is 19.8 amps.I assume that I can get more power out of the Li battery, draw it down more, and think that a total of 20ah at 24 volts would be roughly equivalent. The demands for this use should be less than for an e-bike since diving or boat maintenance will be sporadic.

I am located in Malaysia and would therefore like to find a e-bike battery supplier in SE Asia. My main issue is quality. There are thousands of suppliers of these things on various internet sites and I have no way of judging the quality of the batteries or bms's they resell or produce. Because of problems finding supplies on the island I'm located (Pulau Langkawi) I do not want to make my own battery but prefer to buy one already encased. (Living in North America is like paradise when one wants or needs to either make or buy stuff! There are no electric bikes or electric bike sellers on the island.

I am thinking of using two 24v 10 or 15ah battery packs as made for e-bikes in part because of their mass production and in part because of storage concerns on a sailboat. The compressor will be operated from a dinghy so storage in the dinghy with possible salt water around is also to be considered. I am thinking of mounting the battery cases on the inside of the transom while diving with a splash cover if necessary and removing them to the sailboat when not in use. I can charge them from a 110v inverter on the boat.

Does anyone know of a reliable manufacturer of e-bike batteries in a case located in Taiwan or China? Or does anyone have better ideas?

 

[dogman dan]

The box to put the battery in is the least of the problems. Any watertight container the right size will do fine, so stop obsessing about the case. Typical bike 10 ah batteries in a metal box aren't particularly well sealed for a marine enviroment anyway.

So do better with your own watertight box, even if homemade. Make it roomy, so the bms can cool when you use it, or charge it. Locate the charger outside the box, or open it to charge. The charger really needs cooling air.

Then just get a 24v 20 ah pouch cell lifepo4 from a decent vendor. It will meet your amps requirements ok. No smaller. Easier than tying two 10 ah packs together anyway.

The one I particularly trust is Pingbattery.com. But others on Ebay are cheaper, without the reputation for customer service if there is a defect. Most of the battery vendors ship from china btw.

 

[Gordo]

Last summer I built a 12V supply for a dive compressor using 4 x 100Ah Thundersky Cells. The original battery was an 8-D which lasted @ 30 minutes. The new battery lasts 90 minutes and weighs @ 1/5.

http://www.everspring.net/product-battery.htm

 

[dogman dan]

Larger prismatic cells would be the way to go, if he wanted more run time. I believe you can get the TS in 20 ah size though. If he has the money, 50ah would allow him to run the battery with much less strain on each cell, theoretically greatly extending the lifespan of it.

But even with just a smaller pingbattery, he'd be very likely to get a pretty good lifespan. 500 or even more cycles, up to 1000 possible. That's quite a few dives. Buck a dive or close to it, plus the nickel to recharge.

 

[Grey beard]

Having been a boater for most off my life, I shy away from things that are not built for the marine environment with its high corrosion. The other thing I shy from is things that may cause fires. There is a history of these lightweight batteries catching fire, sometimes spontaneous, and sometimes when charging. The % isn't huge, and some batteries are better that others.
On a boat, the only % to shoot for is zero.
I would stick to LA or SLA batteries myself.

 

[dnmun]

that is not true. there is no 'history' of lifepo4 packs catching fire. that is an outright false statement.

any battery can short out and catch something on fire, so SLA will be the same risk. but lifepo4 do not catch fire even when overcharged or over discharged.

if your boat generator puts out up to 30V then you can charge directly from the generator on the motor. without using the inverter. for a 24V lifepo4 pack you need 29.2-29.6V to fully charge it. if you can only charge it part way up with the generator then you can finish using an inverter to drive the charger.

 

[Grey beard]

Go to the right hand, top of the page, search, and type in fire.

Dnmum
"that is an absolute false statement". REALLY? I think that is the most disingenuous statement I've seen on here. Especially when I've seen your coments in threads about fires.

In this case he lives on the boat. In his own words, "Maintainance will be sporadic." Fires on boats can be life threatening, and not a good place for this technology.

 

[dumbass]

Go to the right hand, top of the page, search, and type in fire.

Dnmum
"that is an absolute false statement". REALLY? I think that is the most disingenuous statement I've seen on here. Especially when I've seen your coments in threads about fires.

In this case he lives on the boat. In his own words, "Maintainance will be sporadic." Fires on boats can be life threatening, and not a good place for this technology.

Personally, I see nothing wrong with using lifepo4 cells on a boat provided they are properly setup in the first place with proper safety factors built it. As Dnmim points out all bateries can cause a fire including SLAs. There is little to no maintainance required on a properly built lifepo4 pack. Build it right for your personal needs and it will perform with no problem. If your worried about a lifepo4 cell catching on fire you better stop putting that cell phone up to your ear.

Bob

 

[Gordo]

The only way you can get close to zero risk is to paddle an empty aluminum boat. No fuel, no electricity, no wood an no clothes. Having seen the results of several LA explosions and witnessed one, your statement must come from pure ignorance?
What powers the boat in your avatar? Nice Corvair powered by what?

Having been a boater for most off my life, I shy away from things that are not built for the marine environment with its high corrosion. The other thing I shy from is things that may cause fires. There is a history of these lightweight batteries catching fire, sometimes spontaneous, and sometimes when charging. The % isn't huge, and some batteries are better that others.
On a boat, the only % to shoot for is zero.
I would stick to LA or SLA batteries myself.

 

[Jeremy Harris]

We've been through this whole risk thing before. If anyone cares to research the number of explosions caused from gassing lead acid batteries, or the number of violent reactions from lead acid batteries meeting seawater, they'll find there are hundreds, perhaps thousands, of such incidents on boats.

My electric boat has been running safely on first generation Headway LiFePO4 cells for a couple of years, not a hint of a problem. The key is safe design, exactly as is required with any other energy storage system, be it a battery, fuel tank or gas cylinder.

If you design systems to be safe then that's as good as you can do. You can't remove the risk, but you can mitigate them, just as we have to with old lead acid battery technology, fuel tanks or gas bottles, or even diving bottles/compressors.

 

[ebent]

I'm also thinking LiFePO4 is the best choice. I'd give any fuel source the full marine treatment. Marine treatment meaning no short cuts, brand name with good history. Think safety first, price second. Anything less is foolish. Like Jeremy says there is more danger in a bad sla setup. I need to hear more about your electric boat please, Jeremy. Perhaps a link?

 

[dogman dan]

Part of why I didn't recomend lipo, and part of why I didn't recomend trusting the waterproof properties of a cheap bike batteries case.

I should have been more specific about the box though. I just figured the guy was not stupid, and would make it a watertight box. Ammo can for example, or maybe a good aluminum case with a gasket. Good grommets of course for the wiring exit.

I've heard of lifepo4 fires from a dead short. And had a truck of mine burn down from a lead acid battery dead shorted. So yeah, don't short the battery with a flaky wire.

 

[Grey beard]

The only way you can get close to zero risk is to paddle an empty aluminum boat. No fuel, no electricity, no wood an no clothes. Having seen the results of several LA explosions and witnessed one, your statement must come from pure ignorance?
What powers the boat in your avatar? Nice Corvair powered by what?

Having been a boater for most off my life, I shy away from things that are not built for the marine environment with its high corrosion. The other thing I shy from is things that may cause fires. There is a history of these lightweight batteries catching fire, sometimes spontaneous, and sometimes when charging. The % isn't huge, and some batteries are better that others.
On a boat, the only % to shoot for is zero.
I would stick to LA or SLA batteries myself.

If something happens to the Corvair when I'm out abusing it, I can throw it in neutral, coast to a stop, get out, and if it's burning down I can get out my cellphone and get some pictures. When I destroyed the hydro in '77, the safety crews where there in seconds. If my cellphone catches fire I can throw it down. If my bike catches fire while I'm on it, I can get off, throw it down, and use my phone to take pics. If the bike spontaneously combusts in the garage and sets the house on fire, I can walk out the door, join my neighbors, and watch the firemen.
If my boat catches fire halfway to Alaska from Seattle, and I can't get it out, I could die. There is often nobody within hundreds of miles. I've been in motorsports for 50 years, and owned a twin diesel cruiser for 30. You do everything you can to minimize fire risk. Halon, no other fuels but diesel. You can't walk out the door and watch. In my years of motorsports I've seen quite a few LA batteries pop. They make a nice bang, split the case, spray acid all over, but Ive never seen one cause a fire. The little bit of hydrogen goes off and then it's all acid/ water mix, and it a mess, and much swearing and unhappiness occurs.
The hooka dive system he has, was designed to work with LA. Now we're are going to redesign a whole new system. Batteries, enclosure, bms, chargers, none of which are designed with a marine environment in mind. So you sail 30-40 miles to go diving, get in the water and the air stops flowing, you come up and take a look and see fire. It's your home and transportation rolled into one. Me, I'd replace the LA batteries, and if I wanted more time, get a couple more. Weight is not an issue on a liveaboard sailing boat. I love being on the water, but it's a bitch to walk home on.

 

[Dauntless]

that is not true. there is no 'history' of lifepo4 packs catching fire. that is an outright false statement.

Now THERE'S a statement you don't see everyday. At least not on ES.

http://endless-sphere.com/forums/viewtopic.php?f=1&t=593&p=663132&hilit=rocket+fuel#p663132

Dang, I tried and I TRIED to not make this joke, but it's killing me.

. . . .Tell them a hookah smoking catapillar
has given you the call.
-White Rabbit Jefferson Airplane

 

[dogman dan]

I'm not poo pooing the risks. You are absolutely right that out on the water requires an extra layer of caution. I totally understand the concept, since I'm a licenced pilot. In your scenario, you at least could perhaps inflate a BC and float awhile. In the air, you better fix shit in a few seconds. So no flakey jake shit in the air of course.

But it is true, that lifepo4 just doesn't readily burst into flames. The primary risk is the same one that burned my truck, a big fat short caused by some worn down insulation on a wire. Same risk for any chemistry. It would be mandatory to keep the salt outta the bms, just like it's crucial to keep it outa yer radio. But if the bms fails, it simply doesn't mean a battery fire is inevitable. Not with lifepo4.

The prismatic cells recomended by others should add another layer of safety, with the actual cells contianed in a plastc box.

One thing should be considered. If a bms is used, then there is a definite risk of overdischarge or bms failure resulting in a bms cutoff. You sure wouldn't want to be without a tank at that point. Not if you need to come up slow. You might notice air getting weak with a lead battery, but a bms cutoff would shut off the hooka completely with no warning. So like pilots have redundant systems in case of mechanical failure, divers do the same thing, or die.

 

[ebent]

To add to the redundancy for safety buy one of these http://www.spareair.com/ Extra air when you need it.

 

[zeiler]

Well everyone thanks for all that feedback! If I was not cognizant of the added danger of fire when using Li batteries on board a sailboat (I was) I sure would be now (-: .

I too was once a pilot and I've never forgotten the sign I had above my desk at work: The Superior Pilot uses his Superior Knowledge to avoid those situations that require his Superior Skill. That is not to say I considered myself a Superior anything but simply to remind myself to be cautious in whatever risky thing i take on. Hookah diving is a case in point. Hookah it can be argued is more dangerous than Scuba and some consider Scuba unacceptably dangerous. Li batteries are likely more dangerous than LA. Sailing around the world some would say is more dangerous than sitting on one's couch! Driving an e-bike over driving a car or even over pedaling the thing, ditto (-: . Flying a little plane? Of course more dangerous. But the stuff on TV is much more dangerous to your soul!

So why do we make these 'more dangerous' choices? Because of course for their advantages over whatever else is being considered. We try to do a risk analysis and then hopefully fully cognizant of the inherent risks we decide.

We decided on going LiFEPO4 over LA (and battery over gasoline power for the Hookah) for a variety of reasons and in total those reasons make sense of the ad hoc risk analysis. We also decided to go with a Li powered outboard (Torqeedo) for similar reasons. Most of the voyaging sailors, nay all the hundreds we know, use LPG to cook. Enough said.

One slight correction Greybeard in your otherwise well voiced criticism; your interpretation of 'sporadic maintenance' reflects either a hasty read or a careless wording on my part. The Hookah is intended for anchor inspection and/or retrieval in water possibly 20m deep and for 'sporadic maintenance' of the hull and associated underwater parts. In other words the Hookah will likely be lightly used even adding the shallow water recreational diving we intend to do with the unit. In fact in our now eighteen year circumnavigation we have never had to do underwater repairs and have done all our anchor inspection and 'sporadic' hull cleaning by snorkeling. Other maintenance is so far from sporadic I sit here and chuckle. It is a full-time job!

And re the BMS cutoff. The unit will be used by two people with many years of Scuba and snorkeling experience. When there is a sudden cessation of pumping, as can happen when one runs out of gas with a gasoline fired unit as well, one has hose pressure to fall back on possibly with an additional air chamber. And one comes up following one's training. I now do what I intend to do with Hookah using free diving! The necessity for decompression stops are of course avoided by staying outside of those limits.

Please all keep those wonderful comments coming--------at the moment I am leaning towards a Cell-Man designed battery mainly because of all the information on this wonderful site.

 

[dnmun]

you should not still be concerned that the lifepo4 will catch fire though. the reason lifepo4 chemistry is considered safe is exactly because the overcharging does not lead to fire. so his misinformation has already tainted your view of how they function. they do not catch fire.

as far as the risk of having the BMS shut off the battery output, you can add a bypass switch to allow the battery to continue discharging in an emergency even after the BMS has shut off.

you can seal the battery inside a plastic container to keep it water tight with only the charging and discharging leads coming out, and the bypass leads too if you choose to add those. the batteries do not release gasses so they can function normally inside a sealed plastic container.

 

[Jeremy Harris]

Worth looking at what over-charging does to lead acid batteries, too, to retain a sense of perspective. Sealed lead acid batteries are even more dangerous when over-charged. Sometimes I think some folk just lose sight of the real risks when fighting shy of anything "new". Lead acid chemistry and seawater are not a happy mix, as a friend found out when the batteries in his sailing boat got flooded. The chlorine given off was pretty unpleasant. Having acid in the bilges didn't do the boat much good, either.

In my view LiFePO4 is probably safer than any form of lead acid battery, when all the risks are fairly and properly assessed.

 

[Grey beard]

Sorry I misinterpreted about the Maintainance. Ownership of a boat of live aboard size is a full time job. I've seen so many drop-outs living aboard in little bays and coves, that are obviously neglecting the Maintainance of their craft that I made an unfair assumption, I apologise.
You've studied, asked the questions, and made your decision. I'm good with that.
You mentioned LPG and how many use it today, despite the obvious dangers in a boat. The below link is about one that happened earlier in the year where I keep my boat.
http://www.sequimgazette.com/news/article.exm/2012-02-08_boat_explosion_rocks_marina.
He didn't survive.
Good luck with your circumnavigation if you choose to continue it. I love Micronesia and may have stayed there, if I hadn't so much to do on the mainland.
Mike

 

[Caliban]

I use a 48v 20Ahr Ping lifepo4 battery mounted in an explorer case.
http://www.trifibre.co.uk/index.php?route=product/product&path=35_37&product_id=77

This is incredibly robust and guaranteed waterproof so I guess it would suit your application. My 48v battery is a tight ft in the case shown in the link but a 24v battery would be about half the size so there might be a more suitable case size. There are other suppliers of similar waterproof cases such as Pelican so it would be worth looking around for the best match.

I discharge at 20 amps average and there has never been a problem with overheating. The BMS does get slightly warm on charging, although this is a slow charge at only 2 amps, so I generally leave the lid open.

The only modification required would be to drill the case to bring the discharge leads to the outside but a couple of gland nuts would restore the waterproofing.

Do you hook up to shore power? I would imagine that running a generator for the time required to recharge might be an issue?

 

[Gordo]

One slight correction Greybeard in your otherwise well voiced criticism; your interpretation of 'sporadic maintenance' reflects either a hasty read or a careless wording on my part. The Hookah is intended for anchor inspection and/or retrieval in water possibly 20m deep and for 'sporadic maintenance' of the hull and associated underwater parts. In other words the Hookah will likely be lightly used even adding the shallow water recreational diving we intend to do with the unit. In fact in our now eighteen year circumnavigation we have never had to do underwater repairs and have done all our anchor inspection and 'sporadic' hull cleaning by snorkeling. Other maintenance is so far from sporadic I sit here and chuckle. It is a full-time job!

Risk is all relative. In the 1970's-80's I built, owned and managed 3 commercial seafood dive boats. The industry standard at the time was a 14hp Chinese Robin engine on a service station air compressor, filled with mineral oil and using Tampax filters and active charcoal scrubbers. These divers often got serious lung infections. I used OLD 2 cylinder diesel Kabota refrigerator engines that were taken off because the insurance company would not insure the truck load if the engine was over 5 years old. I also used Gast Teflon ring oil-less compressors that are now standard on most Hooka rigs. My divers did not get sick. But they did complain bitterly, because I was using old Japanese engines instead of shiny RED new Chinese gasoline ones. I can remember many, "what do we do if that old diesel quits", questions. My reply was that my greatest worry was a person who questioned our air supply vs then industry standard, when they all carried bailout-bottles, may not have enough brains to come up! I built 11 more identical systems for other boats. Hooka diving for anchors, without a bailout-bottle is counting on your superior skill, while leaving your superior knowledge on deck! Better you 20 meters down sucking on an empty straw than me, and I've done a few free assents before bailout bottles were standard equipment.
Have you changed an underwater thru-hull fitting using a tarp?

 

[dnmun]

you could make the plastic container large enuff so that if it fell overboard it would still float.

was thinking some more about your charging. instead of using the inverter to drive the charger.

assuming your current generator is not high enuff in voltage to charge the pack, and also the need to limit the charging current to something around 1/2C for the ping packs.

so a 24V20Ah pack would be needing about 240 watts of power to charge. your boats generator can produce 1kW i assume. so it would melt the battery if it had direct charging.

if you added a second and very small alternator, such as from a motorcycle that produced about 250W then you could use the AC from the alternator and send it directly to the rectifier diode bridge in the charger where it would get full wave rectification and then that would feed the front end. it could be a switch mode with a power switching mosfet controlled by a pwm IC current controller or the kingpan type charger with the switching npn transistors up front.

or you can take the DC right from the rectifier diodes in the alternator and then develop a feedback circuit to control the field exciter current in the alternator so that it put out the final charging voltage that balances the pack.

if you take the AC from the alternator in front of the diodes and feed it to the charger input then you would need to have the alternator create a high enuff voltage that the front end of the charger would function. it might require that you adjust some of the passive components like the gate-source resistor in the power mosfet type or the base resistor in the npn transistor type, to make it switch at the voltage the alternator could produce and you would just adjust the alternator AC output voltage up to the point where the charger would run and pump current to the back end, and then all the charger functions would be handled by the feedback circuit in the back end.

this would allow you to be charging the pack the entire time the boat motor is running, assuming it is something like a small perkins with the alternator added on a second belt or fitted onto the same but lengthened generator belt. or the alternator could be mounted on the outboard somehow if there is the need to charge while running in the skiff. or have two setups except that is more expensive and hassle, but is backup.

anyway that would be another way to deal with the charging, and of course you could always charge off the battery later with the inverter to the charger but using an alternator on the boat's motor would save the battery charge and reduce the need to recharge it regularly when the inverter drained it.

 

[dogman dan]

I had a feeling you were not so slacker. A slacker would be just usings any old lead from the junkpile, not interested in improving a device with a lithium battery.

My only concern was that perhaps you were using the hookah for longer dives more regularly, and for deeper dives. Doing something commercial where you would take big risks. Something where a sudden stop of the air would be a catastrophe.

The risk of fire is mainly a risk of a nicked wire shorting on something sharp. As wires melt, they can start a fire. Lifepo4 won't burst into flames. Just put a good fuse after the bms.

Speaking of TV, I was appaled at the risks being taken by hooka divers in Alaska on a tv show, gold dredging. Poster children for diving with sketchy equipment, but at least shallow enough diving to get away with it if the hooka stops.

 

[etriker]

that is not true. there is no 'history' of lifepo4 packs catching fire. that is an outright false statement.

any battery can short out and catch something on fire, so SLA will be the same risk. but lifepo4 do not catch fire even when overcharged or over discharged.

if your boat generator puts out up to 30V then you can charge directly from the generator on the motor. without using the inverter. for a 24V lifepo4 pack you need 29.2-29.6V to fully charge it. if you can only charge it part way up with the generator then you can finish using an inverter to drive the charger.

http://endless-sphere.com/forums/viewtopic.php?f=14&t=41877

They can catch fire and burn.

I am thinking all li ion cells can burn.

http://endless-sphere.com/forums/viewtopic.php?f=14&t=41877#p612370

Have not tried Headway but tried A123.

http://www.youtube.com/watch?v=YVSZHdyWmIo

They will catch fire too !