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Drop In Lithiums


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Are they ready for prime time? I see plenty advertised now at reasonable prices that include sophisiticated BMS's, you can downsize the Ah requirement because you can go so deep on the discharge 

The concern is that they can be a bit of bomb, make the alternator work overtime etc but the advertising is suggesting that the BMS manages that without external temperature sensors. Anyone done it, thoughts?

https://www.jaycar.co.nz/12-8v-100ah-lithium-deep-cycle-battery/p/SB2215

 

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52 minutes ago, waikiore said:

You do need a BMS and unless your charging system can charge at a high rate to suit where is the advantage? For all that extra $

if you use say 30 amps a day then instead of getting a FLA of about 100 or more then you could in theory get a 50 ah lithium. Lighter not too much difference in cost and many times the life

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There's nothing fundamentally wrong with these units.

However, they don't meet the NZ standard for Lithium batteries AUS/NZS 3004.2:2014 which could get you into insurance issues when installed on a boat. A number of other international forums I follow are littered with posts from people who have had insurance declined - doesn't seem to be a problem for NZ... yet. 

The key pros are

  • weight saving per ah 
  • charge time

The key cons are

  • Your charging system
  • Electric winches

Many boats considering Li will have an electric anchor winch. You may need to still carry a traditional battery for your winch thus eliminating weight savings and ending up with a tripple power system. You may consider hooking your winch to your starter battery and managing the problems/risks associated with that.

The key con is that you need to consider changes to your charging system and this will probably be more expensive than the battery. Most boats with LA will be charging directly from the alternator. Many alternators will output more current than the battery is rated for.

So you need to somehow limit the current coming out of the alternator.

The easiest way to do this is using a b2b charger, such as the Orion-Tr Smart DC-DC, or the Sterling Pro DC/DC. The side effect of this is you lose the fast charging time because even high end b2b chargers top out at 50Amps.

So that leaves the more complicated way of limiting the current at the alternator with an external regulator. There's a few options in this area from the dumb balmar mc-614 regulator, to devices that can read the current via a shunt and limit the current such as the VRC-200 or at the top end of the market the Wakespeed ws500. 

Finally you need to consider any solar and those solar controllers. 

Bottom line / tldr;

These 'drop-in batteries' are anything other than drop-in on your boat.  You still have to consider the entire end-to-end system. 

 

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21 minutes ago, Psyche said:

Whats the issue with windlasses? i would have thought it would be an ideal power source for one

The max recommended draw rate from most LiFePo4 is 0.5C.   Some are 1C, 3C and even 10C with external cooling. 

However that isn't the limiting factor with these drop-in's. You're limited by the built-in BMS.   Eg, the Jaycar one you linked is rated to 50Amps max. My low end Maxwell RC8 windlass is rated at 100Amps, once I watched the shunt and it was pulling 87Amps.

Compare that with your current LA battery which can probably sustain 500A for 30 seconds (my optima is rated at 770A)

So that leads to an external BMS with a relay setup. So now the BMS controls  2x200Amp relays one for the charge bus, the other for discharge bus. 

And now you've added another $800+ install to your system... 

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The other key thing I should mention is having something to absorb load spikes if (when) the BMS cuts out.

Sending 100amps back into your alternator because your Li got a bit warm on a hot day and cut out will fry your alternator.

On most NZ boats with our traditional starter/house battery and one alternator this isn't an issue because the start battery becomes the load sink. But a lot of cruising boats have a second alternator for those big house batteries, so this alternator will need protection.

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Yes I'm going through this exercise at the moiment, I went away from dropins, actually they werent even considered seriously because of the downsides.

Ive built a pack from CALB 180 Ahr cells, 2P4S for a 360 Ahr battery. But thats the easy bit. Ive got a Wakespeed WS500 reg for a Compass Marine 200A Alt. Again a resonably easy bit. TAO BMS to look after it all, 3 big contactors, 2 x Midnite Kid solar controllers with current shunt charge termination control. I wil be charging my start batt from the old stock alt, so I'll kinda have 2 separate systems. Voltage spikes etc are taken care of by a very smart BMS wth 6 internal relays and CanBus comms with the WS500. Basically the BMS shuts off chargers and loads before disconnecting the pack for any reason. It also connects the start batt to the load bus so the boat wont go dark at the instant the pack is disconnected.

The battery is just the beginning, the systems around it are just as important, and need to be fit for purpose or your cells wont live to their potential

By no means is this plug and play at all...and by no means cheap.

read these two pages.. over and over

https://marinehowto.com/lifepo4-batteries-on-boats/

https://nordkyndesign.com/featured-articles/

 

 

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1 hour ago, Ladyhawk said:

Yes I'm going through this exercise at the moiment, I went away from dropins, actually they werent even considered seriously because of the downsides.

I determined that the only thing drop-ins were good for was a cheap source of cells.  Rip them apart, pull out the cells and throw the bms and the case on trademe for a few $$.  And then build your battery pack.

Buying cells on their own in NZ is an expensive exercise - 4x100ah cells will set you back around $1200 - where as JayCar have unbranded 100Ah for $809 - for a weekend cruiser these are probably going to be "good enough".

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Psyche if you want to lose even more weight, use AGM batteries,  will throw your engine over and deal with windlass loads no sweat -cheaper than Lithium but you will need to have the capacity to recharge at 25% of the AH rate as a minimum, (I know this from auto racing) 

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5 hours ago, waikiore said:

Psyche if you want to lose even more weight, use AGM batteries,  will throw your engine over and deal with windlass loads no sweat -cheaper than Lithium but you will need to have the capacity to recharge at 25% of the AH rate as a minimum, (I know this from auto racing) 

I have read mainesails blog extensively over the years and its probably the best yachting resource for lithium conversions and as Ladyhawk infers, complex and expensive to get right.

That said, its a very common upgrade for a bike- trade the LA for a drop in lithium. I did it a year ago and its been trouble free. Hence the question for a boat.

The short version from the responses is not yet! 

AGM and Gel al may be useful but in the end the easiest and cheapest option may be replacing like with like.

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That's potentially a bit of good luck.. 

Because you're using it as a start battery you're always into the reducing current part of charge cycle.   So your voltage tops out at 14.6 and your current decreases until bottoming out. 

If you were to get your battery down to 80% DOD or maybe even 50% then you would risk burning out your stator and rectifiers as they would be running at 100% until such time as you got the battery back up to 90ish %

And of course that cheap BMS is another point of failure. If it dies your bike stops. If it dies while you're riding, then you'll likely be rebuilding your rectifiers. 

tldr;

Any time you attach a lithium battery to a charge source you need to consider the impact on that charge source.

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I can only add a little to CD great information above.  Not all Lithiums are created equal. Even though there are some cheap ones out there, they are cheap for a reason. Be very careful on what you buy. Plus, you might be able to discharge a lithium deeper, but that does not mean it is good for it. Regular deep discharge still shortens their life. Fully charging shortens their life. Leaving sitting at full charge shortens their life. Heat shortens thier life. And they are just too darn expensive to have a reduced life. They need careful monitoring to get the maximum life expectancy from them. Unless weight saving is the ultimate goal.

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7 minutes ago, wheels said:

I can only add a little to CD great information above.  Not all Lithiums are created equal. Even though there are some cheap ones out there, they are cheap for a reason. Be very careful on what you buy. Plus, you might be able to discharge a lithium deeper, but that does not mean it is good for it. Regular deep discharge still shortens their life. Fully charging shortens their life. Leaving sitting at full charge shortens their life. Heat shortens thier life. And they are just too darn expensive to have a reduced life. They need careful monitoring to get the maximum life expectancy from them. Unless weight saving is the ultimate goal.

Apparently reject cells from the big manufacturers are bought for cheap and packaged up into the odd brands we see giving huge profit margins and bad reputations. Provided the cells are good quality it seems that the built in BMS is the key to the whole exercise, as I was saying lithiums are a common upgrade and an oem fitment to high end bikes, as a group performance biker are very onto technical benefits and there is very little chatter about lithium issues so i would imagine that cheap and nasty brands simply dont survive. In the RV/Marine world the market is huge and the tech is maturing so I would expect some improvement in the drop in options.

 

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There have been some improvements in Drop in lithium over the last year or two. As BP says above, I've got a couple in Island Time right now, as an experiment. I will post on here next week sometime what I've learnt/found so far, but it's too Ling and complex to write on my ph, while I'm out in the boat.

The basics are that they may be a low(er) cost lithium upgrade for some vessels. They are totally unsuited to others.

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OEM is different.

The charge source is engineered to run at 100% and will have current limiting circuitry. 

Boats are coming off the manufacturing line with Lithium. Fitted with Balmar alternators, cooling ducts and external regulators.  These are designed to run at 100% all of the time. 

The issue is retrofitting without considering the impact on your charge source. Worst case it will lead to a fire in your engine bay. Best case everything will be just fine.

If dropping in a Li, you need to consider it and know what you're getting in for. Or get a professional to provide assurance and do the install. 

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No. That's not their job.

The BMS is the last line of defence to stop you destroying the expensive cells. It should never be activating.

BMSs have three core features:

Over voltage protection - disconnects the battery from the charging source if the batteries exceed a given voltage ~3.7v/cell

Under voltage protection - disconnects the batteries from the discharge bus if the cell voltage drops below a set voltage ~2.2v/cell

Over current protection - disconnects the battery from either the charge or discharge bus if the current is outside parameters. 

(4th) Temperature Sensor - disconnects if the temperature is too high/low.  A lot of BMSs (like the one in the photo above) do not have temperature sensing.

It is true that more advanced BMSs take on the role of managing charge sources via a CANBUS or other complex relay system. Eg they can shutdown the alternator or the solar as the battery approaches a given SoC.

The shutdown values in the BMS are always at the extreme. If your BMS is activating then something is wrong with your system. I mean who wants all the nav lights and instruments to turn off in the middle of the night? 

Your charger(s) should of backed off completely at 3.65v/cell.  You should of had an audible alarm going off at 2.45v/cell.

I am not aware of any dropins that have external comms. This is one of the reasons they fail the NZ standard. 

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