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LTO for SailBoat
#11
Thank you completelycharged.

The boat is now nearly 15 years old so, I'm upgrading the electrical system in advance of the batteries. This will be Victron gear (when it gets here!). It is a little pricey but seems purpose built for marine and gives me a little more flexibility when I'm learning. (And an old guy can write off just about any amount on his beloved boat).

The Victron charger has a number of profiles including for lithium, which can be customized. There is a max voltage of 16V (12V system) so I'm hoping I can tweak their LiFePO4 profile up to this to run the 6s LTO ( ie 2.67 which seems pretty close to full). I'm pretty sure the desulphate / equalize function on my current charger is north of 16V (they do whizz a little faster) so I'm relatively confident all the loads can handle the likely voltages.

I'm keeping lead acid for the start battery. The boat is in Thailand and this is both the readily available battery technology now and well into the future. The house (LTO) bank can have a problem , but the main engine needs to be able to be sorted locally and fast if there is ever an issue. And the cost of one of these starter batteries every 4-5 years is not consequential.

The Victron 12/200 BMS deals withlead acid start battery combined with lithium house. It charges the lead acid first , then the lithium and can self regulate how much charge is taking from the alternator . The alternator is 100 or 120 A.. and my other research told me that lithium could suck all that in and more so needed some kind of limiter to the standard alternator / regulator to avoid overheating.

Most of the nooks and crannies in the boat are already jammed full of stuff! So these batteries have to fit in the old battery bay. More and more I'm doing things in a way that should help make the boat more saleable down the track. For the right buyer , lifelong batteries and night time silent air con in the tropics should be a great feature.. and if they dont want to pay a premium I will simply pull the LTO out, drop in lead acid, and recycle the LTOs to an ESS somewhere.

I've been trying to figure out what's wrong with these batteries from the start.. they seemed too good to be true. This supply hiccup may indicate problem number 1. You're dependent on one supplier (YinLong) who can yank the supply(from the resellers) at any time. Kylin , who seem to have great customer service , jumped from 17.50 -> 30.00 in about 10 days. I'm really hoping this supply gap/price rise is as a result bunch of Americans buying in ahead of 25% tariffs in January rather than something else more structural. We will see.
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#12
Alternators regulate the upper current based on the engine rpm so just avoid running the engine at high rpm when charging or take the alternator 12V coil feed wire and switch it separately so you can then keep the alternator turned off if needed.

I would wire the LTO to the starter and keep the existing battery on float in that case and the reason being was from what difference I saw. Granted I only had a 20hp twin V but that was starting a lot better than the 65Ah lead acid with just 2x6s packs connected, I had an extra pack for capacity to run some computers on the vehicle while it was not moving. I had the starter running (on and off) for the equivalent of over a minute while I was sorting out getting the engine running again. Started up, 55A charge back into the cells. The voltage drop with the starter also knocked the computers out with the lead-acid as the voltage fell too far, but not with the LTO.

With LTO it would be ideal to replace part of the keel balast in a boat but for existing boats near on impossible ! I was thinking more along the lines of shaping the cells to match the shape of the hull so that they could fit each side or along the bottom and only add one cell width to the space used.

I'm surprised that at the momemtn YinLong are not doing what the vehicle manufacturers are doing and recyling their own cells into home or commercial powerwalls. That situation may change but the cell will still end up on the market, just like relatively new Tesla batery packs from crashed cars.

If I had a supplier who quoted 17.50 one week and then quoted 30.00 the next I would not necessarily call that great customer service, depends on their real reasoning for the hike.... special pricing just for you or market wide ?
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#13
Believe the pricing is market wide.. I hit them all and got nothing under $28.. and of course they then make up that in the freight anyway.

Rev 2 for the battery packs.. Will stick with aluminium (aluminum) bus bars to match the pole material.  Needed to beef them up.. essentially anything serial has to take up to 400A.  The load is fused at 300 so battery internals should withstand that and more.  May power (inverter load) should be 200A (per battery.  There will be two batteries.. and I plan to add a 225-250A circuit breaker to one to handle situation if I've run one and accidentally switch them in parallel ie different SOC.

For first build I wont be fusing cells.  Is this necessary in a 5P? I assume if one cell internally shorts it can only take current from the adjacent parallel cells so in this case 4 other cells for a total of 40 * 2.3approx 370W.. if near fully charged.  Interesting in the alternative LiFEPO4 4s54P is would be 53*3*6 W to dump into a shorted cel ie 1017 W ie 3 x the power into a volumetric mass 1/10 the size (32650/66160).

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#14
Add a breaker on each battery pack if your hoping to be at sea and have a cell issue, that way you can switch/trip out either battery pack. Plus, there may be a time when you want to discharge half the pack or keep half a pack fully charged as a reserve.

If an LTO cell in your configuration shorted and was capable of actually holding an internal short (which they are not) then the short circuit current per cell is around 800-1200A depending on the internal resistance age so you would see around 4,000A trying to short into the cell at somewhere around 1.5V, so about 6kW. This would melt the aluminium rather quickly. There is a video of someone with a clamp meter and shorting a cell with welding cables on youtube. The current and power capabilities of the cells is a lot lot higher than you have in your calculation.
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#15
I saw some Toshiba 2.4V 20AH lto for $14 usd piece
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#16
(11-26-2018, 10:55 PM)Jason Morris Wrote: I saw some Toshiba 2.4V 20AH lto for $14 usd piece

Where did you see them ,Jason?
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