Re: [electricboats] Battery Recommendations

My experience with having LFP batteries shipped to me is that they're shipped at around 50% SOC.  So I wouldn't expect to receive a fully-discharged battery.  And fully discharging an LFP battery can be hard on it.  So their comment about it being okay is off, in my view.

 

Prices like what you're seeing ($340 for 1.6kWh) usually indicate 'Made In China'.  Not a guarantee of low quality, but suggestive.  At least they're responsive to your issue; some similarly-priced brands are much less responsive.  There are so many Chinese-brand LFP batteries out there that it's difficult to keep up with the offerings.  And my impression is that a lot of them will miss the mark reliability-wise, as the primary goal seems to be to produce batteries at the lowest cost possible.  Many corners are cut as a result.

 

I recently picked up a pair of 12V x 100Ah LFP batteries from WattCycle for one of my UPSs.  I found that brand on one of Will Prowse's lists of recommended battery brands.  Price was good, and so-far-so-good on performance/reliability (six months in).  But I don't see a 48V model from them near the size you have (32Ah).

 

There are, of course, 'Made In USA' brands of LFP batteries (Battle Born for example).  Prices are usually much higher, and not as many make 48V models.

 

Are there better options?  Probably, but it depends on your priorities.  Usually we want the lowest-priced battery (for its capacity) that is still 'reliable' (won't leave me dead in the water).  But reliability is difficult to determine, and that's usually what you're trading off for a better price.  Battery teardowns can help expose the quality of a given battery brand/model (both design and execution), and that plays a large part in reliability.  I suggest looking for a teardown video of any candidate battery brand/model you have in mind that meets the rest of your requirements (price, capacity, size, weight, ...).

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[electricboats] Battery Recommendations

I appreciated the recent product recommendations for chargers and controllers. Just the right information at just the right time for me. Would anyone have similar guidance for batteries?

Based on limited internet specs and reviews, I purchased a GrenePower 51.2V, 32Ah LiFePO4 battery to power an ePropulsion Spirit 1.0 Evo Remote motor. It appeared to be well-designed, with good packaging and adequate documentation. However, there was no meaningful charge level – either voltage with multi-meter or from its own LED display. Response to my concern was that receiving a fully discharged battery should not alarm me. However, when it would not accept a charge – with flashing red/green on charger – I again expressed my concern, and they agreed to send a return label.

Is this an anomaly? Or do we have to accept the high probability of receiving batteries with bad cells or a faulty BMS? With 28% more capacity and 25% of the cost compared to an ePropulsion battery, this one still might be worth pursuing. Are there better options?

Thanks for any suggestions,

Walter Pearson

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Re: [electricboats] Solar system on a sailboat for 96v battery?

Big Thanks to Jerome, that is exactly the thing the OP needs.

 

And after being educated by Jerome, I was able to find almost the same thing on the big A webstore (just 72V instead of 96V).

I didn't need the 96V but I did need the 12A.

I only need 48V for the boat, and 72V for my Ebike, so I got some of these;

Re: [electricboats] Solar system on a sailboat for 96v battery?

Hello there,

I have my system battery bank in 96VDC too, and it is indeed more complex to find components than when you stay below 48VDC. That being said, you can source the components directly from China, with a lot more to choose from. In my situation, I have 8 strings of 5 panels in series, attached to 4 industrial MPPT controllers from IPandee. Each string is at around 200VDC. I have no shading problem on my boat, other than droppings from birds, so going with panels in series to up the voltage was an easy choice.

In your case, as you are on a sailboat and you will have some shading, you are correct that you should avoid putting your panels in series. I would avoid adding a DC-DC converter to boost the panel voltage before the MPPT though. A DC-DC has a ~95% efficiency, so it is a shame to lose power there. We never have enough power... ;-)

Based on what you described, I would go with a product such as this one https://www.aliexpress.com/item/1005005825627193.html, one per panel, and keep a few as spares. See Alibaba or Aliexpress for other products, I just Googled and found that one, but I am sure there are other brands doing boost and MPPT charging for 96VDC banks.

As an additional safety precaution, I would suggest you add a way to cut power from the panels to the MPPT charger when the BMS signals that the charge should stop. Cheap electronic components like the one I linked do not have compatibility to communicate on the BMS data bus to start and stop the charge, and only stop the charge when the battery bank reaches a set voltage. The key concern here is if there is a bug in the MPPT software that would not stop the charge, this could lead to a very serious security hazard, so the best way to avoid that is to cut the feed from the panel to the MPPT when the BMS says "stop the charge". 

I hope this helps.

Jerome

On Fri, May 9, 2025 at 11:10 PM Circe Strauss via groups.io <neriad6=gmail.com@groups.io> wrote:

I have the sailboat kit from Thunderstruck-EV, configured for 96v upon their advice for my power needs. Had I known the grief it would cause trying to find the electronics for 96v, I would never have gone with this. Unfortunately, I've already installed he ME1616 and had a custom gearbox machined for it. It would cost thousands to reconfigure the system for two 48v motors at this point.

 

I'm trying to set up the solar system rn, and wondering if anyone else has done this. I bought four Hyundai panels, bifacial, 48VOC. I thought I was going to just hook them up in series, but it's been pointed out to me that partial shading of the solar array would shut the whole thing down. So, as a starting point, I made a design:

 

Having a heck of a time finding a DC-DC converter with a ~100v output. Saw one on Amazon, (DROK DC Boost Converter 900W) with a prominent warning label about frequent returns. 

 

Maybe I'm going about this the wrong way. If anyone has done this, would greatly appreciate your advice.

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Re: [electricboats] Solar system on a sailboat for 96v battery?

[Edited Message Follows]

What about this? Split the battery pack in two and charge each half at 48V with it's own controller (would still need to string 2 panels together to get enough voltage).

Kinda like center tapping a transformer but center tapping the battery with the negative side of one charger and the positive side of another charger.

If you program both chargers the same, feed them with equal length wires from bus bars that are fed from all panels, and have a 16s balancer, I think it could work.

 

Those Genasun GVB-8-Li-56.8V-WP are almost exactly what I need for my boat, but they are only rated at 8A (while saying that people have been using them up to 9A without issue). My panels Max Power Current is 10.72A while the Short-Circuit Current is 11.26A.

My panels are only 370W with a VOC of 41.4V (Vmp of 34.5V) and I have been trying to figure out a way to mount 3 of these panels when I only have room for 2.

So at 405W I don't think the OP could use these (let alone the fact that the highest voltage I see for these is 62V).

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Re: [electricboats] Solar system on a sailboat for 96v battery?

Generally, you need higher voltage going into a charge controller than the battery voltage you are trying to charge (unless you have a boost controller like Paul above). The OP has 48VOC panels, so a max voltage of 2 in series of 96, but when charging will probably fall to around 84V.

A "96V" battery will have a working voltage calculated at 102.4V with a 116.8V needed to top of the charge, so 2 panels will not work for the OP.

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Re: [electricboats] 48V Backup Charger

Buy it. I have two similar ones that are only 17A (but realistically only charge about 15 to 15.5A according to my shunt). I use one of them for when I get no sun for three days and my pack gets below about 50%. It seems to work fine, it has a green light that is steady on when in bulk charging and blinks when tapering off charge on top. I try not to let it top them off completely because I cant program the shut off point, but I have forgot to keep an eye on it and it stopped when it was supposed to.

 

Before I got these 17A ones I used a 15A (actually charged about 13A) that was for 48V lead acid golf cart batteries. That one only would charge to about 56V if I remember correctly. But since it was half the price of a LFP charger (and I got it on sale for even cheaper) and most of the power in LFP batteries is around 52V, I figured I would try it out. It also worked fine although I never let it complete its charge cycle. I would set a timer on my phone and check my voltage every 30 minutes until I got to about 54V and turn it off. This 54V is would equate to about 95% of my amp hour capacity.

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