Battery Recommendations

#32827

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

#32828

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.

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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.

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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).

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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.

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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, ...).

#32829

Thanks for your insight. I have not found any reviews specific to this battery. There are some posts regarding GrenePower batteries and don't see any red flags. Perhaps I might try again - after I determine my refund was credited. My ePropulsion battery is certainly high-priced and even so has reliability issues. It shuts down suddenly with over 40% charge remaining and finding the cure is not straightforward. Support from GrenePower was very good - after the initial smoke-blowing. ePropulsion support is negligible. Maybe I can get Will to do a tear-down? The search continues...

#32830

I have 4 of these currently running in my home UPS system, 2 are 2 months old, 2 are 5 months old, and no problems yet. These may be a larger (and heavier) than what you are looking for but they have built in Bluetooth and are still way cheaper that the epropulsion.

A black battery with a black cover

AI-generated content may be incorrect. ?

#32831

I also have 4 of the 100 Ah LFP batteries (with Bluetooth) from WattCycle, I have had a problem with one. It disconnected itself (may have been my fault) and would not take a charge or show any voltage across the terminals. The Bluetooth app showed crazy cell voltages from 3.2V to negative 0.8V.

I researched and found some people had good luck disconnecting and re-connecting the internal BMS so that is what I wound up doing and it cured my problem and showed cell voltages nearly identical, and also nearly full. No issues since.

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Why I say it may have been my fault is because I had left this one battery connected to a 2500 watt 12V inverter (12” long 8ga wire) in the front floorboard of my truck. I had been using this as a portable 110v power supply for a 7 ?” circular saw. I had left it connected so I wouldn’t have to use a resistor to reconnect it when I needed it again. But the next week when I went to use it, the inverter power switch was on but no lights or output from the inverter. I guess the switch got turned on while bouncing around and I thought my only issue was a discharged battery but it was the BMS issue above. It was easily fixable but I prefer things that don’t break, as opposed to something that has a good warranty or is easily fixible when it does break.

#32832

When your epropulsion battery quits with 40% remaining, what exactly does it do?

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Because if you are running near full throttle when it shuts off, then it comes back on and you are able to use it at lower throttle settings, then that would indicate voltage sag cutoff.

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This could be because of the teny tiny wires epropulsion uses that cannot take much current without significant voltage drop.

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Voltage sag may not be your problem at all, I’m just thinking out loud.

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I saw one video of someone that hacked their electric outboard (don't remember the brand) and put in larger wires to the circuit board with larger connectors. If I remember correctly, he did this because his OEM connectors kept failing (something like every 6 months), NOT because of voltage sag.

I guess he was disconnecting and reconnecting several times a week on his dingy, while cruising and putting his dingy on deck when moving the big boat. And after a few months the pins in the OEM connectors would loosen up and he would have to wiggle it to even get it to work at all.

#32833

I do transport my boat batteries here and there, so weight is an issue. The GrenerPower at about 33 lbs.was about all I can handle. I have thought about going down to the next size.

#32834

I have only day sailed with the Spirit motor and battery, so my speeds were always low and would rarely use up more than 10% charge. I was gathering data on self discharge in order to figure out how to charge in the off season and on day 28, the system would not turn on until I connected the charger. It did accept a charge. I have repeated this sudden drop in charge level while idle. The first time was with cables connected and I subsequently found out Bluetooth is drawing power looking for the wireless remote even when the system is off and even though my remote is the wired model.

The sudden drop also occurs with the cables disconnected, but takes months instead of days. Charging after these events is more rapid than should be possible which indicates to me there is still capacity there, but the BMS has seen a cell it doesn't like and shuts things down. A dealer informs me that I would have to substantiate the problem, send the battery for analysis, and then hope for a fix or a replacement. My warranty would run out before all that could happen, so hence the search for alternative power.

#32835

I just bought a DC house 12v 50ah battery for a trolling motor I use for trolling motor I use on my dinghy. Only got a couple hours use so far, but it seems good and it only weighs 20 lbs. Good luck.?

#32836
Edited

Ok then, "self discharging" disconnect at around 40% means that your BMS is working fantastic, better than most. I am surprised that the epropulsion people didn't tell you as much.

Lithium batteries will completely not work again if you drain them down to zero volts. It is recommended to store lithium batteries long term at around 50%. So having a BMS that disconnects at around 40% could very well be a battery saver. To store them over the winter you need to charge them a little every month or get a programable charger that you can set to turn on at 45% and turn off at 55%. Since batteries "wear out" more on the top and bottom of the charge, this "middle charging" will have the least degrading effect on the batteries.

This is especially helpful with a battery that only has 500 cycles. This tells me that it is not a LFP (LiFePO4) battery but some kind of Lithium, maybe LMC (Lithium Manganese Cobalt), because the lowest cycle count I have ever seen on a LFP was 1000.

It being something like a LMC battery tells me that it is most likely a 12S battery when they call it a 48V and will need a 50.4V charger for a 12S lithium battery.

The GrenePower 51.2V, 32Ah LiFePO4 that I found on amazon is a LFP battery and will need a 58.4V charger for a 16S LFP battery. If you have a programable charger then you can charge either one of them to whatever you want.

Most LFP batteries that are called 48V are this 16S (16 cells in series) and output their power at mostly 51.2 Volts, but you have to be careful, I have seen some 15S LFP batteries. These 15S LFP batteries would put out most of their power at 48Volts which would be fine for your electronics but would need a special charger (limited at 54.7V) because if you used a standard 58.4V charger on one it would kill the batteries.

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Being that weight is your primary concern, your best bet might be to stick with the Greenpower 32Ah, if you can get one that works.

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The Greenpower looks like it uses the cylindrical cells in a 16S, 8P configuration. Couple reasons I personally don't like cylindrical cells is there is a lot of empty space between them, so they are less power dense for their size. Another is that for every P more than 1, the battery is that many more times likely to fail, for example an 8P battery is 7 times more likely to fail than a 1P battery.

But I don't know of any LFP batteries that small that don't use the cylindrical cells. I think all the LFP batteries that are less than 100Ah use them, so it might be your only option.?

You might be able to find an even lighter battery that uses LMC chemistry (or more Ah for same weight) but they will be more expensive, and they can catch fire.

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So again, your best option may be the Greenpower (or similar).

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