Can I trust Chinese Amazon alternatives

[Skipper Jon]

Hi there,

Total newbie. Absolutely no technical expertise. Just trying to get a little bit of input from those with experience.

A bit of background. My wife and I live on board a 45ft sailing yacht with our three cats full time. We’re originally from the U.K. but are currently berthed in Montenegro. After 18 months full time cruising, we’ve decided to replace our existing lead acid battery bank with lithium. This is a no brainier now that the cost has reduced significantly. However, we are on a budget so I still need to shop around. I have very little technical expertise but my friend is an electrical engineer. He will be helping me with the install.

We have 2x 370w mono panels routed through a Victron MPPT. We also have a 500w wind turbine via a separate MPPT. Both charge sources are connected to a Victron Multiplus 3000 charger/inverter. I anticipate a domestic bank of 800ah LiFePo4, with 200ah lead acid service bank (for short but high load windlass and bowthruster operations) and 110ah lead acid starter battery.

Originally, I liked the idea of building my own batteries but then I saw Will's video about budget complete batteries like Chins and Ampere Time. Unfortunately, Amazon does not deliver to Montenegro so I suppose my first question is whether I can have confidence in buying from Aliexpress or Alibaba? There seems to be a lot of price variation even when the technical specifications are quite similar. This suggests there are quality issues to say the least. From what I’ve seen, the SOK and, possibly Basen, look pretty good.

Any guidance would be much appreciated. Thanks in advance.?

 

[Smokin]

Stick with lead acid. No fire.

 

[Shinebox]

Pretty hard to get LFP on fire. Other lithium chemistries not so much…. Many boats through the years have caught fire due to poorly maintained LA systems.

As for the original question, I would be nervous about the Amazon drop ins. The tear downs that Will has done do not inspire confidence. Generally there is no low temp protection, and often the innards are slapped together with brass bus bars, inadequate cables and low quality BMS with low charge/discharge ratings. Sometimes you can get lucky and the quality isn’t so bad! If I we’re going that route, I would try to get something that Will had torn down and found to be OK for your requirements.

One last point about your windlass. I don’t really understand having a separate lead bank to service this load. With Lead you will have voltage drop whilst using the windlass due to Peukerts constant. The lithium however is a perfect match for such a load. Say your windlass is drawing about 80-100 amps. Your Lithium could deliver this without even blinking. Now with a cheap drop in you could have issues with the mosfets on the bms having too low a rating if you happened to be servicing other loads while using the windlass.

You could circumvent all of this things by assembling a pack with raw cells and using a BMS that uses external contactors for shutting off charging/discharging loads. Slightly more involved installation than the cheap drop in and probably a bit more expensive if you got a quality BMS, but the system would be quite a bit more robust.

 

[Don B. Cilly]

Alibaba/Express are a bit of a Wild West territory. But then so is Amazon lately.
The main advantage of Amazon is (was) the no-questions-asked return&refund policy, but it doesn't apply to all articles.
Which doesn't mean you can't find good vendors in China. You can. How to find them... try searching this forum for a start.

About the windlass/thruster, aren't they already wired to the engine battery? And do you ever operate them with the engine off?

800 Ah of LFP are... quite a lot. You could probably do with less - on a 45'? You should :·)
Hard to properly charge with those panels and a little wind generator, too.
-

 

[Shinebox]

Alibaba/Express are a bit of a Wild West territory. But then so is Amazon lately.
The main advantage of Amazon is (was) the no-questions-asked return&refund policy, but it doesn't apply to all articles.
Which doesn't mean you can't find good vendors in China. You can. How to find them... try searching this forum for a start.

About the windlass/thruster, aren't they already wired to the engine battery? And do you ever operate them with the engine off?

800 Ah of LFP are... quite a lot. You could probably do with less - on a 45'? You should :·)
Hard to properly charge with those panels and a little wind generator, too.
-

Agreed. 800ah lfp is a ton. I have 540ah, which replaced 600ah of LA, and that is plenty on a 48’ sailboat. I only have 100watts of solar, and that does the trick for my use case, although I think I’m going to add another 100watt panel this season. The OPs solar setup, assuming good exposure (plus he has wind) sounds great to me. A friend’s boat that I race on has 400 watts of solar, and 400ah @24v. We run refrigeration pretty much all the time on a DC compressor, and while sailing all of the winches are Electric… these are massive winches. The 400 watts is mostly sufficient to deal with this, in fact a couple of seasons ago, the alternator regulator crapped out, and all we had was the solar, and that kept the bank going just fine, albeit with somewhat reduced use of the refrigeration.

 

[Skipper Jon]

Thanks for the replies guys. I knew there would be a lot to consider... and you've proved me right ?.

Very interesting about windlass. I mentioned an LA bank as I'd read on another (sailing) forum that lithium was not suitable. I already have 4 reasonably new LA batteries so thought I could repurpose but may be not. All food for thought.

I agree that 800ah seems huge but in addition to the usual fridges, instruments, etc. we have a freezer as well as newly installed but as yet unused, 12v aircon, watermaker and dive compressor. I just wanted to make sure I'd covered all bases from the outset.

I'll keep researching and seeking advice. One good thing as this lifestyle is the availability of time ?.

 

[Shinebox]

I should say, and I realized this after posting, that the charge discharge limitations that these cheaper drop ins have would be largely mitigated by the size of your bank. If all your cables are of equal length from your distribution bus to each battery, then they should share loads evenly, thus reducing charge and discharge rates.

I use lithium for my windlass, and I anchor a lot. Works great.

 

[joanna_lannie]

I feel like this still requires guts hahaha, maybe you can buy cheap and good LiFePO4 batteries, but you may also buy cheap and bad batteries. It should be noted that do not buy LiFePO4 batteries that are too cheap, and you will most likely be fooled. Also, if you have the budget, LiFePO4 batteries are better than lead-acid batteries, don't always get obsessed with lead-acid batteries...