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**newhaul** · 04-08-2018, 20:06

Quote:

Originally Posted by Delfin

If your daily use is only 50 amps, 100 amps will do you. We use 300@24vdc and a 600 amp LiFePO bank is more than enough. Managed correctly, you'll get 1000's of cycles at a higher, more stable voltage with 1/4 the charging time.

actually a daily usage of 30 to 50 ah and 100 ah would not be enough for me I want 200 eventually for my bad weather cushion.
Now I could do just fine with the 100ah and at 30 ah I have 3 days if no charging .
With 400 solar and 400 wind I'm sure you are correct that 100ah will be plenty .

john61ct · 05-08-2018, 03:20

Quote:

Originally Posted by newhaul

dmd power thru Alibaba.com

Also found a guy online that is doing a test of the bank so far so good.

Is this what you bought?

What happened with the guy?

**newhaul** · 05-08-2018, 06:46

Quote:

Originally Posted by john61ct

Is this what you bought?

What happened with the guy?

yes John that is the company I purchased through.
He didn't do much of a followup just to say it had been working just fine for a year. No he didn't provide much information .
I will begin testing Wednesday evening at the boat . I will keep much better notes and I will post them here .
The pack I got .
Has these specs ( the weight listed is about half the actual weight) and looks like this except its the 100 not the 200.

KTP · 05-08-2018, 08:27

Quote:

Originally Posted by newhaul

yes John that is the company I purchased through.
He didn't do much of a followup just to say it had been working just fine for a year. No he didn't provide much information .
I will begin testing Wednesday evening at the boat . I will keep much better notes and I will post them here .
The pack I got .
Has these specs ( the weight listed is about half the actual weight) and looks like this except its the 100 not the 200.

20mOhm internal resistance with 125A peak discharge current?

At that current level, I^2 * R says about 300 watts will be dissipated by heat in the battery!

**newhaul** · 05-08-2018, 08:32

Quote:

Originally Posted by KTP

20mOhm internal resistance with 125A peak discharge current?

At that current level, I^2 * R says about 300 watts will be dissipated by heat in the battery!

ok however in my install it would not see more than 10 amp draw at any point in its life.
So I fail to see a point .

Btw these are designed to run inverters in mobile / portable situations.
I definitely will not be stressing the power limits of the pack beyond the initial testing .

john61ct · 05-08-2018, 09:21

Here's a HowTo for running a standard 20-hour load test, basically from CMS / MaineSail.

https://www.expeditionportal.com/for...4#post-2470133

Very useful even when commissioning even a trusted vendor's battery.

Then after a few years, you can get an accurate picture of capacity decline in order to retire the bank at an appropriate time, avoiding unexpected failure.

Best done after the breaking in process for that purpose, but in this case do it first.

**newhaul** · 05-08-2018, 09:28

Quote:

Originally Posted by john61ct

Here's a HowTo for running a standard 20-hour load test, basically from CMS / MaineSail.

https://www.expeditionportal.com/for...4#post-2470133

Very useful even when commissioning even a trusted vendor's battery.

Then after a few years, you can get an accurate picture of capacity decline in order to retire the bank at an appropriate time, avoiding unexpected failure.

Best done after the breaking in process for that purpose, but in this case do it first.

I fully intend on doing a test for capacity. I have a known 5 amp draw on the boat and it will be run through my spare solar controller with its ah counter . ( not hooked up to any charging source) . That will give me a benchmark for later testing and monitoring.
I will do writeup and report here next weekend.

Maine Sail · 07-08-2018, 04:58

Here's what one guy got when buying direct from China.... As far as I know he is still in dispute resolution but the company is still fighting it. Cells were not even the Ah capacity claimed.

https://youtu.be/SDJIMi_xkNk

"After two weeks of fighting, AliExpress buyer protection has been completely unhelpful."

**newhaul** · 07-08-2018, 06:09

Quote:

Originally Posted by Maine Sail

Here's what one guy got when buying direct from China.... As far as I know he is still in dispute resolution but the company is still fighting it. Cells were not even the Ah capacity claimed.

https://youtu.be/SDJIMi_xkNk

"After two weeks of fighting, AliExpress buyer protection has been completely unhelpful."

have not cracked my case but the weight is about right .
Ran a simple test yesterday no ah counter but an approx 4 amp constant draw ( Pieter cooler 6 pack size) 18 hours from full to 10.20v ( the refer specs call for minimum of 10 volts till safety shutdown) for an estimated 72ah ( will know more on Friday after testing on boat wilt ah counters and specific known draw)

john61ct · 07-08-2018, 13:31

Woah Nellie! Don't do that again, **way** too low!

Even with much higher-bottom lead banks 10.5V is defined as 0% SoC, and you should IMO only go there say 6-10 times over the years, and **immediately** start recharging, not let them sit there that low.

To go that low with LFP I believe you are risking murder, instant permanent damage.

For sure you removed many hundreds of lifetime cycles off the back end.

And if the batt now performs below rating, we won't know why.

11.9V is the lowest I'd go personally.

If Maine Sail comes back I hope he'll advise the proper bottom point for a 20-hour load test, and other details for how LFP protocols differ from lead.

john61ct · 07-08-2018, 13:45

Of course who knows what the actual flavour of lithium chemistry these are.

I'm guessing LiPo or NMC, aka Lithium*Nickel Manganese Cobalt Oxide,*lithium-mananese-cobalt-oxide, LiNiMnCo, NCM,*Li[NiMnCo]O2

In which case never mind.

That really is the first fact needs to be determined.

**newhaul** · 07-08-2018, 16:42

Quote:

Originally Posted by john61ct

Woah Nellie! Don't do that again, **way** too low!

Even with much higher-bottom lead banks 10.5V is defined as 0% SoC, and you should IMO only go there say 6-10 times over the years, and **immediately** start recharging, not let them sit there that low.

To go that low with LFP I believe you are risking murder, instant permanent damage.

For sure you removed many hundreds of lifetime cycles off the back end.

And if the batt now performs below rating, we won't know why.

11.9V is the lowest I'd go personally.

If Maine Sail comes back I hope he'll advise the proper bottom point for a 20-hour load test, and other details for how LFP protocols differ from lead.

actually the minimum by specs is 9.8 when the bus system auto disconnects to protect the bank. And a max charging of 14.5.

**newhaul** · 07-08-2018, 17:50

Quote:

Originally Posted by Maine Sail

Here's what one guy got when buying direct from China.... As far as I know he is still in dispute resolution but the company is still fighting it. Cells were not even the Ah capacity claimed.

https://youtu.be/SDJIMi_xkNk

"After two weeks of fighting, AliExpress buyer protection has been completely unhelpful."

I did it a bit smarter purchased via PayPal. But so far so good and its just 250 bucks