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Daly BMS Woes

Tex

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Joined
Dec 16, 2019
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Ok, long story. Just got off Skype with Daly rep, they are going to replace my faulty BMS apparently. So the full story for what it's worth. I recently purchased 4 x LiFePO4 200 amp hour prismatic cells from Shenzhen RJ Energy company cost was US$687 (AU$1,090 landed), (US$162 of that was shipping) so not cheap considering I can buy a quality 200 AH SLA for about AU$300 in Oz.
However, because this is a system in a caravan the weight is a major consideration. The reason for this purchase is because my current Vision brand 100 amp LiFePO4 mono block battery has a maximum discharge of only 50 amps, and won't run our 12 volt 1500 watt Latronics inverter with any decent load.

As well as the 4 x 200 amp hour cells, (on Wills recommendation) I also purchased a Daly DG4S200A 12 volt 4S 200 amp BMS, (US$99.62 delivered) so actually much cheaper than the numbers Will has been talking about. Also (on Wills recommendation) I also ordered a Victron 200 amp Battery disconnect, and an ISDT BG-8S cell balancer.

After the fiasco with the Victron BD's I cancelled the order for the 200 amp BD, and purchased a 250 amp continuous relay instead. I don't necessarily need the relay because the BMS is rated at 200 amp continuous and 400 amps for 10 seconds peak, but I may consider putting it in at some stage. I assembled the battery pack with double sided foam tape (leaves a 2 mm. gap between cells), and fitted it to a rotor molded heavy plastic box protected by the foam the batteries came in, purchased a plug for the balancer, fitted terminals to the BMS cell wires and the balancer wires, fitted the supplied bus bars, and then checked the balance and all the voltages at the plug end of the sensor cable against the cell voltages, all good. I then balanced the cells to exactly the same (4 digits) voltages, unplugged balancer and plugged the BMS balance plug in. Check output with multi-meter, nada, zip, bugger all! Try a 250 watt load, nothing.

So after 3 days talking back and forth with Daly and AliExpress and running various tests and taking photos to no avail, it appears it's a dud, very disappointing. Even though I purchased this BMS on AliExpress and it was made by Daly, it was supplied by Deligreen power Co. and whilst their price was good I would issue two warnings, firstly it is extremely difficult to select the correct model you require on their web site, in fact I had to email them to tell them what I wanted. Secondly they supply an instruction page which has numerous serious mistakes, not good. Daly now tell me they will replace it, and they want the old one back, they haven't yet told me how we will achieve that. After Wills issues today with the Daly temp sensor fail I'm not holding my breath.

My other beef is with the BG-8S balancer, it seems to work ok if you get all the cells pretty close to start with using ceramic resistors etc. and balances within a few digits on the 4th number i.e. 3.342 - 3.344 is close enough to trigger the blue "balanced" screen. However, when I got it there where instructions to update the OS to version 1.0.0.24. Not too intuitive but I downloaded the update and performed it and confirmed. Now this update states that it fixes the "Single cell" bug, I take this to mean it wouldn't previously measure the voltage of a single cell, well guess what,? It still won't, neither the power plug nor the balance plug or both will wake it when connected to a single cell. ISDT want me to send them a video of the issue, laughable! This stuff should just WORK!

So one other comment I would make regarding Wills schematic is that it takes no account or ELV loads connected to the solar regulator (in my case a Victron 75/15 MPPT connected to 2 x 200 watt panels, with a Victron BlueSmart Lion charger for occasional backup. Accordingly I have updated the schematic to include a small Victron Battery disconnect on the ELV output from the regulator, you can see that here: https://tinyurl.com/qwh7fhs

I hope this info is of some use to you guys.

This is all very annoying because I have more important things to think about at the moment, I live in Victoria in Oz, and as of an hour ago Victoria is a declared disaster area, most of Vic and NSW is on fire, 3,700 houses lost, eight confirmed dead, 28 missing, huge numbers of holiday makers trapped in seaside resorts, and tomorrow is rated as "Catastrophic" on our fire scale.

Retired five years ago after 25 years experience in solar power and Marine navigation Aids industries.

Cheers Tex260Z

Update!

As Will said recently the 6mm. threads into alumuninium on these aluminum case prismatic cells really suck!

In dealing with Daly over the failure of my 200 amp BMS they got me to do a bunch of test and take photos of the result.
Of course this meant removing and refitting the terminal bolts numerous times, and on the very last one, bingo! stripped thread. :(
So, several hours later it is repaired with a Helicoil, and I think actually better than new.
For what it's worth I had no issues with drilling and re tapping to fit the Helicoil however, I did not dare going any deeper than the original hole depth.
I sharpened the drill bit to the flattest angle possible so I could clean out the hole right to the bottom, and I ground off most of the taper from the end of the tap as well.
The only issue is it is not possible to remove the tang from the bottom of the hole, if I have to do another one I would grind the tang slightly shorter so it could be broken off.
Daly requested that I mail the faulty BMS back to them and they are sending a replacement, I will be pissed off if they don't refund the freight cost (with tracking as requested).

I just can't figure why you would put a 6mm. (by about 10mm. deep) terminal on a 200 amp hour battery? It is also interesting to note that the cable size on my 1500 watt inverter is exactly four times larger than the leads on a Daly BMS, hate to think how hot they are going to get.
 
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