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Mecer 720w 12v Lead Acid Inverter with Lithium Battery Upgrade Issue


DjLiLaLRSA

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Hello everyone,

 

So i purchased a 12v 50AH Vestwood Lithium battery on special, as Lead Acid batteries just dont last and i thought a 50AH Lithium would be a good upgrade (and worthy downgrade from 100AH to 50AH) to allow better and longer battery life in my Inverter.

 

Since i did read up before, about people replacing with a Lithium battery in their Mecer IVR-1200LBKS with most forums stating it worked fine, and/or worked great, i thought it would be as simple as finding a drop in replacement and swopping batteries and it would work. But it didnt.

 

If i have the Lithium battery installed, it wont start on the 10 amp charge setting, then when on the 20 amp setting the inverter runs the fan for a few hours and then stops the fan with the green LED solid instead of flashing, which usually indicates the battery has been charged. So all looks good, but as soon as power is removed / load shedding starts, the inverter just turns off, and if i press the power button nothing happens. 

 

I have checked the Lithium battery voltage which shows 13.72 volts, which to my knowledge would mean the battery is working and did charge.

 

Does anyone know why the inverter would do this, or what i can do to make this battery work with this inverter,  i cant really afford another battery.

The inverter is only charging an Online 1KVa UPS which powers my devices, but the issue happens even when there is no load.

 

When i put my old 100ah Lead Acid battery back, it works just for only around 15 minutes due to the battery being old.

 

Also, what is the best amp selection for each type of battery?

Lithium - 10 or 20 amp??

Lead Acid - 10 or 20 amp??

Gel - 10 or 20 amp??

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56 minutes ago, DjLiLaLRSA said:

The inverter is only charging an Online 1KVa UPS

Did you try and an use a diffrent type of load? Plug a lamp in and see if it works. Why do you use an inverter feeding a ups? If it is a tower ups they are normally also modified sine wave why not just use the Mercer inverter to power whatever.

56 minutes ago, DjLiLaLRSA said:

 

Lithium - 10 or 20 amp??

Vestwood 50ah battery specs= Max 50A, Suggested=30A so use 20A

56 minutes ago, DjLiLaLRSA said:

Lead Acid - 10 or 20 amp??

Initial charge current should not exceed 0.3 x C so for 100ah lead= 30amp max so use 20amps same for Gel. 

Edited by TaliaB
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15 hours ago, TaliaB said:

Did you try and an use a diffrent type of load? Plug a lamp in and see if it works. Why do you use an inverter feeding a ups? If it is a tower ups they are normally also modified sine wave why not just use the Mercer inverter to power whatever.

It is an Online / Pure Sinewave UPS, it has 3 x batteries which i have replaced and is now running 3 x 28ah Lead Acid batteries, it has options to install all the way up to 100ah batteries, and can change the charger accordingly.

I work in IT and i need an online power source as i look after / maintain / repair a lot of servers, hence why that is in front of the Inverter as it is more important, add to that i have my router, TV and WIFI mesh after the UPS as well which will protect the load, unlike an inverter.

15 hours ago, TaliaB said:

Vestwood 50ah battery specs= Max 50A, Suggested=30A so use 20A

Initial charge current should not exceed 0.3 x C so for 100ah lead= 30amp max so use 20amps same for Gel. 

I had it set to 20amp and it charged the full cycle, fans went quiet and the LED went solid green, as soon as power was removed from the Inverter, which had 0 load and was in fact charging through the UPS, for testing, as soon as no power to it, it just turns off, no beep, no warning, just dead.

If i press the power button, nothing happens, if i keep it pressed in for 20 seconds, nothing happens.

When i put the 100ah lead acid battery back, it works perfectly just for only the 15 minutes till the battery is dead, i have checked with the meter the charge on the lead acid battery at full charge and when its dead, and it does seem to be working according to its specifications, so there is no issue with the inverter.

 

So my other question, you are saying:

Lead Acid = 10 amp

Gel = 20 amp

Lithium = 20 amp?

 

Thank you for the quick response.

 

I do have a feeling the issue is with the Vestwood BMS, so i sort of wasted money until i can find a good prices inverter that will take it, which has to happen in the next 3 months since the Vestwood charged and i have read it is bad to leave a lithium battery with charge for longer than 3 months.

 

EISH.

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46 minutes ago, DjLiLaLRSA said:

Lead Acid = 10 amp

If lead capacity is 100ah = 20A if lead is 50ah = 10A same goes for gel they are also family of LA.

46 minutes ago, DjLiLaLRSA said:

I do have a feeling the issue is with the Vestwood BMS

Connect a dc load directly to the battery 12v automotive indicator globe and see if it drives the load if it does increace the load to 2 x 12v 55w head light lamps monitor the dc voltage across the terminals if it drives the 2 x 55w head lamps it is doubtful that the bms is faulty.

Edited by TaliaB
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52 minutes ago, DjLiLaLRSA said:

I do have a feeling the issue is with the Vestwood BMS, so i sort of wasted money until i can find a good prices inverter that will take it, which has to happen in the next 3 months since the Vestwood charged and i have read it is bad to leave a lithium battery with charge for longer than 3 months.

Well that is a bit silly.  Long term storage of Lithium batteries is recommended at 50% SOC.  Nothing would be simpler than to discharge your battery to 50%.  For instance, you can use a 12V 5W LED.  Such an LED would draw a current I = P/V = 5/12 = 0.42 A.  Assuming your 50Ah battery is fully charged you want to discharge it by 25Ah.  So you need 25Ah / 0.42A = 59.5 hours.

You could use other known 12V lamps such as an old 50W halogen, or some 12V car bulb and repeat the above calculation to figure out for how long to run the light of a particular wattage..


As to the rest of your problem, I am really confused.  Does your UPS run from 12V?  You have 3 lead acid batteries connected in parallel?  Running two inverters in series is just plain silly. It seems you require a pure sine for your IT stuff and the Mecer is Modified Sine only.

The best would be to get rid of both inverters and buy a 1KVA 12V Axpert inverter.  They cost R4500 at takealot.  Then sell your old inverters.

The other thing you could consider is to use your Mecer as a battery charger only, and your sine-inverter as an inverter only.  In this case you would get rid of your lead acid batteries and connect the Lithium instead.  But this is really clunky.  A 12V Axpert inverter is the better option.  It would switch from grid to inverter in about 10mS which should be acceptable for your IT equipment.

 

Edited by Modina
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11 hours ago, Modina said:
Quote

Well that is a bit silly.  Long term storage of Lithium batteries is recommended at 50% SOC.  Nothing would be simpler than to discharge your battery to 50%.  For instance, you can use a 12V 5W LED.  Such an LED would draw a current I = P/V = 5/12 = 0.42 A.  Assuming your 50Ah battery is fully charged you want to discharge it by 25Ah.  So you need 25Ah / 0.42A = 59.5 hours.

 

 

Thank you for that information i will have to get a 12v LED and connect it.

 

11 hours ago, Modina said:
Quote

 

As to the rest of your problem, I am really confused.  Does your UPS run from 12V?  You have 3 lead acid batteries connected in parallel?  Running two inverters in series is just plain silly. It seems you require a pure sine for your IT stuff and the Mecer is Modified Sine only.


 

 

So i have a Mecer Modified Sinewave inverter, 720w or 1200va, with a 100ah lead acid battery thats dying, connected to that i have an old MGE Pulsar 1000 Online UPS, which has 3 x 28ah 12v batteries connected instead of the 3 x 7ah that are standard.

The reason for the UPS is protection, since inverters dont protect from spikes as well as dont always kick in fast enough unlike a UPS. 

The reason for the Inverter before the UPS, is the added runtime, which when running a server or 2 and load shedding kicks in, to get them shut down if they are half way through something like an OS install or VM migration, is not always quick and easy.

 

11 hours ago, Modina said:

 

Quote


The best would be to get rid of both inverters and buy a 1KVA 12V Axpert inverter.  They cost R4500 at takealot.  Then sell your old inverters

 

I will definitely look into this, thank you.

 

11 hours ago, Modina said:
Quote

 

The other thing you could consider is to use your Mecer as a battery charger only, and your sine-inverter as an inverter only.  In this case you would get rid of your lead acid batteries and connect the Lithium instead.  But this is really clunky.  A 12V Axpert inverter is the better option.  It would switch from grid to inverter in about 10mS which should be acceptable for your IT equipment.

 

 

You mean the Sine Wave UPS?

With the Axpert, since it is an inverter and not a UPS, i would still need a UPS anyways, but since i am looking for something to run the 50ah Lithium this is a good option and idea, thank you for the reply. 

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If your UPS runs from 36V then my suggestion will not work.  It's a pity it uses such a voltage.  If it was 12, 24 or48V you would have had more options.  Your batteries now have 4x more capacity than the 7Ah and your UPS charger might battle to keep them charged.

Axpert inverters can be considered as an off-line UPS.  In UPS mode they are specified to switch over within 10mS.  An online UPS like yours runs 24/7 from batteries/charger and thus doesn't need to switch over.

Here is an example of a 1KW 12V Axpert inverter.
https://www.takealot.com/five-star-1-2kva-1kw-pwm-12v-solar-hybrid-inverter/PLID92571048

 

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On 2023/05/20 at 12:39 PM, Modina said:

If your UPS runs from 36V then my suggestion will not work.  It's a pity it uses such a voltage.  If it was 12, 24 or48V you would have had more options.  Your batteries now have 4x more capacity than the 7Ah and your UPS charger might battle to keep them charged.

 

- Yeah it is a pity. Would have been nice to add Lithium to it, had it been a 24v or 48v, one battery and it would have been sorted.


Axpert inverters can be considered as an off-line UPS.  In UPS mode they are specified to switch over within 10mS.  An online UPS like yours runs 24/7 from batteries/charger and thus doesn't need to switch over.

Here is an example of a 1KW 12V Axpert inverter.
https://www.takealot.com/five-star-1-2kva-1kw-pwm-12v-solar-hybrid-inverter/PLID92571048

 

- Thats why i use the online UPS, it is safer for servers / critical loads, and has a better efficiency. My client has a 6kva UPS, it uses 16 x 12v 9ah batteries, this is  to get the voltage as close to 220v as possible to allow best efficiency and fast changeover when there is a power issue.

I have a solar company coming on Tuesday so i will also see if they have some good deals, or else i will definitely be looking at the Axpert, thank you for all the helpful information.

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  • 2 weeks later...

Just an update for anyone else who may have an issue like mine.

 

I contacted Geewiz, and they helped replace the battery and explained there has been some bad batteries in the Vestwood 50ah battery range, its just random batteries and not a single batch number so they cant say which are good or bad.

They replaced the battery with a SecurityProd 50ah lithium and its now working perfectly.

 

Thanks for all the help.

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