Lithium battery charging

[discomatt]

With no power at home I thought I would plug the house fridge into the van and run it through the inverter. Nup batteries in the van have dropped to 8.8 volts WT now the Redarc system just says no battery monitor connected WT ( WT = what the )
Any ideas ? Can I pull a battery out and charge it with a normal battery charger with a few battery chemistry settings but no lithium setting or do I need a different battery charger all together?
Any help would be appreciated because I am loosing my mind with all the BS going on lately....

 

[boobook]

I know you have a decent amount of AH capacity in your batteries Matt, What power rating is the fridge and inverter?

Lithiums should not be at 8.8V and sound uncharged.

I would not recommend using a SLA charger unless the battery manufacturer specifically says it is ok.

EDIT. I am a bit confused about the chargers.

1)Isn't there an appropriate 240v lithium battery charger in the van that you would use?
2)If there is no power how can you use any 240v charger?

You may need a small plug pack 12v simple DC power supply to restart the Lithium controllers. Sometimes battery chargers wont recognise the batteries and wont start when below 10V

 

[CTL]

The Redarcs won’t fire up under a certain battery voltage. Do you have a solar panel with an attached regulator? If so, hook it up directly to the battery and get some charge into it. Then the Redarc will take over.
You must have a parasitic draw. Most likely the inverter.

 

[discomatt]

Inverter was turned off so I don’t think it is that. I think I left the Redarc in touring mode when I put the cover over the van and that is why they are so flat. Being at 8.8 volts I guess is the reason the Redarc battery management system isn’t recognising any battery at all. Yes the inverter is big enough to run the house fridge, it is 2000 watt inverter.

 

[peterfermtech]

I would of thought that at 8.8v the BMS should have disconnected the battery unless is just a leakage voltage.
Assuming that your lithium does have a BMS it should have protected the battery from fully discharging and should also protect the battery from over voltage so you should be able to charge with a standard charger. Once you get the battery voltage back up then you can let the redarc take over again.

 

[Triton14]

Hope you get it sorted DM, out of curiousity Im looking for a discharge chart for L-ion similar to the AGM one I have.
From what I understand you can discharge a L-ion by 80% compared to 50% for an AGM, so does that mean you can discharge to 8.44 volts without damaging the battery life??

 

[boobook]

Hope you get it sorted DM, out of curiousity Im looking for a discharge chart for L-ion similar to the AGM one I have.
From what I understand you can discharge a L-ion by 80% compared to 50% for an AGM, so does that mean you can discharge to 8.44 volts without damaging the battery life??

Yes and no.

You can generally discharge to 80% no problem, even more but that is about 12.9V. The discharge curve is very different to a SLA. You really need a Battery monitor that measures the discharge amps like a BMY 712

 

[discomatt]

Now I am really confused on what the issue is, yesterday the Redark DC-DC said no battery connected, check voltage 8.8, remove batteries, charge 2 with battery charger for an hour or so each just to get something back into them. Let them sit, the 3rd battery after sitting disconnected went up to 10.8v so I reset the BMS and reconnected it, charged from solar panel fine.
Go out this morning the 2 batteries I charged still had some voltage in them all good, the van has gone back to no battery connected.
Re install all 3 batteries , reset BMS again to correct battery chemistry and AMP/H now they are charging from the solar and look OK.
So why is the system crapping out over night ?
Either batteries are shot, can they be load tested like normal batteries?
Or the Redark unit has crapped out but that is unlikely I would think.
Any ideas ?

 

[callmejoe]

Hey @discomatt Matt there is a Facebook group, might pay to seek info on there also. As your well aware its got a huge amount of buttons, switches, and electronic wiss stuff and it could be a simple over sight of something simple that domeone else has already problem solved.

 

[phs]

Now I am really confused on what the issue is, yesterday the Redark DC-DC said no battery connected, check voltage 8.8, remove batteries, charge 2 with battery charger for an hour or so each just to get something back into them. Let them sit, the 3rd battery after sitting disconnected went up to 10.8v so I reset the BMS and reconnected it, charged from solar panel fine.
Go out this morning the 2 batteries I charged still had some voltage in them all good, the van has gone back to no battery connected.
Re install all 3 batteries , reset BMS again to correct battery chemistry and AMP/H now they are charging from the solar and look OK.
So why is the system crapping out over night ?
Either batteries are shot, can they be load tested like normal batteries?
Or the Redark unit has crapped out but that is unlikely I would think.
Any ideas ?

Any chance of hooking the lithium up to the car ?
Ie replacing the one that’s there, jump start go for a drive and Check battery

just need to make sure that there’s only similar Chem batteries connected, ie pull the secondary if you have one

 

[peterfermtech]

I assume the BMS you are referring to is the redark but the batteries should have an internal BMS which basic task is to prevent the battery from being over charged or under charged. Once the charge in the batteries dropped to a certain level then they would have switched off to prevent any further discharge. The 8.8v you were detecting was probably a low current voltage from the BMS detection circuit. You needed current put back into the battery so the circuit could switch on and give a voltage to the redark. Your batteries should be perfectly OK.

 

[boobook]

Sounds to me like there is some load still on that is draining the battery overnight.

Did you connect all 3 batteries or just the one that you didn't charge?

 

[shaun0]

Jumper leads from from other battery straight to Lithium for a little while to bump charge up then shes right. Done this on mine 2 or 3 times and no issues.

 

[discomatt]

I now have all 3 batteries back in the van and hooked up to the BMS ( Redark DC_DC) and charging via solar panels, voltage is back up to 12.8 so that looks ok. I have tripped all breakers so there is no chance of any power drain over night.
Fingers crossed it is ok tomorrow morning after they have had no charge for the night, that will tell me whether the batteries have packed it in or not.
The 8.8 was from my multi meter, I have no idea what the batteries internal BMS would shut off at but I was very surprised to see 8.8
I think the issue has arisen because I left it on touring mode instead of storage when I put the cover on it so no charge going in but I would have thought there wouldn't be enough drain to totally flatten the batteries so quick, the cover was on for about 6 weeks so maybe it was

 

[smitty_r51]

I would suggest you have dropped a cell... I had the same with mine. Read 13v but as soon as I left it an hour out dropped top 9v. I can separate my four cells so I could find the ones that showed a different voltage and replace it.

 

[peterfermtech]

This should give an idea about what a lithium battery internal BMS should be doing.

 

[discomatt]

Thanks for that video @peterfermtech very informative.
I think it is all OK after a couple of days charging it is now holding charge and the Redark seems to be working as it should.
We now have our power back after the storms so tomorrow I will give it a full charge with 240 then I will put some loads on it to make sure it's all working and so I don't get any nasty surprises when we can finally get out and do some camping.
Thank God for us loosing power or I wouldn't have found the problem until we hooked up the van to go away

 

[allanmac]

Good to hear you got the power back & batteries seem to working ok now Matt.. Whilst you have heaps of solar & lithium batteries, I still think it is a good idea to hook up to 240v every couple of months or so. Whilst our agm is no where near as efficent as your lithuim setup, I hook up to 240 every 3 or 4 weeks to top it up; (Bosch agm is nowhere near as good as the Fullriver we had in our previous van), and run the aircon/heater just to ensure all is working ok.

 

[CTL]

Good to hear you got the power back & batteries seem to working ok now Matt.. Whilst you have heaps of solar & lithium batteries, I still think it is a good idea to hook up to 240v every couple of months or so. Whilst our agm is no where near as efficent as your lithuim setup, I hook up to 240 every 3 or 4 weeks to top it up; (Bosch agm is nowhere near as good as the Fullriver we had in our previous van), and run the aircon/heater just to ensure all is working ok.

Treating lithiums like AGMs is not a smart idea. Totally different management required for lithiums.

 

[peterfermtech]

There is stories out there saying how careful you have to be and others that say just to use them the same as lead acid. From my experience it is somewhere in between and the trick is understanding how a lithium works and probably more importantly how the BMS works. Just keep in mind when you are recharging that a lithium will take full current almost right up to fully charged. This could mean that your charging system is running at 100% for a number of hours and could overheat.