Sudden battery problems after welding

[Majten]

Hi,

I have a home built camper van, which we now have been living in full time for one year. The electrical systems consists of various components, a Renogy DC/DC charger, an MPPT from Victron, an inverter from Victron and 3 x Renogy 100ah lithium batteries with self heating.

It is all grounded in the chassi of the van. I recently had a damage repaired after hitting a tree, and suddenly, the batteries started dying on me. I had a look in the app and it seems like the voltage started fluctuating considerably the day the workshop took in in and started working on it (including welding). If I start the car, and the DC/DC charger starts charging, the batteries come back and the shunt shows the charge at 100 %. However, if I run e.g. the diesel heater and some other loads, eventually, the voltage drops to below 10V, and the batteries' under-voltage protection (I assume) switches them off.

Could this potentially be due to poor grounding from the workshop when they were welding the damage? My grounding in the chassi is quite close to the spot where the damage was.

I'll attach two few screenshots from the shunt, one showing the time when it went into the workshop, and the following drops in voltage, and what the voltage looks like when running a few loads over a period of time.

Thanks for any input!

 

[Steve_S]

I'm sorry to inform you but the batteries got fried, they should have been disconnected as well as the rest of the solar gear which "may" have been damaged. Respectable body shops will disconnect the car battery prior to attacking the vehicle with a Mig/Tig just in case. Do check your SCC & DC-DC charger as well to be sure they are still functioning properly.

 

[newbostonconst]

Does your shunt show you are charging to the rated capacity....? So say you have 280ah cells when the battery is at 10 volts and then you charge it all the way up, then the shunt should show a increase of about a 280ah difference between when it is charged and discharged.

You can also charge and then let them sit disconnected to see if they loose charge.

If you loosing charge quickly that energy has to go somewhere and always turns to heat eventually. You can look for what is getting warm provided you battery is taking a charge to full capacity.

Good Luck

 

[Zwy]

Hi,

I have a home built camper van, which we now have been living in full time for one year. The electrical systems consists of various components, a Renogy DC/DC charger, an MPPT from Victron, an inverter from Victron and

3 x Renogy 100ah lithium batteries with self heating.

Self heating takes power......

It is all grounded in the chassi of the van. I recently had a damage repaired after hitting a tree, and suddenly, the batteries started dying on me. I had a look in the app and it seems like the voltage started fluctuating considerably the day the workshop took in in and started working on it (including welding).

It is possible the impact damaged something. Years ago I owned a collision repair shop and many vehicles would experience dead batteries after an impact due to breaking of the battery plates.

Could it be the shop welding on the vehicle? That is possible but would depend on where the welding was done and where the ground cable was attached. In years past, the recommendation was to disconnect the battery in the vehicle to prevent damage to the electronics of the system. Over time that has been shown to not be the case. In order for damage to electronics to occur, current would have to pass thru the system or there was induced current by crossing a wire with the welding cables.

If I start the car, and the DC/DC charger starts charging, the batteries come back and the shunt shows the charge at 100 %. However, if I run e.g. the diesel heater and some other loads, eventually, the voltage drops to below 10V, and the batteries' under-voltage protection (I assume) switches them off.

I would pull the batteries, charge them off the vehicle and test capacity.

Could this potentially be due to poor grounding from the workshop when they were welding the damage? My grounding in the chassi is quite close to the spot where the damage was.

I'll attach two few screenshots from the shunt, one showing the time when it went into the workshop, and the following drops in voltage, and what the voltage looks like when running a few loads over a period of time.

Thanks for any input!

The causes could be many, you need more testing first to determine why the problems exist.

 

[Geokilroy]

I agree with removing the batteries and charging them separately. This would make sure they are close to balanced (cells internally and all 3 batteries themselves). With pre-made batteries, the cells inside can go out of balance. Give each battery a full charge and make sure they are all the same state of charge then run a capacity test on the set of 3 batteries. This would pinpoint or eliminate bad batteries.

 

[BradCagle]

Looking at your graphs, your batteries are not actually getting anywhere near a full charge. I suspect the shut is wrong, and you just need to get a good charge.

 

[TomC4306]

Self heating takes power......

But they use charging power, not battery power.

 

[Zwy]

But they use charging power, not battery power.

I'm wondering if the only charging is from the vehicle. If that is how charging is done, and engine running time is short or occasional, then most likely the battery heating will not be complete and thus the battery won't be charged.

Even if there is solar, it is possible there isn't enough PV production to first heat the battery and then charge it. Considering the time of the year and with flat mounted panels, this is a high possibility.

 

[TomC4306]

All true. Perhaps a couple of ground panels for winter.