Split charge relay capable of charging 360Ah Battery Bank?

[Vanlife Bandit UK]

yes, when you get a multimeter verify the voltage on the terminals. If the MT50 LCD is reading 13.6 volts the battery terminal have to be 13.6 volts also. If the battery terminals are 13.2 volts, then you have a .4 volts voltage drop, you compensate by raising the bulk voltage by .4 volts (from 14.4 volts to 14.8 volts) and just keep checking it at various times, sometimes you have to adjust it several times to get it right. The only correct battery voltage is directly from the terminals with a multimeter or some meter (that is verified to read accurate) the controller MT50 LCD is usually not reading accurately unless verified with a multimeter.

By raising the bulk voltage you increase the amps going into the battery. On my Lifepo4 system (14.6 volts max) at bulk setting of 14.2 volts I get 8 amps, at 14.4 volts I get 10 amps, at 14.6 volts I get 12 amps. I can adjust how far I want the battery to be charged, at 14.2 volts it will never reach full charge but its a good setting when In summer and I don't use too much power. At 14.6 volts I can fast charge the battery and it will usually activate the BMS, I rarely keep it 14.6 volts unless its cloudy and need max amps. I usually have it at 14.4 volts, where it gets the battery up to about 95 percent.

On an AGM lead acid You need it at 14.4 volts to fast charge at all times, they require full charge everytime. Some AGM's might actually need 14.7 volts. I have a fullriver 27ah agm that requires 14.7 volts, charging it at 14.4 volts won't top it off. On the side of the battery it might say the max voltage, if yours say 14.4 to 14.7 volts, go with the max.

Thanks for the follow up info. That's pretty clear. I'll have to have a closer look at the MT50 and see how to change that setting. I set the battery type to 'Sealed' and pretty much left it at that. At first glance I don't see the bulk voltage, it's probably under a different heading.
I've uploaded a video showing the multimeter reading on the battery bank terminals as I read out the reading on the MT50 in real time. I think this concludes that there is no voltage drop in this case, although it did lag at the end of the vid by around 0.1. See what you think.
If there's no V drop, then I think the combination of the autumn weather along with the fridge/freezer is draining the batteries and they are struggling to get re-charged fully. It could also be the settings on the charge controller come to think of it?
I'm not using the PC nor instant pot as I feel there's no power left to get through the night.
My solution is to purchase a 30Amp Victron DC to DC battery charger so that the batteries get some juice (particularly in the morning). If this works well, then I may purchase another 120AH battery to and a (Dumb) mains battery charger as my noco genius 10 battery charger only goes upto 230Ah - I can use it for the engine battery instead.
View attachment voltage drop.mp4

 

[jonyjoe303]

The readings are accurate, no voltage drop. And you have the setting correct with "sealed battery" which is 14.4 volts. Just verify the sealed batteries require 14.4 volts, and not something higher. My 27ah fullriver agm which I'm using as a start battery (requires 14.7 volts bulk) , I have to top it off everyday with a 14.7 charger, If I only let the alternator charge it to 14.4 volts after about a week it will produce slow cranks when I try to start the engine.

I think the batteries are so low and the solar is just no longer able to keep up. About 2 years ago when I drained my 220ah lifepo4 to 10 percent, the 240 watt solar panel I had was no longer able to keep up with charging it, it limped along for almost a month at 10 percent, it wasn't until I upgraded to a 365 watt panel that I was finally able to charge it back up to 100 percent but it took about 5 days. But once I got it back to 100 percent the 365 watt panel was able to keep up with it.

The noco genius 10 will work on your system, but it charges only at 10 amps and it will take a while to fully charge. The only reason it says its only good up to 230ah is probably because it has a timer (23 hours?) to shutoff after several hours. After it shutsoff just unplug it and reconnect it and it will restart the charge again, and it will keep charging until its full, no matter the size of the battery.

epever settings, boost charging voltage is same as bulk charging voltage.


agm bulk voltages examples, every brand battery has their on specs on side of battery. (absorption voltage same as bulk voltage)

 

[Vanlife Bandit UK]

The readings are accurate, no voltage drop. And you have the setting correct with "sealed battery" which is 14.4 volts. Just verify the sealed batteries require 14.4 volts, and not something higher. My 27ah fullriver agm which I'm using as a start battery (requires 14.7 volts bulk) , I have to top it off everyday with a 14.7 charger, If I only let the alternator charge it to 14.4 volts after about a week it will produce slow cranks when I try to start the engine.

I think the batteries are so low and the solar is just no longer able to keep up. About 2 years ago when I drained my 220ah lifepo4 to 10 percent, the 240 watt solar panel I had was no longer able to keep up with charging it, it limped along for almost a month at 10 percent, it wasn't until I upgraded to a 365 watt panel that I was finally able to charge it back up to 100 percent but it took about 5 days. But once I got it back to 100 percent the 365 watt panel was able to keep up with it.

The noco genius 10 will work on your system, but it charges only at 10 amps and it will take a while to fully charge. The only reason it says its only good up to 230ah is probably because it has a timer (23 hours?) to shutoff after several hours. After it shutsoff just unplug it and reconnect it and it will restart the charge again, and it will keep charging until its full, no matter the size of the battery.

epever settings, boost charging voltage is same as bulk charging voltage.
View attachment 32956

agm bulk voltages examples, every brand battery has their on specs on side of battery. (absorption voltage same as bulk voltage)
View attachment 32957

Hi there, thanks very much for the info and your time spent on this and apologies for slow reply. Had a problem getting through to tech support among other things unrelated.
The absorption votage is 14.8v for my AGM batteries.
Max battery charge rate spec is 25% of bank no more than 30Amps 14.8v which will be fine for the DC to DC charger but I'd probably need to turn off the solar whilst driving and charging from the alternator as the charge may be too high? I've fitted a PV isolator switch so that's not a problem if needed.
Quick question though, would I need to turn off the solar when charging with a 30A DC to DC charger on my 240Ah batt. bank? Would the DC to DC be charging the 240Ah batt bank at max safe capability or will it not really matter if I had the solar charging at the same time as well?
Also, if I added another 120Ah battery to the bank making it in total 360Ah, would the max charge rate increase to 45Amps? Or have I got this twisted?
Seeing as my batteries charge to 14.8v then I will need to change the 'Boost charging voltage' setting from 14.4v to 14.8v on my c/c. I think? I would need to change the bulk (boost) charge rate to 14.8v. but leave all the other settings the same.
I think this is correct.
I'm hoping that the 30A dc to dc charger will solve the issue along with changing the boost setting to 14.8v without having to buy another battery. If I did though, are you saying that the NOCO genius 10 would be able to charge the bank at 10A but I would need to switch it off after say 23hrs to charge upto 360ah?
Here's another question I have; the Optimum Operating Current (Imp) for each solar panel is 5.38A. Does that mean that the 4 x 100W panels COULD bring in upto a total of 21.52A (4 x 5.38A)?
Tech support stated that fitting another battery after just 2.5 months of cycling on my already fitted bank would be fine. 4 - 5 months they said was fine, so that's an option.
Many thanks,
Si
update: to change the boost charge rate to 14.8v I had to change the equalize charge to 14.8v to on the c/c.

 

[jonyjoe303]

400 watts divided by 14.8 volts will give you about 27 amps in the best conditions (summer with the sun overhead and a low battery) .

You don't need to disconnect the solar, the solar controller when it see's a full a battery will reduce the amps going into the battery. Even with the DC to DC charger and solar charging to the max it would be less then 60 amps, well within the max charge rate of the 240ah battery bank.

If each battery can handle 30 amps, 3 batteries will be 90 amps max. That would be 25 percent of 360 ah.

The noco10 manual doesnt mention when it switches off, but when it does just reconnect and it will see the battery is still low and restart the charging cycle again. There is no way the noco 10 will know what size AH the battery is, it charges only by what the battery voltage is. One thing I recommend is to get some sort of LED volt/amp meter and connect between the charger and battery so you can see the voltage/amps in realtime to see if the charger is actually getting the battery to 14.8 volts.

Charging your battery to the recommended 14.8 volts should help, my agm which charges by the alternator has poor performance when its only charged to 14.4 volts. As long as your charge controller can get the battery up to 14.8 volts everyday you should be good. Charging your battery to the max everyday will make them last longer, My 27ah fullriver agm that is doing engine start duty I bought in 2013 and it was "old stock" when I bought it for 45 dollars, its a 10 year old battery but I always charge it to the max.

Picture of my dc to dc 2 amp charger that I use to top off my agm start battery. This would be comparable to your noco 10, but I have an LED volt/amp meter so I can tell exactly what the charger is doing. At 14.7 volts and .13 amps, the battery is about 99 percent full. The LED meter is much better than the blinking lights on the noco 10.

 

[Vanlife Bandit UK]

Many thanks for the clarification.
I've disconnected the freezer and have plugged in the noco charger. I'm gonna charge the batteries from the mains each day/evening for about a week, or as long as needed. I'll re-set the noco as well, as you suggested. Hopefully some sun will come out to help to. I'll be using minimum electric in the van for the time being until I can get the batteries up to full charge.
I'm definitely going to get the 30A DC to DC charger and possibly even another 120Ah battery. With all that, and the proper setting on the solar C/C I think I should be all set.

Gotta say, the info you have provided has been invaluable and has really set me straight on a few things electric wise in the van, so, massive appreciation for your time and effort in this.

Si