I have a system i would like to upgrade, need your expert assistance all!

[Vegan.Omen]

Hi guys,

Great to be among you peeps, and share with you my goal. I bought a converted van which has an electrical system (see photos) and i would like to upgrade the batteries to lifepo4 from the 2 110ah wet leisure i have currently (which are only getting up to 12.5v stable charge when using a noco g7200 even after repair mode).

I have a few things i wanna say, so if you feel like helping, please ref the number so i know what we talking about (if i can be so bold)

1. I would also like to add some usb ports. the only usb it currently has that runs off 12v has 2 slots, 1 is 2.1a, the other is 1a. if i use both, it seems to stop, and then restart charging, like its not able to do both at the same time. im assuming this may be the cable? either way, cables are hidden behind the build so wondering how i can upgrade that without ripping the walls apart haha

2. i have 110ah x2 lead batts, i believe with my epever 30a mppt, coco g7200 shore power charger and sterling bb1230 that i have bases covered for the upgrade and was planning to build my own cells with a bms from overkill or the other guys which have low temp disconnect. Part a) do you think i should be ok with the current system i have to just put that in? Part B) Has anyone seen a good battery case they have built into or do you have any ideas as the current batteries are low profile (below the drivers seat in the van) and id like to keep them there if poss. Also, any ideas on heating them so they dont fall below 0 degrees as i dont wanna ruin them

Thank you for your consideration and apologies for the long ass post!

Solar love!
Damien

 

[Vegan.Omen]

Adding photos

 

[Hedges]

It sounds like you have a problem with charge voltage, unless the batteries have some cells so dead they can't be pulled up.
If you disconnect everything from the batteries, what voltage do they settle to?

If the problem is with chargers, getting that working might give acceptable service from your existing batteries.
If you're going to change batteries, you need chargers that work properly and are able to be adjusted for the parameters of the new ones. Have you determined whether they support LiFePO4?

Wringing out all problems you can with the existing batteries will reduce the chance of damaging new ones.
As for freezing, some people do have heaters set up (and some packaged batteries include that), but simply disabling charging when cold might be sufficient. A BMS that includes low temperature disconnect of the charging port would enforce it. When you got your van warmed up during the day, charging could resume.

Also, the advice is always to do a power audit before buying anything. Know how big a battery you'll need so you buy something that meets your needs.

 

[Vegan.Omen]

It sounds like you have a problem with charge voltage, unless the batteries have some cells so dead they can't be pulled up.
If you disconnect everything from the batteries, what voltage do they settle to?

If the problem is with chargers, getting that working might give acceptable service from your existing batteries.
If you're going to change batteries, you need chargers that work properly and are able to be adjusted for the parameters of the new ones. Have you determined whether they support LiFePO4?

Wringing out all problems you can with the existing batteries will reduce the chance of damaging new ones.
As for freezing, some people do have heaters set up (and some packaged batteries include that), but simply disabling charging when cold might be sufficient. A BMS that includes low temperature disconnect of the charging port would enforce it. When you got your van warmed up during the day, charging could resume.

Also, the advice is always to do a power audit before buying anything. Know how big a battery you'll need so you buy something that meets your needs.

i have done a power audit and i think at peak, i would use 60ah in a day max

the batteries are 3 years old and i think the previous guy went below 50% as good few times so i have tried to repair with the noco and its given me a bit more but max at around 12.5/7... when charging it gets up to 13.5 but then when it stops, it drops to 12.5/7 again... i can't atm isolate the battery as i would have to take off the seat and i dont have the tools rn to do so :-/

i have checked the parts and they all support lifepo4, so im guessing maybe the wiring is where i may need to change perhaps

what do you think of the set up in the photos? does it look ok?

 

[Hedges]

I'm not sure what everything in the photos is. What matters is amperage, wire gauge, fuses.
Lithium may be able to deliver higher current into a short circuit than FLA, several thousand amps. A fuse with "AIC" rating of 10,000A might be good, as well as amperage rating not higher than what the wires can carry.

60 Ah, 12V, 720Wh. LA batteries about 70% efficient, need 1000 Wh of charging. In the summer (5 hours effective sun) with tilted panels, 200W of PV might do it. Flat on roof, 300W or so. In winter could require 500W tilted or 1000W flat. But you've got shore power charger too.

12.5V after charging stops doesn't sound too bad. Question is how long it can support your loads before dropping to a voltage representing 50% DoD.

Page 22 shows 12.5V could be 80% charge. Would be nice to see if an extended charging at suitable voltage brings it higher. Might need an equalization charge. If you can't check individual cell voltages, could use a hygrometer to check specific gravity.

https://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf

Lead-acid it simple and reliable, and might be a good choice for replacement batteries if you won't be discharging 50% every night. Lithium gives more cycles, but unless you cycle often you may not get extra value. And you have to deal with having BMS and restrictions on cold charging. They are easily damaged if used outside of allowed parameters.