tshermanator
New Member
- Joined
- Feb 16, 2022
- Messages
- 2
Hi there, Im in the early phases of building a power system for an adventure van - keeping it fairly straight forward with an all in one charger/inverter/controller (Growatt SPF 3000TL) and 2 24v 200ah lifepo4 batteries in series. I have another system running my home AC & critical loads off of 2 MPP LV6548s running in parallel and two identical 24v 200ah packs arranged in series - throughout this build I haven't been able to stop scheming ways I might be able to combine the two packs when the van is parked to double my home power capacity but quickly exceeding my knowledge..
My plan is to use a 350a Anderson connector to connect the van while parked. The batteries are already wired with 2/0 and protected by a T class fuse, and the total run to my other pack and inverters should be 5-6ft tops. The batteries are these (seems likely they are CHINS/ampertime units) which do have a BMS and do support parallel and series operation up to 4 units.
From what I've been able to gather it seems simply attaching the two groups of batteries in parallel without first balancing their state of charge will cause a surge of current from the more highly charged battery to the less charged battery causing at best my fuses to blow, at worst a fire. That said it seems like there are quite a few products that dynamically combine battery banks to enable charging while a vehicle is running then isolating batteries when they are not.. I'd assume it'd be fairly common with these type of systems to attach a fully depleted lifepo4 bank to a fully charged (and charging) lead acid car battery which I'd have thought would result in the same bad surge? do these systems have some mechanism to prevent this? Looking at something like this for example: victron-cyrix
Alternatively my LV6548s have a dry contact relay I can set up to trigger when the batteries are depleted.. perhaps I could use this to trigger a pair of heavy duty latching relays switching from the bank in the house to the bank in the van or vice versa whenever one is depleted.
Are either of these strategies at all plausible or am I barking up the wrong tree?
My plan is to use a 350a Anderson connector to connect the van while parked. The batteries are already wired with 2/0 and protected by a T class fuse, and the total run to my other pack and inverters should be 5-6ft tops. The batteries are these (seems likely they are CHINS/ampertime units) which do have a BMS and do support parallel and series operation up to 4 units.
From what I've been able to gather it seems simply attaching the two groups of batteries in parallel without first balancing their state of charge will cause a surge of current from the more highly charged battery to the less charged battery causing at best my fuses to blow, at worst a fire. That said it seems like there are quite a few products that dynamically combine battery banks to enable charging while a vehicle is running then isolating batteries when they are not.. I'd assume it'd be fairly common with these type of systems to attach a fully depleted lifepo4 bank to a fully charged (and charging) lead acid car battery which I'd have thought would result in the same bad surge? do these systems have some mechanism to prevent this? Looking at something like this for example: victron-cyrix
Alternatively my LV6548s have a dry contact relay I can set up to trigger when the batteries are depleted.. perhaps I could use this to trigger a pair of heavy duty latching relays switching from the bank in the house to the bank in the van or vice versa whenever one is depleted.
Are either of these strategies at all plausible or am I barking up the wrong tree?
