Old and new batteries in parallel?

[Supine]

I had 2 EC37 Energizer batteries in an Ellies 24v modified sine wave inverter from Builders that needed replacing - they went from 8 hours of backup time to under 2. I just replaced them with new deep cycle gel batteries.

I am now sitting with 2 older batteries that I don't know what to do with. My Optimate smart charger indicates that they are in good condition (for what that's worth)

Does anyone have thoughts on whether I can use these older batteries in parallel with the new batteries to get increased capacity? I did a search on the internet and get conflicting advice. On the one hand people say not to use dissimilar batteries in parallel, but then there are articles like this that say it will be fine?

 

[Lupus]

Don't mix old and new batteries, you'll just drag the new down to the old ones level. Perhaps look for a decently priced inverter and redeploy them?

 

[Neuk_]

Don't mix old and new batteries, you'll just drag the new down to the old ones level. Perhaps look for a decently priced inverter and redeploy them?

Yep, don't mix old and new batteries, rather repurpose the old elsewhere.

 

[BBSA]

Most people advise against it, but if you do it add a load balancer to equalizes the state of charge.

 

[thehuman]

Call around, you could get upto r10 per kg for batteries.

 

[lived666]

I had 2 batteries for around 2 years and then purchased 2 new ones to add to the system and I get easily 8 - 10 hours powering tv, pc and routers when load shedding doesn't come back on. As yet inverter has yet to shut down because batteries have reached critical 50% levels.