5 Batteries at 225ah and 1 at 216ah - Problem?

[Noles149]

Hey Guys,

I bought an EZGO Shuttle a few weeks back and the previous owner replaced one of the batteries in the pack with an Interstate 216ah, while the others are all 225ah.

My cart will run for a max of 3.5 hours if I had to guess. Is the difference in batteries the reason they're not running that long?

I've read up on batteries here and think i'm more confused than when I started out.

[sportcoupe]

Yes your range is limited to the battery with the lowest ah rating. Your reported range of 3.5 hours is really good IF you are using a digital volt meter to monitor the pack and only discharging it to 50% state of charge.

A golf cart is built to ride from hole to hole on smooth paths and usually can go at least 2 rounds of golf before needing recharged.

[Noles149]

I've only let it get to a half charge after driving around for for an hour and a half or so.

Should I change out the newer battery and get something at 225ah?

[radioman]

If the batteries are doing the job keep them fully charged after each use. I would suggest you leave it alone and run it for awhile. The 216 ah battery might be delivering more than the 225 ah rated batteries since they are not new.

[Revolution]

I can't see how that pack will work for long. Even in the best matched batteries, slight differences in each one and in each individual cell will eventually lead to under charging some and over charging others.

In your case the problem will be amplified. The lower amp hour battery will most likely be discharged more and overcharged more ever charge cycle. Depending on the age of the older batteries I would either replace the whole pack, find a used but good replacement for the undersized battery, or just run them as is till you need a complete new set.

edit to add: watch your water levels closely!

[Noles149]

Thanks for the responses. The 3.5 hours was definitely an over estimation.

We just took it out and it'll make it through 12-13 holes before the battery dies.

I'll check the voltage on all of them after it charges tomorrow.

[eflyguy]

Originally Posted by Revolution

I can't see how that pack will work for long. Even in the best matched batteries, slight differences in each one and in each individual cell will eventually lead to under charging some and over charging others.

This. It's not about Ah. It's about the resistance of the batteries and how they will charge and discharge. The lower rated battery will discharge faster, to a lower voltage, and then cause an artificially lower overall pack voltage as the whole pack recharges. This leads to over-charge of the "good" batteries, which significantly reduces their life. Also, as this one battery is being discharged to a lower % of it's capacity, it's also not going to last as long - although the over-charge issue will probably kill the pack sooner.

[radioman]

Run it. Keep them watered, clean and charged after each use. The lower rated battery might be the best one in the pack. Since previous owner replaced one battery the rest are suspect they would have reduced ah capacity. The lower ah battery might have been the best choice to replace one battery in a bank of slightly higher rated batteries that are not new.