Replace only one battery
 

I was told by two battery dealers that if I replace one bad battery I have, that is no good as another battery will only weaken the other batteries. This is for a 2005 Par Car that we use as a second cart for short trips. I have one battery that will not come up to 6 volts. 5.8 was the most it came up to. Do not want to put the money in for all new battier, thinking of just buying one new one and see what happens. Has anyone ever had this experience?

I have replaced a bad battery that was two years old with another one that was two years old (courtesy of Battery Boys)

Depending on how old your batteries are, you might get away with using a new one

If they are several years old, you might want to find someone who is getting all new batteries and exchange yours for one of their old ones

Your ideal situation is to find a used one of same age and brand if you want to nurse the set along.
If you went the new route, i would tell you that is you had another failure that you would then bite the bullet and replace the remaining 7 batteries.

I worked for an electric utility and all of our substations had multiple cell batteries, for 4 cells to 60 cells, and we regularly replaced ONLY the bad cells. We also did monthly maintenance and voltage checks on these batteries. I would replace the single battery, with a NEW battery, and monitor the all of the batteries monthly, with a simple voltage check, and water level check.

Or can buy battery analyzer like the ANCEL BTS200 and you will know exactly the condition of each battery. Course you have to check them independently.

BTS200 and similar runs around $40.

Amazon.com

Ask them to explain why that is so. Might be fun to see their faces.