Yes, another newbie battery question

[Great white north]

Could pose a problem in a unbalanced pack , the newer batts will quickly be drawn down to the other older batts , although it depends how old your existing batts are if they are less then a year , prob no problem anything more I would not do it

[Olman]

Originally Posted by hookemtx120

One other quick one (I hope), it turns out my batteries are not as old as I thought. Can I add two 6 volt batteries to my existing pack that have a much higher AH like the T145 or will that cause problems?

I would not do that. I would try to get the same batteries (brand and ah rating) you have so that they will have the same charge and discharge rates. That way they will be more balanced. Having old batteries mixed with new batteries is not always a good idea for the same reasons. If your batteries are fairly new and in good shape you should be OK. My 6 were a year old when I added the other 2. They were however the same exact batteries. All seems fine.

[hookemtx120]

Thanks, I was thinking that was the case, I just wish the batteries that were put in before I got the cart were higher ah rating. I am not sure I want to add two more batteries that are only 210 AH. Will need to think about dealing with what I have or just biting the bullet and replacing everything.

[Olman]

Originally Posted by hookemtx120

Thanks, I was thinking that was the case, I just wish the batteries that were put in before I got the cart were higher ah rating. I am not sure I want to add two more batteries that are only 210 AH. Will need to think about dealing with what I have or just biting the bullet and replacing everything.

I bought my batteries then found the forum. I happen to luck out and got 230's. I f I had bought 210's, I would have run them till they crapped and never looked back. For me it would depend on how old and in what shape your 210's are. If they are good, buy two more and don't worry about it. Pretend you never went on this forum and you would never know the difference.

[JohnnieB]

Originally Posted by hookemtx120

Thanks, I was thinking that was the case, I just wish the batteries that were put in before I got the cart were higher ah rating. I am not sure I want to add two more batteries that are only 210 AH. Will need to think about dealing with what I have or just biting the bullet and replacing everything.

One option that hasn't been mentioned is adding two used batteries to the existing 36V pack to get 48V.

Basically, you have three choices with multiple options for some choices:
1. Run the 36V-210AH pack as is until if fails, or no longer provides the performance and/or range you desire.

2. Add two 6V batteries to the existing 36V pack and run it until if fails, or no longer provides the performance and/or range you desire.
Options: Add new batteries or used batteries

3. Bite the bullet and replace existing 36V pack with an all new battery 48V pack.
Options: Six 8V or Eight 6V.

Choices 1 & 3 are fairly straightforward, but choice 2 gets a little complicated.
If one of the batteries fails in an otherwise good pack that still has a couple more years of useful life left in it, the typical fix is to replace the failed battery with a used one about the same age as the rest of the batteries in the pack. However, if a used one cannot be found, and a new one has to be installed, the new battery will quickly age and become the same age as the rest of the batteries in the pack, so it has to be replaced at the same time as the others. In other worlds, it is a sacrificial battery, or at least a portion of its normal life expectancy is sacrificed.

Here comes the tricky part.
As batteries age, there storage capacity (AH rating) decreases and the batteries are charged in series, so the average pack voltage determines how much the battery pack is charged and the batteries with the higher storage capacities tend to be undercharged while the batteries with lower storage capacities tend to be overcharged. Flooded Lead-Acid batteries tolerate overcharging far better than they do undercharging, so the net result is the higher storage capacity batteries loose storage capacity.

The same concept applies to adding additional batteries to the pack to increase the pack voltage.

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In a nutshell, If faced with wanting to improve my cart's performance and increase its range now, but wanted to put off buying completely new 48V battery pack for a year or so, I'd add a couple used batteries to the existing pack. The same age and AH as the others if possible, but if not, I'd go with used batteries in the 225AH range, which should be easier to find.

If I couldn't find any used batteries, I'd use new economy or super-economy grade batteries. The existing 210AH batteries no longer have a 210AH capacity, so a new 200AH batteries would suffice.

[hookemtx120]

Thanks JohnnieB. The local Continental place says he keeps my exact battery in stock for $100. So $200 for batteries and a new charger from Scotty and I guess I would be in business for a little while longer. I could then decide after seeing it's performance in hunting season later this fall/winter, if I want to upgrade to better batteries. I still am nervous since my lease is spread out with lots of hills and my hauling corn/people/deer (hopefully) that my existing pack is good enough. I will soon find out when I head out there for a work weekend in March.

Thanks again everyone for your input.

[JohnnieB]

Before installing the two new 210AH batteries, repeatedly charge existing pack with your 36V charger to recover as much of their storage capacity as possible. That way the old batteries won't drag down the new batteries as far.

The pack that came with my cart (T-105 Trojans) would only charge to 85% Soc and I charged the living daylights out of them for a couple weeks and got them up to 95% SoC. Then I went to float charging and ended up running them 2 years before I upgraded to 42V.

[hookemtx120]

Thanks again for the responses.

As I still debate in my head what in the world to do, I thought I would add another question to this post since it still relates to a newbie battery question. At one point does it makes sense to add a 12volt battery just for accessories and want type of 12 volt do you use? Do you use a deep cycle or one of those 12 volt batteries like for riding mowers? Thanks for helping out a confused mind.

[JohnnieB]

It depends on how many amps your 12V accessories draw and how much you use them.

You mentioned a pair of 55W halogens. Together they draw will draw a bit over 9A and you don't want to discharge that battery over 50% SoC either, so an 18AH battery will run them (alone) for about an hour and 36AH will get you 2 hours of seeing where you are going.

A deep cycle battery would have a longer useful lifespan, but some people use SLI (car type) batteries, motorcycle batteries, lawnmower batteries and most anything they can lay their hands on at a reasonable price.

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There are two options for powering accessories.
Auxiliary battery.
Pros: No power is drawn from main battery pack.
Cons: Needs to be charged separately, so you need a 12V charger, needs to be replaced occasionally and it takes up room you could use for a battery in the main power pack.

DC to DC Converter (aka Voltage Reducer)
Pros: No need for separate charger, lasts forever and doesn't take up much room.
Cons: It does draw power from the main pack, so range is reduced. How much range is reduced depends on how many amps the 12V accessories use and how long they are used.

This is the one I have: http://www.cartsunlimited.net/DC_Reducer.html It works with a 36V, 42V and 48V packs. (26V to 60V input -- 12V @ 30A out)

[kojo]

Hookem I got my two additional batteries from a golf cart dealer for $35 each. They were Trojan T-605's, only 210AH but they matched other 6 as far as AH goes(208AH). Try a dealership, because if their like the one close to me they do maintenance on people's cart's and change out the set for a new set so they may have some. Mine were only about 1 1/2yrs. old and when I got them home I load tested them w/ the one's that Advanced Auto Parts has, checked their hydrometer readings and all was good. Alot better than $200.