Solar Golf Cart Chargers

[yurtle]

It also never hurts to put it on charger anytime one is available. If I'm home, even if it's only for an hour, it's charging. If you visit a neighbor who has theirs fully charged, plug 'er in.

[JohnnieB]

Originally Posted by BorisM

..................am I killing the batteries by not charging them fully for four consecutive days a week ?

Yes.

Perhaps "killing" is too strong of a word and "reducing their life expectancy" is more correct.

When a battery is fully charged, there is a negative plate made of Lead and a positive plate made of Lead Dioxide and an electrolyte consisting of Sulfuric Acid diluted with water.

When the battery is used, the Sulfuric Acid combines with the Lead and Lead Dioxide to form Lead Sulfate and electrons are released. The Lead Sulfate collects on the plates.

When a battery is charged, electrons are added to the battery reversing the chemical reaction that occurred during discharge and the Lead Sulfate returns to being Sulfuric Acid, Lead and Lead Dioxide.

Unfortunately, as soon as Lead Sulfate molecules exist on the battery's plates, they start forming a crystal latticework and Crystalline Lead Sulfate does not break down into its original chemistry as easily as Non-Crystalline Lead Sulfate, so the Discharge/Recharge cycle is not 100% efficient and over time the active surface of the plates become covered with Crystalline Lead Sulfate. This is the natural aging process that kills lead-acid batteries.

The deeper a battery is discharge, the more Lead Sulfate exists and the longer a battery sits in a partially discharged state, the more time the Lead Sulfate has to crystallize.

Therefore, the higher the average SoC (State of Charge) maintained, the longer the useful lifespan of the battery.

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At a minimum, your cart should be placed on charge every night. Letting it the batteries go for three or four days in progressively lower States of Charge is aging them at a faster rate.

Adding a solar charging system in addition to putting on charge every night might be beneficial, but it sounds like the cart is drive for a few miles and then sits for hours at the pool, tennis court and other places. I don't know about your wife & kids, but when I park my cart someplace, I try to park it in the shade so the seat doesn't get hot and solar panels don't work too well in the shade.

[yurtle]

Originally Posted by JohnnieB

Yes.

Perhaps "killing" is too strong of a word and "reducing their life expectancy" is more correct.

I said he's "killing useful life", sorta in between.

[Volt_Ampere]

A full day of solar charging might be equal to 15 minutes of wall charging. I didn't do the math but you can if you know the current output of the panel.

[BorisM]

I hear all of you and thank you for the answers. What I gather is that solar panels are a waste of money and effort, got it.

My problem is as follows: if a golf cart must be plugged in every time it is idle, or at least overnight, then what is the point of "powerful" batteries that you cannot/should not use to the fullest? What I mean is if, let say, good Trojan batteries allow 30 miles driving range, but one is not supposed to use them for more than 15 miles because one is reducing the life expectancy of an expensive battery, then why not buy a cheap battery that only gives you 20 miles driving range and use it at 95 % ?

[yurtle]

The higher the amp-hours, the less you will discharge them, and the longer they will last. I got nine years out of my last set, but that's unusual. If you run a pack below 50% and leave it that way for days, they won't last very long at all.

Go to cartsunlimited.net and read everything about batteries. Also, Trojan's website had a lot of videos and .pdfs.

[JohnnieB]

Originally Posted by BorisM

I hear all of you and thank you for the answers. What I gather is that solar panels are a waste of money and effort, got it.

My problem is as follows: if a golf cart must be plugged in every time it is idle, or at least overnight, then what is the point of "powerful" batteries that you cannot/should not use to the fullest? What I mean is if, let say, good Trojan batteries allow 30 miles driving range, but one is not supposed to use them for more than 15 miles because one is reducing the life expectancy of an expensive battery, then why not buy a cheap battery that only gives you 20 miles driving range and use it at 95 % ?

Your numbers are off a bit, but the reasoning isn't and it is a good question.

When the guys on the forum state their cart's driving range, it is based on not discharging their pack below 50% SoC, so the differences in range is based on the AH rating of the batteries if the efficiency of the cart, the terrain driven over, the weight carried/pulled and the driving style remain the same.

Based on the AH rating, there are about 5 grades of batteries ranging from super-economy to super-premium and most battery manufacturers have batteries that fall into two or more of those grades. Basically, there are more differences between the different grades of batteries from the same manufacturer than there is differences between batteries of the same grade made by different manufacturers.

The minimum grade of battery to put in your cart is determined by the efficiency of the cart, the terrain driven over, the weight carried/pulled and the driving style, plus the typical distance driven between daily charges.

For some people, an economy battery will suffice while others may need at least the standard grade (225AH) and others may need premium or super-premium grades. Upping to a higher grade than needed will increase the cart's range and the lifespan of the battery pack, but whether that is cost effective or not depends on the local price of the batteries.

Typically, the best bang for the buck is the highest AH batteries your budget will allow at the cheapest price you can find locally.

The first attachment is a list of various grade 6V deep-cycle batteries by various manufacturers. The list is sorted by AH and then by brand name.

The percent above/below the standard grade (225AH) indicates the increased or decreased range and the lifespan trend. (Lifespan is not a linear relationship to AH like range is)

The second attachment is a chart showing relative lifespan based on average SoC. A battery with fewer AH will be discharged to a lower average SoC when used in the same cart and driven under the same conditions and, therefore, will not last as long before it needs to be replaced.

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In my opinion, installing a 120W solar charger as a supplement to the regular daily charging with a conventional charger would keep the pack at a higher average Soc, since you'd add about 1.4 kWh to an 8.6kWh battery pack daily if it sat in the sun about 12 hours each day, but it'd probably take a decade or more to recover the investment, so it's not cost effective.

[BorisM]

JohnnieB.
From what I understand the best possible scenario for an electric golf cart battery pack is to be installed in a golf cart that is never driven and plugged into a dpi charger 24/7/365. Then the second best scenario is to charge it as soon as it discharges to 80%, etc. Realistically thou, how many people can actually do that?

[yurtle]

24/7/365.25. Don't forget leap years.

[yurtle]

I drive mine anywhere from once a week to seven days a week. Weekends often run off and on all day long, with up to four passengers. I plug mine in every evening, and if I go home for an hour or more, I plug it in.

As I said, I got nine years out of my last pack, but YMMV. I'll be happy if I get six out of my current setup, as I'm pulling a lot more amps, BUT, I'm not driving any further, so the real difference is heavy foot syndrome.