Charger for golf cart batteries

[mjalar51]

Hello,

We have been using 2 6v Costco 210 AH batteries wired in series for our camper van. Our only charging system for these has been the 200 W solar system mounted on the roof. It has worked pretty well now for a couple years. Besides running LED lights and charging phones, the largest load is the 45 qt Whynter frig. As long as we are parked in the sun, all is good. (We are next go to try to figure out how to charge 2 ebike batteries when away from the grid.)

Here is my main question:
What is a good battery charger to use to top up these house batteries when shore power is available? Most of the battery chargers I see for sale have much smaller AH capacity than 210 AH. Would it be ok to use a smaller charger? Perhaps  it would just take longer to charge the batteries? I was hoping to find something we could stash away and only use occasionally when the sun doesn't shine.

We are considering a switch to use the van alternator as a charging option but are not ready to start that yet.

Thanks. Mark

 

[29chico]

The similar Trojan t-105 flooded battery is rated as a max of 13 percent charge rate of the battery amp hours.  So 27.3 amps max charge rate for a 210 amp battery such as yours.  Deep cycle lead acid flooded cell batteries don’t take kindly to very fast charging or discharging.

 

[Wabbit]

/\x2 on what 29Chico said.

I use a crappy Walmart 2/10/25 amp charger off my genny or when I'm in a shore power\solar not deployed situation. It works, but when I get around to upgrading it, I will be going with a Meanwell rsp-500-15 setup. No idea of how to do that, but I'm sure there's "how to's" that will get me close and the forums here to get me across the finish line. Best of luck!


EDIT: spelling

 

[B and C]

I have a Progressive Dynamics fully automatic charger (45 amp) that I use when I plug into shore power or run the genny. This charges 350 Ah of AGM batteries. I don't want to babysit a manual charger.

 

[Weight]

I'm using the ProNautic 45 amp charger I installed before I got solar. It charged 6 EGC2 batteries.

 

[mjalar51]

So a smaller charger (lower amperage) might be slower but better for the long term health of the deep-cycle batteries?

 

[B and C]

Batteries will only take so much charge based on how deeply discharged they are. You could connect a 1000 watt charger and the batteries will only accept a portion of it based on charge. A good smart charger will allow you to plug into shore power and not have to keep monitoring state of charge as it will not cook your batteries the way a dumb charger will. Your 200 watt solar system is far smaller than a 45 or 60 amp charger.

 

[Trebor English]

So a smaller charger (lower amperage) might be slower but better for the long term health of the deep-cycle batteries?

It might be nice, polite, politically correct, to charge slower but if that means not taking the time to charge fully it is much worse for the long term health of the battery.  If you consistently charge to 95% full that becomes your new capacity.  If you lose 5% of your capacity every 6 weeks the first hint that something is not right is when the fridge quits.  A year of losing 5% every 6 weeks gets your battery capacity below half.  Then, like a pair of double As, you throw them away and get new ones.  

On the other hand a charger that can put out 45 amps will get your battery up to 80% - 85% much more quickly.  It will then actually hold 14.4 volts (or whatever your absorption voltage is) for hours.  During that time the charge current will taper down to almost none.   It takes a long time to get all the lead sulfate converted back to lead and sulfuric acid.

 

[Weight]

Not as small as 10 amp.