New member with charger question

jay1028

New Member
I'm new here and have a 99 Ezgo TXT we purchased a week ago. it came with the Powerwise charger and the batteries are new (C8) Trojan. Everything works fine but there will be times that the cart may not be used for a week or two. I have not been able to find any chargers that will perform the float charge function. They cut off and never come back on if the pack voltage drops. My only experience is with car and bike batteries and if they are not used for a while, it is advised to float charge them, and that can be done for extended periods of time since the electrolyte does not boil. Is this a concern that I should have with this deep cycle batteries?

Jay
 

HotRodCarts

Cartaholic
Welcome to the forum...

Trojan and most other golf cart battery manufactures say to charge the batteries every 30 days when not in use. That's what I've always done and have had very good luck with the cart batteries (knock on wood)...

BU sells a 36 volt and 48 volt battery tender type chargers that are supposed to keep the batteries charged when sitting for longer periods. One of my neighbors at the lake bought one and left it plugged in for two weeks and when he came back to the lake all six batteries were bone dry. These were 1 year old Trojans and I filled them the week before so we know they were full when he left the charger plugged in.
 

gornoman

Well-Known Member
I bet that unit is going back to BU, eh?

Is there a chance that he set it incorrectly? I have no knowledge of the controls.

There are battery maintainers at Cabella's.
 

HotRodCarts

Cartaholic
Gorno,

It didn't have any controls just a on off switch. You connect it to + - on the pack and plug it in.
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It said on the instrutions "can be left on the batteries indefinitely"
I used over 2 gallons of distilled water to fill the batteries after that thing was plugged in for 2 weeks lmao...

EDIT:
Here's a link to the 36 volt model he had...
Battery Maintainer
 

HotRodCarts

Cartaholic
I'm not sure, he hasn't been out at the lake the last few weeks. He was pissed off and said he was going to call BU and raise hell. I'll find out next time I see him. I told him to get his money back and not to exchange it for another one.
 

jay1028

New Member
Trojan states that a float voltage is 39.6 for a 36v pack. Since it looks like you may not be able to depend on buying a float charger doing what it printed in its documentation, I may just build a float charger and see how it works out. I have some small 1 amp 12v transformers. I am going to connect two in series and after a bridge rectifier and a cap. see what the voltage is. Even two 16v chime transformers may work. We'll see.

Jay
 

Andy4639

Member
Float charging.

I had a old computer printer charger that the output was 36 volts. I hook this up to my 04 PDS cart during the winter months when the cart sit's for a long peroid of time. It has worked well for me.
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JRay

Cartaholic
Andy you are always thinking outside the box when it comes to these electric carts, Good Job.
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jay1028

New Member
Andy, you were very lucky. 36 volts is not a normal power supply rating.

After a few days of testing, attached is the schematic of what I did.

http://i245.photobucket.com/albums/gg52/ja.../36vfloat-1.jpg

I used two bell transformers wired the secondaries in series so that their output is 42 vac. I get the feeling that these transformers are not tightly controlled in production or from vendor to vendor because the one in my house for the door bell measures 18v but is stamped 16v at the output screws.

Not knowing exactly how to calculate what value dropping resistor would be needed, I did the whole design empirically over a period of a few days. After the pack came off the charger at 44v, the float charger was connected and adjusted for 100ma to the battery pack as a starting point. After 6 hours, the pack was at 39.8v and there was a bubble or two noticed in a battery cell. In my particluar instance I reduced the float current to 60ma and checked again over night. Battery voltage was 39.3 and no bubbles. My final resistor ended up at 100 ohms even. At 60ma, the transformers were just warm to the touch as was the 100 ohm 1 watt resistor. Removed the float charger for 5 hours and the battery pack has dropped to 38.5v. Connected the float charger again and after 6 hours, the pack was back at 39.3v again.

What does anyone think? Any ideas if this is a good idea? Trojan mentions a float voltage, but nowhere is there a stand alone float charger that I could find for a 36v pack.

Jay
 
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