Ezgo 28115g04 charger adjustment

[tonyq60]

We have EZGO cart TXT and the 28115g04 charger.

Lucky finds as we got the charger last year at estate sale and cart last month at a different one.

Anyway it had no batteries and we had access to some 12 V AGM batteries that are amazing units at 120 amp hour so for our use great.

However the charger is built for flooded cells which usually have a higher end voltage.

We are wondering if anyone else has AGM batteries with same charger and if they are holding up well.

The unit looks like it is brute force regulated meaning simple transformer to diodes to batteries so adjusting charging voltage likely out.

Since these are not a constant voltage style charge like the telecom systems we are accustomed to it seems these charge in a brute force mode until a somewhat higher voltage is seen then they stop.

Okay for flooded as water can be added but not do good for AGM.

We would like to adjust the voltage setting for shutoff at a lower point and there is a POT on the control board but we will ask before tinkering.

Anybody else been there?

Looking for better charger as well.

SIDES NOTE: cart came with a 48 volt charger that is available for trade...

Sent from my SAMSUNG-SGH-I337Z using Tapatalk

[lockman1]

Moved to Electric EZGO, and a courtesy bump!

[BobBoyce]

Originally Posted by tonyq60

We have EZGO cart TXT and the 28115g04 charger.

Lucky finds as we got the charger last year at estate sale and cart last month at a different one.

Anyway it had no batteries and we had access to some 12 V AGM batteries that are amazing units at 120 amp hour so for our use great.

However the charger is built for flooded cells which usually have a higher end voltage.

We are wondering if anyone else has AGM batteries with same charger and if they are holding up well.

The unit looks like it is brute force regulated meaning simple transformer to diodes to batteries so adjusting charging voltage likely out.

Since these are not a constant voltage style charge like the telecom systems we are accustomed to it seems these charge in a brute force mode until a somewhat higher voltage is seen then they stop.

Okay for flooded as water can be added but not do good for AGM.

We would like to adjust the voltage setting for shutoff at a lower point and there is a POT on the control board but we will ask before tinkering.

Anybody else been there?

Looking for better charger as well.

SIDES NOTE: cart came with a 48 volt charger that is available for trade...

Those AGMs are underpowered, and will not live long in a golf cart environment. You need to be able to replace lost electrolyte, and that cannot be done with AGM type cells. I understand the desire to be "maintenance free", but that is not the way. Consider switching to a Lithium pack if you don't want battery maintenance.

[JohnnieB]

The Powerwise 28115 charger is a ferroresonant transformer type charger and its charge profile is based on the attached recommendations from Trojan Battery for their Lead-Acid Deep-cycle Wet-Cell batteries.

Basically, it starts out in a constant current mode (18A - 20A) until the on-charge voltage climbs to about 42V and then the amps start decreasing as the on-charge voltage increases. As the amps decrease to about 5A as the on-charge voltage approaches about 45V and the charger shuts off.

The max recommended charging amps for AGM is roughly 1/2 of what the max recommended charging amps for a wet-cell is and the 120AH batteries are roughly 1/2 the capacity of the 225AH wet-cell batteries the PW 28115 is designed to charge, so the initial amps (constant current mode) will be about 4X what your 120AH batteries can tolerate.

Also, the max recommend finish voltage for a 36V AGM battery pack is 44.1V and the PW 28115 shuts off at 45V +/-1V. However, you might be able to lower this to 44V or less by adjusting the pot on the control board. Of course, the AGM batteries will probable be cooked before the on-charge voltage gets that high due to the 4X higher than recommend amps.

Pages 19 and 20 of attached Trojan Battery user's guide have the charging profiles for Wet and AGM batteries.

Here is a website with some chargers that will work with AGM batteries, but not sure if they'll charge a 120AH 36V pack. http://www.cartsunlimited.net/chargers-36-48v.html

[tonyq60]

We never plan on replacing electrolyte. ..proper operation means you do not loose any.

Normal GC batteries are maybe 200 ah and a set of six while these are maybe 120 ish amp hours with only 3 and rated for 100 discharge.

Max discharge rating of over 4000 amps indicating very low internal resistance.

For our use the lesser amp hours will not matter as we are not cruising and less weight makes for better operation on the grass.

Other battery options yes but those exceed our needs and budget.

Originally Posted by BobBoyce

Those AGMs are underpowered, and will not live long in a golf cart environment. You need to be able to replace lost electrolyte, and that cannot be done with AGM type cells. I understand the desire to be "maintenance free", but that is not the way. Consider switching to a Lithium pack if you don't want battery maintenance.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk

[tonyq60]

Thanks for the answer.

That is what we were suspecting.

Online searches found no good usable data so we ask here as others likely been there.

Spent many years managing vrla or Agm battery plants for telecom switches and communications sites so very well versed in the charging and use of this type of battery.

The ones we have are cycle service for ups type loads where high currents both charge and discharge are expected instead of the common float service ones common to cell sites and switches.

The charger works fine and does not exceed rate of charge but the end voltage being too high causes battery to be in equalize mode when it should be fully charged and either charger off or floating.

Float charge should not exceed 0.1% C where C =120 (cannot remember exact ah today) so float charge should not exceed 0.12 amps.


Also of minor note is fully charged in generic terms 2.25 VPC is considered fully charged, this would be 40.5 VDC total.
Each battery model has specific voltage but generic value can be close enough for general discussion.

Charging above that point for short periods will attempt to equalize the battery plant but most VRLA/AGM batteries will void warranty if equalized.

Charger is still at 5 amps when it should be fully charged so for short term we will need to manually control it.

Was looking at tinkering with the pot to cause the charger to turn off at lower voltage or we may just build something.

Originally Posted by JohnnieB

The Powerwise 28115 charger is a ferroresonant transformer type charger and its charge profile is based on the attached recommendations from Trojan Battery for their Lead-Acid Deep-cycle Wet-Cell batteries.

Basically, it starts out in a constant current mode (18A - 20A) until the on-charge voltage climbs to about 42V and then the amps start decreasing as the on-charge voltage increases. As the amps decrease to about 5A as the on-charge voltage approaches about 45V and the charger shuts off.

The max recommended charging amps for AGM is roughly 1/2 of what the max recommended charging amps for a wet-cell is and the 120AH batteries are roughly 1/2 the capacity of the 225AH wet-cell batteries the PW 28115 is designed to charge, so the initial amps (constant current mode) will be about 4X what your 120AH batteries can tolerate.

Also, the max recommend finish voltage for a 36V AGM battery pack is 44.1V and the PW 28115 shuts off at 45V +/-1V. However, you might be able to lower this to 44V or less by adjusting the pot on the control board. Of course, the AGM batteries will probable be cooked before the on-charge voltage gets that high due to the 4X higher than recommend amps.

Pages 19 and 20 of attached Trojan Battery user's guide have the charging profiles for Wet and AGM batteries.

Here is a website with some chargers that will work with AGM batteries, but not sure if they'll charge a 120AH 36V pack. http://www.cartsunlimited.net/chargers-36-48v.html

Sent from my SAMSUNG-SGH-I337Z using Tapatalk