12 Volt shuts down on 2018 72 volt TXT

[JMM3]

I have a 2018 72 volt TXT with wet/lead acid Trojan 1275 plus batteries.

When battery charge level gets down to around 1/2 (have gauge that looks like gas gauge) everything 12 volt will shut down momentarily when I accelerate. When I reach speed - no more acceleration - the 12 volt comes back on. In other words, as I accelerate, lights and accessories will shut off and then when I reach cruising speed they will all come back on.

I am assuming as the battery charge level falls, when I accelerate the controller and motor are sucking voltage and resultantly, the voltage converter/reducer doesn’t receive its minimum needed voltage so it shuts down momentarily through acceleration? What do you all think?

If this is the case, is there a voltage converter/reducer out there that has more forgiving voltage input range? The stock convert/reducer is a plastic box with no cooling fins - DPI 67-72 volt input, 13 volt 30 amp output.

I live in the Villages, FL so long trips are sometimes necessary. Also should mention the cart has been reprogrammed so acceleration is quicker than stock setting. Has anyone else had this problem or know a fix? Thanks!

[ojo]

It looks like a gas gauge, but it's meaning is different. On an electric cart, half gauge or 50% SOC is empty. Never discharge the batteries below!

[JMM3]

Ojo, I have checked the gas/electric gauge and it seems E for empty is calibrated to represent 50% SOC on the batteries. Tested with hydrometer a couple years ago. I was worried about that, too.

I see in your description you have a 350 watt converter/reducer on your cart. What is the input voltage range on it?

I was looking at replacing the stock converter/reducer with one thas an input range of 48 to 72 volts thinking this might solve my issue. It has 360 watt 30 amp output. Plenty for lights and accessories.

Stock converter/reducer has input voltage range of 67-72 volts and I think this might be my problem?

[JMM3]

Actually, I might have answered my own question here…. Ojo, you got me thinking…. Looking at SOC % and resulting voltage for Trojan 1275 plus on Trojan website, the batteries would have to be less than 10% SOC for voltage to drop below the minimum 67 volts the stock converter/reducer needs. I never take them anywhere near that. So does that just mean the stock converter/reducer is going bad and needs to be replaced?

[ojo]

I understand so far, but not sure what can cause this. Higher amp draw when accelerating on low batteries were my suggestion. To exclude an undervoltage problem, i'd check the pack voltage when a reducer shut down happens. My own reducer is a cheap one from ebay, unfortunately no technical details available.