Poor driving range and rapid power drop

Greetings. I have a deer in the headlight approach to addressing my issue. I bought a used 2003 GEM e4 825 in an auction not knowing what I would be getting. After getting it home I purchased 6 new Trojan batteries. The car looks to come to life OK which made my day but life not so rosy since. The on board charger only seems to charge to 60%. After dropping below 50% it won’t charge. I have to charge individually. At that point the gauge will show 100%. Driving less than two miles I can watch the battery capacity drop to 50%. This drive range is unacceptable. Dropping to below 50% so quickly and having to charge each battery can’t be the norm. So why the quick battery drain only going less than 15mph?

See if a battery is in backwards. See if each battery in the string jumps up 13 volts to about 80v total.
Test maximum voltage before charger turns off. Is each battery the same?

You will also want to check the battery acid/fluid level monthly and make sure the level is appropriate. Often it should be topped off to the bottom of the filler tube and no more. And it should NEVER get to the point of exposing the lead plates.

I would also use a volt meter and measure the voltage of each battery when your display says you are at 50% capacity. That’s roughly about 12.2V and at 12.0V you are likely damaging your battery to the point of lowered capacity.

Just as some automobiles will get damaged by running out of fuel, or oil the lead acid battery powered vehicles do need to be operated in a certain way to eliminate damaging components. And you are on the right path suspecting the charger and hopefully not too much damage has been done to the batteries.

Another thing I do is periodically check each battery cable connection point after a long ride. I just open up the compartments and feel the connection point for warmth. Slightly warmer than ambient temp is ok, anything more and you’ll want to clean and retighten the connection.

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You might also check the charging profile on the charger. Were the existing batteries flooded? Or were they Gels?

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Sorry for the delay. I was out of town and just got around to checking the batteries. I was really hoping one of the batteries was in backwards but I don’t think that is the case. I checked the four batteries in the back and they look to be hooked up correctly. Not sure about the two batteries in the front. Not sure where the cables run. They are in series. How would I check to see if they are hooked up wrong? When I put the new batteries in I pulled one old one out at a time and replaced it with a new one. I would think they are correct but I guess the previous owner could have put them in wrong and I just duplicated. The batteries have been charging for just about a week. Turning on the key shows 75% charge. I closed the master switch and checked each battery

Left side rear
12.5 v Top front battery Bottom front battery
12.53v 12.6v 12.55v
Right side rear

Those are all low and not fully charged.

It was already asked if you have lead acid or gel batteries?

While what the previous battery type was can be interesting, more important is what battery type the battery charger is set to. Important because different battery technologies have different charging profiles.

I put the lead acid Trojan batteries in new. Lead acid batteries were in there before. Just a couple of months old at this point. Seems like two seperate issues to me. The percent charge and rapid power consumption. Of concern to me is that at 100% charge (charging individually) I can only drive less than 2 miles before I get under 50% charge. I was thinking 20- 30 miles would be expected. I was hoping one of the batteries would be in backwards. I guess that could be a straight forward fix. Certainly the 4 in the back are in series correctly. The front two are in series but can’t say they are in with series the back ones since I don’t know how the wiring travels from the back ones. I don’t know how you would determine the charge profile.

Even brand new batteries you’d want to open each cell and verify the fluid level is full.

And because they are all in series, if any one of them has failed or become capacity deficient then it will effect the whole system.

One more thing to check would be your brakes and the free movement of your wheels. If a brake cylinder is stuck you could be pushing against brakes all the time.

On my 2002, the positive and negative cables come through the bulkhead on the passenger side. The positive is the shorter one (originally came with a red cap) and goes to the upper battery. the series cable between the batteries is on the drivers side. You can meter the wires or pull the dash to verify.

A 2003 came stock with a zivan NG1 charger. There should be a sticker on the front of the charger with the various profiles. On the top of the charger, there is a round sicker disk, under that there is a rotating micro switch. Match the letter on the switch to the profile that you want based on your battery types.

Looking again this afternoon there is labels on the battery wires (B1 - B6) with polarity marked. These seem to correspond to the polarity on all 6 batteries. 1 - 4 seem correct as does battery 5 and 6. Guessing the connections are correct. Battery 5 and 6 are in the front


Most likely correct, as it wouldn’t work at all with two backwards.
Imo, you need to monitor voltage at the controller while driving.