DPI Chargers

coosa

I decided to convert my 2007 PDS cart to 42 volts back in the spring. That turned out to be a great upgrade and made it a much stronger cart. I also bought 7 new Trojan 105s at the time. I bought a DPI Charger from ScottyB and it had issues from the start. I followed their directions, which were really no different from any other charger - plug it into the cart first, then into the 120 volt receptacle. The first time I tried it everything worked as they said it would. All the lights would flash red a few times, then the charger would analyze the battery pack and after a few seconds the charge light would start flashing, and then the needle would move all the way to the right as it began the charging cycle.

But the second time I tried to charge the pack, the lights did the red flashing as before, and then the bottom light started flashing red. After several minutes, it was obvious it was never gonna start charging so I unplugged it and tried again. Same results. I was persistent and on the 5th try it finally went through the correct cycle and worked normally. It continued to work that way for a couple of weeks - sometimes working on the first try and sometimes requiring several tries. Then one day it never would do anything except flash the bottom red light. I tried it multiple times over several days and the thing was just dead. ScottyB told me to contact DPI, that they had great customer service, and they did. I told the guy what was happening and he put a new charger on UPS that day without even waiting for me to send in the old charger.

But the new charger had exactly the same issues. The very first time I tried it, it behaved the same as the previous charger. I unplugged everything and tried again and it worked on the second try. The replacement charger was more consistent than the first one, and it worked most of the time on the first try. After a couple of months, something seemed to happen to it and the needle would only move to the halfway mark when it started charging. It was still charging the cart, so I kept using it, but eventually it got to the same point as the first one and would not work at all.

So a couple weeks back I called DPI again, and again they sent me a new charger. I couldn't believe it, but this one also failed on the first try. I unplugged it and tried again and it worked normally on the second try. I've charged the cart 5 or 6 times with it, and it has failed several times just like the first 2.

When it works, it does a great job of charging the batteries, and this pack seems like it is continuing to get stronger. I know these are popular chargers and have a great reputation. Has anyone else had issues similar to mine? I've wondered if they have some kind of problem specific to the 42 volt charger; I'm sure they don't sell as many of those as the 36 and 48 models. It has a 3 year warranty, but at the rate I'm going its gonna take a dozen chargers to get me out of warranty with them.

Thanks for any ideas.

BGW

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scottyb

That's a lot of chargers. It's got to be something wrong with the cart or one of the batteries. Can you ID the batteries and their age? All the same model and age?
Can you list all 7 batteries and give SOC for each cell?

JohnnieB

The Power On LED (bottom LED) flashing means "Charge Level Unbalanced" and DPI's explanation of the error code says it is due the the battery pack being unbalance and give an example of some batteries being much higher charged than the others.

Since the batteries are connected in series and the DPI charger is only connected to the ends of the series chain, it has to be looking at something other than individual battery voltages to trigger this error code. The only two electrical parameters the DPI can see are voltage and amps, so if one or the other or both isn't what is expected during the detection phase, or at the beginning of the bulk charge phase, the error is triggered.

The first thing I'd check is the seven individual battery voltages while at-rest, while on-charge and while on float-charge.
They should all be within 0.1V of each other whether on charge or at rest.

If the pack is balanced, Pop the top off the charge receptacle and compare the voltage between the + and - brass terminals with the voltage between the main + and - lead terminals of the battery pack. They ought to be identical, or very close to it.

Excessive resistance in the wires (and 50A fuse if one is installed) from the charge receptacle to the battery pack might emulate an unbalanced battery pack from the DPI's perspective.

However, the wires and fuse aren't likely to change in resistance between charging attempts. That leaves the female radsoks in the charge receptacle. They are 10 years old and may need some TLC.

I've never tried it, but I understand a .22 caliber bore brush and contact cleaner works .

FWIW, my 42V DPI has been working perfectly since Nov-2012.

coosa

Thanks for the replies. I can't get to it right now, but I will post the battery info later today. But this was one of the first things I checked and the batteries are all very consistent, much more so than when I used the old EZGO Powerwise chargers. I bought the pack on the same day I ordered the charger, which was some time back in March. I followed your break in instructions exactly and I can tell they are getting still getting stronger. I checked the pack voltage before using it this morning and it was 45.9. It was 45.3 the last time it failed on me, so I went out and ran it another mile and it fired right up when I tried the charger again.

I use my cart almost every day, but some days I run it less than a mile and I always charge it at the end of the day as you guys have said to do. I've wondered if the fact that voltage was often still close to 100% was part of the problem. But both times before I sent the chargers back I ran the cart down to 50% and they still would not come on. Whatever caused it, both chargers would not work at all when I gave up and sent them back. And I have certainly wondered if its possibly something I'm doing or some issue with my cart that is causing this, and that's the reason I decided to ask here.

JohnnieB, I have cleaned everything you suggested multiple times. Every time the chargers have completely quit on me, I've simply switched the cables back to 36 volts and plugged in the old Powerwise and it works 100% of the time. I charge the other battery with a 6 volt charger when I do this. The fact that the old charger works great makes me doubt that there could be anything seriously wrong with my cart or pack, but I know the DPI works differently so I certainly could be wrong about that.

My thinking is that there is some component DPI is using in the 42 volt charger that is faulty. I know they are an American company and make a great product, but my guess is that many of their components have to come from China. And if they got a bad batch of something from China and its specific to the 42 volt charger, they may not even realize it. I have tried to talk to someone at DPI, but the customer service people I've spoken with don't really seem to be involved in the manufacturing side.

Anyway, I'll try everything you guys said and will post back later. Thanks for the help!

JohnnieB

It may very well be a bad batch of parts.

Hint: E-mail your questions and request it be answered by engineering.
I've had pretty good luck using this technique.

coosa

I went out and checked the voltage on the pack and all batteries. I numbered them like this if facing forward. 1 is on the driver side and is the extra battery I added:
1,2,3,4
5,6,7

The cart had been to the garden and back earlier, which is about a .6 mile trip. Pack voltage was 44.8. I ran it to the mailbox and back, a 1.5 mile journey. I waited 10 minutes and read everything again. Pack voltage was 44.4 this time. Here are the first and second readings of the batteries:

1 - 6.41, 6.35
2 - 6.42, 6.35
3 - 6.43, 6.35
4 - 6.41, 6.33
5 - 6.43, 6.35
6 - 6.43, 6.35
7 - 6.45, 6.36

I believe all of these readings are well within normal range, and I can't see my battery pack being an issue for the charger.

I removed the charge receptacle and tested the terminal screws before making the trip and it was 44.8, exactly the same reading as at the pack. I took the opportunity to clean the radsocks well, although they appeared clean already. I had never used a .22 bore brush, but it did fit well. I also sprayed it with electronic cleaner.

After the second series of tests, I was through with the cart for the day so I plugged up the charger. The first try failed, and left me with the bottom light flashing red. I unplugged both connections and tried again. This time it worked without a hitch, and its charging now. I would say that the success rate of this third charger is running about 75%. Many days it will work the first try, and only once has it failed to work on the second try. It took 3 tries that time. Having to unplug it and try again is not a big deal; I'm just concerned by the fact that this is exactly the way the first 2 worked before their complete failure.

Thanks for any ideas anyone has. I will forward all this to DPI and see if anyone there has an idea what might be happening, but I really lean to the idea that they got a bad batch of components for their 42 volt chargers.

scottyb

Keep us posted. My 42v DPI has been rock solid doing charge duties on two 42v carts.

WalterM6

Have you ever tried plugging it into another 120ac outlet?

JohnnieB

Those two sets of voltages look good.

There is one other set of voltage measurements I'd make, that being while on charge.

The greatest differences in individual battery voltage would be when the maximum amps are flowing. The bulk charge phase is constant current at about 20A, but the voltage applied to the pack climbs, so you have to be pretty quick. Maybe someone making measurements and someone else writing the results.

Also, checking the voltage at the battery pack's main terminals vs the charge receptacle with 20A flowing would show resistance in the charge loop, while measuring it with very little current flow won't.

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Does there happen to be an air compressor or air conditioner, or other heavy load, on the same branch circuit as the DPI is plugged into. I'm grasping at straws a little, but low AC voltage might cause the DPI to misbehave at startup.

coosa

Yes, I tried it with both of the first 2 chargers. I moved the charger from my shed to the carport for about 3 weeks with the second charger, but it didn't make any difference.

JohnnieB, I'll run that test next week.

Thanks again for all the replies. I just wanted to know if it could possibly be something I'm doing wrong or something wrong with my cart or pack. I was also hoping someone else had a DPI 42 volt that has caused issues, but it is looking like I'm just a lucky guy. :(