Sunday, March 25, 2012


So after my trip to the beach I was back on board taking advantage of the mild weather to continue to look at the battery charging issue with the fourth battery. For two weeks the 48 volt battery string has been charging via the solar panels and the Paktrakr load has been disconnected off of the fourth battery. There was a little surprise when I plugged in the Dual Pro charger. It showed the second battery to be a little down chargewise compared to batteries one and three:

I've seen this before you never know which battery may be slightly down when you plug in the charger as they all do not come up the same way everytime. But, my concern is with the fourth battery in the string which earlier in this investigation was not even able to achieve a full charge. It is now behaving more like the other three.  Twenty minutes later and this what I saw on the Dual Pro display:

One hour later and the first and third batteries were now fully charged and the second and fourth batteries were still somewhere in the 90 to 99% range:

Finally after about one hour and twenty minutes all four batteries were fully charged:

I once again took some voltage readings of each battery after they were fully charged:

1                  13.7
4 (suspect)   13.3

These latest reading shows all four batteries even more in balance than when previously tested. Which leads me to believe that keeping the load from the Paktrakr off of battery four is beneficial in keeping it in balance with the other three batteries. I think I'll will do one more charge test in the near future and then conduct a load test on each battery before I fully can say that all batteries are ready for BIANKA's fifth season under electric propulsion. However things are looking more promising that they are.



Bob Lemke aka "deckofficer" said...

Are you pulling a load from one battery in a series string?

Bob "deckofficer"

Capt. Mike said...


I did orginally. I had a Paktrakr battery monitor which drew 25 milli amps from the suspect battery. I had had no problems but, this winter I added a data recording cable which added a little extra load to that battery. Which is when the battery problem started. I have disconnected both devices and that seems to have solved the problem.

Bob Lemke aka "deckofficer" said...

Like you, I would not have thought 1/40 of an amp would cause an issue. Lets see, 14 days @ 25 mils = 8.4 a/hr, OK, sounds like you found the problem.


Capt. Mike said...


Yep. Plus there was the additional load I added when I installed the Paktrakr data cable into the mix. I still need to measure how much that was. I'm glad it looks like I won't have to spring for a new battery. Though at first since it would not complete a full charge it looked like I might. Glad I took the time to investigate what was going on.

John K said...

This could possibly be part of your problem:

You may already know this, but it was news to me when I read it.
Wiring a bank the "normal" way results in unavoidable voltage losses at every connection with the back of the string getting much less charge voltage and doing much less work than the front.

Capt. Mike said...


Yes, there are all sort of little issues involving battery banks one needs to be aware of. Even when just parralleling 12 volt batteries as shown in the links you provided. I am considering re aranging the order of the batteries in my 48 volt string once I finish up looking at the condition of the suspect battery. One thing I won't be doing is running a parasitic load like the Paktrakr full time in the future.