Got a lesson on batteries and chargers

I had my Terrova out for the 2nd time Friday afternoon to troll Bandits on KY Lake( the 1st time was to just get used to the Terrova controls). I had put my Interstate series 27 ( bought new in Jan) batteries on my MinnKota on-board charger until they showed fully charged. When we got to the lake, we trolled for no more than an hour at 1.6-1.7mph, which was 6-7 on my remote display, when I had to start kicking the motor speed setting up to maintain 1.7 until it was 10. Soon it wouldn't keep up to speed so I cranked up my 75 and we finished out a great day.

While I was on my way home, I called a friend who sold me the batteries and asked if he could get me a new one in case one of mine was bad. He had a new 27 at this store Sat AM. We checked both of my batteries and they showed 13.2 volts and no unusual drop under load. I ended up calling our local Interstate distributor and he asked me to bring the batteries in for him to check them. When he checked the batteries with a hydrometer, one showed 60% charge and the other just over 70%, both at 13.2 volts. He asked about how I charged them. I told him about the on-board and he said that was my issue. Apparently a big local Ranger dealer uses Interstates on all their boats and were having lots of batteries returned as bad. When they got back to the distributor, the batteries checked good, just low on charge. Seems some of the on-board chargers kick off on a certain voltage, leaving the batteries only partially charged. That is apparently what happened to me.

The dealer told me if I wanted to trade up to series 29 Interstates, he would do it for $20 each. I figured that was a no-brainer since I also got new warranty. He also gave me a battery hydrometer to check mine at home.

I came home and put my regular chargers on the new 29s and charged them over-night. I'm going to charge them this way, with all wires removed, for a while. I'm kind of leery about the on-board now but love the convenience I had when running a 12 volt system with the 27s in parallel.

My question, how do you set up your on-boards when charging the batteries. Do you unhook the wires? Remove the + to - jumper wire? Unplug the motor? Any input would be most welcome. This is my 1st 24 volt system and I want it to be my last---hoping for several years at my current set-up.

I've got a Minn Kota 80 lb hand op on 24v. I just plug in my onboard charger and leave it plugged in till I'm ready to go fishing again. I do check the water about every two weeks in Summer and once a month the rest of the year. My batteries (interstate) are on their 4th year and still strong. I have been told it's important to unplug your TM when charging if it has any electronics in it (most do nowadays). The charger is one i picked up at Bass Pro when I got the boat four years ago.

I would suspect a bad charger.

Back to the basic's. All new batterys need to be brought up to full charge with a battery charger before their first use or they will get a memory load and not charge beyond that point and the on board charger will not take it to full charge. The onboard charger is probably okay but the battery was never properly charged before it left the place where it was sold. Someone has posted about proper battery care on here that will explain it better than I am doing right now. Check in the archives. Good luck, Ferdi aka Fred

anyone know why it's important to unplug the TM when charging? I fished yesterday for about 3, 3.5 hrs, got home and charged up the batts overnight using the on board charger. Did not notice anything abnormal on the TM performance. I noticed a difference today, had basically the same issue as OP on my Tracker pt175 w/ a MG 43# 5 speed. After 4 hrs of trolling anywhere from 1-2mph and various speeds inbetween looking for the right speed today, light to no wind, no current to speak of (HOT) the TM just would not maintain the speed. When I got home, I checked the TM batt with a DVM, read 11.94v, thought well, I ran the batt down good, but I did notice that I had left the TM plugged in up front, which is something I normally don't do for safety reasons since I fish solo alot and don't want to accidently hit the foot control with a knee and wack a body part with the TM prop. The only real difference in the boat was my wife went with me today and was solo yesterday.

Hope you don't mind, but I'd run across some good battery info when I was researching PV solar for my bus. Much of this won't apply, but there's much good info to be had regarding battery care/charging.

The 12volt Side of Life (Part 1)

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Originally Posted by mrdux

I had my Terrova out for the 2nd time Friday afternoon to troll Bandits on KY Lake( the 1st time was to just get used to the Terrova controls). I had put my Interstate series 27 ( bought new in Jan) batteries on my MinnKota on-board charger until they showed fully charged. When we got to the lake, we trolled for no more than an hour at 1.6-1.7mph, which was 6-7 on my remote display, when I had to start kicking the motor speed setting up to maintain 1.7 until it was 10. Soon it wouldn't keep up to speed so I cranked up my 75 and we finished out a great day.

While I was on my way home, I called a friend who sold me the batteries and asked if he could get me a new one in case one of mine was bad. He had a new 27 at this store Sat AM. We checked both of my batteries and they showed 13.2 volts and no unusual drop under load. I ended up calling our local Interstate distributor and he asked me to bring the batteries in for him to check them. When he checked the batteries with a hydrometer, one showed 60% charge and the other just over 70%, both at 13.2 volts. He asked about how I charged them. I told him about the on-board and he said that was my issue. Apparently a big local Ranger dealer uses Interstates on all their boats and were having lots of batteries returned as bad. When they got back to the distributor, the batteries checked good, just low on charge. Seems some of the on-board chargers kick off on a certain voltage, leaving the batteries only partially charged. That is apparently what happened to me.

The dealer told me if I wanted to trade up to series 29 Interstates, he would do it for $20 each. I figured that was a no-brainer since I also got new warranty. He also gave me a battery hydrometer to check mine at home.

I came home and put my regular chargers on the new 29s and charged them over-night. I'm going to charge them this way, with all wires removed, for a while. I'm kind of leery about the on-board now but love the convenience I had when running a 12 volt system with the 27s in parallel.

My question, how do you set up your on-boards when charging the batteries. Do you unhook the wires? Remove the + to - jumper wire? Unplug the motor? Any input would be most welcome. This is my 1st 24 volt system and I want it to be my last---hoping for several years at my current set-up.

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You need a new battery dealer. The one you have doesn't know anything about charging batteries.

Your onboard is far and away the best way to charge your batteries.

CatFan,I respect your judgment much more than a tech who I met once for a few minutes. Thanks for your input. I have been using batteries in lots of applications for all my life but this scenario is news to me.

Here we go; I charged my brand new series 29 Interstates over night and disconnected the chargers this AM. Charging was done with Schumacher SSA-1500A digital chargers (I have 2 due to my other vocation) The battery charge showed 100% charge at 13.3 volts on both when I connected all battery wiring and headed to the lake. I ran my Terrova at 5- 6/10 while going upwind and 3/10 when going with the wind to maintain a speed of 1.7mph. I was able to maintain this rate for 3 hours then the speed dropped off noticeably. I used the outboard for the last hour to push and the TM to steer. The maximizer showed no bars when I put the TM up. When I got home, I disconnected the TM plug and the + to - jumper. One of the chargers showed 20% charge at 11.8 volts and the other showed 55% before I started charging. Water level in both was fine. I am charging both at 15 amp setting and this charger will drop back the charge to trickle as they get to 100%.

Do you feel that this performance is in the ballpark for my set-up? I was hoping for longer battery life myself. I currently have a 50 amp circuit breaker on the + cable and plan on upgrading to a 60amp.

Thanks for the replies.

Those Schumachers are good chargers and are very similar to your onboard in charging method.

The 13.3V you are seeing is known as a surface charge. It is an effect that raises the plates and terminals of the battery to the voltage of the charger without actually charging the battery's chemical reserve to that level. Since a charger can't tell if it is seeing surface charge or actual battery charge, it's hard for a charger to accurately indicate state of charge when a battery nears full charge. 13.1V to 13.3V is the voltage that chargers apply to the battery in float mode when they are maintaining the battery. Your real charge should be very close to 12.65V. It's useful to occasionally turn the charger off, let the batteries sit overnight, and then measure the voltage and check the specific gravity in each cell. Write it down and keep track of it because it will tell you a lot about your batteries.

No need to disconnect the jumper between batteries when charging, but unplugging the TM is a good idea both when charging and when you aren't using it. Bad things are unlikely to happen even if you leave it plugged in, but they won't happen if you unplug it for sure.

I did a rough calculation over in your "Battery Life when Trolling Cranks" thread that gave abut 174 to 195 minute run time with the 27s. Doing the same calculation on the 29M, would give you 228 minutes at 50% or 281 minutes at 30%.

From that, since it was a worst case calculation, I'd have thought you would have seen better battery performance with the 29s than you did

In reality, it doesn't matter what numbers you put on paper, it's on the water that counts.

I'd be a little concerned about the batteries being at different voltages when you finished. They should be drawn down equally. I'd keep a close eye on the voltages on the two batteries, and if they continue to differ, it might indicate a weak battery. Smaller Interstate dealers are notorious for having old stock, and one battery that had been there for a few months longer could have lost a portion of its capacity.