Long Term Charging During Storage ?

[R_C]

I'm sure this has been discussed before but I can't find any threads. I have a new house bank of three Trojan T1275s for a total capacity of 450 Ah. When I put the boat on the hard for six months unattended how should I maintain the batteries? Do I just leave a three-stage charger on? I have both a Xantrex TrueCharge 40+ and Iota DLS-90 with IQ4. Both indicate they can be used long term. Will six months of float charging in Florida summer heat boil off enough water to expose the plates? Thanks.

- Rick

[Kettlewell]

I have a very small solar panel, I believe it is 5 watts, that I leave hooked up in Florida sun. It is actually supposed to be used when you leave your RV in storage someplace. I think I got mine at WalMart. Works great. In the winter up north I leave some solar panels hooked up through a regular charge controller. They are fused both at the battery end and between the panels and the charger, just in case.

[R_C]

I have also been considering a small solar panel. But I think I'd need more than 5 watts to maintain a 450Ah bank. According to Nigel Calder's book, I'd need a panel rated at 0.3% of the Ah capacity of the bank (0.003 * 450 = 1.35A). So, I'd need around 19 watts (1.35A * 14V = 18.9W).

Since the boat will be on the hard, I'm not worried about galvanic corrosion. I'm more concerned about overcharging with one of the chargers or undercharging with solar. I wondered if anyone has had any problem keeping an Iota DLS charger or a temperature-compensated Xantrex TrueCharge powered on long term.

- Rick

[btrayfors]

Rick,

I have two Iota chargers which have been on 24/7 for the past four-to-five years, each maintaining a bank of two Trojan T-105's.

The IQ4 will assure the proper float voltage (usually about 13.6VDC).

HOWEVER, with ANY flooded batteries you need to check them periodically for water loss. Mine have WaterMiser caps and these help, but you still need to check them every few weeks if you're going to leave them on a charge. BTW, WaterMiser caps make it MUCH easier to check water levels and to add water if needed....just flip up the caps.

The best strategy is a bit of a catch-22, though:

On the one hand you certainly want to maintain flooded batteries at or near their full-charge state to avoid sulphation, and because of their relatively high rate of self-discharge this means you have to keep them pretty much under charge most of the time.

On the other hand, you certainly don't want them to run dry, since this could do serious damage.

Problem is, it's really unpredictable as to when they'll suddenly decide to run dry, with no visible reason. So, you have to check them. There's simply no way around this.

AGMs and Gels can be left much longer without charging, of course, but they bring their own set of plusses and minusses, including much higher cost.

Bill

[R_C]

Bill,

Six years ago, I bought AGMs for their low self-discharge rate but I couldn't justify the cost this time around. Maybe that was a bad decision. Now I'm not sure what to do. I'll be away from the boat for six months so there's no way to check the water or get someone else to do it. Would undercharging with a solar cell be safer than the risk of overcharging? Countless boats are stored unattended for months in boat yards. Do all such boats with lead acid batteries just replace them every year?

My T-1275s are the Plus series with the flip top SureVent caps. Are WaterMiser caps substantially different? A quick search suggests they do reduce the need for watering.

After two months of daily use I have not yet had to add any water. Then again, I'm away from shore power so I'm not fully charging. Does the need for water change as batteries age or is it just unpredictable as you suggest?

- Rick

[btrayfors]

Rick,

Well, when I was away from my boat regularly for months at a time (boat was in the BVI; I was traveling overseas), I sure went thru a lot of batteries! At that time, I told the yard to plug in the charger every few weeks, but they didn't, and that's not a good strategy anyway. Thank heavens T-105s were about half the price then that they are now :-)

I had a small solar panel which was supposed to keep up the T-105 bank for the windlass. Never ran them dry, but didn't keep up either.

Yes, battery water needs can change with the age and condition of the batteries, but it's not a very predictable thing. It seems, sometimes, that batteries are whimsical in their need for watering.

In your case, I guess I'd try a modest size solar panel w/controller. Leave the batteries fully watered (to the bottom of the filler ring), and hope for the best.

Anyone have a better solution?

Bill

[R_C]

Bill,

How about using an electronic timer to periodically start and stop the charger? Your description reminded me that the previous owner installed a 24-hour time switch to run a charger for some fixed interval each day. What if there were 7-day or 30-day timers? Wouldn't it suffice to run the charger a few hours each week or month? Would that minimize water loss yet still maintain the batteries?

- Rick

[Pblais]

How about using an electronic timer to periodically start and stop the charger?

It's commonly done here where folks keep their boats in the water over winter. The timer makes sure the battery is charged but not over charged.

If you use the good Iota chargers they are prety smart at doing it.

I use my solar panels. They are regulated and I like to avoid being plugged in. The shore power company might send you a jolt now and again. Shore power can lead to trouble. A lightning strike can induct the power line and you get a burst in the back door.

On the hard the small solar panels will do a nice job of it and avoid the power connection. Plugged in a good charger should be fine too. They should go to float and stay there.

[R_C]

Paul,

The water loss is what bothers me. I suspect a continuous float charge would increase the chance of water loss over a solar panel, which is active only a fraction of the day or the timer solution.

I have an Intermatic 30A 24-hour time switch and they make a 7-day version of the same switch. Right now the 7-day switch seems like a good solution. I could use it to run the Xantrex TrueCharge for a few hours once a week. I'm hoping that will keep the batteries charged and minimize water loss over six months.

- Rick

[Pblais]

The water loss is what bothers me. I suspect a continuous float charge would increase the chance of water loss over a solar panel, which is active only a fraction of the day or the timer solution.

That could be. I get water loss in the summer since it is warmer, more sun, and we use the boat a whole lot. if we head down to NC it's a motorboat trip most all the way and I know I use a lot more water then. I never need the shore charger in the slip at home.

I just ordered Water Miser battery caps. They cut down on the water loss and reduces acid loss as well. I never liked the Trojan caps all that much.

Since we keep boats in the water here over winter the timer is a good idea and many boats at the dock use them. Much farther north and most people haul. You just have to get a decent one installed. The ones you use in the house to turn a lamp on and off are way under designed for heavy duty use in the winter. Those kind of things are what start boat fires. I would think the timer would carry you 6 months if everything was all setup properly.

[R_C]

Originally Posted by Pblais

I just ordered Water Miser battery caps. They cut down on the water loss and reduces acid loss as well. I never liked the Trojan caps all that much.

Since we keep boats in the water here over winter the timer is a good idea and many boats at the dock use them. Much farther north and most people haul. You just have to get a decent one installed. The ones you use in the house to turn a lamp on and off are way under designed for heavy duty use in the winter. Those kind of things are what start boat fires. I would think the timer would carry you 6 months if everything was all setup properly.

I'll check out the Water Miser caps. I'm not sure how much different they are than the flip top SureVent caps on the Trojan T-1275 Plus series but anything to reduce water use over six months can't hurt.

This is the 7-day timer I'd install: 7 Day 30 Amp | Intermatic, Inc.
My Xantrex TrueCharge 40+ is already connected to the 24-hour version of this switch in the same NEMA1 case. I'd just replace the 24-hour with the 7-day switch. They're both 30Amp rated switches. I'll just need to guess how many hours per week I should charge. I'm thinking four hours should suffice.

- Rick

[R_C]

Below is Trojan Battery's response:

I do not know if the Water Miser caps fit our T1275. We do not recommend using such caps as evaporation of water is normal and expected when using flooded, lead-acid batteries. During storage, you are only replenishing capacity loss during self-discharge of your batteries. Our batteries typically self-discharge 5 - 10% per month. Assuming 10% as the worst-case scenario, for the T1275 this means 15 amp hours per month need to be replinished by charing. Generally if you recharge your batteries every 4 - 6 weeks, they will be kept in good condition. Thanks.

Above is the reply to an email I sent to Trojan's tech support asking if the Water Miser caps fit their T-1275 and whether they have any suggestions for unattended charging during storage. The 5-10% self-discharge rate is the same rate I recall for the AGMs I had earlier so maybe storage isn't such a problem. Even if it doesn't quite keep up with the self-discharge rate, a small solar panel seems like a good solution. Thanks for all the comments and suggestions.

- Rick

[slowshoes]

Originally Posted by R_C

Above is the reply to an email I sent to Trojan's tech support asking if the Water Miser caps fit their T-1275 and whether they have any suggestions for unattended charging during storage. The 5-10% self-discharge rate is the same rate I recall for the AGMs I had earlier so maybe storage isn't such a problem. Even if it doesn't quite keep up with the self-discharge rate, a small solar panel seems like a good solution. Thanks for all the comments and suggestions.

- Rick

Rick, I don't know if water miser caps fit T-1275's either, as I have T-105's. I've used the water miser caps with my T-105's since new, and I don't have to water my batteries nearly as much as my old bank of batteries. I'm 4 years into my T-105's and their still in great shape.

Usually during storage, I just plug in my onboard 3 stage charger for 3 or 4 days every 6 weeks or so. This isn't really much of a hassel for me as the marina I store at has electrical outlets readily available.

[djmarchand]

You don't need to worry about water loss if you leave your batteries hooked up to a good three stage charger.

I left my boat hooked up to shorepower and unused for about 8 months. The water level in the Trojan T-105 batteries had dropped a little, but less than half of the availalbe freeboard. T-105s have more than the typical lead acid freeboard, BTW.

So I would check the level at least once during your layup period to be safe, but checking every 2-3 weeks is way overkill.

And FWIW a solar panel has the same effect. If you use a big one with a solar controller then that controller is doing exactly what a 3 stager would be doing- limiting the voltage to about 13.5.

And if you use a small solar panel without the controller then you risk under or over charging. I had a 32 watt panel hooked up to two Group 27 batteries. I needed to add water every thee months or so. This was in SoCal with its high sunlight.

David

[R_C]

Originally Posted by djmarchand

You don't need to worry about water loss if you leave your batteries hooked up to a good three stage charger.

I left my boat hooked up to shorepower and unused for about 8 months. The water level in the Trojan T-105 batteries had dropped a little, but less than half of the availalbe freeboard. T-105s have more than the typical lead acid freeboard, BTW.

David,

Thanks. I'm glad to hear you've had success with long term charging and minimal water loss. I'm now leaning in the direction of just leaving the Xantrex TrueCharge 40+ on while the boat is on the hard.

- Rick