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Battery Charger Advice

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ilnadi
Captain

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452 Posts

Initially Posted - 04/03/2006 : 14:56:46

Trying to choose between two chargers, they are both 10Amp two-bank. I know it is not a whole lot of charging power but our charging to use ratio is pretty good. I just need a new charger I can leave connected without fear of cooking batteries.

- XANTREX Truecharge 10Tb Battery Charger

- Guest Waterproof Series Battery Charger 10a

Nadi ex-C25
http://www.sailblogs.com/member/enka
http://building-spindrift11s.blogspot.com/

Edited by - on

Bubba
Admiral

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USA
542 Posts

Response Posted - 04/03/2006 : 19:01:35

I can't compare the two, but I can tell you that I've had the Xantrex Truecharge 10TB for a couple of years and it works very well. I take it for granted now. It's a three-stage charger, so it charges quickly and then drops off to a trickle to keep the batteries at their peak. It has fuses for each battery circuit and I believe it has a thermal cut-off. The 10-amp model doesn't need a cooling fan, so you don't hear it running. Here's a run-down on my electrical set-up: http://mywebpages.comcast.net/frayed-knot/projects/electrical.htm

Edited by - on

Sea Trac
Master Marine Consultant

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Vanuatu
1357 Posts

Response Posted - 04/03/2006 : 19:05:12

Me, too, with the Xantrex.

Edited by - on

Waterboy
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USA
204 Posts

Response Posted - 04/03/2006 : 20:42:07

I have the Guest 10 amp, and use it to charge two 6v golf cart batteries in series underneath the V-berth. I don't have exact specs on the batteries, but I think I'm close to 400 amp-hours. This is more than the Guest 10 amp says its rated for, but I've had very good results. It's a three stage charger like the Xantrex. I also have a Xantrex Link-10 battery monitor I'm quite pleased with. I think both companies make excellent products. I'm betting you'll find a bigger difference in how you use your batteries and charger rather than which with charger you choose, IE., use it often but don't overcharge (I'm told even three or four stage chargers have boiled batteries dry), and don't discharge your batteries below a certain level if at all possible. When my bank drops below 12 volts I want to get them charged asap, below 11 I start to worry about degrading the batteries, and I keep a jug of distilled water on board to top off low cells.

Edited by - on

Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 04/03/2006 : 21:59:12

I installed a Truecharge 20 about 5 years ago. I've been very satisfied with its performance, except for one problem. In that time, it has cooked three flooded cell deep cycles to death, two group-27s, and now a group-24.

BUT! Here's what I think causes that, and if I'm right, it's not the charger's fault. Smart chargers vary their charging rate based on several things: battery technology (flooded, gel, AGM), tempurature (climate selector switch, or ambient temp at the charger, or actual internal battery temp), internal battery resistance, and (here's the point I'm getting to) battery voltage (at rest obviously, with the charger output at 0 amps).

The charger makes certain assumptions about state of charge based on resting voltage. And for a flooded cell battery, voltage has a lot to do with the specific gravity of the electrolyte. And it's assumed the specific gravity of the electrolyte started out at some industry standard. (I don't have the exact numbers handy.)

But when I (and probably many of you) picked up my brand new batteries from the big box discount store, and checked the fluid level, they weren't topped up. so what did we do about that? We diligently added the finest distilled water the grocery store had on the shelf. Thus screwing up the specific gravity of the electrolyte right from the git-go. Ever since, the smart charger has been diligently struggling to get the resting voltage up to some ideal value. But with the permanently diluted electrolyte, it never quite gets there. But it keeps trying, until the battery is cooked to death. And every time we add more distilled water, we're making the situation worse instead of better, by further lowering the maximum possible specific gravity of the electrolyte. Ok, I think I've beat that to death.

Once upon a time, back when I worked as a professional Honda motorcycle mechanic, the regional Honda rep. was absolutely fanatical about how we treated new bike batteries. Seriously, Honda would come down hard on any dealership which was as slack as most car battery peddlers are. The batteries arrived vacuume sealed. We were not to unseal and activate them unless and until we were sure they would be sold within a week or so. Then we were to break the seal, add acid, wait 20 to 30 minutes, top up the acid again to the full mark, then trickle charge for a day or so, then top up with acid one more time. Every dealership had to have a dedicated battery activation bench with a bulk container of acid, hydrometer, electrical test equipment, and an approved commercial multi-output trickle charger.

So what can we do about it? When I bought my most recent pair of flooded cell deep cycle group-27s, I checked the fluid right there in the store (to the annoyance of the sales staff). When I couldn't find even one battery with enough electrolyte in it, I asked to have a pair of them topped up with acid. Ha! Well, I had to at least ask. So I took them as is, and went to my local auto parts house where they sell batery acid by the pint. I dumped something like a quart or two into the batteries before reaching the high water mark. Yikes! See what a difference that would make in electrolyte specific gravity over the life of the battery?

It's much too soon to say if that made a big difference. I'll try to pay attention to how much water the new batteries go through, and try to remember to report back here if it seems like a lot less than before. I'll also be buying a new cranking battery this week. You can bet it will be low on fluid too, and I'll be topping it up with acid, not water.

If anybody out there knows something more or different about this topic, please speak up.

-- Leon Sisson

Edited by - on

ilnadi
Captain

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452 Posts

Response Posted - 04/03/2006 : 22:09:06

Thanks for all the feedback. I will chekc the batteries again, but at least the fluid level looks OK. The existing charger has not gone to "maintain" since it cooked a battery a year ago and I have not left it plugged in since then when we are nor around. Time to upgrade.

Edited by - on

frog0911
Master Marine Consultant

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USA
1349 Posts

Response Posted - 04/03/2006 : 23:36:32

Be sure and read the instruction manual before you purchase. I made this mistake, but luckey me I did read it before I installed it. I initially got the Guest dual bank 10 amp charger, but after reading the manual I took it back. The reason is there is a statement that basically says, do not operate any system while the batteries are charging or damage could occur to the charger and/or batteies. The Xantrex allows you to charge while using electrics in the boat. According to the manual, the Xantrex senses when an increase draw is placed on the system and if in any mode other than bulk charge the charger will automatically drop back to the bulk charge mode and restart its cycle. This is very important in order to maintain battery life if you are overnighting at a marina and want to run lots of electrics. So don't make the mistake of assuming all battery chargers, when operating, will maintain your batteries when under load. Read the manual first very carefully.

Edited by - on

Waterboy
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204 Posts

Response Posted - 04/04/2006 : 18:21:36

Leon,
We're a little off the topic of chargers here but since it's batteries we're charging I think we're close enough. Having killed deep cycle batteries in the past, I read your response with much interest, and re-read it after doing a little research to be sure I understood what you were saying. As a motorcycle mechanic, you added acid to new batteries containing no fluid or electrolyte at all, correct? And with your most recent battery purchase, you topped off essentially new batteries with acid?

From what I've read recently, the former is required to 'activate' the batteries, and the latter probably ok (although finding 'new' activated batteries with low electrolyte levels is disturbing).

Googling 'battery maintenance' and 'adding acid to batteries' got some interesting results (various links below). Manufacturers and other battery gurus universally concur that distilled water and NOT acid should be added to already activated batteries. Several reasons were given, and the most prevalent seemed to be adding acid would likely screw up the electrolyte levels and potentially ruin the battery. Another cited explosion potential. While one manufacturer states only water vapor is lost under normal use, another states 'the gases from the battery condensing on metal parts cause most corrosion', indicating, to me, loss of electrolyte. When I've cleaned my battery posts and top with a baking soda solution, there's always some fizzing, indicating to me a reaction between the bs and acid lost from the battery.

A couple things I did not know were that battery electrolyte levels apparently fluctuate with the state of charge, so water should be added to a fully charged battery. Also, one site warned of hazardous chlorine gas being given off if the electrolyte were to come in contact with seawater. Gulp!

What to do? I'm disturbed that Leon found 'new' batteries with low fluid levels, and next time I buy batteries I'll check not just the level but the specific gravity. If the levels were low enough to expose the plates, I wouldn't buy them period. Perhaps these 'new' Group 27's, while unused, had been sitting quite a while. I know batteries will discharge gradually while unhooked, but will water and/or electrolyte also evaporate resulting in low fluid levels? Can I buy unactivated batteries and add my own acid to assure I'm getting a truly new battery?

As for maintaining my own batteries, the next thing I'm going to do is get a hydrometer and actually measure the specific gravity and compare it to the voltage (I've been relying on the Link 10's voltmeter). If the s.g. and voltage output agree, and fluid levels are ok I'll just charge 'em. If fluid levels are low but s.g. is above 1.2, I'll add water. If s.g. is low, I may try adding a little dilute acid.

Battery maintenance links:

http://www.ibsa.com/www_2001/content/faqs/tech_talk/maintenance/faq_tech_maint.htm

http://www.trojanbattery.com/Tech-Support/BatteryMaintenance/Watering.aspx

http://www.batterystuff.com/tutorial_battery.html

http://www.alton-moore.net/batteries.html

http://www.fieldlines.com/story/2005/12/9/235852/100

Edited by - on

Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 04/04/2006 : 20:36:21

Waterboy,
Thanks for your careful research and additional comments.<blockquote id="quote">quote:<hr height="1" noshade id="quote">As a motorcycle mechanic, you added acid to new batteries containing no fluid or electrolyte at all, correct? And with your most recent battery purchase, you topped off essentially new batteries with acid?<hr height="1" noshade id="quote"></blockquote id="quote">Yes, that's what I'm saying. Perhaps I could have made the connection between sloppy battery activation practices and low fluid level at delivery more clear.

When the vacuume seal was first broken, fresh was acid added to the absolutely dry battery cells up to the full mark. Over a period of maybe 15 minutes to an hour, the plates and separators slowly absorbed acid. That's why it was so important to go back and add acid once or twice more.

What I'm speculating happened to the boat batteries I bought, is the folks who first dumped the acid in the new dry batteries didn't going back later to top them up with additional acid after that first filling had soaked in. (Or trickle charge them for a day, for that matter.) I can't imagine new activated boat batteries sitting around a warehouse (in Florida during spring commissioning season

) long enough for a significant amount of water to have evaporated.

And yes, when charging, flooded cell batteries don't just outgas pure water vapor. Take a look at the steel hold down hardware around most any car battery. It's ate up, right? More specifically, as my smart charger was busy slow cooking my old batteries to death, liquid was accumulating in the bottom of the plastic battery boxes. I checked, and that liquid was very definitely acid, not water. I also verified the battery cases weren't leaking -- it all came out the vents.<blockquote id="quote">quote:<hr height="1" noshade id="quote">If fluid levels are low but specific gravity. is above 1.2, I'll add water. If specific gravity is low, I may try adding a little dilute acid.<hr height="1" noshade id="quote"></blockquote id="quote">If I were a bit more fanatical (or new batteries were more expensive), that's what I'd do. I thought about the idea of playing around with the smart charger's equalization mode, a hydrometer, turkey baster, fresh acid, distilled water, etc. to try and restore the original internal chemistry. Then I got in the car and went to get new batteries.

-- Leon Sisson

Edited by - on

Waterboy
Navigator

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USA
204 Posts

Response Posted - 04/04/2006 : 20:50:11

[/quote]If I were a bit more fanatical (or new batteries were more expensive), that's what I'd do...Then I got in the car and went to get new batteries.

-- Leon Sisson
[/quote]

Leon, you've introduced a whole 'nother multivariate equation into the decision matrix ... which I do not care to scribe or solve. I use golf cart batteries I get fairly cheap in Phoenix (they're already activated). Batteries et al are all very interesting, but at some point ($$ or level of energy required to address issues) it's easier to just get new batteries.

Greg

PS - I bet you're correct about them adding acid just once and not checking the level later.

Edited by - Waterboy on 04/04/2006 20:52:04

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