One more Guest charger question

O

OffLeash

New member
Hi all
Sorry for another Guest charger questions but I could not find anything in the archives on how do you tell if the guess charger is just starting to fail?

Here is the problem that has me scratching my head.
I have the original 5-5-10 20 amp Guest charger with the 5s connected to the starter batteries for each engine and the 10 connected to a house bank with 2 group 30's.
The house and the starboard are on the same switch and showing 13.6 when charging. But the separate port engine is only showing 12.7 when charging.

Does that mean that charger is going bad or is it possibly the battery?
Thanks for any help on this.
 
Trick question since you have Starboard and house together.

The best way to test the battery is to load test it. Harbor freight has load chargers which are fairly in-expensive--and may be easier to check the battery in place than take it out and have it tested at your local auto parts store.

The Guest charger "float" voltage is 13.3--so the battery charger is charging the two combined batteries.

If a fully charged battery is disconnected from the charger, it will read 12.6 to 12.8 volts (slight variation as to type of battery). So in this case it is acting as if the battery is fully charged and the charger is not working on this leg.

I would suggest that you isolate the batteries. Then run each of them down--putting a 10 amp current draw for several hours for example. Then measure each battery voltage with a separate volt meter. record this

Keeping the batteries isolated, then turn the battery charger on. After a couple of minutes record the battery voltage. Each of the batteries should be charging, and the voltage should be in the high 13's to up to 14.4.(from the charger) If any of the batteries are less than this, it is suspect that the charger is failing-.

To be sure, you can switch the leads from the charger, and check to see if it acts the same way on the other battery. (Not always easy to do on the Tom Cat). One of the items in my "electrical test kit" is a set of jumper cables, with alligator clips on each end, about 5 feet long of #12 wire. All kinds of uses, for diagnostics.

Also make sure that all connections (especially ground, since it seems to be neglected) are bright and shinny and have dielectric grease under the connections,.

On occasion measuring voltage from a MFD at the helm can be misleading. For that reason I set up all of my boats with a digital volt meter for each battery--may be one meter with a 5 way switch--(as I did with my Tom Cat, since I had 5 batteries, rather than 3 batteries). Buy the load tester anyway....
 
That Guest charger is a loser. You should replace it anyway, not debate if you can get some more use out of it. Got rid of mine years ago.

If you don't replace it, you could lose a couple of batteries in addition to replacing the charger.

Boris
 
Hey Bob...Thanks for suggestions.

Sorry, I was not real clear but the Starboard Starter and House bank are set up on a Dual (off-1-both-2) battery switch so they should be isolated. The port is on a separate On/off switch.
(Funny, I have always been concerned that there is no way to use the port starter as a back up to the Starboard starter. You idea to get some jumper cables for testing would also fix this concern.

Because I suffer from "Battery state paranoia", I did add a stand alone voltage meters with impulse switch for each of the 3 battery banks so I can check them independently whenever I want.

The 2 Guest 5 amp circuits are connected to the 2 isolated starter batteries and all the Guest Charge indicators lights showing green. Because the voltage on the two 5 amp battery circuits are showing different voltage is why I am concerned it is going down. I did check and both fuses on the battery charger line to the lower voltage battery and they appear to be OK.

The charger is 9 years old and with all the negative comments, maybe I should just bite the bullet and switch it out as preventative.
 
I agree with the decision to switch to a better charger. Personally I like chargers which are more than just minimal chargers, and can take the "abuse" of dock side higher current drain. I happen to put in Mastervolt, but Blue Seas, and Victron all make great higher end chargers. These all have fans, (which the Guest don't), and can handle the higher current draw of house loads, dock side.

I would still have a way to test all batteries--and either a load tester or a device to draw down a known amount, such as a light bulb, with clamps.

The Tom Cats were wired all sorts of ways. Mine had it set up so that one position on the starboard would go to house, or starboard, the port would go to port, or starboard bank--so it could lead to all sorts of confusion! I re-did it.
 
If you're open to suggestions, I'll make one. I have a Xantrex charger, now on its second boat, going on 16 years. All you need is a 20 amp, because lead acid batteries have a steep decreasing charge curve from max to 5-10 amps. They run <$300

Another thought is to get a combination inverter/charger. They do cost more, but if you want/need an inverter, it's all in one package. Get a true sine wave one if you go this route, it'll be easier on your equipment. Modified sine wave usually are some form of square wave where they have a lot of harmonics.

Don't forget to run the appropriate wiring.

Boris
 
Good advise Boris, I have fried a few things with the modified wave inverter presently on my boat. Got a catalogue from Binnacle Boy - have been drooling over the Zantrex Freedom HFS inverter/charger. 1000watts true sine wave and 55amps charging. Built in transfer switch. $499.CAD. Not sure if I can get the funds requisition form approved though. 8)

Agree 20amps is more than enough for the average 100amp hour battery. For flooded lead acid cells it is not recommended to charge them at more than 1/5 of their rated capacity. The 55amp charger on the Zantrex would be good for a pair of group 31's in parallel.

Regards, Rob
 
Thanks for the ideas.
A combo unit would be great but we just added a 1500w inverter and 230ah house bank last summer...Then, I added a battery monitor an realized the one bank charging problem. Duhhhhhh.....

Right now I am leaning toward a newer design 3-bank dry mount ProNautic 1220P (20amp or maybe 30amp). The company is promoting the following which appeal to me.
- It is supposed to Automatically direct charging capabilities to the bank that needs it and condition each bank once a month. I Really need "Automatic" because I am usually clueless as to how to manage batteries.
- It seems to have a good monitoring system to help me identify problems in the future...again...a problems with my cluelessness issue.
- According to the installation manual I should be able to use the same wiring from the Guest charger although, I may move it from under seat to the hanging locker to make it easier to read.
- Defender sells it just a little over $300 but you can find it as low as $227 on the internet so it doesn't break the bank.
-It won some kind of innovative design award when it was introduced and I really cannot find any bad reviews.

While I know there is a bunch of threads on chargers I only saw one mention of this particular unit and it was about installation issues. if you do have some experience or thoughts I am all ears.
Thanks....
 
journey on":2jcpglcp said:
That Guest charger is a loser. You should replace it anyway, not debate if you can get some more use out of it. Got rid of mine years ago.
Click to expand...
Oh oh. I have been recharging my batteries using this Guest portable charger, every week or so in the winter when I'm not running my boat very often. Would I be better off with another charger?
 
I'm not sure what a Guest portable charger is. If it's like my portable charger, you'd be better off with a fixed smart 3 step charger. On the other hand, it may be such an animal.

So, I attach my portable charger to a battery when it needs to be charged; it may be run down, lost its charge over time or anything else. What I use it is for a short term charge.

The advantage for a fixed charger is that it charges to a definite profile: maximum current until it reaches 13.6 VDC, then a constant 13.6 V and when it reaches some low level of current it will go to float charge. And it will usually charge more than one battery. If your portable charger does that, no need to change. If it doesn't you might consider upgrading the charger. Of course a fixed charger would be wired into the boat's 110 VAC system and would be charging any time the boat is plugged in, which may be an advantage also.

The batteries on Journey On get a lot of use and need a lot of care. They also sit unused for long periods and I can let them float.

Boris
 
I have been using a 6 amp variety of the Guest portable charger for many years, for topping off car batteries, my Caracal batteries, etc. They are 3 stage and work very well--being potted, make them quite weather resistant.

OffLeash--what are you running on the 1500 Watt inverter? 20 to 30 amp charger will not be a lot, depending on how much you use the inverter, and how you are powering the charger. Looking at the ProMariner, it looks like good specs, and it has a variable speed fan, temp compensated (on edit: I pulled the manual, and it comes with a temp sensor for the battery. That would move it up a notch in preference.) I would look into the reliability of the unit. ProMariner has been around a long time. They have had some very good products, and some only fair products--for some reason had not caught on as much as some of the other companies. I have used them in the past, and had reasonably good success. I think that the Blue Seas Charger sort of set the standard recently. But they have not been out that long, to see how they do on the reliability. I do like that they are made in the USA. If I didn't have the Mastervolt, I would probably do the Blue Seas. They are all are fairly easy to hook up. The one feature of the Blue seas, is the it is totally independent for each battery--so that one battery can be floating and the other still in absorption.
 
Thanks Bob
Our Inverter does not get used much. Maybe 5 minutes for a 1000w hot water maker or 10 minutes for a 1200w toaster oven from time to time. We use the diesel stove mostly. The house battery bank is 230ah so I am guessing this would be a little small if we used it a lot.

We power the charger off dock power. Often we end up at docks with only 15 amp vs 30amp service up here. I noticed we pop the circuit breakers from time to time. They advertise that their latest energy saving 1220"P" series uses 1/10 of the AC power of competitors to do the same charge. I don't understand this kind of electrical magic but if it is real I was hoping it may help.

The Blue seas 25amp charger looks pretty good and does meet the projected needs of the housebank. The information panel looks better and has some nice info. It is pricey but there is a lot to be said for the name Blue Seas.

This energy efficient version of the ProNautic has only been out 2 year so not a lot of history and since I have not found many reviews positive or negative I was hoping someone might of had some experience before I decide what charger is best for my situation.
Thanks
Mike
 
When we were building spacecraft, I found out that their battery chargers operated at high frequencies. This gave good efficiency and light weight, though I don't remember the exact numbers. The downside was that you had to design for those high frequencies both the circuits and shielding. I'm not a circuit designer so I don't know those problems, but I know that shielding was a bear.

Also looking at the Xantrex chargers (just because, others probably may be the same,) they give some interesting numbers. For input on a 12 v, 10 amp charger the numbers are 104 VAC, 2.5 watts and a PF of 0.95. Multiplying that gives an input of ~275 watts RMS. For output they quote 10 amp (max). For 13.6 VDC, that's an output of 136 amps, dc.

So efficiency is output/input and is equal to 136/275=0.5, or about 50%. Xantrex quotes 77%. Larger chargers give approximately the same results.

If you want to make it lighter and more efficient, go to higher frequency. Since DC battery chargers transform 110 VAC input to a lower ~12 VAC and then transform it to the output ~12 VDC, the transformers for one get smaller with frequency and efficiency goes up.

So that's how chargers can get more efficient. Since you can't get better that having the input power equal to the output power, any claims of 1/10 the input power can be ignored unless they mean the power consumed by the internal circuitry. But that's not much to begin with, worst case ~1/2 of the input power.

I realize you may not have wanted to know. However ....

Boris
 
Ok...I thought I would close the loop on this thread since I started it in case others stumble into the same situation I had.

The problem: 3 battery banks...The port engine start battery was not showing the same charge voltage as the other banks, so I:
Checked the battery ...NO PROBLEM
Checked the Battery voltage gauges...NO PROBLEM
Checked the Fuses and continuity on the positive feed line from the charger...NO PROBLEM
Upgraded the charger (Needed to do this anyway)...OK ..NO PROBLEM
Still ...no charge the port battery????

...OK....So the only thing I had not checked was the ground wire continuity. Guess what...there was no ground wire!!!!
The only ground wire to the port battery was from the outboard engine.

Who ever originally wired the boat never actually added a boat ground wire to the port battery...jand no one ever noticed. Not even the technician who replaced the battery last year.
I added a small bit of 10g wire and it works great now. I guess the moral of the story is Check everything , no matter how improbable...
 
The only ground wire to the port battery was from the outboard engine.

Who ever originally wired the boat never actually added a boat ground wire to the port battery...jand no one ever noticed. Not even the technician who replaced the battery last year.
I added a small bit of 10g wire and it works great now. I guess the moral of the story is Check everything , no matter how improbable...
Click to expand...

Just curious--generally there is a ground wire connecting all of the batteries. Thus you have charging from the engine alternator, if the positive switch was so configured.

In your case, you indicate, that there was no ground wire specifically from the battery charger?

It should be the practice to put a ground wire from the battery charger to each battery...So I assume that this was the issue.
 
Hey Bob
My system was wired so all the ground wires from the Guest Charger went to a common ground BusBar for the boats and then to the batteries. However there was no ground wire from the boat Common ground to the port battery. It was totally isolated

I wondered if there was any reason to have the ground wires from the Charger go directly to each of the three battery banks vs going to a common boat ground but could not find anything on the internet about it.
 
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