Alternator Boosters

[Sammy]

Has anyone had experience of using an alternator booster any make. Are they any good I am using a 50 amp alternator and to banks of batteries split 1/90amp and 1/200amp. would I get a quicker charge on my auxilery battery bank when required. I sail a lot of the time and I run a fridge I find everything is OK untill I let the batteries get too low and then have trouble getting the power back in in a reasonable length of time.
Any help gratfully received.
Chris

 

[Guest]

I use an Xalt booster and Xalt no voltage loss splitter. These have performed without trouble for over 2 years. Starting again I would use the same except that I would go for the 3 sources in and 3 or 4 outputs which will regulate the charge according to the battery in the lowest state of charge. These items are made by Driftgate.

 

[philip_stevens]

I've also got the Driftgate X-Alt and X-Split arrangment for three batteries. No problems have manifested in three years, and I expect none. "Drifgate 2000" did put upgraded software into my X-Alt last winter, (better ramping of charge) and it performs even better now.

To parallel the two domestic batteries, I have two relays energised from the alternator charge warning lamp. When the alt is charging, the lamp goes out, and the relays energise. The domestic and engine batteries are separated with the X-Split.

I have no connection with DG2K but would recommend their products.

Look at Driftgate 2000 at www.dg2k.co.uk

regards,
Philip

 

[Guest]

Have a look at www.adverc.co.uk or tel:01902 380494
They have a free info pack about batteries and charging. It is well worth a read before you invest in too much. I have no direct experience of their products.

 

[davidt]

I strongly recommend Adverc. They are helpful, knowledgeable and make a good product. I have a TWC (the forerunner of Adverc) on my boat in the Med where I use the fridge 24/7. I consider it (the TWC) to be one of the most essential pieces of kit on my boat. Don't leave port without one!

David T

 

[dick_james]

If you have a 50A alternator, a booster will not make it produce any more than that but one of the most basic functions they do perform is to convert the alt. from machine sensed to battery sensed. It will then charge at the full rate for longer, overcoming volt drops in cables (and especially splitter diodes). I chose Sterling a year or two back because it was the cheapest around and whilst it does the job and has been reliable, it tended to boil the batteries unneccessarily and I had to adjust the charge voltages down. Now having learnt a lot more about the subject I would go for an Adverc.
Dick James

 

[Guest]

I have a 20amp Sterling mains charger plumbed in. I presume they have similar charging schedules. It works fine, but I set the max voltage at 14.4V when I installed it.

They have alternative setting of 14.8V which made me nervous. If you do use it, then I think I would limit the adsorption period to below what they suggest. 14.8V would be above gassing voltage at almost any temperature. I know it may sometimes be good to use this to condition the batteries, but I don't think that regular use at such a voltage is risk free from what I have gathered on the subject.

It would seem more sensible to me use 14.4V, and have a longer absorption period to ensure the batteries are fully charged.

You do need to check the electrolyte levels frequently in my experience if you are charging above 14.0V (standard alternator voltage).

In fact, having seen all the batteries seriously fried on a boat by a faulty Adverc during a trip, I do not have a smart regulator on my engine. I have the original 60amp alternator - however it is of the twin output variety (internal diodes), with the sensor wire looking at the house bank. I get a very steady 14.0-14.1V on both banks, which is fine for me since I can regularly put the house bank on the mains charger (it is not connected to the engine battery to avoid frying it).

One day, when I buy my big gone-cruisin-no-work-nomore boat, it will have twin alternators - one big with a smart regulator for the house, and another standard small one for the engine.

Best advice to be had is in Nigel Calders books IMHO. His new book is fantastic - 600 pages on how to buy and equip exactly the type of boat I want. Great stuff.

 

[hugh_nightingale]

I can agree with most of this but see a posting below (if it is still there)

I would strongly recommend NOT following any advice that directly connects batteries in parallel for charging, do include a diode or some method to control the current to each battery.

 

[philip_stevens]

Why do you "strongly recommend that batteries are not parall'led"?? Having been a MN Electrical Officer for 25 years, I am interested. Yes, I know one battery could be completely flat, but good proceedures should prevent one being completely flat while the other isn't. The again, one could have gone duff, but......

Mine have been parallel'd for five years with no adverse effect. Before this, my previous boat had the batteries paralled for the time I had ner - seven years. Again with no adverse effect.

If you use diode separation, you get a voltage drop. One of the few non-diode splitters is made by Driftgate, the X-Split. This is used on my boat to separate the engine battery from the domestic (relay paralled for charging) batteries.

Please explain why not relay parallel'd.

regards,
Philip

 

[Sammy]

O.K. I think my question has been answered and I am looking into the Adverc which does appear to be the better bet. I know a fair bit about managing battery banks, relays versus Diods etc. Have run a number of hire boats over many years so I learnt about that bit many years ago.
Thanks for all who replied will post my results when I have installed.

 

[hugh_nightingale]

Sorry Philip, I wasn't ignoring you. I tend not to log on so often now as it takes up so much time and we of the PBO meetings group have our own site which seems to take up even more time.

This has been the subject of several postings, here is part of a reply to one.

well there you go, you've answered your own question.

Some of the systems I have seen have had batteries permanently in parallel (the Adverc manual for instance shows this)

"If I understand, the problem with putting them in parallel is that one will tend to discharge the other." If this is the case then its because the batteries are different, they almost always will be so from material problems. So you don't leave them connected in parallel but switch between them as they are used. (Its a good idea anyway as it gives you some indication of how much capacity you have left and a forewarning that you need to do some charging).

But the same applies in charging. As an extreme example, imagine charging 6 cells of NiCd (nominal 1.2V/cell) in parallel with 6 lead acid cells (nominal 2.2V/cell). The NiCds would be fried and the lead acids would get nothing. Note the word nominal: NiCd can go to 1.5V/cell, lead acid used to be 2.45 now more like 2.35V/cell. The point is they all differ. You can end up (going back to 2 lead acids in parallel) with one battery always being fried and one not receiving full charge. Then you have a system that has not achieved the capacity you thought you had and one battery that is not going to last so long.

Now what happens if one of the batteries gets a really duff cell. Its usually just one or maybe twoof the cells, bits fall off the plates and short out the cell or the plates sulphate up and the cell goes high impedance. This is the same as the extreme case above.

To a certain extent, these days, all alternators are a bit smart. They may not do "so called" three stage charging but they certainly do two stage. They all in some manner monitor the battery voltage, it may be at the alternator terminals or it may be at the battery terminals.

It is just not good practice. WE tend to get away with it. Where there is reasonably poor wiring between the batteries this helps as it puts a bit of "equalising" resistance in the circuit. This is all the diodes do and they can only compensate for, say, a 1.4V difference between batteries, if one cell of one battery was s/c you are just as buggered.

When you put two batteries in parallel for jump starting there is an enormous pulse of current from the good to the dead battery limited only by the internal impedance of the cells and the wiring. despite what some car manuals say I strongly advise you to NOT have one car engine running while you try to start the other. This is then another problem, two alternators both trying to control two batteries.

As a final comment, for us what is the point of more than one battery. Its not just extra capacity, its not just extra cranking current. Its back up. You wire two in parallel and one goes down you lose both.


Then another question about how the X-split work and claims zero loss (now I believe they have changed this to low loss)

Ah, that was my question, well one of them, how does this x-split work and have zero loss.
NOTHING has zero loss, even the big fat wire has loss, even a relay has loss.

A 1-both-2 switch is a very good answer for a discharge problem where, say, the main starting battery has failed and you want extra umph sort term. Charging, though, is entirely different. Oh, you will get some charge in and the situation is very much improved if you have two batteries of EXACTLY the same type, capacity, age, usage.

Batteries that require the same "nominal" charging voltage don't necessarily require exactly the same voltage. Some figures I looked up last night give a cell voltage of 2.125 with acid at 1.28 Specific Gravity and 2.05 with 1.21 acid. This is a difference of 0.45V over a six cell battery, i.e. one at 12.80V and another at 13.25. Cells degrade with age, evaporation etc. The acid deteriorates. Something I didn't realise, everytime it is recharged the lead plate (negative) becomes more crystaline. The lead oxide plate (positive) is the pastey one and I believe doesn't always recover. There are physical as well as chemical changes going on in there.

Two completely separate charging circuits is the ideal solution. Diodes are the cheap engineering solution, at least it gives a chance of protection. Connecting in parallel does not, especially permanent connection.


And yet another one:

Oh dear, I'm beginning to wish I had never replied to this one.

Yes, batteries are a string of cells, and yes we get away with a lot. In theory if you have more than 4 in series you SHOULD put in some method of equalising the charge during charging. Yes it IS a compromise.

"In our case, we purchased two identical batteries, same time same source, so they will be as matched as they possibly can be from the outset, for pairing up." That's exactly what I said is a best starting position if you have no other choice. Also note that your 104 batteries were charged in series NOT parallel. What you can do is give them a good blast in series (in theory you've got to keep below the gassing voltage, about 2.39V/cell) and get up to 80-100% capacity, THEN drop back to C/20 almost for ever which equalises up the cells, bringing lower capacity or more heavily discharged cells up to standard.

Exactly, yotties want and indeed need a simple solution. People that are using big UPS batteries tend (I hope) to know what they are doing and apply a bit of regular maintenance. And here I am talking REAL maintenance for REAL reliability. Probably a monthly full inspection, capacity check and may include a full cycle of discharge/charge.


Philip, I am not saying here that I am THE expert on batteries or battery management. It seems good sense to at least take on board as many of the good points as possible. You hear - if you do "A" for 5 years like Joe he has had no problems. If you jump out of an aeroplane without a parachute you may get away with it, at least two people did. But I strongly recommend that you don't try it. If you jump start a car with both engines running you may get away with it but there is a likehood that in a few weeks the starter car will lose its alternator diode pack (note, its not immediate). But I strongly recommend that you don't try it. Only have one engine running, or potentially running, at a time. May be poor analogies.