Solar vs Alternator

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m1taylor

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The dynastart on my Vire 6 engine has unfortunately given up charging - it will still start the engine however. I think parts are either prohibitively expensive or no longer available. So I was wondering about the viability of charging via a solar panel? The draw on the battery is only starting the engine (heavy, but infrequent draw), a NASA depth sounder, and a Rule 500 automatic bilge pump (which comes on briefly every 5 mins to check for water). About how many watts solar panel would I need to keep that lot going?
 
it all depends on how often you start the engine i would have said a lot of variables come into it and i would have thought that the cost of a big enough solar panel to do the job would be more than repairing your alternater.
you say parts are expensive try a local electric motor rewinding company ,i've had them help me out in the pasr,also a local lucas uk they usually have their own workshops and the guys are pretty good,i've seen them work miracles on some very old stuff.
another idea can you run an alternater of maybe the propshaft or something like that ,.anything that spins can usually have a pulley mounted on it ,it doesn.t have to go on a shaft with care you can bolt to another pulley etc.

http://www.lsuk.co.uk/branch.asp

lucas branch website
 
The Only Official UK Vire Agent is here and services dynastarts . The site has helpful information concerning charging problems.

As it starts the engine it may not have severe problems.

There is an unofficial site for the engine here
 
As said already the size of solar panel you require will depend upon the number of times you start the engine. Even so I think on a dull weekend when you have started the engine several times whether you can start it one more time will always be a worry. Can you hand start it if necessary?

You will have to estimate the battery drain per start and compare that with the useful battery capacity so that you have adequate battery power in the short term and also compare the battery drain in say a weekend with the likely input from a solar panel before the following weekend. You should only be looking at about 1 Ah per start if the engine starts easily so even a smallish battery will give you quite a few starts without recharging but to replenish that in the course of 5 days before "next weekend" I think you will need at least a 10 watt panel, larger to be on the safe side, and that is not allowing for the bilge pump.

I think you should seriously investigate the reasons for your Dynastart not generating. It could be an open circuit in a winding, it could be worn brushes or it could be a faulty control box. Windings and brushes should be relatively easy to check out with a multimeter. It they are OK then the control box is suspect. Replacements are available the only snag being that older types have a combined regulator and solenoid (Siba ones IIRC) while the modern replacements (Bosch ?) have the two separate. That means some small alterations in the wiring.

I know about the external wiring as I had to advise someone recently on fitting the new type in place of the old and completely rewiring the system as well but I have had no dealings with the insides of any of it. One of the websites mentioned seems to have a fair bit of info.

My advice is to diagnose the problem with the Dynastart and determine the cost of repairs before going down the solar panel route ... excellent things though they are. If the bilge pump takes much out of the battery then you might want to fit one anyway.
 
Before you give up I'd strongly recommend you take your Dynastart to a local auto electrician - it just might be that he will be able to fix it, and for a lot less than any solar panel.
 
Well, I am not sure about the repairs - a recon dynastart is around £200. But you can get a Solar Panel capable of putting 10 amp hours back into the battery for around £125? The Vire website impies these wretched Dynastarts do overload on a batteries, and overheat/burn themselves out and keep breaking? If the draw per engine start is 1 amp hour, the in theory the solart panel putting up to 10 amp hours per day should be fine. But am I on the worng track completely?
 
[ QUOTE ]
But you can get a Solar Panel capable of putting 10 amp hours back into the battery

[/ QUOTE ] Sorry that is a meaningless statement. Even the smallest of panels will put 10Ah into a battery given long enough.
It should be possible to get one large enough to do it in say 5 days, ie between one weekend outing and the next, for the amount you suggest though.

To do it in one day, as John Wilson says, will need something considerably larger and more expensive.
 
How inconvenent would it be if the dynastart became yet worse and failed to start the engine?

Don't the electrical problems warrant further investigation?
 
[ QUOTE ]
How inconvenent would it be if the dynastart became yet worse and failed to start the engine?

[/ QUOTE ] That's true but from what I have seen, and as already indicated I have delved into the external circuit wiring quite thoroughly, the starting function and the generating function seem to be quite separate.
 
[ QUOTE ]
You should only be looking at about 1 Ah per start if the engine starts easily

[/ QUOTE ] I have now discovered that the starting current is only 20 to 40 amps. That means only about 1/10 Ah per start even if it took as long as 10 seconds to get it going. A 10 watt panel will probably produce about 3Ah per day, if orientated correctly, in sunny conditions, and would therefore be more than enough. So Jimminy's suggestion that you could get a panel that will recharge in 1 day for around £125 is quite realistic after all.
 
I have relied on solar power alone for my little boat for 20 years in Oz summer sun but if I had an engine I would much prefer a generator on the engine. So yes fix the dynastart or as some people do fit an alternator as well. Solar has its place but an alternator on an engine has real power. good luck olewill
 
If it is any help, I had a Bosch dynastart which developed a problem [caused a fire ]. It turned out that the dynastart was controlled by two relays. One relay switched the battery to the starter function. The other changed the function to charging when it sensed it to be possible.

Corrosion had set in. I found that sealed relays were avaialble for construction site type equipment and these solved the problem till the boat was sold 5 years later at least!
 
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