Volvo MD2 battery problem

[Gwho?]

Hi I did a quick search for info and found manuels etc but still not sure.

Problem is I have an MD2 that was running fine. Batteries have been sat all winter with no trickle charge but as i have just bought the boat it seamed to start no worries I have left them. Last few outings it's been a struggle to start till this weekend it didn't. Batteries dead. They are not the standard batteries as they are out of a JCB and are 120 Ah. The man says 60Ah max so would I be right in thinking the Dynamo/alternater is not strong enough to charge them?
What harm will the extra Ah make to the running of the engine?

Any ideas of the best solar panel charging option for them?

Have taken them off and plugged them in to charge at home and see if that helps. Not keen to be stranded with the family and not able to start the engine.

Ta for the help in advance.

 

[[448]]

Assuming that your MD2 has a dynastart, I think you would be better off with a couple of 60 amp batteries. For what it is worth, I have an MD2B with dynastart and 2 batteries for an escort diesel and seem to manage OK. I have a small solar panel that seems to give half an amp in bright sunlight permanently connected to each battery alternating about monthly.
Dave

 

[Gwho?]

Cheers for that Dave. Thought the 120 might be too much for it. Can I alter the Dynamo to produce more charging power?

What about the difference between domestic and engine batteries? As I understand it one will give of power to start the engine then trickle charge of alternater. The domestic can be drained out completely over night and charge up of the alternater aswell.

Any recomendations?

Also notice many different wattages of solar panels. How do you know what you need?

Nick

 

[[448]]

Cheers for that Dave. Thought the 120 might be too much for it. Can I alter the Dynamo to produce more charging power?

What about the difference between domestic and engine batteries? As I understand it one will give of power to start the engine then trickle charge of alternater. The domestic can be drained out completely over night and charge up of the alternater aswell.

Any recomendations?

Also notice many different wattages of solar panels. How do you know what you need?

Nick

I've always used 'engine' batteries and never had any problems, but I don't have a fridge or radar.
I suppose the first thing to think about a solar panel is where to put it. This will govern the physical size, and then get the most 'powerfull' panel of that size. You may need a regulator.
Dave

 

[Plevier]

Your problem is not the size of the batteries or of the alternator.
Either something is faulty or it's your use pattern.
The batteries will have been somewhat down after being left. What chance have they had to recharge? How long do you run for and what other loads are on at the time?
At normal alternator voltage having a big alternator is irrelevant unless it's to support other loads. The battery won't take the high rate for long and once it gets to 80% charge it won't take much current at all. Putting in the rest of the charge will take a day or two - yes! - at that voltage. So in practise batteries that are only charged from alternators rarely run above about 80% charge level. Most cars are in this condition.
Charge them at home for several days (assuming your charger is regulated at around 14V) then see how they behave. Think about what other loads are on.

 

[Gwho?]

Only owned the boat for a few weeks now so usage pattern hard to judge at the moment.

I did run the engine for a good 6 hours through the Crinnan Canal on low revs then for another 2 hours working hard but didn't seem to have fully charged them. That was at the start of May and been over last 2 Sundays and struggled to start.

Tested whilest running the engine batteries give 12.4 volts before starting and maintained that when running. If the Dynamo was charging would I see an increase of voltage?

 

[Plevier]

Is it a dynamo not an alternator?
If so you may well have a persistent problem. Dynamos just can't produce the required output unless the revs are quite high. Trying to recharge a flattened battery this way is an uphill task. In the days of dynamos on cars it was accepted that batteries would need top up charges. There were always rows of them fizzing away in my Grandad's garage business!
With a charged battery the dynamo should get up to at least 13.8V running at high-ish revs but not at low cruising revs. Two hours even at high revs won't have much effect on a flat battery - you would genuinely need more like two days. It will be adjustable by a two or three coil electromechanical regulator that is adjustable if you can find the instructions but there isn't usually much in hand.

With a typical alternator you'll get at least 13.8V, maybe up to 14.4V, and plenty of current capability at anything much above idling speed.
Modern batteries will take higher charge voltages without gassing than the old high antimony content ones used to so there has been a trend towards setting them at 14.2-14.4 giving a much better charge rate.

Worth looking at changing to an alternator if you are practical enough to DIY, probably too expensive to pay to get it done.

 

[[448]]

12.4 volts is well on the way to being flat. If you are only getting 12.4 when running, either the battery is u/s or the dynastart isn't charging. My dynastart pushes 14 volts and 12 amps after starting. Batteries show nearly 13 volts after standing for a week or more. I would bite the bullet and buy a battery such I mentioned earlier, or get the dynastart/regulator checked.
As mentioned above fitting an alternator might help if you can sort the brackets/belts.
Dave

 

[Gwho?]

Thanks for the advice. All helpfull.

Where would you sorce the volvo alternater spares? Are they standard retro fit kits or is it a case of manufacturing something etc?

It sounds like a dry land winter project so any experience of booster packs and carry out to the boat when needed to make sure she starts?

Ta

 

[Plevier]

I would suspect you'll be on your own - unless someone on here has done it - but does http://www.marinepartseurope.com/en/volvo-penta-explodedview-7742090-30-13795B.aspx help with any ideas?

These http://www.dmstech.co.uk/pdfs/ppp_commercial_range_01.pdf are good portable packs but won't be the cheapest. One of the smallest ones - or next up - should do you.

 

[Gwho?]

Cheers for that. I've emailed them to see if they have full kits.

Had a wee look this weekend and not sure I'll have enough room to fit though.

Maybe solar panels are the best way. See Nasa have a new one thats not outragous price. Said max is 100ah though would this still trickle charge my 120ah batteries?