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johnjo
johnjo

Posted: Fri Dec 05, 2008 8:39pm

Post Subject: Battery charging

Hi Tony, I have four 12volt Delphi SEALED Freedom Stationary batteries, Load test amps 300, 115Ah. They are designed for UPS use but I am going to make use them, linked together, [in a 12v system] on our NB. What is the best battery charger to use to charge them OUT of the boat. I have a standard car charger but I'm sure you have said somewhere that they could damage leisure batts. On the NB I have a 'Sterling Marine Power' International Range, [Metallic Blue case] advanced 4 step switched mode battery charger/power pack and also a 'Sterling Marine Power' [Black finned case] combined Inverter/charger 4amp 600w continuous [800w max] [modified sine wave]. All this info is gleaned from the labels, I don't know specific model No's. The present setup on the NB is 2 leisure and 1 starter, [they are of the type you can top up], and maintained by the Blue Sterling unit. [The black unit is not in use at the moment, could I set this up to maintain the newer 4 leisure batts]. The batts are at present in the engine well, but I'm going to raise them onto the swim in a ply box and cover, away from the cooling hoses which at the moment go over the top of the batts to the skin cooling tank. What size cables should I use for the new setup [4 Leisure & 1 Starter]. I understand that it is best practice to use cables of equal length and conect all the leisure + to one seperate terminal and the same for the Neg including starter neg if included in with the leisure] can I put all 6 leisure together or should I keep them as is and install the newer set of 4 separately and run as two banks and separate the boat wiring appropriately so if one set packs up for any reason, I still have some 12v power available. I hope I've given as much info as you need. Regards John

johnjo
johnjo

Posted: Fri Dec 05, 2008 11:29pm

Post Subject: Battery charging

Just realised I haven't given any alternator info, at the moment can't give any, all I know is it looked pretty standard, similar to that which is fitted to medium sized engines in diesel cars and vans, and is run by a three cyl Perkins of about 1989 age. I'm going to the NB about the 11th Dec and will let you know then if required. Sorry about that. Regards John

Tony-B
Tony-B

Posted: Sat Dec 06, 2008 9:57am

Post Subject: Battery charging

Dear John, First of all you need to ascertain from Delphi what the maximum charging voltage is for the batteries. Being sealed it may be lower than for normal batteries. If it is lower then you need to ensure any charger you use (including the "blue Sterling unit") can be set for this voltage. I suspect they may be normal wet lead acid batteries with normal voltages , but you MUST check. The next thing to do is to talk to Sterling to find out exactly what you have. Your data from the black unit looks a bit uninformative to me. I find it hard to imagine Sterling combi-unit only charging at 4 amps. You need to ascertain if either unit is multi-stage or a single stage charger. As long as the voltage is set correctly for your batteries any multi-stage charger - including two stage car ones - should be OK. look on the Smartguage website and buried in the technical notes you will find an explanation about why one big bank is usually better than two smaller ones (apart from charge splitting implications)and then make your decision about one or two banks. I can not answer the cable question because you give no indication of run length and maximum current flow but the calculations for cable size are on my website (in the course notes) and probably on the Smartguage site (TB-training.co.uk) but you will not go far wrong with starter sized cable but it depends upon the maximum current flow. Make sure the domestic (including charging) positive and negative cables are at opposite ends of the bank. Tony Brooks

johnjo
johnjo

Posted: Sat Dec 06, 2008 9:01pm

Post Subject: Battery charging

Hi Tony, thanks for your reply. They are wet type. There is a small window on top through which the charge state is indicated, green full, black needs charging, red replace. ** VR is 14.5v +/- 0,2, VHR 13.5v, LVD 12.0v, LVDH 1.5v. To overcome electrolyte stratification, it is recommended that the battery be given an equalization charge at six month intervals. An equalization charge consists of charging the battery (which is fully charged) at 16 volts/27°C (80°F) for six hours. An equalization charge promotes gassing which will effectively mix the electrolyte. Equalization charging will also balance individual batteries within strings in multiple battery systems.** All between the the two lots of **'s is taken from a technical sheet I found on the net and is just for your info, feel free to comment or not. I will get in contact with 'Sterling' next week. Regards John

Tony-B
Tony-B

Posted: Sun Dec 07, 2008 9:26am

Post Subject: Battery charging

John, You can use any battery charger on those cells, but if its an old single stage one, like we used to use on cars, then you would need to monitor the specific gravity so you knew when to stop charging. Multi-stage chargers of any sort for wet cells will be fine. Please note those windows only tell you about one cell and will not work if that cell looses electrolyte. Have a look on the Smartgauge site to see what Mr Gibson thinks about automatic (as opposed to manual) equalisation charges. However my thoughts are if you are on a shore line for long periods then a short automatic equalisation charge is probably better than nothing. One problem with equalisation charging of sealed cells is that you are likely to drive a certain amount of water out of them each time and there is no way of replacing it. Tony Brooks

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